Understanding the neural repair-promoting properties of olfactory ensheathing cells

YEXNR-11731; No. of pages: 16; 4C: Experimental Neurology xxx (2014) xxx–xxx

Contents lists available at ScienceDirect

Experimental Neurology journal homepage: www.elsevier.com/locate/yexnr

1

Review

4Q1

Kasper C.D. Roet a,⁎, Joost Verhaagen a,b,⁎⁎ a

9

a r t i c l e

10 11 12 13 14

Article history: Received 19 March 2014 Revised 2 May 2014 Accepted 6 May 2014 Available online xxxx

15 16 17 18 19 20 21 22 23 24 25

Keywords: Olfactory ensheathing Clinical Transplantation Neural repair Molecular mechanisms Axon regeneration Tissue repair Screen Bioinformatics Functional genomics

a b s t r a c t

P

i n f o

R

E

C

T

E

D

Olfactory ensheathing glial cells (OECs) are a specialized type of glia that form a continuously aligned cellular pathway that actively supports unprecedented regeneration of primary olfactory axons from the periphery into the central nervous system. Implantation of OECs stimulates neural repair in experimental models of spinal cord, brain and peripheral nerve injury and delays disease progression in animal models for neurodegenerative diseases like amyotrophic lateral sclerosis. OECs implanted in the injured spinal cord display a plethora of pro-regenerative effects; they promote axonal regeneration, reorganize the glial scar, remyelinate axons, stimulate blood vessel formation, have phagocytic properties and modulate the immune response. Recently genome wide transcriptional profiling and proteomics analysis combined with classical or larger scale “medium-throughput” bioassays have provided novel insights into the molecular mechanism that endow OECs with their pro-regenerative properties. Here we review these studies and show that the gaps that existed in our understanding of the molecular basis of the reparative properties of OECs are narrowing. OECs express functionally connected sets of genes that can be linked to at least 10 distinct processes directly relevant to neural repair. The data indicate that OECs exhibit a range of synergistic cellular activities, including active and passive stimulation of axon regeneration (by secretion of growth factors, axon guidance molecules and basement membrane components) and critical aspects of tissue repair (by structural remodeling and support, modulation of the immune system, enhancement of neurotrophic and antigenic stimuli and by metabolizing toxic macromolecules). Future experimentation will have to further explore the newly acquired knowledge to enhance the therapeutic potential of OECs. © 2014 Published by Elsevier Inc.

R

46

N C O

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical perspective on OEC: from discovery to therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The discovery of olfactory ensheathing cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0 0 0

Abbreviations: ADAMTS1, ADAM metallopeptidase with thrombospondin type 1 motif, 1; ATP, adenosine triphosphate; APP, amyloid beta precursor protein; ANGPT2, angiopoietin 2; Ara-C, arabinosylcytosine; GBA, beta-glucocerebrosidase; BDNF, brain derived neurotrophic factor; L1CAM, cell adhesion molecule L1; CNTFRalpha, ciliary neurotrophic factor receptor; CNTF, ciliary neurotrophic growth factor; COX-2, cyclo-oxygenase-2; CYR61, cysteine-rich, angiogenic inducer; ENTPD2, ectonucleoside triphosphate diphosphohydrolase 2; ESM1, endothelial cell-specific molecule 1; EGFR, epidermal growth factor; FGF2, fibroblast growth factor 2; CX3CL1, fractalkine; FZD1, frizzled class receptor 1; GAL-C, galactosylceramidase; GFRA1, glial cell line derived neurotrophic factor family receptor alpha 1; GFAP, glial fibrillary acidic protein; GDNF, glial-derived neurotrophic factor; GRO, growth-regulated oncogene; IL6, interleukin-6; LEPRE1, leprecan; LIPR, leukemia inhibitory factor receptor; LPL, lipoprotein lipase; P75/NGFR, low affinity nerve growth factor receptor; MBP, myelin basic protein; MMP2, matrix metalloproteinase 2; MSLN, mesothelin; MAP, microtubule-associated protein; CDH2, N-cadherin; NGF, nerve growth factor; NEFL, neurofilament, light polypeptide; NCAM1, neuronal cell adhesion molecule 1; NRP1, neuropilin 1; NT4/5, neurotrophin 4/5; NID2, nidogen 2; NFKB, nuclear factor KappaB; SERPINE1, plasminogen activator inhibitor-1; ON, olfactory nerve; ONF, olfactory nerve fibroblast; PAMP, pathogen-associated molecular pattern; PAR1, proteinase-activated receptor-1; P2X, purinergic receptor P2X, ligand-gated ion channel; P2Y, purinergic receptor P2Y, G-protein coupled; RHOA, ras homolog family member A; RARA, retinoic acid receptor, alpha; ROCK, Rho-associated protein kinase; RND1, Rho family GTPase 1; S100, S100 calcium binding protein; SCARB2, scavenger receptor class B, member 2; SPARC, secreted protein acidic rich in cysteine; SEMA, semaphorin; SMAD7, SMAD family member 7; THBD, thrombomodulin; TIMP2, TIMP metallopeptidase inhibitor 2; PLAT/tPA, tissue-type plasminogen activator; TGF, transforming growth factor; TNF, tumor necrosis factor alpha; TNFRSF1A, tumor necrosis factor receptor superfamily, member 1A; TH, tyrosine hydroxylase; VEGF, vascular endothelial growth factor; VAV1, vav 1 guanine nucleotide exchange factor. ⁎ Correspondence to: K.C.D. Roet, Boston Children's Hospital, F.M. Kirby Neurobiology Center, Center for Life Sciences, 3 Blackfan Circle, Boston, MA 02115, USA. ⁎⁎ Correspondence to: J. Verhaagen, Department of Neuroregeneration, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105BA Amsterdam, The Netherlands. E-mail addresses: [email protected] (K.C.D. Roet), [email protected] (J. Verhaagen).

U

50 Q2 51 Q3 52

R O

Department of Neuroregeneration, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105BA Amsterdam, The Netherlands b Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Boelelaan 1085, Amsterdam 1081HV, The Netherlands

47 45 44 49 48

O

5 6 7 8

F

3

Understanding the neural repair-promoting properties of olfactory ensheathing cells

2

http://dx.doi.org/10.1016/j.expneurol.2014.05.007 0014-4886/© 2014 Published by Elsevier Inc.

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

. . . . . . . . . . . . . . . . . . . . .

74

Introduction

Q3 76

Historical perspective on OEC: from discovery to therapy

77 78

The discovery of olfactory ensheathing cells The profound regenerative capacity of the mammalian primary olfactory system is unique. After damage to the neurons in the olfactory neuroepithelium or to the primary olfactory nerve fibers that form the olfactory nerve new primary olfactory neurons are generated from basal cells in the olfactory epithelium (Graziadei and Graziadei, 1979). The axons of these newly formed neurons grow through the lamina propria into the olfactory nerve layer (ONL) of the olfactory bulb and make new synaptic contacts in the glomeruli on dendrites of mitral, tufted and juxtaglomerular cells (Costanzo, 1985; Doucette et al., 1983; Farbman, 1992; Harding et al., 1977). When nerves from the periphery enter the central nervous system, the PNS–CNS transition zone is normally marked by astrocytes that form the glia limitans (Doucette, 1991). In 1991 it was discovered that the olfactory nerve differs from other nerves that enter the CNS in that this transition zone contains a specialized type of glial cell, the olfactory ensheathing glial cell (OEC) which originate from the neural crest (Barraud et al., 2010; Doucette, 1991). After a lesion, OECs guide the olfactory axons of the newly formed olfactory neurons through the lamina propria towards the ONL and into the glomeruli where they reinnervate their target cells (Doucette, 1990, 1991; Raisman, 1985). Thus OECs form a continuously aligned cellular substrate or pathway that actively supports regeneration of primary olfactory axons from the periphery into the CNS (Li et al., 2005b, 2012). In this review we will refer to OECs derived from the ONL of the olfactory bulb as OB-OECs and OECs derived from the lamina propria as LP-OECs when appropriate. Although these two cell types have many properties in common, some important cellular and molecular differences have been noted (Table 1). If we use the abbreviation OEC the text refers to both subtypes of OECs.

91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

(Ramon-Cueto and Nieto-Sampedro, 1994). In the following years, a large number of studies demonstrated that OB-OEC and LP-OEC implants do promote axonal regeneration after various spinal cord lesions (Franssen et al., 2007; Li et al., 1997; Raisman, 2007; Ramon-Cueto, 2011; Ramon-Cueto et al., 2000; Richter and Roskams, 2008; Ruitenberg and Vukovic, 2008; Tetzlaff et al., 2011; Toft et al., 2013), including a chronic spinal cord lesion (Munoz-Quiles et al., 2009). Implanted OECs not only promote axonal regeneration in the lesioned spinal cord and brain, but these cells also promote functional reconnection of injured axons (Takeoka et al., 2011; Ziegler et al., 2011) remyelinate axons, stimulate blood vessel formation, reorganize the glial scar, have phagocytic properties and modulate the immune response (Barbour et al., 2013; Franklin et al., 1996; Imaizumi et al., 2000a; Li et al., 1997, 2005b, 2012; Plant et al., 2011; Raisman et al., 2012; Ramer et al., 2004; Ramon-Cueto et al., 1998; Roet et al., 2011; Smale et al., 1996; Wewetzer et al., 2005).

115

OECs also have beneficial effects in other nervous system injuries or diseases In the last decade, an increasing number of studies have reported improved functional recovery and/or fiber tract regeneration following implantation of OECs in a variety of animal models for neurodegenerative diseases and non-spinal cord pathologies, including amyotrophic lateral sclerosis (ALS), Parkinson's disease and stroke. Here we briefly highlight some of these findings. Firstly, adult OB-OECs improved functional recovery in rodent models for Parkinson's disease when cotransplanted with dopaminergic cells (Agrawal et al., 2004; Johansson et al., 2005; Shukla et al., 2009). Secondly, postnatal OB-OECs promoted survival of rats in a rat model for ALS through neuroprotection and remyelination (Li et al., 2011, 2013). Thirdly, adult OB-OECs enhanced recovery of learning and memory in a rat model for cognitive dysfunction (Srivastava et al., 2009). In this study OECs were implanted with neural progenitor cells in the lesioned hippocampus where they apparently provided neurotrophic support. Fourthly, human derived LP-OECs mixed with olfactory fibroblasts promoted neural plasticity and decreased neurological deficits in murine models for stroke (Shyu et al., 2008). Moreover, postnatal OB-OECs increased myelination and reduced infarct size in a rat model for stroke (Shi et al., 2010; Shyu et al., 2008). Finally, both LP- and OB-OECs improved functional laryngeal reinnervation (de Corgnol et al., 2011; Paviot et al., 2011) and OB-OECs stimulated regeneration of adult rat optic nerve and sciatic nerve axons after a lesion (Guerout et al., 2011; Li et al., 2003; You et al., 2011). Taken together, following transplantation in various peripheral

131 132

D

E

T

C

E

R

89 90

R

87 Q4 88

O

85 86

C

83 84

N

81 82

U

79 80

. . . . . . . . . . . . . . . . . . . . .

P

75 Q2

. . . . . . . . . . . . . . . . . . . . .

F

Implantation of OECs in spinal cord lesion paradigms . . . . . . . . . . . . OECs also have beneficial effects in other nervous system injuries or diseases . The first clinical studies show that implantation of OECs is safe . . . . . . . . Challenges for successful OEC based therapeutic strategies . . . . . . . . . . The neural repair promoting properties of OECs . . . . . . . . . . . . . . . . . . . . Classical molecular and cellular characterization of OECs . . . . . . . . . . . . . . Microarray and large scale proteomic studies . . . . . . . . . . . . . . . . . . . Bioinformatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High throughput and high-content cellular screening . . . . . . . . . . . . . . . Lipid presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . Balanced ligand and receptor expression to regulate axon growth and guidance Modulation of the extracellular matrix . . . . . . . . . . . . . . . . . . . Formation of a structural cellular pathway . . . . . . . . . . . . . . . . . Stimulation of angiogenesis . . . . . . . . . . . . . . . . . . . . . . . . Amelioration of the immune system . . . . . . . . . . . . . . . . . . . . ATP hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Loss of function versus gain of function cellular screening . . . . . . . . . . . . . . Animal studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . From bioassay to in vivo study: a big step with many uncertainties . . . . . . . . . Perspective on OEC research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

O

53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

R O

2

Implantation of OECs in spinal cord lesion paradigms The unique anatomical position and function of OECs in the primary olfactory system prompted Ramon-Cueto and Nieto-Sampedro in 1994 to purify these cells and to examine their regenerative properties as cell implants after rhizotomy of the dorsal root in rats. Implanted OECs, derived from the adult olfactory bulb (OB-OECs), stimulated regeneration of injured dorsal root ganglion axons into the spinal cord in all eight experimental animals, while in contrast, no axonal growth beyond the lesion was found in the spinal cords of any of the control animals

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

116 117 118 119 120 121 122 123 124 125 126 127 128 129 130

133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219

Challenges for successful OEC based therapeutic strategies As discussed above, an impressive number of studies have reported enhanced neural repair after implantation of OECs in a variety of animal models for nervous system pathologies. However, approximately 20% of the studies investigating OECs in spinal cord lesion paradigms reported minimal or no beneficial effects (Franssen et al., 2007). Since investigators tend to not publish negative results this may be an underestimation of studies that failed to show efficacy. The reported discrepancies can partially be explained by differences in the timing of OEC implantation and the type of lesion used. However, two other factors are probably of critical importance. First, a number of studies that investigated the survival of OECs implanted in the contused rat spinal cord, using fluorescent labels or a Y-chromosome specific probe, reported very low survival rates, which varied from approximately 1 to 3% (Barakat et al., 2005; Li et al., 2010b; Pearse et al., 2007). These disappointing

255

Classical molecular and cellular characterization of OECs

256

Since the discovery of OECs, researchers have searched for the molecules that govern their pro-regenerative properties. In culture, OECs appear to switch to an axon growth promoting state and this process is dependent on external cues. Cultured adult OB-OECs express P75/ NGFR (Ramon-Cueto et al., 1993) and this receptor is also induced in OECs in the ONL after deafferentation of the OB (Turner and PerezPolo, 1993). Interestingly, olfactory neurites also express P75/NGFR and grow preferentially on P75/NGFR positive OECs. When the axons are ensheathed by OECs, P75/NGFR expression in both the axons and the OECs becomes undetectable. Laminin is abundantly present in the olfactory pathway (Doucette, 1996; Tisay and Key, 1999). Laminin also regulates spreading and migration of postnatal LP-OECs in culture and increases their neurite outgrowth promoting capacity (Tisay and Key, 1999). Postnatal OB-OECs express CNTF and its α-receptor subunit (Wewetzer et al., 2001). Interestingly, the expression of these molecules can be regulated by treatment with forskolin which is known to increase intracellular cAMP levels and can also induce expression of GFAP (Doucette and Devon, 1995; Wewetzer et al., 2001). Classical immunochemistry, in situ hybridization, biochemical analysis and quantitative PCR, revealed that OECs express a wide variety of signaling molecules that are involved in neural repair. These include neurotrophic factors such as NGF, BDNF, NT4/5, and GDNF (Boruch et al., 2001; Lipson et al., 2003; Woodhall et al., 2001) and several growth factor receptors (Wewetzer et al., 2001; Woodhall et al., 2001), as well as axon growth-promoting cell adhesion and extracellular matrix molecules, including CDH2, NCAM1 and L1CAM (Doucette,

257

O

F

The neural repair promoting properties of OECs

R O

172 173 Q6

C

170 171

E

168 169

R

166 Q5 167

R

164 165

N C O

162 163

U

160 161

P

The first clinical studies show that implantation of OECs is safe The promising results obtained with implantation of OECs in animal models for spinal cord lesions or neurodegenerative diseases have stimulated researchers to investigate the therapeutic potential of OECs in human pathologies. In Australia, a phase I/IIa clinical study was initiated to examine the effects of implantation of human OECs for treatment of chronic spinal cord injury (Feron et al., 2005; Mackay-Sim et al., 2008). Three male paraplegic patients with complete thoracic injuries received autologous implantation of OECs that were isolated and purified from nasal biopsies. A control group was included that did not receive surgery. After three years, no adverse effects were detected. However, there were also no significant functional improvements. Another trial with LP-OECs in Poland, including six patients suffering from chronic thoracic paraplegia, showed no adverse effects of both the mucosa biopsy and the transplantation of the LP-OECs after one year (Tabakow et al., 2013). In this trial the 3 patients receiving OEC transplants did show functional improvements with two patients improving from American Spinal Injury Association class A (ASIA-A) to ASIA-B and ASIA-C. The third patient remained in ASIA-A, but showed improved motor and sensory function in the spinal cord below the injury. No improvements were observed in the control group. To assess the importance of these promising observations a larger group size is required. Safety and possible efficacy were also shown in six patients with complete chronic spinal cord injuries in China which received fetal OB-OEC transplants (Rao et al., 2013). A Spanish group has investigated the therapeutic potential of implantation of LP-OECs or autologous mesenchymal stromal cells in patients suffering from amyotrophic lateral sclerosis (Gamez et al., 2010). They concluded that although no significant side effects were found, progression of the disease was not altered. It should be noted that three of these four studies were conducted with LP-OECs and one with fetal OB-OECs. At this moment, the safety and efficacy of adult OB-OECs have not yet been adequately tested in patients. In China, fetal OB-OECs were implanted in hundreds of patients suffering from chronic spinal cord injuries or neurodegenerative diseases including amyotrophic lateral sclerosis, cerebral palsy and multiple sclerosis (Huang et al., 2009). Although beneficial effects were claimed, in most cases/studies, no proper control group was included and there was only minimal follow-up of the patients. This complicates the interpretation of the results. Other studies that examined the neuropathology or disease progression in a relatively small number of ALS patients that received fetal OEC implantations in China report no beneficial effects (Giordana et al., 2010; Piepers and van den Berg, 2010). Overall, implantation of LP-OECs and fetal OB-OECs in humans appears to be safe and well-tolerated and promising results have been obtained. However, future clinical trials with adequate group sizes have yet to show beneficial effects of OEC implants in patients with spinal cord injury or ALS.

220 221

D

158 159

survival rates have recently been corroborated using non-invasive longitudinal bioluminescence imaging of adult OB-OECs transplanted in a spinal hemisection lesion (Roet et al., 2012). This indicates that OECs mainly exert beneficial effects during a relatively short postlesion period and only a relatively small number of cells continue to promote neural repair over an extended period of time. Secondly, OECs can have different pro-regenerative molecular profiles that have distinct effects on neural repair. These molecular profiles have been shown to depend on the OB-OEC donor species (Wewetzer et al., 2011), the OEC subtype (olfactory mucosa versus olfactory bulb) (Guerout et al., 2010) and OB-OEC purification methods (Novikova et al., 2011). To maximize neural repair, it is therefore necessary to select or genetically engineer OECs with a molecular profile that is most favorable for repair. For example, the gene expression profile of OB-OECs shows a predominant activation of genes involved in nervous system development whereas the genes that are activated in LP-OECs appear to be more involved in wound healing processes (Guerout et al., 2010). After implantation in the crushed dorsolateral funiculus of the rat spinal cord both postnatal OEC subtypes promote angiogenesis, endogenous Schwann cell infiltration, and axonal sprouting (Richter et al., 2005). However, implantation of LP-OECs results in increased growth of TH positive axons and a significant increase in autotomy while OB-OECs increase growth of substance-P positive axons (Richter et al., 2005). A study that compared implantation of OB-OECs versus LP-OECs in the lesioned rat vagus nerve reported only functional recovery after implantation of OB-OECs (Paviot et al., 2011) and only OB-OECs and not LP-OECs enabled axon regeneration and restoration of forepaw grasping in a rat rhizotomy paradigm (Ibrahim et al., 2013). It has been reported that in contrast to OB-OECs, LP-OECs require sufficient levels of purification before implantation to stimulate neural repair (Mayeur et al., 2013). Taken together, in our view the future success of OEC-based therapies for treatment of nervous system pathologies will depend on a much more profound understanding of the molecular machinery that determines their survival and pro-regenerative properties in the primary olfactory system and following transplantation in the CNS.

E

or central locations, OECs have a beneficial impact on a wide range of nervous system pathologies.

T

156 157

3

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254

258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282

4

t1:4

Table 1 The literature references that are discussed in the current article and that describe studies on OECs. If clearly indicated in the specific reference, the following is presented: the subtype of OECs that is studied, the type and age of the OEC donor species, the OEC purification method and the main finding for each reference. Reference

OEC subtype

Donor species

Age of donor species

Purification method

Main findingsa

Agrawal et al. (2004)

OB-OEC

Rat

Adult

None

Au et al. (2007)

LP-OEC

Mouse

Postnatal

Anti-Thy 1.1-mediated lysis

Babiarz et al. (2011)

OB-OEC/LP-OEC

Rat

Postnatal/adult

P75 immunopanning

Barakat et al. (2005)

OB-OEC

Rat

Adult

P75 immunopanning

Barbour et al. (2013)

OB-OEC

Rat

Adult

P75 immunoaffinity

Barraud et al. (2010) Boruch et al. (2001)

N/A nOEC (homogeneous clonal cell line)

Chicken/Mice Rat

N/A

N/A N/A

De Corgnol et al. (2011)

LP-OEC

Rat

3 or 4-week old

None

Devon and Doucette (1992)

OB-OEC

Rat

Embryonic

None

Doucette and Devon (1995)

OB-OEC

Rat

Embryonic

None

Doucette (1990) Doucette (1991)

OB-OEC N/A

Rat

Adult

N/A N/A

Doucette (1996)

N/A

Rat

Adult

N/A

Fairless et al. (2005)

OB-OEC

Rat

Postnatal

Field et al. (2003)

LP-OEC

Rat

Adult

Franklin et al. (1996)

OB-OEC cell line

Rat

Postnatal

N/A

Franklin et al. (1996)

OB-OEC

Rat

Postnatal

N/A

Franssen et al. (2008)

OB-OEC

Rat

Adult

P75 immunopanning

Franssen et al. (2009)

OB-OEC

R

t1:1 t1:2 t1:3

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

Rat

Adult

P75 immunopanning

Gamez et al. (2010)

OB-OEC

Human

Fetal

Human

Fetal

Rat

Postnatal

Co-transplantation of OB-OECs with ventral mesencephalic cells restores functional deficits in rat model of Parkinson's disease SPARC from LP-OECs stimulates Schwann cells to promote neurite outgrowth and enhances spinal cord repair. Juvenile and adult OB-OECs bundle and myelinate dorsal root ganglion axons in culture. 2.3 +/− 1.4% Of the transplanted OB-OEC survived after 3 months. OB-OEC treated rats showed significant numbers of raphe projecting axons reaching at least 8 mm distal from the injury site OECs originate from the neural crest. nOECs express mRNA for NGF, BDNF, NT-4/5, and neuregulins, but not for NT-3 or CNTF. In addition, nOECs secrete NGF, BDNF, and neuregulin, but retain NT-4/5 intracellularly. LP-OECs improve functional laryngeal reinnervation in a rat model of nonselective vagus nerve section and anastomosis OB-OECs myelinate dorsal root ganglion neurites in vitro. Elevated intracellular levels of cAMP induce OECs to express GAL-C and GFAP but not MBP. OECs express L1/Ng-CAM and NCAM. The olfactory bulb contains a specialized type of glial cell, the OB-OEC. Laminin, fibronectin and collagen type IV are expressed in the lesioned adult ON layer. N-cadherin differentially determines Schwann cell and OEC adhesion and migration responses upon contact with astrocytes. LP-OECs have a rounded outer surface enclosed in a continuous single basal lamina, overlapping processes enwrap interweaving territories of tightly apposed aligned axons. Schwann cell-like myelination following transplantation of an OB-OEC cell line into areas of demyelination in the adult CNS. OB-OECs are able to produce peripheral-type myelin sheaths around axons of the appropriate diameter Gene expression profiling of OB-OECs and Schwann cells indicates distinct tissue repair chAra-Cteristics of OB-OECs. OB-OECs do intermingle with meningeal fibroblasts while Schwann cells do not. No significant adverse events or changes in the decline compared with the disease' s natural history were observed Neuropathologic analysis does not support a beneficial effect of fetal OEC implantation into the frontal lobes of ALS patients OB-OECs and LP-OECs fundamentally differ in their gene expression pattern. P75 high OB-OECs overexpress genes implicated in modulation of extracellular matrix and cell sorting, whereas P75Low OB-OECs overexpress genes involved in the inflammatory response and axonal guidance. OECs transplantation into brain and spinal cord is feasible and safe. RhoA–ROCK–myosin pathway regulates morphological plasticity of cultured OB-OECs. OB-OECs and not LP-OECs enabled axon regeneration and restoration of forepaw grasping, a difference most probably caused by differences in OEC yields (50% versus 5%) Transplanted OB-OECs remyelinate and enhance axonal conduction in the demyelinated dorsal columns of the rat spinal cord.

t1:5

t1:6 t1:7

O

R O

t1:9 t1:10

t1:11

t1:12

C

E

t1:19

t1:21

C

t1:23

t1:24

Honore et al. (2012)

OB-OEC/LP-OEC

U

Guerout et al. (2010) t1:26

N

Giordana et al. (2010) t1:25

O

t1:22

OB-OEC

R

t1:20

Rat

O4-positive galactocerebrosidenegative (FACS)

T

t1:17

t1:18

D

E

t1:16

P

t1:13 t1:14 t1:15

F

t1:8

N/A

P75 immunoaffinity (beads) Differential cell adhesion/FACS (P75 low and P75 high)

t1:27

Huang et al. (2009)

Human

Fetal Adult

Differential cell adhesion

Postnatal

None

t1:28

Huang et al. (2011)

OB-OEC

Rat

Ibrahim et al. (2013)

OB-OEC/LP-OEC

Rat

Imaizumi et al. (1998)

OB-OEC

Rat

t1:29

t1:30

t1:31

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

5

Table 1 (continued) Age of donor species

Main findingsa

Reference

OEC subtype

Donor species

Purification method

Imaizumi et al. (2000a)

OB-OEC

Pig

Imaizumi et al. (2000b)

OB-OEC

Pig

Johansson et al. (2005)

OB-OEC

Rat

Adult

Differential cell adhesion

Lakatos et al. (2000)

OB-OEC

Rat

Postnatal

Lakatos et al. (2003)

OB-OEC

Rat

Postnatal

O4-positive galactocerebrosidenegative (FACS) O4-positive galactocerebrosidenegative (FACS)

Lamond and Barnett (2013)

OB-OEC

Rat

Postnatal

P75 immunoaffinity

Leaver et al. (2006)

OB-OEC

Rat

Adult

P75 immunoaffinity

Leung et al. (2008)

LP-OEC + OB-OEC

Rat

Postnatal

Ara-C

Li et al. (1997)

OB-OEC

Rat

Adult

None

Li et al. (2003)

mix of OB-OEC and ONF OEC surrounding the olfactory nerves

Rat

Adult

None

Rat

Adult

N/A

t1:33

None

t1:34

t1:36

O

t1:35

t1:40

t1:42

Li et al. (2005b)

D

t1:41

t1:43

Li et al. (2010b) b

P

t1:39

R O

t1:37

t1:38

t1:44

E

Rat

OB-OEC

Rat

Postnatal

Li et al. (2013)

OB-OEC

Rat

Postnatal

Stimulation with NT-3

Lipson et al. (2003)

OB-OEC

Rat

Adult

N80% P75/S100beta positive

Liu et al. (2010)

OB-OEC

Rat

Postnatal

Ara-C + differential cell adhesion

Lopez-Vales et al. (2004)

OB-OEC

Rat

Adult

P75 immunoaffinity (beads)

LP-OEC

Human

Adult

Stimulation with NT-3

OB-OEC/LP-OEC

Rat

Postnatal

Differential cell adhesion (OB-OEC)/stimulation with TGFalpha (LP-OEC)

Rat

Postnatal

N90% P75 positive (OB-OEC)

Munoz-Quiles et al. (2009)

OB-OEC/immortalized OB-OEC OB-OEC

Rat

Adult

P75 immunopanning

Nan et al. (2001)

LP-OEC

Mouse

Adult

N/A

Novikova et al. (2011)

OB-OEC

Rat

Adult

Differential cell adhesion/P75 immunoaffinity (beads)

Pastrana et al. (2006)

OB-OEC/TEG3 (immortalized)

Rat

Postnatal

None

T

Li et al. (2011)

C

t1:45

t1:49

Mackay-Sim et al. (2008) t1:50

U

Mayeur et al. (2013)

t1:51

Moreno-Flores et al. (2003) t1:52

R

N C O

t1:48

R

t1:47

E

t1:46

Stimulation with NT-3

t1:53 t1:54

t1:55

t1:56

Xenotransplantation of transgenic pig OB-OECs promotes axonal regeneration in rat spinal cord. Xenotransplantation of myelin-forming OB-OECs from pigs genetically altered to reduce the hyperacute response in humans are able to induce elongative axonal regeneration and remyelination Co-transplantation of OB-OECs with dopamineneuron-rich ventral mesencephalic tissue improves functional recovery in rats with 6-OHDA lesions OB-OECs will migrate into an area containing astrocytes while Schwann cells do not. OB-OECs induce less host astrocyte response and chondroitin sulfate proteoglycan expression than Schwann cells following transplantation into adult CNS white matter. Schwann cells but not OB-OECs inhibit CNS myelination via the secretion of connective tissue growth factor. OB-OECs promote the long-distance growth of adult retinal ganglion cell neurites in vitro. OECs are attracted to, and can endocytose, bacteria Transplantation of OB-OECs enhances repair of adult rat corticospinal tract Transplanted OB-OECs and ONFs promote regeneration of cut adult rat optic nerve axons. OECs and ONFs maintain continuous open channels for regrowth of olfactory nerve fibers and OECs phagocyte axonal debris b1% of implanted OECs survived and this number is related to the motor function recovery of the contused cord. Transplantation of OB-OECs into spinal cord prolongs the survival of mutant SOD1(G93A) ALS rats through neuroprotection and remyelination. Intracranial OB-OEC transplant protects both upper and lower motor neurons in amyotrophic lateral sclerosis. OB-OECs express NGF, BDNF, GDNF, and CNTF mRNA, while NT3 and NT4 mRNA were not detectable. The identification of four hundred and seventy nonredundant plasma membrane proteins and 168 extracellular matrix proteins in OB-OECs. OB-OECs promote functional and morphological preservation of the spinal cord after photochemical injury and increase neoangiogenesis and up-regulation of COX-2 and VEGF expression in astrocytes. Transplantation of autologous LP-OECs into the injured spinal cord is feasible and is safe up to 3 years of post-implantation. OB-OECs and LP-OECs induce electrophysiological and functional recovery, reduce astrocyte reactivity and glial scar formation and improve axonal regrowth. However, LP-OEC transplants require purification. High level of APP expression in neuritepromoting OB-OECs and immortalized OECs. Rats with complete spinal cord injury that were transplanted with OB-OECs 4 months after injury exhibited progressive improvement in motor function and axonal regeneration. LIFR, IL-6, and IL-6R are upregulated in LP-OECs 3 days after bulbectomy. The age of OB-OECs in culture and the method of cell purification could affect the efficacy of OB-OECs to support neuronal survival and regeneration after spinal cord injury. Genes associated with adult axon regeneration promoted by OECs: a new role for matrix metalloproteinase 2.

F

t1:32

(continued on next page)

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

6

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

Table 1 (continued) Reference

OEC subtype

Donor species

Age of donor species

Paviot et al. (2011)

LP- and OB-OEC

Rat

Pearse et al. (2007)

OB-OEC

Rat

Adult

Human

Fetal

Purification method

Main findingsa

None

Efficiency of laryngeal motor nerve repair is greater with OB-OECs than with LP-OECs Transplantation of Schwann cells and/or OB-OECs into the contused spinal cord: Survival, migration, axon association, and functional recovery. No indications that implantation of OECs is beneficial for treatment of ALS. Purified OB-OECs fail to myelinate dorsal root ganglion axons. Remyelination of the nonhuman primate spinal cord by transplantation of H-transferase transgenic adult pig OB-OECs. LP-OECs reduce scar and cavity formation, promote angiogenesis and promote regeneration after spinal cord injury. Immunocytochemical properties of pure OB-OEC cultures. OB-OEC transplants promote regeneration of transected dorsal root axons into the spinal cord. In vitro enfolding of olfactory neurites by p75 NGF receptor positive OB-OECs. OB-OECs promote long-distance axonal regeneration in the transected adult rat spinal cord. OB-OEC transplants enhance functional recovery of paraplegic rats and motor axon regeneration in their spinal cords. OEC transplantation in spinal cord injury appears clinically safe after 24 months. LP-OECs and OB-OECs exhibit differential integration and migration and promote differential axon sprouting in the lesioned spinal cord. Bioluminiscence established to follow OB-OEC cell survival in rats; the bioluminescent signal of OB-OECs was b0.3% after 98 days. A multilevel screening strategy defines a molecular fingerprint of OB-OECs and identifies SCARB2, a protein that improves regenerative sprouting of injured sensory spinal axons. Genetic engineering of OB-OECs can result in more effective axonal outgrowth and can lead to enhanced recovery after injury. CX3CL1/fractalkine regulates branching and migration of monocyte-derived cells in the mouse olfactory epithelium. Mouse OB-OEC enhance axon outgrowth of dorsal root ganglion neurons on a myelin substrate in vitro. FGF/heparin differentially regulates Schwann cell and OB-OEC interactions with astrocytes: a role in astrocytosis. Transplated OB-OECs reduced the infarct volume, decreased mortality, and improved neurological deficits in a focal ischemia model in the rat. Survival and function of neural stem cells-derived dopaminergic neurons is enhanced by cotransplantation of OB-OECs in parkinsonian rats. Implantation of LP-OECs and ONFs promotes neuroplasticity in murine models of stroke. OB-OEC expressed plasminogen activator inhibitor-1 promotes axonal regeneration. Labeled OB-OECs were observed only within the graft after implantation following fimbria-fornix transection and not in the adjacent neural tissue. OB-OECs are effective promoters of retinal ganglion cell neurite outgrowth in coculture. OB-OECs provide neurotrophic support for co-transplanted neural progenitor cells resulting in improved recovery of cognitive dysfunction. Reactive astrocytes in glial scar attract OB-OEC migration by secreted TNF-alpha in spinal cord lesion of rat. Transplantations of autologous LP-OECs were safe, feasible and potentially beneficial.

t1:58

P75 immunopanning

t1:60

Piepers and Van Den Berg (2010) Plant et al. (2002)

OB-OEC

Rat

Adult

P75 immunopanning

Radtke et al. (2004)

OB-OEC

Pig

Postnatal

N98% P75 positive

Ramer et al. (2004)

LP-OEC

Mouse

Postnatal

Anti-Thy 1.1-mediated lysis

Ramon-Cueto and Nieto-Sampedro (1992) Ramon-Cueto and Nieto-Sampedro (1994) Ramon-Cueto et al. (1993)

OB-OEC

Rat

Adult

N/A

OB-OEC

Rat

Adult

P75 immunopanning

OB-OEC

Rat

Adult

N/A

Ramon-Cueto et al. (1998)

OB-OEC

Rat

Adult

P75 immunopanning

Ramon-Cueto et al. (2000)

OB-OEC

Rat

Adult

P75 immunopanning

Rao et al. (2013)

OB-OEC

Human

Fetal

None

Richter et al. (2005)

OB-OEC/LP-OEC

Rat

Postnatal

Anti-Thy 1.1-mediated lysis (LP-OEC)/P75 immunopanning (OB-OEC)

Roet et al. (2012)

OB-OEC

Rat

Adult

Roet et al. (2013)

OB-OEC

Rat

Adult

Ruitenberg et al. (2003)

OB-OEC

Rat

Adult

P75 immunopanning

Ruitenberg et al. (2008)

LP-OEC

Mouse

Adult

N/A

Runyan and Phelps (2009)

OB-OEC

Mouse

Adult

P75 Immunopanning

Santos-Silva et al. (2007)

OB-OEC

Rat

Postnatal

O4-positive galactocerebrosidenegative (FACS)

Shi et al. (2010)

OB-OEC

Rat

Postnatal

Stimulation with NT-3

N

t1:59

Rat

Adult

Differential cell adhesion

Human

Adult

None

Human

Young/adult

N99% S100beta + GFAP positive

Smale et al. (1996)

mix of LP-OEC and ONF OB-OEC (immortalized) OB-OEC

Rat

Fetal

Sonigra et al. (1999)

OB-OEC

Rat

Adult

None

Srivastava et al. (2009)

OB-OEC

Rat

Adult

None

Su et al. (2009)

OB-OEC

Rat

Adult

N95% S100beta positive

Tabakow et al. (2013)

LP-OEC

Human

Adult

None

t1:61

t1:62

t1:65 t1:66

P

t1:67

R O

t1:64

O

t1:63

t1:68

D

t1:69

R

t1:73

t1:77

Shukla et al. (2009)

OB-OEC

Shyu et al. (2008) Simon et al. (2011) t1:80

U

t1:78 t1:79

R

C

t1:76

O

t1:75

T

E

t1:72

t1:74

P75 immunopanning

C

t1:71

E

t1:70

P75 immunopanning

t1:81 t1:82

t1:83

t1:84 t1:85

F

t1:57

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

7

Table 1 (continued) t1:86

Reference

OEC subtype

Donor species

Age of donor species

Purification method

Main findingsa

Takeoka et al. (2011)

OB-OEC

Rat

Adult

P75 immunopanning

Tisay and Key (1999)

LP-OEC

Rat

Postnatal

None

Toft et al. (2013)

OB-OEC

Rat

Postnatal

P75 FACS sorting

Turner and Perez-Polo (1993)

N/A

Rat

Adult

N/A

Vincent et al. (2005)

LP-OEC + OB-OEC

Rat

Postnatal

Ara-C

Vincent et al. (2007)

LP-OEC + OB-OEC

Rat

Postnatal

Ara-C

Wang et al. (2008)

OB-OEC

Mouse

Postnatal

N/A

Wewetzer et al. (2001)

OB-OEC

Rat

Postnatal

N95% P75 positive

Wewetzer et al. (2005)

OB-OEC

Rat

Postnatal

O4 and p75 immunoaffinity

Wewetzer et al. (2011)

OB-OEC

Dog

Adult

P75 immunoaffinity (beads)

Windus et al. (2007)

LP-OEC

Mouse

Postnatal

S100beta labeling

Windus et al. (2011)

LP-OEC

Mouse

Witheford et al. (2013)

LP-OEC

Rat

Postnatal

Axon regeneration can facilitate or suppress hindlimb function after OB-OEC transplantation. Laminin and matrigel enhanced the spreading and migration of olfactory ensheathing cells and increased their neurite outgrowth-promoting activity. OB-OECs promoted greater axonal regeneration than OB-derived fibroblasts. Peripheral lesioning dramatically reduced expression of glomerular p75NGFR while inducing expression of p75NGFR in the ON layer. Genetic expression profile of OECs is distinct from that of Schwann cells and astrocytes. Bacteria and PAMPs activate nuclear factor kappaB and Gro production in a subset of OECs and astrocytes but not in Schwann cells. A specialized subgroup of OB-OECs activate the Wnt/beta-catenin signaling reporter in the developing mouse olfactory nerve layer. OB-OECs express CNTF and its alpha receptor subunit. Phagocytosis of O4+ axonal fragments in vitro by p75 negative OB-OECs. CNPase is a novel marker for in situ detection of canine but not rat OECs. Motile membrane protrusions regulate cell–cell adhesion and migration of LP-OECs. Stimulation of LP-OEC motility enhances olfactory axon growth. LP-OECs promote corticospinal axonal outgrowth by a L1-CAM-dependent mechanism.

Woodhall et al. (2001)

OB-OEC

Rat

Postnatal

Wu et al. (2011a)

LP-OEC

Rat

Adult

You et al. (2011)

OB-OEC

Rat

Postnatal

t1:87

t1:88 t1:89

t1:90

F

t1:91

t1:93 t1:94 t1:95

P

t1:96 t1:97

S100beta labeling

D

t1:98

C

t1:101

t1:102

288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309

N95% P75 positive

OB-OECs express NGF, BDNF, GDNF and their receptors. Delayed OB-OEC transplants reduce nociception after dorsal root injury. OB-OECs enhance Schwann cell-mediated anatomical and functional repair after sciatic nerve injury.

E R

1990; Fairless et al., 2005; Witheford et al., 2013). OECs also express a number of other proteins that can promote axon growth or regeneration such as SERPINE1 (Simon et al., 2011) and cytokines, including IL6 and CX3CL1 (Nan et al., 2001; Ruitenberg et al., 2008). Several of the beneficial effects of OEC implants have been productively studied in vitro. The use of bioassays has provided the opportunity to examine the role of specific molecules and cellular interactions that underlie important aspects of the pro-regenerative functions of OECs, including their axon-growth promoting properties, their interaction with astrocytes, their immuno-modulatory and phagocytic properties and their capacity to myelinate axons. Co-cultures of OB-OECs with neurons have shown that these cells stimulate axon growth in a variety of neurons and that the stimulating effect on axon extension is not restricted to primary olfactory neurons (Leaver et al., 2006; Runyan and Phelps, 2009; Sonigra et al., 1999). OB-OECs intermingle much better with host scar cells than Schwann cells after implantation in the lesioned spinal cord (Pearse et al., 2007). This was studied in co-culture and confrontation assays. Cultured OB-OECs do migrate into an area with astrocytes or intermingle with meningeal fibroblasts while Schwann cells do not (Franssen et al., 2009; Lakatos et al., 2000). This difference between OB-OECs and Schwann cells is at least partly mediated by a differential regulation of N-Cadherin (Fairless et al., 2005). OB-OECs also induce a less severe host astrocyte response after implantation in the spinal cord than Schwann cells (Lakatos et al., 2003). This effect has been reproduced in culture: astrocytes become reactive when they encounter Schwann cells, in contrast astrocytes maintain a more benign phenotype when they encounter OB-OECs (Lakatos et al.,

R

286 287

Adopted from reference titles and abstracts. Article in Chinese.

N C O

284 285

b

U

283

a

T

t1:100

Anti-Thy 1.1-mediated lysis (LP-OEC)/P75 immunopanning (OB-OEC) Bovine pituitary extract enrichment Stimulation with NT-3

E

t1:99

t1:103 t1:104

R O

O

t1:92

2000; Santos-Silva et al., 2007). A molecular analysis provided strong indications that heparan sulfate proteoglycans and members of the fibroblast growth factor family are involved in this differential induction of the astrocyte stress response (Santos-Silva et al., 2007). Important aspects of the phagocytosis and immune function of LP-OECs and OBOECs have also successfully been studied in vitro (Chuah et al., 2011; Leung et al., 2008; Wewetzer et al., 2005). In a mixed population of OB-OECs and LP-OECS, exposed to Escherichia coli or lipopolysaccharide, the inflammatory transcription factor, NFKB, translocates to the nucleus and this leads to a functional activation of the OECs (Vincent et al., 2007). Finally, implanted OB-OECs can remyelinate spinal cord axons (Franklin et al., 1996; Imaizumi et al., 1998, 2000b; Radtke et al., 2004) and can myelinate dorsal root ganglion neurites in vitro (Babiarz et al., 2011; Devon and Doucette, 1992), although this has been disputed (Plant et al., 2002). In contrast to OB-OECs, the higher expression of CTGF in Schwann cells has been shown to inhibit CNS myelination (Lamond and Barnett, 2013).

310

Microarray and large scale proteomic studies

327

Genome wide transcriptional profiling and large scale proteomics combined with gene ontology and molecular pathway analysis have provided novel opportunities to study the molecular composition of OECs. These screening techniques have given us an unbiased and unprecedented insight in the molecular characteristics of OECs. Six genome wide microarray studies (Franssen et al., 2008; Guerout et al., 2010; Honore et al., 2012; Pastrana et al., 2006; Roet et al., 2011,

328 329

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326

330 331 332 333 334

360 361 362 363 364 365

370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398

C

358 359

E

356 357

R

354 355

R

352 353

O

350 Q7 351

C

348 349

N

346 347

U

344 345

High throughput and high-content cellular screening

439

Gene-ontology and pathway analysis tools are essential to uncover patterns in gene expression data sets that point to the presence of interesting functionally linked molecular pathways or networks. However, the number of genes indicated by means of these bioinformatics approaches is usually still far too large to be tested in classical cellular assays and/or labor-intensive preclinical animal models for neural transplantation and repair. Therefore it is of great importance to further define the potentially most important genes for in vivo studies. In recent years, huge advances have been made in the fields of microscopy, robotics and with techniques to interfere with gene function at a large scale. This has resulted in the development of fully integrated and automated cell culture and high throughput automated microscope systems that are combined with sophisticated morphometric analysis software such as the Cellomics KineticScan HCS reader and PerkinElmer's Opera High Content Screening System. This allows gain or loss of function studies on large numbers of genes in cellular bioassays that are tailored to detect effects of a gene on cell survival/death, proliferation, cytoskeletal changes, neurite outgrowth or synapse formation. This so-called “cellomics” approach yields information on sets of target genes that are functionally linked to a biological parameter of interest, for instance neuronal survival or neurite outgrowth. Recent studies have employed “cellomics” to screen genes, initially identified by microarray, for their role in the process of neurite outgrowth (Blackmore, 2012; Blackmore

440 441

F

The microarray and proteomics studies have identified large cohorts of genes that are highly expressed in OECs and that are potentially functionally connected. The functional dissection of these broad molecular signatures poses a significant challenge. The selection of “interesting” genes from microarray datasets, including those prepared of cultured OEC, was initially based on relatively arbitrary criteria because investigators typically tend to select a gene for further study based on what is already known about its function. For instance, MMP2 was selected for functional and immunohistochemical analysis from the genes that were higher expressed in short term cultured OB-OECs rather than long term cultured OECs. Loss and gain of function bioassays revealed the importance of MMP2 for the neurite outgrowth promoting properties of OECs (Pastrana et al., 2006). Based on the same microarray data, this research group later also investigated the role of SERPINE1, PAR1 and THBD as regulators of OB-OEC-dependent axonal regeneration (Simon et al., 2011). SPARC was selected from the proteome analysis of conditioned medium of LP-OECs after 2 and 6 passages based on high expression levels (Au et al., 2007). Functional analysis showed that SPARC expression in LP-OECs is important for axonal regeneration and that it can modulate the activation state of Schwann cells. Although the study of the function of selected molecules has resulted in important new insights into the molecular biology of OECs, it is now essential to move from individual molecules to an understanding of how multiple genes function in the context of molecular pathways, and how these pathways interact in OECs to promote successful regeneration (Geschwind and Konopka, 2009). The Gene Ontology project (GO, http:// www.geneontology.org/) and the Kyoto Encyclopedia for Genes and Genomes (KEGG, http://www.genenome.jp/kegg/) categorize genes into biologically meaningful gene groups based on their functional annotation (Guerout et al., 2010; Liu et al., 2010; Ogata et al., 1999). Genes are grouped in hierarchical classes that fall in one of three main categories:

342 343

O

368 369

341

R O

Bioinformatics

339 340

399 400

P

367

337 338

“biological process”, “cellular component” and “molecular function”. The application of these web-based bioinformatics tools revealed that OB-OECs express significantly more genes involved in tissue repair than Schwann cells (Franssen et al., 2008) and OECs from the ONL express more genes involved in nervous system development than OECs from the olfactory mucosa (Guerout et al., 2010). A limitation of the GO-based analysis of microarray data sets, namely the lack of insight in direct functional interactions of genes or proteins, is at least partially resolved by pathway or molecular network analysis tools, including Ingenuity Pathway Analysis (IPA) and Agilent's GeneSpring. IPA is an interactive database that allows the investigator to identify specific previously identified pathways and to build new pathways based on genes detected in a particular microarray experiments. A meta-analysis on publicly available micro array datasets on early passage OB-OECs revealed highly significant overrepresentation of neurite outgrowth, blood vessel development, migration and immune regulatory associated molecules and their molecular interaction networks as well as a the possible importance of OB-OEC ecto-ATPase activity (Roet et al., 2011). The proteins that have multiple functional connections with other molecules in a pathway or network are usually defined as “Hub” genes. These Hub genes can belong to a variety of functional classes and are likely to serve key regulatory functions in specific biological processes. For instance, the transcription regulator SMAD7 was identified as a Hub gene that may be important for the stimulation of blood vessel development by OB-OECs, whereas the cell surface protein APP was identified as a possible Hub gene for the stimulation of neurite outgrowth (Roet et al., 2011). The growth factors, FGF2, EGFR and TGF have been identified as Hub genes in the wound healing pathways in OB-OECs (Guerout et al., 2010). The current bioinformatics databases are continuously upgraded as new information about individual gene and protein interactions and their function becomes available. Therefore we predict that, as these databases are filled with more and more information, a re-analysis of the existing OEC-microarray datasets will allow the discovery of novel as yet hidden molecular characteristics of OEC. Furthermore novel computational tools to study gene regulation are emerging, such as algorithms to detect transcription factor binding site overrepresentation analysis, which can lead to the identification of transcription factors that coordinate the activation of specific sets of repair promoting genes (Geeven et al., 2011).

T

366

2013; Vincent et al., 2005) and two large scale proteomic studies (Au et al., 2007; Liu et al., 2010) have investigated the transcriptome and proteome of various preparations of cultured OECs (reviewed in (Roet et al., 2011)). The microarray studies have shown that OB-OECs or a mixture of LP-OECs and OB-OECs not only has many similarities with Schwann cells [as shown previously by using more classical analysis techniques (Wewetzer et al., 2002)] but also displays molecular characteristics that are distinct from Schwann cells (Franssen et al., 2008; Vincent et al., 2005), early passage OB-OECs have a stronger proregenerative phenotype than late passage OECs (Pastrana et al., 2006), OB-OECs have a distinct gene expression profile from LP-OECs (Guerout et al., 2010), OB-OECs with relatively low P75/NGFR expression overexpress more genes involved in axon guidance (Honore et al., 2012) and OB-OECs in the ONL increase the expression of many neurite growth promoting molecules during regeneration of olfactory axons (Roet et al., 2013). One of the proteomics studies pointed to proteins that appear to make conditioned medium of LP-OECs after two passages superior with regard to their capacity to stimulate neurite outgrowth than conditioned medium of OECs after 6 passages in culture (Au et al., 2007). The other proteomics study revealed the proteins that are in OB-OEC conditioned medium and in the plasma membrane of OECs and that may be important for OEC self-renewal and for their capacity to enhance spinal cord regeneration (Liu et al., 2010). In general, the large scale molecular screens demonstrated that OECs not only express many genes that potentially support neurite outgrowth, but also revealed that the transcriptome of OECs is enriched in genes involved in tissue repair/wound healing, blood vessel formation, myelination, phagocytosis, immune function and regulation of oxidative stress. These distinct molecular signatures are in strong support of the idea that OECs are cells that positively affect multiple tissue repairassociated processes that go beyond their capacity to stimulate of axon outgrowth per se.

D

335 336

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

E

8

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

401 402 Q8 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438

442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

T

E

D

P

R O

O

F

479

C

472 473

Lipid presentation The identification of SCARB2 as a protein that improves regenerative sprouting of injured sensory spinal axons was the main finding of the “Cellomics” screen on the neurite growth promoting properties of OB-OECs. SCARB2 is a protein which mediates the uptake of cholesterol

E

470 471

R

469

474 475

R

467 468

on published microarray datasets provided a number of molecular and functional insights into the neural repair-promoting properties of OB-OECs. Fig. 1 provides a summary of the molecular basis of established and recently proposed synergistic neural repair promoting properties of OECs.

N C O

465 466

et al., 2010; MacGillavry et al., 2009; Moore et al., 2009). By using a “Cellomics” approach we have successfully identified 19 genes expressed by OB-OECs that affect neurite outgrowth of neurons cocultured with OB-OECs (Roet et al., 2013). This screen was performed with adult primary P75 positive OB-OECs plated in a 96-well plate format and transfected with siRNA pools to specifically knockdown a gene of interest. After 72 h, dissociated embryonic DRG were cocultured with these OECs for up to 8 h after which the neurite length was measured automatically in the Cellomics reader to allow assessment of the relevance of the targeted gene for OB-OEC promoted neurite growth. The hits in this screen together with the meta-analysis

U

463 464

9

Fig. 1. The established and proposed synergistic neural repair properties of olfactory ensheathing cells. 1. ATP is released from necrotic and apoptotic cells at high levels which has a toxic effect on cells that express the ATP receptor P2X7. OECs express the ecto-ATPase ENTPD2 which hydrolyzes toxic extracellular ATP and releases ADP. 2. OECs produce and reutilize lipids such as cholesterol obtained from cellular debris. Neurotrophic lipids are secreted in vesicles and are used for rapid axon biosynthesis through interaction with the low density lipid receptor (LDLR). 3. OECs reduce astrocyte reactivity. 4. OECs (re)myelinate regenerating axons. 5. OECs promote angiogenesis by secretion of molecules like ESM1, CTGF and CYR61. 6. OECs produce neurotrophic factors, including NGF and BDNF. 7. OECs phagocyte cellular debris and reutilize obtained lipids which are presented to regenerating axons. 8. OECs modify the extracellular matrix by secretion of growth promoting matrix molecules such as laminin and by secretion of proteolytic enzymes such as ADAMTS1 which cleaves versican, a neurite growth inhibitory molecule. 9. OECs form a structural pathway for regenerating axons. 10. OECs ameliorate the immune system by secretion of molecules that reduce microglia activation such as CX3CL1.

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

476 477 478

480 481 482 483

507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548

Balanced ligand and receptor expression to regulate axon growth and guidance Axonal growth is normally tightly regulated by axon guidance molecules. OB-OECs express the Wnt and VEGF/SEMA receptors FZD1 and NRP1 respectively (Kolodkin et al., 1997; Roet et al., 2013; Soker et al., 1998; Takagi et al., 1995). Knockdown of FZD1 and NRP1 in OB-OECs reduced the neurite growth of co-cultured DRG neurons (Roet et al., 2013). Their expression in OECs may function as a scavenging mechanism for the neurite growth inhibitors WNT1 and SEMA3A respectively, which are both expressed in the spinal cord after a lesion (De Winter et al., 2002; Liu et al., 2008; Niclou et al., 2003). During development the canonical WNT signaling pathway is activated in a subpopulation of OECs which are involved in the formation of glomeruli (Wang et al., 2008). Several WNT proteins, including WNT1 are expressed in the ONL, and activation of the canonical WNT signaling pathway is necessary for olfactory axon target innervation in the forebrain (Petrova et al., 2014; Wang et al., 2008; Zaghetto et al., 2007). In addition to NRP1 and FZD1, NRP2 and most members of the FZD family are also expressed above background in OB-OECs together with all class 3 SEMAs and almost all WNTs (NCBI GEO dataset GSE19250). The coexpression of NRP1 and its ligand SEMA3A in motor neurons has been shown to be a controlling mechanism for the guidance of axonal regeneration (Kolodkin et al., 1997; Moret et al., 2007). OB-OECs do express not only many neurotropic and growth factors but also many of their receptors, such as the low affinity nerve growth factor receptor (P75/NGFR), CNTFRaplha, GFRA1, TGFB2 and TrkB (Ramon-Cueto et al., 1993; Roet et al., 2013; Wewetzer et al., 2001; Woodhall et al., 2001). P75/NGFR is induced in OECs in the ONL after deafferentation of the OB (Turner and Perez-Polo, 1993) and as mentioned before, olfactory neurites grow preferentially on P75/NGFR positive OBOECs (Ramon-Cueto et al., 1993). When the axons are ensheathed by OECs, P75/NGFR expression in both the axons and the OECs becomes undetectable. Downregulation of GFRA1 and TGFB2 in cultured OBOECs reduced the neurite length of embryonic DRG neurons (Roet et al., 2013). GDNF has been shown to mediate LP-OEC migration and thereby axon motility (Jing et al., 1996; Windus et al., 2011; Woodhall et al., 2001).

O

F

556 557

R O

505 506

Modulation of the extracellular matrix The composition of the extracellular matrix regulates many processes important for neural repair, including axon growth and guidance, the immune response and angiogenesis. OECs regulate the matrix composition by secreting extracellular matrix proteins, matrix proteases, matrix protease inhibitors and matricellular proteins. In the primary olfactory pathway, layers of interconnected OECs form a permissive pathway for growing olfactory axons (Field et al., 2003; Li et al., 2005a,b, 2012). OECs express a number of neurite growth supporting molecular components of the basement membrane, i.e., collagen type IV, fibronectin and laminin (Doucette, 1996; Kafitz and Greer, 1997; Laurie et al., 1983; Lein and Higgins, 1991; Ramon-Cueto and Nieto-Sampedro, 1992). We have recently identified LEPRE1, a leucine-proline enriched proteoglycan, and NID2, and adhesive protein that binds collagen types I, IV and laminin, (Fox et al., 2008; Kohfeldt et al., 1998; Mayer et al., 1998; Roet et al., 2013; Wassenhove-McCarthy and McCarthy, 1999) as two other basement membrane proteins expressed in OB-OECs and important for neurite growth (Roet et al., 2013). Knockdown of LEPRE1 and NID2 in OBOECs in our “Cellomics” screen reduced their neurite growth promoting capacity whereas overexpression of LEPRE1 in skin fibroblasts significantly increased the neurite length of adult DRG neurons. The gene expression profiling studies have shown that OB-OECs express many matrix proteases and matrix protease inhibitors (Franssen et al., 2008; Pastrana et al., 2006). Matrix proteases can digest and neutralize non-permissive matrix molecules and thereby also remove attached axon growth inhibitory molecules. Matrix protease inhibitors can protect permissive substrates by blocking the function of matrix proteases or they can help guide axonal growth by protecting non-permissive substrates. MMP2 and ADAMTS1, two matrix metalloproteases are important for the outgrowth promoting properties of OB-OECs (Pastrana et al., 2006; Roet et al., 2013). ADAMTS1 activity can release the repulsive axon guidance molecule SEMA3C, an inhibitory protein present in the neural scar, from the extracellular matrix (De Winter et al., 2002; Esselens et al., 2010; Russell et al., 2003; Steup et al., 2000). Overexpression of the matrix metalloprotease 2 (MMP2) inhibitor TIMP2 in skin fibroblasts inhibited neurite outgrowth (Roet et al., 2013). OB-OECs also express at least 6 members of the serine protease inhibitor gene family (SERPINB6b, SERPINE1, SERPINF1, SERPING1, SERPINH1, SERPINI1) (Franssen et al., 2008; Simon et al., 2011). Knockdown of SERPINI1 and SERPINF1 decreases neurite outgrowth of co-cultured DRG neurons (Roet et al., 2013). SERPINI1 is an inhibitor of PLAT/tPA which is expressed in neurons and glia, plays a prominent role in regulating neuroplasticity and synaptogenesis (Gveric et al., 2003; Miranda and Lomas, 2006; Samson and Medcalf, 2006) and which together with several other members of the fibrinolysis system, SERPINE1, SERPINF1, PAR1 and THBD, has been implicated in neural repair (Roet et al., 2013; Simon et al., 2011; Tanimoto et al., 2006; Yamagishi et al., 2009). In summary, the gene expression profiles observed in OB-OECs clearly indicate that these cells organize the extracellular matrix. The net-effect of the action of proteases and their inhibitors on neural repair will be very much dependent on the composition of the extracellular substrate and the presence and localization of additional signaling molecules. Since these components are also strongly influenced by neighboring cell types, including fibroblasts, astrocytes and blood-borne cells that are present at a neural injury site, translatable functional

P

503 504

549 550

D

501 502

The co-expression of axon guidance molecule receptors, axon guidance molecules and neurotrophic/growth factors and their receptors allows for autocrine and paracrine signaling. The examples presented above indicate the importance of this balanced expression for neural repair and suggest that their repair-promoting properties can be regulated by their own signaling molecules as well as by those from neighboring OECs or other cells.

T

499 500

C

497 498

E

495 496

R

493 494

R

491 492

O

490

C

488 489

N

486 487

to cells as well as cholesterol efflux by high affinity binding of high density lipoprotein (HDL) (Eckhardt et al., 2004; Ji et al., 1997; Kozarsky et al., 1997; Mulcahy et al., 2004) and which transports GBA from the endoplasmic reticulum to the lysosome (Reczek et al., 2007). SCARB2 expression is upregulated in the ONL immediately after a lesion, and remains high during the ingrowth of newly formed axons, knockdown of SCARB2 in OB-OECs decreases neurite growth of co-cultured embryonic DRG neurons and overexpression of SCARB2 in skin fibroblasts increases neurite outgrowth of adult DRG neurons in vitro (Roet et al., 2013). Although the mode of action of SCARB2 still needs to be determined, considering SCARB2's known functions, it is most likely related to lipid transfer mechanisms. Such mechanisms are important for rapid axon membrane biosynthesis during regeneration after a nerve injury (Boyles et al., 1989; Jurevics et al., 1998; Li et al., 2010a) and cholesterol-containing lipoproteins secreted by glia can strongly enhance neurite outgrowth and synapse formation of cultured retinal ganglion cells and dorsal root ganglion neurons (Handelmann et al., 1992; Hayashi et al., 2004; Mauch et al., 2001), a process which is mediated through the low density lipid receptor family on the neuronal processes. It is known that damage to the peripheral or central nervous system leads to the synthesis of proteins involved in lipid and cholesterol metabolism (Dawson et al., 1986; Ignatius et al., 1986; Mahley, 1988; Seitz et al., 2003) and that pharmacological or genetic interference with local cholesterol reutilization decreases axonal outgrowth (Goodrum et al., 2000). Since OECs normally guide and stimulate regrowing olfactory axons towards their targets, they are perfectly positioned to provide lipids necessary for this growth and it is therefore likely that there are molecular mechanisms in OECs that regulate this process.

U

484 485

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

E

10

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

551 552 553 554 555

558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 Q9 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

613 insights will require the studies in relevant in vivo lesion paradigms (see 614 Q10 Animal studies).

637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675

Stimulation of angiogenesis Several studies have reported increased angiogenesis in vivo after transplantation of LP-OECs or OB-OECs (Lopez-Vales et al., 2004; Ramer et al., 2004; Richter et al., 2005). To date, the molecules responsible for these effects have not been identified in functional studies. However, 55 genes were identified that have been linked to blood vessel development and that are differentially regulated in OB-OECs in ≥3 microarray datasets (Roet et al., 2011). SMAD7 was identified as a HUB gene in the blood vessel development molecular interaction network and was directly functionally connected to 8 other genes in this network. Of particular interest are also ESM1, CYR61 and ANGPT2, which showed an average 38.7, 7.2, and 5.4 fold higher expression in OBOECs respectively. ESM1 mediates VEGF-A induced angiogenesis (Roudnicky et al., 2013) and CYR61 is a secreted protein and potent stimulator of angiogenesis that acts directly on endothelial cells (Brigstock, 2002). ANGPT2 promotes neovascularization (Asahara et al., 1998) and increased expression of ANGPT2 has been reported in GFAP and NG2 positive cells after a spinal cord injury and these expression levels were positively correlated with improved locomotor function (Durham-Lee et al., 2012). Amelioration of the immune system Two secreted and by OEC expressed immune-modulatory proteins, CX3CL1 and S100A9 (Roet et al., 2013; Ruitenberg et al., 2008), stimulated outgrowth of DRG neurons and knockdown of a third immunemodulatory protein, TGFB2, resulted in decreased neurite length in the “Cellomics” screen, suggesting that it supports neurite extension. CX3CL1, a cytokine also known as fractalkine, is predominantly expressed by neurons (Verge et al., 2004) and its receptor, CX3CR1, is expressed by microglia and astrocytes as well as in several types of neurons (Hughes et al., 2002; Meucci et al., 1998; Verge et al., 2004). There are strong indications that CX3CR1 expression in microglia protects against microglial and macrophage neurotoxicity (Cardona et al., 2006; Holmes et al., 2008) and CX3CL1 expressed by OECs can therefore have a direct or indirect protective effect on neurons. TNF is functionally connected to 13 of the 19 genes that affect neurite outgrowth in the “Cellomics” screen. This suggests a central role for TNF in the repair promoting molecular properties of OB-OECs. TNF can induce the expression of ADAMTS1, CX3CL1, MSLN, NCAM1,

697 698

O

F

ATP hydrolysis The ecto-ATPase ENTPD2 is highly expressed in early passage OBOECs in 5 published microarray datasets (Roet et al., 2011). This expression has been confirmed by ICC and IHC (unpublished data). EctoATPases are membrane-associated enzymes that hydrolyse extracellular ATP and have a role in extracellular ATP homeostasis. High levels of ATP released from cells in following tissue damage leads to an increase of calcium in the cytosol and cell death (Verderio and Matteoli, 2001; Wang et al., 2004). Ecto-ATPases are upregulated after damage to the nervous system and decrease toxic ATP levels which, depending on the specificity of the Ecto-ATPase, can result in an increase of neuroprotective ADP (Abbracchio et al., 2009; Braun et al., 1998; Schubert and Kreutzberg, 1993). ENTPD2 preferentially hydrolyzes ATP, not ADP (Braun et al., 1998). Therefore the detection of ENTPD2 in the metaanalysis has led to the hypothesis that ENTPD2 expression by OB-OECs could have a significant impact on cell survival and tissue repair observed following transplantation of these cells in the brain and spinal cord. There are two major classes of ATP receptors, P2X (ion channels; 7 subtypes) and P2Y (G protein-coupled; 8 subtypes) receptors (Abbracchio et al., 2006; Burnstock and Kennedy, 1985; Erlinge and Burnstock, 2008). These ATP-receptor variants are found on a number of different cell types, including neurons, astrocytes, microglia, epithelial cells, immune cells and platelets and are involved in several processes, such as neurotransmission, inflammation, proliferation, apoptosis and migration (Burnstock, 2008). Application of antagonists for the ATP P2X7 receptor can improve behavioral recovery, reduce gliosis and diminish the immune response after a spinal cord injury (Peng et al., 2009). Moreover, administration of P2X3/X2X3, P2X4 and P2X7 antagonists has been shown to reduce nociceptive signaling (Chu et al., 2010; Inoue et al., 2005; Jarvis et al., 2002). A reduction in nociception was also observed after implantation of LP-OECs in a dorsal root injury model (Wu et al., 2011a). There are also a number of studies that link ATP signaling to ALS. P2X7 receptor expression is increased in activated microglial/macrophage like cells in human disease affected dorsolateral white matter regions (Yiangou et al., 2006). Astrocytes derived from SOD1G93A rats (ALS model) are toxic for motor neurons, however, pharmacological inhibition of the P2X7 receptors on these astrocytes abolishes this toxicity whereas stimulation of the P2X7 receptor induces a neurotoxic state in wild type astrocytes which induces death of motor neurons (Gandelman et al., 2010). Another study on SOD1G93A rats reported a strong increase of the ATP receptor P2X4 in degenerating motor neurons in the ventral horn of the spinal cord (Casanovas et al., 2008). These neurons appeared to recruit activated microglia and showed a

R O

635 636

P

633 634

676 677

D

631 632

NRP1, RND1 and TGFB2 (Ahn et al., 2004; Giraudo et al., 1998; Hatipoglu et al., 2009; Scotto d'Abusco et al., 2007; Sivasubramanian et al., 2001; Vargas et al., 1994; Zer et al., 2007) and it suppresses the expression of LPL, RARA, SERPINF1 and TIMP2 (Geier et al., 2005; Halin et al., 2010; Kawasaki et al., 2010; Watari et al., 1999). Moreover, TNF induces NFKB, which interacts with VAV1 (Houlard et al., 2002; Yu et al., 2008) and S100A9/S100A8 dimers induce TNF secretion which can lead to enhanced NGF secretion by fibroblasts (Hattori et al., 1993; Sunahori et al., 2006). Our microarray data shows that several TNF receptors including TNFRSF1A are expressed in cultured OB-OECs and are upregulated in the ONL directly after lesion (data not shown). TNF is secreted by reactive astrocytes after a spinal cord lesion and can stimulate OEC migration in a dose depending manner (Su et al., 2009). Blocking TNFRSF1A in vitro or in the lesioned spinal cord has been shown to attenuate OB-OEC migration (Su et al., 2009). The data presented in this study together with the available literature suggests that TNF signaling not only enhances OEC migration but also can activate a number of genes in OECs that promote neurite outgrowth. This may help to ameliorate the well-documented negative effects of TNF after a spinal cord lesion (Beattie et al., 2010; Esposito and Cuzzocrea, 2011).

E

629 630

T

627 628

C

625 626

E

623 624

R

621 622

R

619 620

N C O

617 618

Formation of a structural cellular pathway The formation of the fascicle-like cellular tunnels formed by OECs in the olfactory nerve provides a permissive pathway for axon growth (Boyd et al., 2005; Raisman and Li, 2007; Windus et al., 2007) and requires reorganization of the cytoskeleton. It has been shown that the persistence of these cellular protrusions is dependent on the activity of the actin regulating RHOA pathway (Huang et al., 2011). Two of the proteins that were identified in the “Cellomics” screen, RND1 and VAV1 (Roet et al., 2013), are also proteins that regulate cytoskeletal remodeling (Hornstein et al., 2004; Riou et al., 2010) and the formation of cellular protrusions (Ishikawa et al., 2003; Spurrell et al., 2009). VAV1 is an important component of a signaling pathway that regulates focal adhesion kinase (FAK) (Spurrell et al., 2009), and ITGA7, another hit in the knock-down screen, also interacts with FAK (Chernousov et al., 2007). The cell adhesion molecules ITGA7 and MSLN (Roet et al., 2013) may also play a role in reorganization of the glial scar. OB-OECs express several other genes with well-defined roles in cytoskeletal (re)organization, process formation and cell motility, including MAP1B, MAP2, NEFL and APP (Moreno-Flores et al., 2003; Roet et al., 2011). APP has also been identified as a HUB gene in a molecular network of neurite outgrowth associated molecules (Roet et al., 2011) and these findings emphasize the importance of the cytoskeletal organization for neural repair.

U

615 616

11

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696

699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740

789

Animal studies

790 791

Gene expression profiling and proteomics followed by gene ontology and/or pathway analysis and high content cellular screening will narrow down the most promising set of molecular targets involved in OECmediated repair. To establish the function and therapeutic value of a gene in the OEC-mediated neural repair process it is still necessary to examine this in-vivo in an animal model for a nervous system pathology and neural transplantation. These studies may include transgenic animals, viral-vector mediated gene delivery and/or systemic or local administration of specific agonists or antagonists or compounds. The function of SPARC (identified in a proteomics screen discussed above) was studied in vivo by isolating and transplanting LP-OECs from SPARC null mutant mice and wild-type mice (Au et al., 2007). The mice that received LP-OECs deficient in SPARC showed a reduction in

769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786

792 793 794 795 796 797 798 799 800 801 802

C

767 768

E

765 766

R

763 764

R

761 762

O

760

C

758 759

N

756 757

U

754 755

F

787 788

In total, the role of 102 genes was examined with a loss of function approach in co-cultures of OB-OECs and embryonic DRG in the “Cellomics” screen (Roet et al., 2013). Ten of the 19 genes that significantly affected neurite length were selected for gain of function studies in fibroblast-adult DRG co-culture assays. Of these 10 genes, overexpression of 5 genes significantly increased neurite length. In addition, 13 genes that did not affect neurite length in the loss of function assays were selected for the gain of function assays based on pre-existing knowledge about their function and their regulation after peripheral deafferentation of the olfactory nerve layer. Of these 13 genes, only 1 gene significantly increased neurite length. Thus, 50% of the genes detected in the loss-of-function screen had also an effect on neurite outgrowth in the gain-of function screen, while only 8% of the genes that had no effect on neurite length after knockdown in OECs showed an increase of neurite length after overexpression in fibroblasts. These data suggest that selecting candidate genes for the overexpression screen via a large knock-down screen increased the success rate of the gain of function screen approximately six fold. Although the success rate in the overexpression screen was higher when candidate genes were chosen based on the loss of function screen, half of the genes that had an effect in the loss of function screen had no effect on neurite outgrowth in the gain of function bioassays. We noticed this for ADAMTS1, BM385941, MSLN, RND1 and VAV1. There are several factors that may explain this (Holtmaat et al., 1998). First, different cell types were used for the loss and gain of function assays. It is possible that a number of the genes we investigated act on neurite outgrowth in a cell specific molecular pathways in either the OECs or the target neurons. For instance, it is known that DRG neurons become sensitive for myelin inhibition between postnatal days 1 and 5 and that this change coincides with a drop in intracellular cAMP levels (Cai et al., 2001; Mukhopadhyay et al., 1994). Second, the mechanism by which a gene can stimulate neurite outgrowth may be dependent on coexpression of other genes. Absence of a gene will then affect neurite outgrowth more strongly than overexpression (Feldman and Randolph, 1991). Third, the endogenous expression level of the gene may have already reached a maximum effect on neurite outgrowth so that overexpression is not effective anymore.

748 749

O

752 753

747

R O

Loss of function versus gain of function cellular screening

745 746

803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820

From bioassay to in vivo study: a big step with many uncertainties

821

In our multi-level screening study, the function of S100A9, SCARB2 and SERPINI1 was selected for functional validation in the lesioned rat dorsal column (Roet et al., 2013). These genes were selected because they had strong effects on neurite outgrowth in both the loss of function and gain of function bioassays. Overexpression of these 3 genes in fibroblasts resulted in a robust increase of neurite length of cultured adult DRG neurons. Ex vivo gene delivery of SCARB2 resulted in a significant increase of regenerating dorsal column fibers in vivo but overexpression of S100A9 and SERPINI1 did not. There are several possible reasons for the absence of an effect of S100A9 and SERPINI1. The circumstances in the in vivo situation are very different from those in the bioassay used to identify these genes. A spinal cord injury site constitutes a complex cellular microenvironment that contains many molecular signals not present in the simplified bioassay. Reactive astrocytes, activated microglia, infiltrating macrophages and endogenous SCs could change the molecular profile of the implanted fibroblasts or may modify the signaling pathways in the regenerating axons (Leal-Filho, 2011; Schwab et al., 2006; Thuret et al., 2006; Wu et al., 2011b). In the bioassay the fibroblasts were in direct contact with the cell bodies and the axons of the DRG neurons while in the spinal cord the transduced fibroblast was transplanted in the vicinity of the transected axons. Finally, the overexpressed proteins can also have unintentional effects on cells in the lesioned spinal cord. For instance, S100A9 is involved in a variety of inflammatory processes and can stimulate cytokine production in macrophages (Averill et al., 2011; Gebhardt et al., 2006; Sunahori et al., 2006). Taken together, our results highlight the challenge to translate observations made in bioassays to the actual situation in the injured nervous system in vivo.

822

Perspective on OEC research

850

OECs are cells that harness an impressive neural repair-promoting potential that can be useful to promote repair in a number of neuropathological conditions. By using the technical advances that have been made in transcriptome and proteome analysis, bioinformatics, highthroughput microscopy, image analysis and robotics, a much more profound understanding of the specific molecular mechanisms that form the basis of the synergistic pro-regenerative properties of OECs can now be realized. Although many cell types may promote axon growth, and/or stimulate angiogenesis, and/or have phagocytic properties and/ or secrete growth factors, the uniqueness of OECs appears to be that the molecular pathways for many of these processes are present and act in a coordinated fashion in one cell type, that is the OEC (Fig. 1). A profound understanding of the different molecular pathways that are present in OECs and the accompanying functional phenotypes will

851

P

751

743 744

outgrowth of specific subsets of axons and a decrease in the number of ED1 positive macrophages at the lesion site when compared to those that received wild-type OECs. OB-OECs normally express brain derived neurotrophic factor in small amounts (Woodhall et al., 2001). However, adult OB-OECs genetically modified to over-express brain derived neurotrophic factor showed enhanced regenerative sprouting of the rubrospinal tract and improved functional recovery after implantation in the lesioned rat dorsolateral funiculus (Ruitenberg et al., 2003). SCARB2 was identified as an important factor for the neurite growth promoting properties of OB-OECs in the multi-step screening approach discussed above (Roet et al., 2013). Implantation of skin fibroblasts that overexpress SCARB2 in rats concomitant a dorsal funiculus lesion resulted in enhanced neuronal sprouting towards the lesion center. These results suggest that at least part of the pro-regenerative properties of OECs can be transferred to less permissive cellular substrates. These studies demonstrate that it is possible to investigate the role of specific molecules in the pro-regenerative properties of OECs in the complex physiological context of a spinal cord injury.

T

750

downregulation of the neuronal marker NeuN. It has been shown that implantation of OECs in the spinal cord of this same rat model increases the survival of the animals through neuroprotection and by increasing remyelination (Li et al., 2011). These effects may partly be mediated by hydrolysis of extracellular ATP which would decrease P2X4 signaling in motor neurons and P2X7 signaling in astrocytes and microglia. Taken together, the hydrolysis of high levels of toxic extracellular ATP by the ecto-ATPase ENTPD2 expressed by OB-OECs may be an important newly discovered neuro-protective property of OECs which can be relevant for treatment of spinal cord injuries and ALS.

D

741 742

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

E

12

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849

852 853 854 855 856 857 858 859 860 861 862 863 864

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

C

E

R

R

N C O

U

F

874 875

O

Abbracchio, M.P., Burnstock, G., Boeynaems, J.M., Barnard, E.A., Boyer, J.L., Kennedy, C., Knight, G.E., Fumagalli, M., Gachet, C., Jacobson, K.A., Weisman, G.A., 2006. International Union of Pharmacology LVIII: update on the P2Y G protein-coupled nucleotide receptors: from molecular mechanisms and pathophysiology to therapy. Pharmacol. Rev. 58, 281–341. Abbracchio, M.P., Burnstock, G., Verkhratsky, A., Zimmermann, H., 2009. Purinergic signalling in the nervous system: an overview. Trends Neurosci. 32, 19–29. Agrawal, A.K., Shukla, S., Chaturvedi, R.K., Seth, K., Srivastava, N., Ahmad, A., Seth, P.K., 2004. Olfactory ensheathing cell transplantation restores functional deficits in rat model of Parkinson's disease: a cotransplantation approach with fetal ventral mesencephalic cells. Neurobiol. Dis. 16, 516–526. Ahn, S.Y., Cho, C.H., Park, K.G., Lee, H.J., Lee, S., Park, S.K., Lee, I.K., Koh, G.Y., 2004. Tumor necrosis factor-alpha induces fractalkine expression preferentially in arterial endothelial cells and mithramycin A suppresses TNF-alpha-induced fractalkine expression. Am. J. Pathol. 164, 1663–1672. Asahara, T., Chen, D., Takahashi, T., Fujikawa, K., Kearney, M., Magner, M., Yancopoulos, G. D., Isner, J.M., 1998. Tie2 receptor ligands, angiopoietin-1 and angiopoietin-2, modulate VEGF-induced postnatal neovascularization. Circ. Res. 83, 233–240. Au, E., Richter, M.W., Vincent, A.J., Tetzlaff, W., Aebersold, R., Sage, E.H., Roskams, A.J., 2007. SPARC from olfactory ensheathing cells stimulates Schwann cells to promote neurite outgrowth and enhances spinal cord repair. J. Neurosci. 27, 7208–7221. Averill, M.M., Barnhart, S., Becker, L., Li, X., Heinecke, J.W., Leboeuf, R.C., Hamerman, J.A., Sorg, C., Kerkhoff, C., Bornfeldt, K.E., 2011. S100A9 differentially modifies phenotypic states of neutrophils, macrophages, and dendritic cells: implications for atherosclerosis and adipose tissue inflammation. Circulation 123, 1216–1226. Babiarz, J., Kane-Goldsmith, N., Basak, S., Liu, K., Young, W., Grumet, M., 2011. Juvenile and adult olfactory ensheathing cells bundle and myelinate dorsal root ganglion axons in culture. Exp. Neurol. 229, 72–79. Barakat, D.J., Gaglani, S.M., Neravetla, S.R., Sanchez, A.R., Andrade, C.M., Pressman, Y., Puzis, R., Garg, M.S., Bunge, M.B., Pearse, D.D., 2005. Survival, integration, and axon growth support of glia transplanted into the chronically contused spinal cord. Cell Transplant. 14, 225–240. Barbour, H.R., Plant, C.D., Harvey, A.R., Plant, G.W., 2013. Tissue sparing, behavioral recovery, supraspinal axonal sparing/regeneration following sub-acute glial transplantation in a model of spinal cord contusion. BMC Neurosci. 14, 106. Barraud, P., Seferiadis, A.A., Tyson, L.D., Zwart, M.F., Szabo-Rogers, H.L., Ruhrberg, C., Liu, K. J., Baker, C.V., 2010. Neural crest origin of olfactory ensheathing glia. Proc. Natl. Acad. Sci. U. S. A. 107, 21040–21045. Beattie, M.S., Ferguson, A.R., Bresnahan, J.C., 2010. AMPA-receptor trafficking and injuryinduced cell death. Eur. J. Neurosci. 32, 290–297. Blackmore, M.G., 2012. Molecular control of axon growth: insights from comparative gene profiling and high-throughput screening. Int. Rev. Neurobiol. 105, 39–70. Blackmore, M.G., Moore, D.L., Smith, R.P., Goldberg, J.L., Bixby, J.L., Lemmon, V.P., 2010. High content screening of cortical neurons identifies novel regulators of axon growth. Mol. Cell. Neurosci. 44, 43–54. Boruch, A.V., Conners, J.J., Pipitone, M., Deadwyler, G., Storer, P.D., Devries, G.H., Jones, K.J., 2001. Neurotrophic and migratory properties of an olfactory ensheathing cell line. Glia 33, 225–229. Boyd, J.G., Doucette, R., Kawaja, M.D., 2005. Defining the role of olfactory ensheathing cells in facilitating axon remyelination following damage to the spinal cord. FASEB J. 19, 694–703. Boyles, J.K., Zoellner, C.D., Anderson, L.J., Kosik, L.M., Pitas, R.E., Weisgraber, K.H., Hui, D.Y., Mahley, R.W., Gebicke-Haerter, P.J., Ignatius, M.J., et al., 1989. A role for apolipoprotein E, apolipoprotein A-I, and low density lipoprotein receptors in cholesterol transport during regeneration and remyelination of the rat sciatic nerve. J. Clin. Invest. 83, 1015–1031. Braun, N., Zhu, Y., Krieglstein, J., Culmsee, C., Zimmermann, H., 1998. Upregulation of the enzyme chain hydrolyzing extracellular ATP after transient forebrain ischemia in the rat. J. Neurosci. 18, 4891–4900. Brigstock, D.R., 2002. Regulation of angiogenesis and endothelial cell function by connective tissue growth factor (CTGF) and cysteine-rich 61 (CYR61). Angiogenesis 5, 153–165. Burnstock, G., 2008. Purinergic signalling and disorders of the central nervous system. Nat. Rev. Drug Discov. 7, 575–590. Burnstock, G., Kennedy, C., 1985. Is there a basis for distinguishing two types of P2-purinoceptor? Gen. Pharmacol. 16, 433–440.

872 873

R O

878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943

871

P

References

869 870

Cai, D., Qiu, J., Cao, Z., McAtee, M., Bregman, B.S., Filbin, M.T., 2001. Neuronal cyclic AMP controls the developmental loss in ability of axons to regenerate. J. Neurosci. 21, 4731–4739. Cardona, A.E., Pioro, E.P., Sasse, M.E., Kostenko, V., Cardona, S.M., Dijkstra, I.M., Huang, D., Kidd, G., Dombrowski, S., Dutta, R., Lee, J.C., Cook, D.N., Jung, S., Lira, S.A., Littman, D.R., Ransohoff, R.M., 2006. Control of microglial neurotoxicity by the fractalkine receptor. Nat. Neurosci. 9, 917–924. Casanovas, A., Hernandez, S., Tarabal, O., Rossello, J., Esquerda, J.E., 2008. Strong P2X4 purinergic receptor-like immunoreactivity is selectively associated with degenerating neurons in transgenic rodent models of amyotrophic lateral sclerosis. J. Comp. Neurol. 506, 75–92. Chernousov, M.A., Kaufman, S.J., Stahl, R.C., Rothblum, K., Carey, D.J., 2007. Alpha7beta1 integrin is a receptor for laminin-2 on Schwann cells. Glia 55, 1134–1144. Chu, Y.X., Zhang, Y., Zhang, Y.Q., Zhao, Z.Q., 2010. Involvement of microglial P2X7 receptors and downstream signaling pathways in long-term potentiation of spinal nociceptive responses. Brain Behav. Immun. 24, 1176–1189. Chuah, M.I., Hale, D.M., West, A.K., 2011. Interaction of olfactory ensheathing cells with other cell types in vitro and after transplantation: glial scars and inflammation. Exp. Neurol. 229, 46–53. Costanzo, R.M., 1985. Neural regeneration and functional reconnection following olfactory nerve transection in hamster. Brain Res. 361, 258–266. Dawson, P.A., Schechter, N., Williams, D.L., 1986. Induction of rat E and chicken A-I apolipoproteins and mRNAs during optic nerve degeneration. J. Biol. Chem. 261, 5681–5684. de Corgnol, A.C., Guerout, N., Duclos, C., Verin, E., Marie, J.P., 2011. Olfactory ensheathing cells in a rat model of laryngeal reinnervation. Ann. Otol. Rhinol. Laryngol. 120, 273–280. De Winter, F., Oudega, M., Lankhorst, A.J., Hamers, F.P., Blits, B., Ruitenberg, M.J., Pasterkamp, R.J., Gispen, W.H., Verhaagen, J., 2002. Injury-induced class 3 semaphorin expression in the rat spinal cord. Exp. Neurol. 175, 61–75. Devon, R., Doucette, R., 1992. Olfactory ensheathing cells myelinate dorsal root ganglion neurites. Brain Res. 589, 175–179. Doucette, R., 1990. Glial influences on axonal growth in the primary olfactory system. Glia 3, 433–449. Doucette, R., 1991. PNS–CNS transitional zone of the first cranial nerve. J. Comp. Neurol. 312, 451–466. Doucette, R., 1996. Immunohistochemical localization of laminin, fibronectin and collagen type IV in the nerve fiber layer of the olfactory bulb. Int. J. Dev. Neurosci. 14, 945–959. Doucette, R., Devon, R., 1995. Elevated intracellular levels of cAMP induce olfactory ensheathing cells to express GAL-C and GFAP but not MBP. Glia 13, 130–140. Doucette, J.R., Kiernan, J.A., Flumerfelt, B.A., 1983. The re-innervation of olfactory glomeruli following transection of primary olfactory axons in the central or peripheral nervous system. J. Anat. 137 (Pt 1), 1–19. Durham-Lee, J.C., Wu, Y., Mokkapati, V.U., Paulucci-Holthauzen, A.A., Nesic, O., 2012. Induction of angiopoietin-2 after spinal cord injury. Neuroscience 202, 454–464. Eckhardt, E.R., Cai, L., Sun, B., Webb, N.R., van der Westhuyzen, D.R., 2004. High density lipoprotein uptake by scavenger receptor SR-BII. J. Biol. Chem. 279, 14372–14381. Erlinge, D., Burnstock, G., 2008. P2 receptors in cardiovascular regulation and disease. Purinergic Signal 4, 1–20. Esposito, E., Cuzzocrea, S., 2011. Anti-TNF therapy in the injured spinal cord. Trends Pharmacol. Sci. 32, 107–115. Esselens, C., Malapeira, J., Colome, N., Casal, C., Rodriguez-Manzaneque, J.C., Canals, F., Arribas, J., 2010. The cleavage of semaphorin 3C induced by ADAMTS1 promotes cell migration. J. Biol. Chem. 285, 2463–2473. Fairless, R., Frame, M.C., Barnett, S.C., 2005. N-cadherin differentially determines Schwann cell and olfactory ensheathing cell adhesion and migration responses upon contact with astrocytes. Mol. Cell. Neurosci. 28, 253–263. Feldman, E.L., Randolph, A.E., 1991. Mannose 6-phosphate potentiates insulin-like growth factor II effects in cultured human neuroblastoma cells. Brain Res. 562, 111–116. Feron, F., Perry, C., Cochrane, J., Licina, P., Nowitzke, A., Urquhart, S., Geraghty, T., MackaySim, A., 2005. Autologous olfactory ensheathing cell transplantation in human spinal cord injury. Brain 128, 2951–2960. Field, P., Li, Y., Raisman, G., 2003. Ensheathment of the olfactory nerves in the adult rat. J. Neurocytol. 32, 317–324. Fox, M.A., Ho, M.S., Smyth, N., Sanes, J.R., 2008. A synaptic nidogen: developmental regulation and role of nidogen-2 at the neuromuscular junction. Neural Dev. 3, 24. Franklin, R.J., Gilson, J.M., Franceschini, I.A., Barnett, S.C., 1996. Schwann cell-like myelination following transplantation of an olfactory bulb-ensheathing cell line into areas of demyelination in the adult CNS. Glia 17, 217–224. Franssen, E.H., de Bree, F.M., Verhaagen, J., 2007. Olfactory ensheathing glia: their contribution to primary olfactory nervous system regeneration and their regenerative potential following transplantation into the injured spinal cord. Brain Res. Rev. 56, 236–258. Franssen, E.H., De Bree, F.M., Essing, A.H., Ramon-Cueto, A., Verhaagen, J., 2008. Comparative gene expression profiling of olfactory ensheathing glia and Schwann cells indicates distinct tissue repair characteristics of olfactory ensheathing glia. Glia 56, 1285–1298. Franssen, E.H., Roet, K.C., de Bree, F.M., Verhaagen, J., 2009. Olfactory ensheathing glia and Schwann cells exhibit a distinct interaction behavior with meningeal cells. J. Neurosci. Res. 87, 1556–1564. Gamez, J., Carmona, F., Raguer, N., Ferrer-Sancho, J., Martin-Henao, G.A., Marti-Beltran, S., Badia, M., Gratacos, M., Rodriguez-Gonzalez, E., Seoane, J.L., Pallero-Castillo, M., Burgos, R., Puiggros, C., Pasarin, A., Bori-Fortuny, I., 2010. Cellular transplants in amyotrophic lateral sclerosis patients: an observational study. Cytotherapy 12, 669–677. Gandelman, M., Peluffo, H., Beckman, J.S., Cassina, P., Barbeito, L., 2010. Extracellular ATP and the P2X7 receptor in astrocyte-mediated motor neuron death: implications for amyotrophic lateral sclerosis. J. Neuroinflammation 7, 33.

D

877

867 868

T

876

also be important for the selection of the appropriate OEC subtype (e.g. OB- or LP-OECs) for specific clinical applications. The hypotheses that will and have already resulted from this emerging integrated biological analysis can be tested in vivo e.g. by investigating the efficacy of modified OEC or other cellular implants in spinal lesions or other neuropathologies. We predict that this will lead to 1. Important new molecular insights in the mechanisms that govern successful regeneration; 2. Methods to further enhance the therapeutic potential of OECs perhaps to a level that is sufficient to merit further clinic application; and 3. The possibility to transfer certain neural repair promoting properties of OECs to other cell types and tissues (e.g. Schwann cells or bone marrow stromal cells) that are used to promote neural repair.

E

865 866

13

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029

D

P

R O

O

F

Imaizumi, T., Lankford, K.L., Burton, W.V., Fodor, W.L., Kocsis, J.D., 2000a. Xenotransplantation of transgenic pig olfactory ensheathing cells promotes axonal regeneration in rat spinal cord. Nat. Biotechnol. 18, 949–953. Imaizumi, T., Lankford, K.L., Kocsis, J.D., Sasaki, M., Akiyama, Y., Hashi, K., 2000b. Comparison of myelin-forming cells as candidates for therapeutic transplantation in demyelinated CNS axons. No To Shinkei 52, 609–615. Inoue, K., Tsuda, M., Koizumi, S., 2005. ATP receptors in pain sensation: Involvement of spinal microglia and P2X(4) receptors. Purinergic Signal 1, 95–100. Ishikawa, Y., Katoh, H., Negishi, M., 2003. A role of Rnd1 GTPase in dendritic spine formation in hippocampal neurons. J. Neurosci. 23, 11065–11072. Jarvis, M.F., Burgard, E.C., McGaraughty, S., Honore, P., Lynch, K., Brennan, T.J., Subieta, A., Van Biesen, T., Cartmell, J., Bianchi, B., Niforatos, W., Kage, K., Yu, H., Mikusa, J., Wismer, C.T., Zhu, C.Z., Chu, K., Lee, C.H., Stewart, A.O., Polakowski, J., Cox, B.F., Kowaluk, E., Williams, M., Sullivan, J., Faltynek, C., 2002. A-317491, a novel potent and selective non-nucleotide antagonist of P2X3 and P2X2/3 receptors, reduces chronic inflammatory and neuropathic pain in the rat. Proc. Natl. Acad. Sci. U. S. A. 99, 17179–17184. Ji, Y., Jian, B., Wang, N., Sun, Y., Moya, M.L., Phillips, M.C., Rothblat, G.H., Swaney, J.B., Tall, A.R., 1997. Scavenger receptor BI promotes high density lipoprotein-mediated cellular cholesterol efflux. J. Biol. Chem. 272, 20982–20985. Jing, S., Wen, D., Yu, Y., Holst, P.L., Luo, Y., Fang, M., Tamir, R., Antonio, L., Hu, Z., Cupples, R., Louis, J.C., Hu, S., Altrock, B.W., Fox, G.M., 1996. GDNF-induced activation of the ret protein tyrosine kinase is mediated by GDNFR-alpha, a novel receptor for GDNF. Cell 85, 1113–1124. Johansson, S., Lee, I.H., Olson, L., Spenger, C., 2005. Olfactory ensheathing glial co-grafts improve functional recovery in rats with 6-OHDA lesions. Brain 128, 2961–2976. Jurevics, H., Bouldin, T.W., Toews, A.D., Morell, P., 1998. Regenerating sciatic nerve does not utilize circulating cholesterol. Neurochem. Res. 23, 401–406. Kafitz, K.W., Greer, C.A., 1997. Role of laminin in axonal extension from olfactory receptor cells. J. Neurobiol. 32, 298–310. Kawasaki, M., Miura, Y., Yagasaki, K., 2010. Effects of sulfur amino acids, L: -methionine, L: -cystine and L: -cysteine on lipoprotein lipase and hormone-sensitive lipase in differentiated mouse 3T3-L1 adipocytes. Cytotechnology 62, 225–233. Kohfeldt, E., Sasaki, T., Gohring, W., Timpl, R., 1998. Nidogen-2: a new basement membrane protein with diverse binding properties. J. Mol. Biol. 282, 99–109. Kolodkin, A.L., Levengood, D.V., Rowe, E.G., Tai, Y.T., Giger, R.J., Ginty, D.D., 1997. Neuropilin is a semaphorin III receptor. Cell 90, 753–762. Kozarsky, K.F., Donahee, M.H., Rigotti, A., Iqbal, S.N., Edelman, E.R., Krieger, M., 1997. Overexpression of the HDL receptor SR-BI alters plasma HDL and bile cholesterol levels. Nature 387, 414–417. Lakatos, A., Franklin, R.J., Barnett, S.C., 2000. Olfactory ensheathing cells and Schwann cells differ in their in vitro interactions with astrocytes. Glia 32, 214–225. Lakatos, A., Barnett, S.C., Franklin, R.J., 2003. Olfactory ensheathing cells induce less host astrocyte response and chondroitin sulphate proteoglycan expression than Schwann cells following transplantation into adult CNS white matter. Exp. Neurol. 184, 237–246. Lamond, R., Barnett, S.C., 2013. Schwann cells but not olfactory ensheathing cells inhibit CNS myelination via the secretion of connective tissue growth factor. J. Neurosci. 33, 18686–18697. Laurie, G.W., Leblond, C.P., Martin, G.R., 1983. Light microscopic immunolocalization of type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin in the basement membranes of a variety of rat organs. Am. J. Anat. 167, 71–82. Leal-Filho, M.B., 2011. Spinal cord injury: from inflammation to glial scar. Surg. Neurol. Int. 2, 112. Leaver, S.G., Harvey, A.R., Plant, G.W., 2006. Adult olfactory ensheathing glia promote the long-distance growth of adult retinal ganglion cell neurites in vitro. Glia 53, 467–476. Lein, P.J., Higgins, D., 1991. Protein synthesis is required for the initiation of dendritic growth in embryonic rat sympathetic neurons in vitro. Brain Res. Dev. Brain Res. 60, 187–196. Leung, J.Y., Chapman, J.A., Harris, J.A., Hale, D., Chung, R.S., West, A.K., Chuah, M.I., 2008. Olfactory ensheathing cells are attracted to, and can endocytose, bacteria. Cell Mol. Life Sci. 65, 2732–2739. Li, Y., Field, P.M., Raisman, G., 1997. Repair of adult rat corticospinal tract by transplants of olfactory ensheathing cells. Science 277, 2000–2002. Li, Y., Sauve, Y., Li, D., Lund, R.D., Raisman, G., 2003. Transplanted olfactory ensheathing cells promote regeneration of cut adult rat optic nerve axons. J. Neurosci. 23, 7783–7788. Li, Y., Field, P.M., Raisman, G., 2005a. Olfactory ensheathing cells and olfactory nerve fibroblasts maintain continuous open channels for regrowth of olfactory nerve fibres. Glia 52, 245–251. Li, Y., Li, D., Raisman, G., 2005b. Interaction of olfactory ensheathing cells with astrocytes may be the key to repair of tract injuries in the spinal cord: the ‘pathway hypothesis’. J. Neurocytol. 34, 343–351. Li, F.Q., Fowler, K.A., Neil, J.E., Colton, C.A., Vitek, M.P., 2010a. An apolipoprotein E-mimetic stimulates axonal regeneration and remyelination after peripheral nerve injury. J. Pharmacol. Exp. Ther. 334, 106–115. Li, Y., Yu, H.L., Chen, L.F., Duan, C.X., Zhang, J.Y., Li, B.C., 2010b. Survival and number of olfactory ensheathing cells transplanted in contused spinal cord of rats. Chin. J. Traumatol. 13, 356–361. Li, Y., Bao, J., Khatibi, N.H., Chen, L., Wang, H., Duan, Y., Huang, H., Zhou, C., 2011. Olfactory ensheathing cell transplantation into spinal cord prolongs the survival of mutant SOD1(G93A) ALS rats through neuroprotection and remyelination. Anat. Rec. (Hoboken) 294, 847–857. Li, Y., Li, D., Ibrahim, A., Raisman, G., 2012. Repair involves all three surfaces of the glial cell. Prog. Brain Res. 201, 199–218. Li, Y., Chen, L., Zhao, Y., Bao, J., Xiao, J., Liu, J., Jiang, X., Zhou, C., Wang, H., Huang, H., 2013. Intracranial transplant of olfactory ensheathing cells can protect both upper and

N

C

O

R

R

E

C

T

Gebhardt, C., Nemeth, J., Angel, P., Hess, J., 2006. S100A8 and S100A9 in inflammation and cancer. Biochem. Pharmacol. 72, 1622–1631. Geeven, G., Macgillavry, H.D., Eggers, R., Sassen, M.M., Verhaagen, J., Smit, A.B., de Gunst, M.C., van Kesteren, R.E., 2011. LLM3D: a log-linear modeling-based method to predict functional gene regulatory interactions from genome-wide expression data. Nucleic Acids Res. 39, 5313–5327. Geier, A., Dietrich, C.G., Voigt, S., Ananthanarayanan, M., Lammert, F., Schmitz, A., Trauner, M., Wasmuth, H.E., Boraschi, D., Balasubramaniyan, N., Suchy, F.J., Matern, S., Gartung, C., 2005. Cytokine-dependent regulation of hepatic organic anion transporter gene transactivators in mouse liver. Am. J. Physiol. Gastrointest. Liver Physiol. 289, G831–G841. Geschwind, D.H., Konopka, G., 2009. Neuroscience in the era of functional genomics and systems biology. Nature 461, 908–915. Giordana, M.T., Grifoni, S., Votta, B., Magistrello, M., Vercellino, M., Pellerino, A., Navone, R., Valentini, C., Calvo, A., Chio, A., 2010. Neuropathology of olfactory ensheathing cell transplantation into the brain of two amyotrophic lateral sclerosis (ALS) patients. Brain Pathol. 20, 730–737. Giraudo, E., Primo, L., Audero, E., Gerber, H.P., Koolwijk, P., Soker, S., Klagsbrun, M., Ferrara, N., Bussolino, F., 1998. Tumor necrosis factor-alpha regulates expression of vascular endothelial growth factor receptor-2 and of its co-receptor neuropilin-1 in human vascular endothelial cells. J. Biol. Chem. 273, 22128–22135. Goodrum, J.F., Brown, J.C., Fowler, K.A., Bouldin, T.W., 2000. Axonal regeneration, but not myelination, is partially dependent on local cholesterol reutilization in regenerating nerve. J. Neuropathol. Exp. Neurol. 59, 1002–1010. Graziadei, P.P., Graziadei, G.A., 1979. Neurogenesis and neuron regeneration in the olfactory system of mammals. I. Morphological aspects of differentiation and structural organization of the olfactory sensory neurons. J. Neurocytol. 8, 1–18. Guerout, N., Derambure, C., Drouot, L., Bon-Mardion, N., Duclos, C., Boyer, O., Marie, J.P., 2010. Comparative gene expression profiling of olfactory ensheathing cells from olfactory bulb and olfactory mucosa. Glia 58, 1570–1580. Guerout, N., Paviot, A., Bon-Mardion, N., Duclos, C., Genty, D., Jean, L., Boyer, O., Marie, J.P., 2011. Co-transplantation of olfactory ensheathing cells from mucosa and bulb origin enhances functional recovery after peripheral nerve lesion. PLoS One 6, e22816. Gveric, D., Herrera, B., Petzold, A., Lawrence, D.A., Cuzner, M.L., 2003. Impaired fibrinolysis in multiple sclerosis: a role for tissue plasminogen activator inhibitors. Brain 126, 1590–1598. Halin, S., Rudolfsson, S.H., Doll, J.A., Crawford, S.E., Wikstrom, P., Bergh, A., 2010. Pigment epithelium-derived factor stimulates tumor macrophage recruitment and is downregulated by the prostate tumor microenvironment. Neoplasia 12, 336–345. Handelmann, G.E., Boyles, J.K., Weisgraber, K.H., Mahley, R.W., Pitas, R.E., 1992. Effects of apolipoprotein E, beta-very low density lipoproteins, and cholesterol on the extension of neurites by rabbit dorsal root ganglion neurons in vitro. J. Lipid Res. 33, 1677–1688. Harding, J., Graziadei, P.P., Monti Graziadei, G.A., Margolis, F.L., 1977. Denervation in the primary olfactory pathway of mice. IV. Biochemical and morphological evidence for neuronal replacement following nerve section. Brain Res. 132, 11–28. Hatipoglu, O.F., Hirohata, S., Yaykasli, K.O., Cilek, M.Z., Demircan, K., Shinohata, R., Yonezawa, T., Oohashi, T., Kusachi, S., Ninomiya, Y., 2009. The 3′-untranslated region of ADAMTS1 regulates its mRNA stability. Acta Med. Okayama 63, 79–85. Hattori, A., Tanaka, E., Murase, K., Ishida, N., Chatani, Y., Tsujimoto, M., Hayashi, K., Kohno, M., 1993. Tumor necrosis factor stimulates the synthesis and secretion of biologically active nerve growth factor in non-neuronal cells. J. Biol. Chem. 268, 2577–2582. Hayashi, H., Campenot, R.B., Vance, D.E., Vance, J.E., 2004. Glial lipoproteins stimulate axon growth of central nervous system neurons in compartmented cultures. J. Biol. Chem. 279, 14009–14015. Holmes, F.E., Arnott, N., Vanderplank, P., Kerr, N.C., Longbrake, E.E., Popovich, P.G., Imai, T., Combadiere, C., Murphy, P.M., Wynick, D., 2008. Intra-neural administration of fractalkine attenuates neuropathic pain-related behaviour. J. Neurochem. 106, 640–649. Holtmaat, A.J., Oestreicher, A.B., Gispen, W.H., Verhaagen, J., 1998. Manipulation of gene expression in the mammalian nervous system: application in the study of neurite outgrowth and neuroregeneration-related proteins. Brain Res. Brain Res. Rev. 26, 43–71. Honore, A., Le Corre, S., Derambure, C., Normand, R., Duclos, C., Boyer, O., Marie, J.P., Guerout, N., 2012. Isolation, characterization, and genetic profiling of subpopulations of olfactory ensheathing cells from the olfactory bulb. Glia 60, 404–413. Hornstein, I., Alcover, A., Katzav, S., 2004. Vav proteins, masters of the world of cytoskeleton organization. Cell. Signal. 16, 1–11. Houlard, M., Arudchandran, R., Regnier-Ricard, F., Germani, A., Gisselbrecht, S., Blank, U., Rivera, J., Varin-Blank, N., 2002. Vav1 is a component of transcriptionally active complexes. J. Exp. Med. 195, 1115–1127. Huang, H., Chen, L., Xi, H., Wang, Q., Zhang, J., Liu, Y., Zhang, F., 2009. Olfactory ensheathing cells transplantation for central nervous system diseases in 1255 patients. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 23, 14–20. Huang, Z.H., Wang, Y., Yuan, X.B., He, C., 2011. RhoA–ROCK–myosin pathway regulates morphological plasticity of cultured olfactory ensheathing cells. Exp. Cell Res. 317, 2823–2834. Hughes, P.M., Botham, M.S., Frentzel, S., Mir, A., Perry, V.H., 2002. Expression of fractalkine (CX3CL1) and its receptor, CX3CR1, during acute and chronic inflammation in the rodent CNS. Glia 37, 314–327. Ibrahim, A., Li, D., Collins, A., Tabakow, P., Raisman, G., Li, Y., 2013. Comparison of olfactory bulbar and mucosal cultures in a rat rhizotomy model. Cell Transplant. Ignatius, M.J., Gebicke-Harter, P.J., Skene, J.H., Schilling, J.W., Weisgraber, K.H., Mahley, R.W., Shooter, E.M., 1986. Expression of apolipoprotein E during nerve degeneration and regeneration. Proc. Natl. Acad. Sci. U. S. A. 83, 1125–1129. Imaizumi, T., Lankford, K.L., Waxman, S.G., Greer, C.A., Kocsis, J.D., 1998. Transplanted olfactory ensheathing cells remyelinate and enhance axonal conduction in the demyelinated dorsal columns of the rat spinal cord. J. Neurosci. 18, 6176–6185.

U

1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 Q11 1110 1111 1112 1113 1114 1115

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

E

14

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

N C O

R

R

E

C

D

P

R O

O

F

Plant, G.W., Harvey, A.R., Leaver, S.G., Lee, S.V., 2011. Olfactory ensheathing glia: repairing injury to the mammalian visual system. Exp. Neurol. 229, 99–108. Radtke, C., Akiyama, Y., Brokaw, J., Lankford, K.L., Wewetzer, K., Fodor, W.L., Kocsis, J.D., 2004. Remyelination of the nonhuman primate spinal cord by transplantation of Htransferase transgenic adult pig olfactory ensheathing cells. FASEB J. 18, 335–337. Raisman, G., 1985. Specialized neuroglial arrangement may explain the capacity of vomeronasal axons to reinnervate central neurons. Neuroscience 14 (1), 237–254. Raisman, G., 2007. Repair of spinal cord injury by transplantation of olfactory ensheathing cells. C. R. Biol. 330, 557–560. Raisman, G., Li, Y., 2007. Repair of neural pathways by olfactory ensheathing cells. Nat. Rev. Neurosci. 8, 312–319. Raisman, G., Barnett, S.C., Ramon-Cueto, A., 2012. Repair of central nervous system lesions by transplantation of olfactory ensheathing cells. Handb. Clin. Neurol. 109, 541–549. Ramer, L.M., Au, E., Richter, M.W., Liu, J., Tetzlaff, W., Roskams, A.J., 2004. Peripheral olfactory ensheathing cells reduce scar and cavity formation and promote regeneration after spinal cord injury. J. Comp. Neurol. 473, 1–15. Ramon-Cueto, A., 2011. Olfactory ensheathing glia for nervous system repair. Exp. Neurol. 229, 1. Ramon-Cueto, A., Nieto-Sampedro, M., 1992. Glial cells from adult rat olfactory bulb: immunocytochemical properties of pure cultures of ensheathing cells. Neuroscience 47, 213–220. Ramon-Cueto, A., Nieto-Sampedro, M., 1994. Regeneration into the spinal cord of transected dorsal root axons is promoted by ensheathing glia transplants. Exp. Neurol. 127, 232–244. Ramon-Cueto, A., Perez, J., Nieto-Sampedro, M., 1993. In vitro enfolding of olfactory neurites by p75 NGF receptor positive ensheathing cells from adult rat olfactory bulb. Eur. J. Neurosci. 5, 1172–1180. Ramon-Cueto, A., Plant, G.W., Avila, J., Bunge, M.B., 1998. Long-distance axonal regeneration in the transected adult rat spinal cord is promoted by olfactory ensheathing glia transplants. J. Neurosci. 18, 3803–3815. Ramon-Cueto, A., Cordero, M.I., Santos-Benito, F.F., Avila, J., 2000. Functional recovery of paraplegic rats and motor axon regeneration in their spinal cords by olfactory ensheathing glia. Neuron 25, 425–435. Rao, Y., Zhu, W., Guo, Y., Jia, C., Qi, R., Qiao, R., Cao, D., Zhang, H., Cui, Z., Yang, L., Wang, Y., 2013. Long-term outcome of olfactory ensheathing cell transplantation in six patients with chronic complete spinal cord injury. Cell Transplant. 22 (Suppl. 1), S21–S25. Reczek, D., Schwake, M., Schroder, J., Hughes, H., Blanz, J., Jin, X., Brondyk, W., Van Patten, S., Edmunds, T., Saftig, P., 2007. LIMP-2 is a receptor for lysosomal mannose-6phosphate-independent targeting of beta-glucocerebrosidase. Cell 131, 770–783. Richter, M.W., Roskams, A.J., 2008. Olfactory ensheathing cell transplantation following spinal cord injury: hype or hope? Exp. Neurol. 209, 353–367. Richter, M.W., Fletcher, P.A., Liu, J., Tetzlaff, W., Roskams, A.J., 2005. Lamina propria and olfactory bulb ensheathing cells exhibit differential integration and migration and promote differential axon sprouting in the lesioned spinal cord. J. Neurosci. 25, 10700–10711. Riou, P., Villalonga, P., Ridley, A.J., 2010. Rnd proteins: multifunctional regulators of the cytoskeleton and cell cycle progression. Bioessays 32, 986–992. Roet, K.C., Bossers, K., Franssen, E.H., Ruitenberg, M.J., Verhaagen, J., 2011. A meta-analysis of microarray-based gene expression studies of olfactory bulb-derived olfactory ensheathing cells. Exp. Neurol. 229, 10–45. Roet, K.C., Eggers, R., Verhaagen, J., 2012. Noninvasive bioluminescence imaging of olfactory ensheathing glia and Schwann cells following transplantation into the lesioned rat spinal cord. Cell Transplant. 21, 1853–1865. Roet, K.C., Franssen, E.H., de Bree, F.M., Essing, A.H., Zijlstra, S.J., Fagoe, N.D., Eggink, H.M., Eggers, R., Smit, A.B., van Kesteren, R.E., Verhaagen, J., 2013. A multilevel screening strategy defines a molecular fingerprint of proregenerative olfactory ensheathing cells and identifies SCARB2, a protein that improves regenerative sprouting of injured sensory spinal axons. J. Neurosci. 33, 11116–11135. Roudnicky, F., Poyet, C., Wild, P., Krampitz, S., Negrini, F., Huggenberger, R., Rogler, A., Stohr, R., Hartmann, A., Provenzano, M., Otto, V.I., Detmar, M., 2013. Endocan is upregulated on tumor vessels in invasive bladder cancer where it mediates VEGF-Ainduced angiogenesis. Cancer Res. 73, 1097–1106. Ruitenberg, M.J., Vukovic, J., 2008. Promoting central nervous system regeneration: lessons from cranial nerve I. Restor. Neurol. Neurosci. 26, 183–196. Ruitenberg, M.J., Plant, G.W., Hamers, F.P., Wortel, J., Blits, B., Dijkhuizen, P.A., Gispen, W. H., Boer, G.J., Verhaagen, J., 2003. Ex vivo adenoviral vector-mediated neurotrophin gene transfer to olfactory ensheathing glia: effects on rubrospinal tract regeneration, lesion size, and functional recovery after implantation in the injured rat spinal cord. J. Neurosci. 23, 7045–7058. Ruitenberg, M.J., Vukovic, J., Blomster, L., Hall, J.M., Jung, S., Filgueira, L., McMenamin, P.G., Plant, G.W., 2008. CX3CL1/fractalkine regulates branching and migration of monocyte-derived cells in the mouse olfactory epithelium. J. Neuroimmunol. 205, 80–85. Runyan, S.A., Phelps, P.E., 2009. Mouse olfactory ensheathing glia enhance axon outgrowth on a myelin substrate in vitro. Exp. Neurol. 216, 95–104. Russell, D.L., Doyle, K.M., Ochsner, S.A., Sandy, J.D., Richards, J.S., 2003. Processing and localization of ADAMTS-1 and proteolytic cleavage of versican during cumulus matrix expansion and ovulation. J. Biol. Chem. 278, 42330–42339. Samson, A.L., Medcalf, R.L., 2006. Tissue-type plasminogen activator: a multifaceted modulator of neurotransmission and synaptic plasticity. Neuron 50, 673–678. Santos-Silva, A., Fairless, R., Frame, M.C., Montague, P., Smith, G.M., Toft, A., Riddell, J.S., Barnett, S.C., 2007. FGF/heparin differentially regulates Schwann cell and olfactory ensheathing cell interactions with astrocytes: a role in astrocytosis. J. Neurosci. 27, 7154–7167. Schubert, P., Kreutzberg, G.W., 1993. Cerebral protection by adenosine. Acta Neurochir. Suppl. (Wien) 57, 80–88.

E

T

lower motor neurons in amyotrophic lateral sclerosis. Cell Transplant. 22 (Suppl. 1), S51–S65. Lipson, A.C., Widenfalk, J., Lindqvist, E., Ebendal, T., Olson, L., 2003. Neurotrophic properties of olfactory ensheathing glia. Exp. Neurol. 180, 167–171. Liu, Y., Wang, X., Lu, C.C., Kerman, R., Steward, O., Xu, X.M., Zou, Y., 2008. Repulsive Wnt signaling inhibits axon regeneration after CNS injury. J. Neurosci. 28, 8376–8382. Liu, Y., Teng, X., Yang, X., Song, Q., Lu, R., Xiong, J., Liu, B., Zeng, N., Zeng, Y., Long, J., Cao, R., Lin, Y., He, Q., Chen, P., Lu, M., Liang, S., 2010. Shotgun proteomics and network analysis between plasma membrane and extracellular matrix proteins from rat olfactory ensheathing cells. Cell Transplant. 19, 133–146. Lopez-Vales, R., Garcia-Alias, G., Fores, J., Navarro, X., Verdu, E., 2004. Increased expression of cyclo-oxygenase 2 and vascular endothelial growth factor in lesioned spinal cord by transplanted olfactory ensheathing cells. J. Neurotrauma 21, 1031–1043. MacGillavry, H.D., Stam, F.J., Sassen, M.M., Kegel, L., Hendriks, W.T., Verhaagen, J., Smit, A.B., van Kesteren, R.E., 2009. NFIL3 and cAMP response element-binding protein form a transcriptional feedforward loop that controls neuronal regenerationassociated gene expression. J. Neurosci. 29, 15542–15550. Mackay-Sim, A., Feron, F., Cochrane, J., Bassingthwaighte, L., Bayliss, C., Davies, W., Fronek, P., Gray, C., Kerr, G., Licina, P., Nowitzke, A., Perry, C., Silburn, P.A., Urquhart, S., Geraghty, T., 2008. Autologous olfactory ensheathing cell transplantation in human paraplegia: a 3-year clinical trial. Brain 131, 2376–2386. Mahley, R.W., 1988. Apolipoprotein E: cholesterol transport protein with expanding role in cell biology. Science 240, 622–630. Mauch, D.H., Nagler, K., Schumacher, S., Goritz, C., Muller, E.C., Otto, A., Pfrieger, F.W., 2001. CNS synaptogenesis promoted by glia-derived cholesterol. Science 294, 1354–1357. Mayer, U., Kohfeldt, E., Timpl, R., 1998. Structural and genetic analysis of laminin–nidogen interaction. Ann. N. Y. Acad. Sci. 857, 130–142. Mayeur, A., Duclos, C., Honore, A., Gauberti, M., Drouot, L., do Rego, J.C., Bon-Mardion, N., Jean, L., Verin, E., Emery, E., Lemarchant, S., Vivien, D., Boyer, O., Marie, J.P., Guerout, N., 2013. Potential of olfactory ensheathing cells from different sources for spinal cord repair. PLoS One 8, e62860. Meucci, O., Fatatis, A., Simen, A.A., Bushell, T.J., Gray, P.W., Miller, R.J., 1998. Chemokines regulate hippocampal neuronal signaling and gp120 neurotoxicity. Proc. Natl. Acad. Sci. U. S. A. 95, 14500–14505. Miranda, E., Lomas, D.A., 2006. Neuroserpin: a serpin to think about. Cell Mol. Life Sci. 63, 709–722. Moore, D.L., Blackmore, M.G., Hu, Y., Kaestner, K.H., Bixby, J.L., Lemmon, V.P., Goldberg, J.L., 2009. KLF family members regulate intrinsic axon regeneration ability. Science 326, 298–301. Moreno-Flores, M.T., Lim, F., Martin-Bermejo, M.J., Diaz-Nido, J., Avila, J., Wandosell, F., 2003. High level of amyloid precursor protein expression in neurite-promoting olfactory ensheathing glia (OEG) and OEG-derived cell lines. J. Neurosci. Res. 71, 871–881. Moret, F., Renaudot, C., Bozon, M., Castellani, V., 2007. Semaphorin and neuropilin coexpression in motoneurons sets axon sensitivity to environmental semaphorin sources during motor axon pathfinding. Development 134, 4491–4501. Mukhopadhyay, G., Doherty, P., Walsh, F.S., Crocker, P.R., Filbin, M.T., 1994. A novel role for myelin-associated glycoprotein as an inhibitor of axonal regeneration. Neuron 13, 757–767. Mulcahy, J.V., Riddell, D.R., Owen, J.S., 2004. Human scavenger receptor class B type II (SRBII) and cellular cholesterol efflux. Biochem. J. 377, 741–747. Munoz-Quiles, C., Santos-Benito, F.F., Llamusi, M.B., Ramon-Cueto, A., 2009. Chronic spinal injury repair by olfactory bulb ensheathing glia and feasibility for autologous therapy. J. Neuropathol. Exp. Neurol. 68, 1294–1308. Nan, B., Getchell, M.L., Partin, J.V., Getchell, T.V., 2001. Leukemia inhibitory factor, interleukin-6, and their receptors are expressed transiently in the olfactory mucosa after target ablation. J. Comp. Neurol. 435, 60–77. Niclou, S.P., Franssen, E.H., Ehlert, E.M., Taniguchi, M., Verhaagen, J., 2003. Meningeal cellderived semaphorin 3A inhibits neurite outgrowth. Mol. Cell. Neurosci. 24, 902–912. Novikova, L.N., Lobov, S., Wiberg, M., Novikov, L.N., 2011. Efficacy of olfactory ensheathing cells to support regeneration after spinal cord injury is influenced by method of culture preparation. Exp. Neurol. 229, 132–142. Ogata, H., Goto, S., Sato, K., Fujibuchi, W., Bono, H., Kanehisa, M., 1999. KEGG: Kyoto Encyclopedia of Genes and Genomes. Nucleic Acids Res. 27, 29–34. Pastrana, E., Moreno-Flores, M.T., Gurzov, E.N., Avila, J., Wandosell, F., Diaz-Nido, J., 2006. Genes associated with adult axon regeneration promoted by olfactory ensheathing cells: a new role for matrix metalloproteinase 2. J. Neurosci. 26, 5347–5359. Paviot, A., Guerout, N., Bon-Mardion, N., Duclos, C., Jean, L., Boyer, O., Marie, J.P., 2011. Efficiency of laryngeal motor nerve repair is greater with bulbar than with mucosal olfactory ensheathing cells. Neurobiol. Dis. 41, 688–694. Pearse, D.D., Sanchez, A.R., Pereira, F.C., Andrade, C.M., Puzis, R., Pressman, Y., Golden, K., Kitay, B.M., Blits, B., Wood, P.M., Bunge, M.B., 2007. Transplantation of Schwann cells and/or olfactory ensheathing glia into the contused spinal cord: Survival, migration, axon association, and functional recovery. Glia 55, 976–1000. Peng, W., Cotrina, M.L., Han, X., Yu, H., Bekar, L., Blum, L., Takano, T., Tian, G.F., Goldman, S. A., Nedergaard, M., 2009. Systemic administration of an antagonist of the ATPsensitive receptor P2X7 improves recovery after spinal cord injury. Proc. Natl. Acad. Sci. U. S. A. 106, 12489–12493. Petrova, I.M., Malessy, M.J., Verhaagen, J., Fradkin, L.G., Noordermeer, J.N., 2014. Wnt signaling through the Ror receptor in the nervous system. Mol. Neurobiol. 49, 303–315. Piepers, S., van den Berg, L.H., 2010. No benefits from experimental treatment with olfactory ensheathing cells in patients with ALS. Amyotroph. Lateral Scler. 11, 328–330. Plant, G.W., Currier, P.F., Cuervo, E.P., Bates, M.L., Pressman, Y., Bunge, M.B., Wood, P.M., 2002. Purified adult ensheathing glia fail to myelinate axons under culture conditions that enable Schwann cells to form myelin. J. Neurosci. 22, 6083–6091.

U

1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287

15

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373

D

P

R O

O

F

Vargas, F., Tolosa, E., Sospedra, M., Catalfamo, M., Lucas-Martin, A., Obiols, G., Pujol-Borrell, R., 1994. Characterization of neural cell adhesion molecule (NCAM) expression in thyroid follicular cells: induction by cytokines and over-expression in autoimmune glands. Clin. Exp. Immunol. 98, 478–488. Verderio, C., Matteoli, M., 2001. ATP mediates calcium signaling between astrocytes and microglial cells: modulation by IFN-gamma. J. Immunol. 166, 6383–6391. Verge, G.M., Milligan, E.D., Maier, S.F., Watkins, L.R., Naeve, G.S., Foster, A.C., 2004. Fractalkine (CX3CL1) and fractalkine receptor (CX3CR1) distribution in spinal cord and dorsal root ganglia under basal and neuropathic pain conditions. Eur. J. Neurosci. 20, 1150–1160. Vincent, A.J., Taylor, J.M., Choi-Lundberg, D.L., West, A.K., Chuah, M.I., 2005. Genetic expression profile of olfactory ensheathing cells is distinct from that of Schwann cells and astrocytes. Glia 51, 132–147. Vincent, A.J., Choi-Lundberg, D.L., Harris, J.A., West, A.K., Chuah, M.I., 2007. Bacteria and PAMPs activate nuclear factor kappaB and Gro production in a subset of olfactory ensheathing cells and astrocytes but not in Schwann cells. Glia 55, 905–916. Wang, X., Arcuino, G., Takano, T., Lin, J., Peng, W.G., Wan, P., Li, P., Xu, Q., Liu, Q.S., Goldman, S.A., Nedergaard, M., 2004. P2X7 receptor inhibition improves recovery after spinal cord injury. Nat. Med. 10, 821–827. Wang, Y.Z., Molotkov, A., Song, L., Li, Y., Pleasure, D.E., Zhou, C.J., 2008. Activation of the Wnt/beta-catenin signaling reporter in developing mouse olfactory nerve layer marks a specialized subgroup of olfactory ensheathing cells. Dev. Dyn. 237, 3157–3168. Wassenhove-McCarthy, D.J., McCarthy, K.J., 1999. Molecular characterization of a novel basement membrane-associated proteoglycan, leprecan. J. Biol. Chem. 274, 25004–25017. Watari, M., Watari, H., DiSanto, M.E., Chacko, S., Shi, G.P., Strauss III, J.F., 1999. Proinflammatory cytokines induce expression of matrix-metabolizing enzymes in human cervical smooth muscle cells. Am. J. Pathol. 154, 1755–1762. Wewetzer, K., Grothe, C., Claus, P., 2001. In vitro expression and regulation of ciliary neurotrophic factor and its alpha receptor subunit in neonatal rat olfactory ensheathing cells. Neurosci. Lett. 306, 165–168. Wewetzer, K., Verdu, E., Angelov, D.N., Navarro, X., 2002. Olfactory ensheathing glia and Schwann cells: two of a kind? Cell Tissue Res. 309, 337–345. Wewetzer, K., Kern, N., Ebel, C., Radtke, C., Brandes, G., 2005. Phagocytosis of O4+ axonal fragments in vitro by p75-neonatal rat olfactory ensheathing cells. Glia 49, 577–587. Wewetzer, K., Radtke, C., Kocsis, J., Baumgartner, W., 2011. Species-specific control of cellular proliferation and the impact of large animal models for the use of olfactory ensheathing cells and Schwann cells in spinal cord repair. Exp. Neurol. 229, 80–87. Windus, L.C., Claxton, C., Allen, C.L., Key, B., St John, J.A., 2007. Motile membrane protrusions regulate cell–cell adhesion and migration of olfactory ensheathing glia. Glia 55, 1708–1719. Windus, L.C., Chehrehasa, F., Lineburg, K.E., Claxton, C., Mackay-Sim, A., Key, B., St John, J.A., 2011. Stimulation of olfactory ensheathing cell motility enhances olfactory axon growth. Cell Mol. Life Sci. 68, 3233–3247. Witheford, M., Westendorf, K., Roskams, A.J., 2013. Olfactory ensheathing cells promote corticospinal axonal outgrowth by a L1 CAM-dependent mechanism. Glia 61, 1873–1889. Woodhall, E., West, A.K., Chuah, M.I., 2001. Cultured olfactory ensheathing cells express nerve growth factor, brain-derived neurotrophic factor, glia cell line-derived neurotrophic factor and their receptors. Brain Res. Mol. Brain Res. 88, 203–213. Wu, A., Lauschke, J.L., Gorrie, C.A., Cameron, N., Hayward, I., Mackay-Sim, A., Waite, P.M., 2011a. Delayed olfactory ensheathing cell transplants reduce nociception after dorsal root injury. Exp. Neurol. 229, 143–157. Wu, J., Stoica, B.A., Faden, A.I., 2011b. Cell cycle activation and spinal cord injury. Neurotherapeutics 8, 221–228. Yamagishi, S., Matsui, T., Nakamura, K., Takenaka, K., 2009. Administration of pigment epithelium-derived factor prolongs bleeding time by suppressing plasminogen activator inhibitor-1 activity and platelet aggregation in rats. Clin. Exp. Med. 9, 73–76. Yiangou, Y., Facer, P., Durrenberger, P., Chessell, I.P., Naylor, A., Bountra, C., Banati, R.R., Anand, P., 2006. COX-2, CB2 and P2X7-immunoreactivities are increased in activated microglial cells/macrophages of multiple sclerosis and amyotrophic lateral sclerosis spinal cord. BMC Neurol. 6, 12. You, H., Wei, L., Liu, Y., Oudega, M., Jiao, S.S., Feng, S.N., Chen, Y., Chen, J.M., Li, B.C., 2011. Olfactory ensheathing cells enhance Schwann cell-mediated anatomical and functional repair after sciatic nerve injury in adult rats. Exp. Neurol. 229, 158–167. Yu, C., Argyropoulos, G., Zhang, Y., Kastin, A.J., Hsuchou, H., Pan, W., 2008. Neuroinflammation activates Mdr1b efflux transport through NFkappaB: promoter analysis in BBB endothelia. Cell. Physiol. Biochem. 22, 745–756. Zaghetto, A.A., Paina, S., Mantero, S., Platonova, N., Peretto, P., Bovetti, S., Puche, A., Piccolo, S., Merlo, G.R., 2007. Activation of the Wnt-beta catenin pathway in a cell population on the surface of the forebrain is essential for the establishment of olfactory axon connections. J. Neurosci. 27, 9757–9768. Zer, C., Sachs, G., Shin, J.M., 2007. Identification of genomic targets downstream of p38 mitogen-activated protein kinase pathway mediating tumor necrosis factor-alpha signaling. Physiol. Genomics 31, 343–351. Ziegler, M.D., Hsu, D., Takeoka, A., Zhong, H., Ramon-Cueto, A., Phelps, P.E., Roy, R.R., Edgerton, V.R., 2011. Further evidence of olfactory ensheathing glia facilitating axonal regeneration after a complete spinal cord transection. Exp. Neurol. 229, 109–119.

N

C

O

R

R

E

C

T

Schwab, J.M., Brechtel, K., Mueller, C.A., Failli, V., Kaps, H.P., Tuli, S.K., Schluesener, H.J., 2006. Experimental strategies to promote spinal cord regeneration—an integrative perspective. Prog. Neurobiol. 78, 91–116. Scotto d'Abusco, A., Cicione, C., Calamia, V., Negri, R., Giordano, C., Grigolo, B., Politi, L., Scandurra, R., 2007. Glucosamine and its N-acetyl-phenylalanine derivative prevent TNF-alpha-induced transcriptional activation in human chondrocytes. Clin. Exp. Rheumatol. 25, 847–852. Seitz, A., Kragol, M., Aglow, E., Showe, L., Heber-Katz, E., 2003. Apolipoprotein E expression after spinal cord injury in the mouse. J. Neurosci. Res. 71, 417–426. Shi, X., Kang, Y., Hu, Q., Chen, C., Yang, L., Wang, K., Chen, L., Huang, H., Zhou, C., 2010. A long-term observation of olfactory ensheathing cells transplantation to repair white matter and functional recovery in a focal ischemia model in rat. Brain Res. 1317, 257–267. Shukla, S., Chaturvedi, R.K., Seth, K., Roy, N.S., Agrawal, A.K., 2009. Enhanced survival and function of neural stem cells-derived dopaminergic neurons under influence of olfactory ensheathing cells in parkinsonian rats. J. Neurochem. 109, 436–451. Shyu, W.C., Liu, D.D., Lin, S.Z., Li, W.W., Su, C.Y., Chang, Y.C., Wang, H.J., Wang, H.W., Tsai, C. H., Li, H., 2008. Implantation of olfactory ensheathing cells promotes neuroplasticity in murine models of stroke. J. Clin. Invest. 118, 2482–2495. Simon, D., Martin-Bermejo, M.J., Gallego-Hernandez, M.T., Pastrana, E., Garcia-Escudero, V., Garcia-Gomez, A., Lim, F., Diaz-Nido, J., Avila, J., Moreno-Flores, M.T., 2011. Expression of plasminogen activator inhibitor-1 by olfactory ensheathing glia promotes axonal regeneration. Glia 59, 1458–1471. Sivasubramanian, N., Coker, M.L., Kurrelmeyer, K.M., MacLellan, W.R., DeMayo, F.J., Spinale, F.G., Mann, D.L., 2001. Left ventricular remodeling in transgenic mice with cardiac restricted overexpression of tumor necrosis factor. Circulation 104, 826–831. Smale, K.A., Doucette, R., Kawaja, M.D., 1996. Implantation of olfactory ensheathing cells in the adult rat brain following fimbria-fornix transection. Exp. Neurol. 137, 225–233. Soker, S., Takashima, S., Miao, H.Q., Neufeld, G., Klagsbrun, M., 1998. Neuropilin-1 is expressed by endothelial and tumor cells as an isoform-specific receptor for vascular endothelial growth factor. Cell 92, 735–745. Sonigra, R.J., Brighton, P.C., Jacoby, J., Hall, S., Wigley, C.B., 1999. Adult rat olfactory nerve ensheathing cells are effective promoters of adult central nervous system neurite outgrowth in coculture. Glia 25, 256–269. Spurrell, D.R., Luckashenak, N.A., Minney, D.C., Chaplin, A., Penninger, J.M., Liwski, R.S., Clements, J.L., West, K.A., 2009. Vav1 regulates the migration and adhesion of dendritic cells. J. Immunol. 183, 310–318. Srivastava, N., Seth, K., Khanna, V.K., Ansari, R.W., Agrawal, A.K., 2009. Long-term functional restoration by neural progenitor cell transplantation in rat model of cognitive dysfunction: co-transplantation with olfactory ensheathing cells for neurotrophic factor support. Int. J. Dev. Neurosci. 27, 103–110. Steup, A., Lohrum, M., Hamscho, N., Savaskan, N.E., Ninnemann, O., Nitsch, R., Fujisawa, H., Puschel, A.W., Skutella, T., 2000. Sema3C and netrin-1 differentially affect axon growth in the hippocampal formation. Mol. Cell. Neurosci. 15, 141–155. Su, Z., Yuan, Y., Chen, J., Cao, L., Zhu, Y., Gao, L., Qiu, Y., He, C., 2009. Reactive astrocytes in glial scar attract olfactory ensheathing cells migration by secreted TNF-alpha in spinal cord lesion of rat. PLoS One 4, e8141. Sunahori, K., Yamamura, M., Yamana, J., Takasugi, K., Kawashima, M., Yamamoto, H., Chazin, W.J., Nakatani, Y., Yui, S., Makino, H., 2006. The S100A8/A9 heterodimer amplifies proinflammatory cytokine production by macrophages via activation of nuclear factor kappa B and p38 mitogen-activated protein kinase in rheumatoid arthritis. Arthritis Res. Ther. 8, R69. Tabakow, P., Jarmundowicz, W., Czapiga, B., Fortuna, W., Miedzybrodzki, R., Czyz, M., Huber, J., Szarek, D., Okurowski, S., Szewczyk, P., Gorski, A., Raisman, G., 2013. Transplantation of autologous olfactory ensheathing cells in complete human spinal cord injury. Cell Transplant. Takagi, S., Kasuya, Y., Shimizu, M., Matsuura, T., Tsuboi, M., Kawakami, A., Fujisawa, H., 1995. Expression of a cell adhesion molecule, neuropilin, in the developing chick nervous system. Dev. Biol. 170, 207–222. Takeoka, A., Jindrich, D.L., Munoz-Quiles, C., Zhong, H., van den Brand, R., Pham, D.L., Ziegler, M.D., Ramon-Cueto, A., Roy, R.R., Edgerton, V.R., Phelps, P.E., 2011. Axon regeneration can facilitate or suppress hindlimb function after olfactory ensheathing glia transplantation. J. Neurosci. 31, 4298–4310. Tanimoto, S., Kanamoto, T., Mizukami, M., Aoyama, H., Kiuchi, Y., 2006. Pigment epithelium-derived factor promotes neurite outgrowth of retinal cells. Hiroshima J. Med. Sci. 55, 109–116. Tetzlaff, W., Okon, E.B., Karimi-Abdolrezaee, S., Hill, C.E., Sparling, J.S., Plemel, J.R., Plunet, W.T., Tsai, E.C., Baptiste, D., Smithson, L.J., Kawaja, M.D., Fehlings, M.G., Kwon, B.K., 2011. A systematic review of cellular transplantation therapies for spinal cord injury. J. Neurotrauma 28, 1611–1682. Thuret, S., Moon, L.D., Gage, F.H., 2006. Therapeutic interventions after spinal cord injury. Nat. Rev. Neurosci. 7, 628–643. Tisay, K.T., Key, B., 1999. The extracellular matrix modulates olfactory neurite outgrowth on ensheathing cells. J. Neurosci. 19, 9890–9899. Toft, A., Tome, M., Barnett, S.C., Riddell, J.S., 2013. A comparative study of glial and nonneural cell properties for transplant-mediated repair of the injured spinal cord. Glia 61, 513–528. Turner, C.P., Perez-Polo, J.R., 1993. Expression of p75NGFR in the olfactory system following peripheral deafferentation. Neuroreport 4, 1023–1026.

U

1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 Q12 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452

K.C.D. Roet, J. Verhaagen / Experimental Neurology xxx (2014) xxx–xxx

E

16

1532

Please cite this article as: Roet, K.C.D., Verhaagen, J., Understanding the neural repair-promoting properties of olfactory ensheathing cells, Exp. Neurol. (2014), http://dx.doi.org/10.1016/j.expneurol.2014.05.007

1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531