- Email: [email protected]
Intracerebral Delivery in Complex 3D Arrays: The Intracerebral Microinjection Instrument
Accepted Manuscript Intracerebral Delivery in Complex 3-D Arrays: The Intracerebral Microinjection Instrument (IMI) Miles Cunningham, Sina Azimi, GuangZhu Zhang PII:
S1878-8750(19)31073-3
DOI:
https://doi.org/10.1016/j.wneu.2019.04.081
Reference:
WNEU 12111
To appear in:
World Neurosurgery
Received Date: 20 January 2019 Revised Date:
8 April 2019
Accepted Date: 9 April 2019
Please cite this article as: Cunningham M, Azimi S, Zhang G, Intracerebral Delivery in Complex 3D Arrays: The Intracerebral Microinjection Instrument (IMI) World Neurosurgery (2019), doi: https:// doi.org/10.1016/j.wneu.2019.04.081. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
RI PT
Intracerebral Delivery in Complex 3-D Arrays: The Intracerebral Microinjection Instrument (IMI) Miles Cunningham1, Sina Azimi1, GuangZhu Zhang2 1
SC
Laboratory for Neural Reconstruction, McLean Hospital, Harvard Medical School 115 Mill Street, Belmont, MA 02451, USA 2 Affiliated BaYi Brain Hospital, Army General Hospital of PLA, Nan Men Cang No.5, Dong Cheng District, Beijing, China
M AN U
E-Mail Addresses: Miles Cunningham - [email protected] Sina Azimi - [email protected] GuangZhu Zhang - [email protected]
TE D
Corresponding Author: Miles Cunningham, MD, PhD Laboratory for Neural Reconstruction, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA Tel: (617) 855-2051 Fax: (617) 855-3894 Email: [email protected]
EP
Short Title: 3D Intracerebral Delivery
AC C
Key Words: Intracerebral Microinjection Instrument (IMI), stereotactic surgery, functional neurosurgery, restorative therapeutics
ACCEPTED MANUSCRIPT
Abstract This video article describes and illustrates the function and application of the Intracerebral Microinjection Instrument (IMI). This newly developed technology allows
RI PT
delivery of therapeutics within the human brain in complex three-dimensional arrays using a single pass or minimal overlying penetrations through brain tissue. The IMI
utilizes a delivery microcannula with a reduced diameter that minimizes local trauma and is capable of delivering precise volumes of therapeutics to discrete brain
SC
substructures. The IMI also permits simultaneous recording of neural activity during the delivery procedure enabling extreme precision using electrophysiological mapping. Surgical planning software designed specifically for the IMI enables strategic placement
M AN U
of multiple injections. This technology platform is presently being used successfully to deliver therapeutic stem cells to restore function in stroke patients. Additional applications of the IMI include delivery of viral vectors for gene therapy, infusion of neurotrophic factors, targeted delivery of chemotherapeutics, and delivery of
AC C
EP
TE D
antiretroviral medications.
ACCEPTED MANUSCRIPT
Introduction As new therapeutics for central nervous system (CNS) disorders are developed, more sophisticated and precise delivery methodology is becoming necessary. The
RI PT
currently used approach for intracerebral delivery has remained virtually unchanged for decades and it continues to present liabilities. Delivery instruments used today are
based on straight and rigid cannula designs with diameters ranging from 0.8 – 2 mm. This presents a problem when the brain target itself is on the scale of the instrument
SC
introducing the therapeutic. In addition, distribution of an agent in 3-dimensional (3D) space requires multiple penetrations of the rigid delivery device. This extends surgical
M AN U
time and each penetration increases the risk of trauma and hemorrhage. These issues have been addressed with the development of the Intracerebral Microinjection Instrument (IMI). The IMI’s unique design enables dissemination of therapeutics in complex 3D arrays from a single or a minimal number of overlying penetrations of brain tissue. The instrument utilizes a specialized “microcannula” with shape memory that is able to target very small brain structures using MRI and
TE D
electrophysiological guidance and deliver accurate volumes of therapeutic. The IMI therefore offers to increase the efficacy of therapeutics by permitting delivery with a high level of precision and reducing localized trauma to an absolute minimum. In addition, the IMI may reduce surgical time and the risk of complications for patients undergoing
EP
restorative neurosurgical procedures. This technology is presently being used to deliver therapeutic stem cells to restore function in stroke patients. Up to one year after having
AC C
a stroke, these individuals have received an unprecedented numbers (~45) of stem cell grafts placed in complex three-dimensional arrays surrounding cystic stroke lesions to optimize reconstruction of white matter tracts. The IMI design was robust and reliable, and similar to numerous preclinical studies in rodents, pigs, and non-human primates, no surgical complications were seen in any of the patients. The transplantation procedure was well-tolerated, the patients’ recovery was uneventful, and they all proceeded to regain function over the subsequent year. We present here a video demonstration that illustrates the mechanics of the IMI and describes its use for delivering restorative therapeutics.
ACCEPTED MANUSCRIPT
Materials and Methods The IMI has been previously described in preclinical studies demonstrating that the technology has numerous advantages over conventional straight, rigid delivery
RI PT
instruments 1-3. The IMI in this demonstration utilizes a microcannula with a diameter of 200 microns; that is, about 4-fold smaller than presently used delivery cannulas. Contained within a “guide cannula”, the microcannula can be extended at a
predetermined angle along a straight or arcing trajectory to reach the injection target
SC
site. After an injection is completed, the microcannula is withdrawn back within the guide cannula, which is then advanced, retracted, and/or rotated to a new
M AN U
predetermined position and the microcannula is then readvanced to the next target. In this manner, injections of therapeutic can be disseminated within a large brain volume and complex structures can be targeted using a single or minimal number of penetrations by the guide cannula. The microcannula may also serve as an electrode capable of recording electrophysiological activity capable of detecting baseline activity as well as evoked responses, therefore enabling the region of interest to be precisely
TE D
mapped with high resolution.
The reduced diameter of the microcannula allows very small, discrete brain structures to be targeted and precise and reproducible volumes can be delivered. Here we demonstrate the IMI mounted on the skull using the StarFixTM Microtargeting
EP
Platform (FHC, Bowdoinham, ME). This platform includes a fixture that is customfabricated for a specific patient using laser sintering technology. The guide cannula is
AC C
first advanced to a predetermined location proximal to the target and it is secured into position. Fine adjustment of the depth of the guide cannula is achieved using the guide cannula microdrive. The microcannula can then be advanced a specific distance along a predetermined trajectory using the microcannula microdrive. The microcannula is capable of delivering very small, accurate and reproducible volumes (nL to µL) as well as large volumes (µL to mL). The IMI therefore provides the neurosurgeon with the ability to disseminate large numbers of small injections as well as infuse large volumes under positive pressure to achieve convection enhanced delivery (CED). The WayPoint NavigatorTM (FHC, Bowdoinham, ME) surgical planning software has been specifically
ACCEPTED MANUSCRIPT
coded for high-precision IMI targeting. This software provides an advanced anatomical atlas to create accurate surgical plans and visualization of deep brain structures. It also allows for intraoperative data streaming for real time neuronal activity analysis. The IMI with WayPoint Navigator is presently being used to deliver therapeutic stem cells for
RI PT
stroke patients in a Phase 1 clinical trial. Thus far, nine subjects with fixed lesions from basal ganglia strokes have received three ascending doses of the neural stem cell line, NSI566 (Neuralstem, Inc., Germantown, MD), of 12, 24, and 72 million cells (N=3 per dose). All 3 cohorts used 3 penetrating trajectories for cell distribution. The straight
SC
Pittsburgh Cell Implantation Cannula was used for the first two dose cohorts
(Kondziolka 2004, 2005) which received 15, 20 µL cell deposits (cohort 1, 40,000
M AN U
cells/ µL; cohort 2; 80,000 cells/ µL). The third cohort received 45, 20 µL deposits (80,000 cells/ µL) delivered using the IMI with grafts being placed strategically in a three-dimensional arrays surrounding the stroke lesion to optimize graft survival and neural reconstruction. NSI566 cells are produced under current Good Manufacturing Practice (cGMP) regulations, Neuralstem presently has two INDs registered with US FDA for the same cells which are undergoing 3 different IRB-approved clinical trials in
Results
TE D
the US.
We illustrate here the use of the IMI to deliver restorative therapeutics. This
EP
instrument is engineered to allow precise 3D distribution of controlled injections from a microcannula using minimal overlying penetrations of a guide cannula.
AC C
We have shown in preclinical studies that this design dramatically reduces trauma at the injection site and allows injections to be distributed in complex 3D arrays 2,3. Using an agarose phantom brain model, we demonstrate the IMI’s ability to deliver multiple injections of virus-sized latex microspheres in 3D space in precise 10 microliter volumes with a high level of accuracy and reproducibility. The consistency in volume and placement of injections can be appreciated as well as the negligible reflux of therapeutic along the path of the microcannula. The IMI is presently being successfully used for human trials of stem cell therapy to optimize delivery, cell survival, and efficacy. It is compatible with all stereotactic devices,
ACCEPTED MANUSCRIPT
including frameless systems, and surgical planning may be achieved with most neurosurgery software platforms. Our trials utilize the WayPoint Navigator Planning System. Each patient’s CT and MRI data is used to determine intracerebral targets, brain entry points, and necessary movement and positioning of the IMI’s guide cannula and
RI PT
microcannula.
Discussion
Intracerebral delivery instruments have traditionally been straight, rigid cannulas to
SC
inject therapeutics, such as neural cell suspension, into deep brain structures. For
example, the Pittsburgh Cell Implantation Cannula has been used by Kondziolka et al. 4,5
to deliver LBS neurons for stroke patients. This injector is comprised of a rigid 890
M AN U
µm stainless steel cannula coupled with a Hamilton-type syringe and is designed to eliminate dead space within the syringe hub. A variation on the standard cannula delivery design was introduced by Mendez et al.6 with a cannula and injector system used in the Halifax Neural Transplantation Program for patients with Parkinson’s disease who underwent neural transplantation of human ventromedial mesencephalic
TE D
tissue. The Halifax Injector is comprised of a 21 gauge (800 µm) stainless steel cannula designed such that cell suspension is delivered simultaneously from two holes on opposite sides of the distal-most portion of the cannula, the second hole being 2 mm proximal to the first hole. The instrument can be rotated to allow deposits to be placed in
EP
different orientations around and adjacent to the axis of the cannula. Marin et al. described an instrument for experimentally injecting solid neural tracers into deep brain
AC C
structures7. This “solid injector” is designed to permit expulsion of solid material (e.g., tracer) from the distal portion of a 30 gauge needle (310 µm) using pressure pulses driving a rod within the needle. An added feature to this device is its capability to record brain activity in the target site. More recently, Silvestrini et al. have described a “radially branched deployment” (RBD) device having a similar design to the IMI that was introduced 10 years prior (Cunningham et al. 2004). The RBD instrument also allows 3D distribution of therapeutics using a guide cannula from which a delivery cannula can be advanced. However, it does not enable simultaneous electrophysiological profiling, and
ACCEPTED MANUSCRIPT
the RBD delivery cannula is 3 times larger than the IMI delivery cannula and therefore might be expected to cause a greater level of localized tissue disruption. While there is clear evidence that reducing localized trauma improves efficacy of brain therapeutics, notably transplanted therapeutic cells 8-11, present delivery
RI PT
instrumentation for human use remains relatively large and unable to target very small structures and deliver accurate microvolumes of therapeutic. Furthermore, present
instruments require multiple penetrations to achieve broader distribution within a given brain volume. These instruments and present delivery methodology have been
SC
considered a liability to the success of newly developed therapeutics, and may have indeed contributed to the failure of promising new medicines 12,13.
M AN U
IMI technology addresses the shortcomings of conventional delivery methodology. The instrument is engineered to deliver a therapeutic with a microcannula having the smallest possible diameter. This allows accurate and reliable injection of very small and discrete targets. The reduced size also minimizes trauma and its sequelae, such as reactive gliosis and up-regulation of neurite inhibiting factors, which can obstruct interaction and efficacy of the therapeutic. Because of its small diameter, there is
TE D
minimal reflux of the therapeutic back along the microcannula track. In addition, the microcannula is capable of multi-unit recording, therefore giving the neurosurgeon the ability profile electrophysiological activity and improve targeting accuracy well beyond that which can be achieved with MRI guidance.
EP
The IMI microcannula is composed of a specialized material allowing extension from the guide cannula at an angle or an arc. Its shape memory enables the
AC C
microcannula to travel along the exact path during extension and retraction thus preventing tissue transection. The configuration of the microcannula can be customdesigned based on the application. These features allow multiple sites to be targeted in 3D space in complex arrays from a single guide cannula trajectory. Reducing the number of passes through brain tissue reduces the risk of trauma and hemorrhage and can substantially shorten the amount of time to perform the surgery. For our ongoing neural transplantation trials, stroke patients have received numerous stem cell injections to strategically place cell suspension at locations that will optimize patient recovery. The surgery is well-tolerated and recovery has been uneventful. There
ACCEPTED MANUSCRIPT
have been no surgical complications or adverse events. These trials have demonstrated the function and safety of the IMI, and they have provided proof-of-concept for human CNS applications. IMI technology may address an unmet need in restorative therapeutic delivery, and it is presently being leveraged to enable sophisticated delivery of other
RI PT
therapeutics, including HIV medicines, chemotherapeutics, and neurotrophic factors.
Conclusion
With the rapid progress in stem cell biology, gene therapy, and other brain
SC
therapeutics, the need for equally sophisticated delivery methodology is being
recognized. IMI technology allows strategic placement of multiple microinjections from a
M AN U
single overlying penetration using MRI and electrophysiological guidance. Over numerous porcine and non-human primate experiments, as well as our clinical trials, the IMI has repeatedly proven to be reliable and safe. When combined with the Waypoint surgical planning software and using the instrument’s ability to map brain activity, unprecedented precision in targeting may be achieved in complex three-dimensional arrays strategically
AC C
EP
TE D
planned to optimize therapeutic benefit.
ACCEPTED MANUSCRIPT
References Bjarkam CR, Glud AN, Margolin L, et al. Safety and function of a new clinical intracerebral microinjection instrument for stem cells and therapeutics examined in the Gottingen minipig. Stereotact Funct Neurosurg. 2010;88(1):56-63.
2.
Cunningham MG, Bolay H, Scouten CW, et al. Preclinical evaluation of a novel intracerebral microinjection instrument permitting electrophysiologically guided delivery of therapeutics. Neurosurgery. 2004;54(6):1497-1507; discussion 1507.
3.
Glud AN, Bjarkam CR, Azimi N, Johe K, Sorensen JC, Cunningham M. Feasibility of Three-Dimensional Placement of Human Therapeutic Stem Cells Using the Intracerebral Microinjection Instrument. Neuromodulation. 2016;19(7):708-716.
4.
Kondziolka D, Steinberg GK, Cullen SB, McGrogan M. Evaluation of surgical techniques for neuronal cell transplantation used in patients with stroke. Cell Transplant. 2004;13(7-8):749-754.
5.
Kondziolka D, Steinberg GK, Wechsler L, et al. Neurotransplantation for patients with subcortical motor stroke: a phase 2 randomized trial. J Neurosurg. 2005;103(1):38-45.
6.
Mendez I, Hong M, Smith S, Dagher A, Desrosiers J. Neural transplantation cannula and microinjector system: experimental and clinical experience. Technical note. J Neurosurg. 2000;92(3):493-499.
7.
Marin G, Henny P, Letelier JC, et al. A simple method to microinject solid neural tracers into deep structures of the brain. J Neurosci Methods. 2001;106(2):121129.
8.
Finsen BR, Pedersen EB, Sorensen T, Hokland M, Zimmer J. Immune reactions against intracerebral murine xenografts of fetal hippocampal tissue and cultured cortical astrocytes in the adult rat. Prog Brain Res. 1990;82:111-128.
10.
SC
M AN U
TE D
EP
AC C
9.
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1.
Finsen BR, Sorensen T, Castellano B, Pedersen EB, Zimmer J. Leukocyte infiltration and glial reactions in xenografts of mouse brain tissue undergoing rejection in the adult rat brain. A light and electron microscopical immunocytochemical study. J Neuroimmunol. 1991;32(2):159-183.
Nikkhah G, Cunningham MG, Jodicke A, Knappe U, Bjorklund A. Improved graft survival and striatal reinnervation by microtransplantation of fetal nigral cell suspensions in the rat Parkinson model. Brain Res. 1994;633(1-2):133-143.
ACCEPTED MANUSCRIPT
Nikkhah G, Olsson M, Eberhard J, Bentlage C, Cunningham MG, Bjorklund A. A microtransplantation approach for cell suspension grafting in the rat Parkinson model: a detailed account of the methodology. Neuroscience. 1994;63(1):57-72.
12.
Bartus RT, Kordower JH, Johnson EM, Jr., et al. Post-mortem assessment of the short and long-term effects of the trophic factor neurturin in patients with alphasynucleinopathies. Neurobiol Dis. 2015;78:162-171.
13.
Bartus RT, Weinberg MS, Samulski RJ. Parkinson's disease gene therapy: success by design meets failure by efficacy. Mol Ther. 2014;22(3):487-497.
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EP
TE D
M AN U
SC
RI PT
11.
ACCEPTED MANUSCRIPT
Abbreviations:
Three Dimensional
CED
Convection Enhanced Delivery
CNS
Central Nervous System
CT
Computerized Tomography
FHC
Fredrick Haer and Company
IMI
Intracerebral Microinjection Instrument
MRI
Magnetic Resonance Imaging
M AN U
TE D EP AC C
SC
RI PT
3D
S1878-8750(19)31073-3
DOI:
https://doi.org/10.1016/j.wneu.2019.04.081
Reference:
WNEU 12111
To appear in:
World Neurosurgery
Received Date: 20 January 2019 Revised Date:
8 April 2019
Accepted Date: 9 April 2019
Please cite this article as: Cunningham M, Azimi S, Zhang G, Intracerebral Delivery in Complex 3D Arrays: The Intracerebral Microinjection Instrument (IMI) World Neurosurgery (2019), doi: https:// doi.org/10.1016/j.wneu.2019.04.081. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
RI PT
Intracerebral Delivery in Complex 3-D Arrays: The Intracerebral Microinjection Instrument (IMI) Miles Cunningham1, Sina Azimi1, GuangZhu Zhang2 1
SC
Laboratory for Neural Reconstruction, McLean Hospital, Harvard Medical School 115 Mill Street, Belmont, MA 02451, USA 2 Affiliated BaYi Brain Hospital, Army General Hospital of PLA, Nan Men Cang No.5, Dong Cheng District, Beijing, China
M AN U
E-Mail Addresses: Miles Cunningham - [email protected] Sina Azimi - [email protected] GuangZhu Zhang - [email protected]
TE D
Corresponding Author: Miles Cunningham, MD, PhD Laboratory for Neural Reconstruction, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA Tel: (617) 855-2051 Fax: (617) 855-3894 Email: [email protected]
EP
Short Title: 3D Intracerebral Delivery
AC C
Key Words: Intracerebral Microinjection Instrument (IMI), stereotactic surgery, functional neurosurgery, restorative therapeutics
ACCEPTED MANUSCRIPT
Abstract This video article describes and illustrates the function and application of the Intracerebral Microinjection Instrument (IMI). This newly developed technology allows
RI PT
delivery of therapeutics within the human brain in complex three-dimensional arrays using a single pass or minimal overlying penetrations through brain tissue. The IMI
utilizes a delivery microcannula with a reduced diameter that minimizes local trauma and is capable of delivering precise volumes of therapeutics to discrete brain
SC
substructures. The IMI also permits simultaneous recording of neural activity during the delivery procedure enabling extreme precision using electrophysiological mapping. Surgical planning software designed specifically for the IMI enables strategic placement
M AN U
of multiple injections. This technology platform is presently being used successfully to deliver therapeutic stem cells to restore function in stroke patients. Additional applications of the IMI include delivery of viral vectors for gene therapy, infusion of neurotrophic factors, targeted delivery of chemotherapeutics, and delivery of
AC C
EP
TE D
antiretroviral medications.
ACCEPTED MANUSCRIPT
Introduction As new therapeutics for central nervous system (CNS) disorders are developed, more sophisticated and precise delivery methodology is becoming necessary. The
RI PT
currently used approach for intracerebral delivery has remained virtually unchanged for decades and it continues to present liabilities. Delivery instruments used today are
based on straight and rigid cannula designs with diameters ranging from 0.8 – 2 mm. This presents a problem when the brain target itself is on the scale of the instrument
SC
introducing the therapeutic. In addition, distribution of an agent in 3-dimensional (3D) space requires multiple penetrations of the rigid delivery device. This extends surgical
M AN U
time and each penetration increases the risk of trauma and hemorrhage. These issues have been addressed with the development of the Intracerebral Microinjection Instrument (IMI). The IMI’s unique design enables dissemination of therapeutics in complex 3D arrays from a single or a minimal number of overlying penetrations of brain tissue. The instrument utilizes a specialized “microcannula” with shape memory that is able to target very small brain structures using MRI and
TE D
electrophysiological guidance and deliver accurate volumes of therapeutic. The IMI therefore offers to increase the efficacy of therapeutics by permitting delivery with a high level of precision and reducing localized trauma to an absolute minimum. In addition, the IMI may reduce surgical time and the risk of complications for patients undergoing
EP
restorative neurosurgical procedures. This technology is presently being used to deliver therapeutic stem cells to restore function in stroke patients. Up to one year after having
AC C
a stroke, these individuals have received an unprecedented numbers (~45) of stem cell grafts placed in complex three-dimensional arrays surrounding cystic stroke lesions to optimize reconstruction of white matter tracts. The IMI design was robust and reliable, and similar to numerous preclinical studies in rodents, pigs, and non-human primates, no surgical complications were seen in any of the patients. The transplantation procedure was well-tolerated, the patients’ recovery was uneventful, and they all proceeded to regain function over the subsequent year. We present here a video demonstration that illustrates the mechanics of the IMI and describes its use for delivering restorative therapeutics.
ACCEPTED MANUSCRIPT
Materials and Methods The IMI has been previously described in preclinical studies demonstrating that the technology has numerous advantages over conventional straight, rigid delivery
RI PT
instruments 1-3. The IMI in this demonstration utilizes a microcannula with a diameter of 200 microns; that is, about 4-fold smaller than presently used delivery cannulas. Contained within a “guide cannula”, the microcannula can be extended at a
predetermined angle along a straight or arcing trajectory to reach the injection target
SC
site. After an injection is completed, the microcannula is withdrawn back within the guide cannula, which is then advanced, retracted, and/or rotated to a new
M AN U
predetermined position and the microcannula is then readvanced to the next target. In this manner, injections of therapeutic can be disseminated within a large brain volume and complex structures can be targeted using a single or minimal number of penetrations by the guide cannula. The microcannula may also serve as an electrode capable of recording electrophysiological activity capable of detecting baseline activity as well as evoked responses, therefore enabling the region of interest to be precisely
TE D
mapped with high resolution.
The reduced diameter of the microcannula allows very small, discrete brain structures to be targeted and precise and reproducible volumes can be delivered. Here we demonstrate the IMI mounted on the skull using the StarFixTM Microtargeting
EP
Platform (FHC, Bowdoinham, ME). This platform includes a fixture that is customfabricated for a specific patient using laser sintering technology. The guide cannula is
AC C
first advanced to a predetermined location proximal to the target and it is secured into position. Fine adjustment of the depth of the guide cannula is achieved using the guide cannula microdrive. The microcannula can then be advanced a specific distance along a predetermined trajectory using the microcannula microdrive. The microcannula is capable of delivering very small, accurate and reproducible volumes (nL to µL) as well as large volumes (µL to mL). The IMI therefore provides the neurosurgeon with the ability to disseminate large numbers of small injections as well as infuse large volumes under positive pressure to achieve convection enhanced delivery (CED). The WayPoint NavigatorTM (FHC, Bowdoinham, ME) surgical planning software has been specifically
ACCEPTED MANUSCRIPT
coded for high-precision IMI targeting. This software provides an advanced anatomical atlas to create accurate surgical plans and visualization of deep brain structures. It also allows for intraoperative data streaming for real time neuronal activity analysis. The IMI with WayPoint Navigator is presently being used to deliver therapeutic stem cells for
RI PT
stroke patients in a Phase 1 clinical trial. Thus far, nine subjects with fixed lesions from basal ganglia strokes have received three ascending doses of the neural stem cell line, NSI566 (Neuralstem, Inc., Germantown, MD), of 12, 24, and 72 million cells (N=3 per dose). All 3 cohorts used 3 penetrating trajectories for cell distribution. The straight
SC
Pittsburgh Cell Implantation Cannula was used for the first two dose cohorts
(Kondziolka 2004, 2005) which received 15, 20 µL cell deposits (cohort 1, 40,000
M AN U
cells/ µL; cohort 2; 80,000 cells/ µL). The third cohort received 45, 20 µL deposits (80,000 cells/ µL) delivered using the IMI with grafts being placed strategically in a three-dimensional arrays surrounding the stroke lesion to optimize graft survival and neural reconstruction. NSI566 cells are produced under current Good Manufacturing Practice (cGMP) regulations, Neuralstem presently has two INDs registered with US FDA for the same cells which are undergoing 3 different IRB-approved clinical trials in
Results
TE D
the US.
We illustrate here the use of the IMI to deliver restorative therapeutics. This
EP
instrument is engineered to allow precise 3D distribution of controlled injections from a microcannula using minimal overlying penetrations of a guide cannula.
AC C
We have shown in preclinical studies that this design dramatically reduces trauma at the injection site and allows injections to be distributed in complex 3D arrays 2,3. Using an agarose phantom brain model, we demonstrate the IMI’s ability to deliver multiple injections of virus-sized latex microspheres in 3D space in precise 10 microliter volumes with a high level of accuracy and reproducibility. The consistency in volume and placement of injections can be appreciated as well as the negligible reflux of therapeutic along the path of the microcannula. The IMI is presently being successfully used for human trials of stem cell therapy to optimize delivery, cell survival, and efficacy. It is compatible with all stereotactic devices,
ACCEPTED MANUSCRIPT
including frameless systems, and surgical planning may be achieved with most neurosurgery software platforms. Our trials utilize the WayPoint Navigator Planning System. Each patient’s CT and MRI data is used to determine intracerebral targets, brain entry points, and necessary movement and positioning of the IMI’s guide cannula and
RI PT
microcannula.
Discussion
Intracerebral delivery instruments have traditionally been straight, rigid cannulas to
SC
inject therapeutics, such as neural cell suspension, into deep brain structures. For
example, the Pittsburgh Cell Implantation Cannula has been used by Kondziolka et al. 4,5
to deliver LBS neurons for stroke patients. This injector is comprised of a rigid 890
M AN U
µm stainless steel cannula coupled with a Hamilton-type syringe and is designed to eliminate dead space within the syringe hub. A variation on the standard cannula delivery design was introduced by Mendez et al.6 with a cannula and injector system used in the Halifax Neural Transplantation Program for patients with Parkinson’s disease who underwent neural transplantation of human ventromedial mesencephalic
TE D
tissue. The Halifax Injector is comprised of a 21 gauge (800 µm) stainless steel cannula designed such that cell suspension is delivered simultaneously from two holes on opposite sides of the distal-most portion of the cannula, the second hole being 2 mm proximal to the first hole. The instrument can be rotated to allow deposits to be placed in
EP
different orientations around and adjacent to the axis of the cannula. Marin et al. described an instrument for experimentally injecting solid neural tracers into deep brain
AC C
structures7. This “solid injector” is designed to permit expulsion of solid material (e.g., tracer) from the distal portion of a 30 gauge needle (310 µm) using pressure pulses driving a rod within the needle. An added feature to this device is its capability to record brain activity in the target site. More recently, Silvestrini et al. have described a “radially branched deployment” (RBD) device having a similar design to the IMI that was introduced 10 years prior (Cunningham et al. 2004). The RBD instrument also allows 3D distribution of therapeutics using a guide cannula from which a delivery cannula can be advanced. However, it does not enable simultaneous electrophysiological profiling, and
ACCEPTED MANUSCRIPT
the RBD delivery cannula is 3 times larger than the IMI delivery cannula and therefore might be expected to cause a greater level of localized tissue disruption. While there is clear evidence that reducing localized trauma improves efficacy of brain therapeutics, notably transplanted therapeutic cells 8-11, present delivery
RI PT
instrumentation for human use remains relatively large and unable to target very small structures and deliver accurate microvolumes of therapeutic. Furthermore, present
instruments require multiple penetrations to achieve broader distribution within a given brain volume. These instruments and present delivery methodology have been
SC
considered a liability to the success of newly developed therapeutics, and may have indeed contributed to the failure of promising new medicines 12,13.
M AN U
IMI technology addresses the shortcomings of conventional delivery methodology. The instrument is engineered to deliver a therapeutic with a microcannula having the smallest possible diameter. This allows accurate and reliable injection of very small and discrete targets. The reduced size also minimizes trauma and its sequelae, such as reactive gliosis and up-regulation of neurite inhibiting factors, which can obstruct interaction and efficacy of the therapeutic. Because of its small diameter, there is
TE D
minimal reflux of the therapeutic back along the microcannula track. In addition, the microcannula is capable of multi-unit recording, therefore giving the neurosurgeon the ability profile electrophysiological activity and improve targeting accuracy well beyond that which can be achieved with MRI guidance.
EP
The IMI microcannula is composed of a specialized material allowing extension from the guide cannula at an angle or an arc. Its shape memory enables the
AC C
microcannula to travel along the exact path during extension and retraction thus preventing tissue transection. The configuration of the microcannula can be customdesigned based on the application. These features allow multiple sites to be targeted in 3D space in complex arrays from a single guide cannula trajectory. Reducing the number of passes through brain tissue reduces the risk of trauma and hemorrhage and can substantially shorten the amount of time to perform the surgery. For our ongoing neural transplantation trials, stroke patients have received numerous stem cell injections to strategically place cell suspension at locations that will optimize patient recovery. The surgery is well-tolerated and recovery has been uneventful. There
ACCEPTED MANUSCRIPT
have been no surgical complications or adverse events. These trials have demonstrated the function and safety of the IMI, and they have provided proof-of-concept for human CNS applications. IMI technology may address an unmet need in restorative therapeutic delivery, and it is presently being leveraged to enable sophisticated delivery of other
RI PT
therapeutics, including HIV medicines, chemotherapeutics, and neurotrophic factors.
Conclusion
With the rapid progress in stem cell biology, gene therapy, and other brain
SC
therapeutics, the need for equally sophisticated delivery methodology is being
recognized. IMI technology allows strategic placement of multiple microinjections from a
M AN U
single overlying penetration using MRI and electrophysiological guidance. Over numerous porcine and non-human primate experiments, as well as our clinical trials, the IMI has repeatedly proven to be reliable and safe. When combined with the Waypoint surgical planning software and using the instrument’s ability to map brain activity, unprecedented precision in targeting may be achieved in complex three-dimensional arrays strategically
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Glud AN, Bjarkam CR, Azimi N, Johe K, Sorensen JC, Cunningham M. Feasibility of Three-Dimensional Placement of Human Therapeutic Stem Cells Using the Intracerebral Microinjection Instrument. Neuromodulation. 2016;19(7):708-716.
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Nikkhah G, Olsson M, Eberhard J, Bentlage C, Cunningham MG, Bjorklund A. A microtransplantation approach for cell suspension grafting in the rat Parkinson model: a detailed account of the methodology. Neuroscience. 1994;63(1):57-72.
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Bartus RT, Kordower JH, Johnson EM, Jr., et al. Post-mortem assessment of the short and long-term effects of the trophic factor neurturin in patients with alphasynucleinopathies. Neurobiol Dis. 2015;78:162-171.
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Abbreviations:
Three Dimensional
CED
Convection Enhanced Delivery
CNS
Central Nervous System
CT
Computerized Tomography
FHC
Fredrick Haer and Company
IMI
Intracerebral Microinjection Instrument
MRI
Magnetic Resonance Imaging
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