beta1

Vol. 215, No. 3S, September 2012

INTRODUCTION: Our laboratory has demonstrated that administration of prophylactic Amifostine (AMF) mitigates the pernicious effects of radiation therapy (XRT) on murine mandibles while preserving new bone formation. This occurs in the settings of both distraction osteogenesis and fracture repair. We hypothesize XRT compromises the biomechanical properties (BPs) of murine mandibles, while prophylactic AMF administration preserves BPs to that of normal, native bone. This knowledge could expand the use of AMF to include reducing long-term, bone-related morbidity associated with XRT administration. METHODS: Male Sprague Dawley rats were randomized into three groups: Control-(n⫽6); XRT-(n⫽11); and AMF/XRT-(n⫽9). Irradiated animals underwent fractionated 70Gy human-equivalent XRT to the left hemi-mandible. AMF/XRT animals received 100mg/kg subcutaneous AMF 45 minutes prior to XRT. Hemimandibles were harvested 8 weeks after XRT for BPs analysis. Statistics were calculated using ANOVA and Tukey post-hoc methods. p Values of ⬍0.05 define statistical significance. RESULTS: Consistent with our hypothesis, we observed the preservation of mandibular BPs of “elastic modulus”, “ultimate load”, and “load energy prior to fracture” in AMF/XRT animals, similar to those of Controls. Surprisingly, we observed statistically significant increases in the same BPs in irradiated animals compared to both AMF/XRT and Control animals. CONCLUSIONS: AMF prophylaxis preserved the BPs of irradiated mandibles, while XRT caused an unexpected increase in BPs. We posit the latter is a non-physiologic, short-term phenomena that will degrade over time, given the development of pathologic fracture and osteoradionecrosis in irradiated bone. Clinical trials may be warranted to determine the efficacy of AMF prophylaxis in preventing bony morbidity in XRT protocols.

Stem cell and intermittent parathyroid hormone therapy creates superior regenerate in murine mandibular distraction osteogenesis following radiation Sagar Satish Deshpande, BS, Steven R Buchman, MD, FACS, Alexis Donneys, MD, Kelly K Gallagher, MD, Catherine N Tchanque-Fossuo, MD, Deniz Sarhaddi, BA, Daniela M Weiss, BSc(Hons), Hongli Sun, PhD, Paul H Krebsbach,DDS DNB, PhD University of Michigan, Ann Arbor, MI INTRODUCTION: Radiation therapy (XRT) is known to be detrimental to bone and soft tissue repair, resulting in an unacceptably high incidence of maladies such as osteoradionecrosis, late pathologic fractures and non-union through a mechanism of direct cellular depletion. We posit that transplanted bone marrow stromal cells (BMSCs), a type of mesenchymal stem cell, will provide sufficient cellular replacement, and, in conjunction with intermittent doses of parathyroid hormone (PTH), will enhance the generation and quality of new bone during distraction osteogenesis (DO). METHODS: 26 Lewis rats were randomLy split into four groups. XRT/DO (n⫽6), BMSC/XRT/DO (n⫽7), and BMSC⫹PTH/ XRT/DO (n⫽6) underwent 35 Gy fractionated XRT of the left

Abstracts

S81

mandible. DO (n⫽7), received no radiation. Two weeks after radiation, animals underwent mandibular distractor placement. The BMSC/XRT/DO and BMSC⫹PTH/XRT/DO received 2⫻10^6 BMSCs intraoperatively to the distraction gap. All were distracted every 12 hrs to 5.1mm. BMSC⫹PTH received 60 mg/kg of PTH concomitantly with distraction and for the 3 subsequent weeks. Animals were sacrificed on post-operative day 40, and mandibles underwent radiomorphometric and biomechanical response analyses. RESULTS: We have previously reported that BMSC treatment restores union quality, radiomorphometric parameters, and partially remediates biomechanical response. Here, we show significantly increased radiomorphometrics and biomechanical response parameters in BMSC⫹PTH/XRT/DO compared to XRT/DO. Ultimate Failure load (N) load (N)

Yield (N)

XRT/DO 1.81 0.56 1.49 BMSC/XRT/ DO 32.21* 30.78* 30.02* BMSC⫹ PTH/ XRT/DO 68.65ⴱⴱ,$ 51.98** 51.98** DO (control) 93.14** 92.89** 70.99**

BVF (unitless)

BMD (mg/ cm3)

0.51

452.42

0.73*

565.54*

0.72* 0.72*

560.85* 554.23*

*⫽p⬍0.05; ** ⫽p⬍0.001 in comparison to XRT/DO. $ ⫽p⬍0.05 in comparison to BMSC/XRT/DO.

CONCLUSIONS: These results indicate that PTH supplementation creates a regenerate of superior biomechanical strength (73.1% of control) when compared to BMSC treatment alone (34.4% of control), rescuing the ability for irradiated bone to undergo distraction osteogenesis, thereby producing a solid, bony union with improved parameters of bone quality.

Connective tissue growth factor enhances keratinocyte adhesion to fibronectin and promotes migration through integrin alpha5/beta1 Elizabeth Kiwanuka, MD, Junker PE Johan, PhD, Edward J Caterson, MD, PhD, Bengt Gerdin, MD, PhD, Elof Eriksson, MD, PhD, FACS Brigham and Women’s Hospital, Boston, MA, Uppsala University, Uppsala, Sweden INTRODUCTION: We have previously shown that connective tissue growth factor (CTGF) promotes keratinocyte migration during reepithelialization. In this study, we investigated whether the CTGFdriven migration involved integrin alpha-5/beta-1 - the principal ligand for fibronectin (FN). METHODS: Adhesions assays were performed by coating wells with 10 ug/mL FN or phosphate buffered saline (PBS). Keratinocytes were seeded in the presence or absence of 200 ng/mL CTGF, 5 mmol/L EDTA, 10 mmol/L Mg2⫹, 10 ug/mL anti-integrin alpha5/beta-1-blocking antibody. Chemotaxsis assays were performed using a modified Boyden chamber. Keratinocytes were pre-incubated with alpha-5/beta-1-antibodies or mouse-IgG for 30 minute, and migration in the absence or presence of 200 ng/mL CTGF was mea-

S82

Abstracts

J Am Coll Surg

sured. Cells were stained and absorbance was measured at 570 nm. A value of 1 was assigned to untreated cells. RESULTS: Cell adhesion increased 1.5 ⫾ 0.3 folds in wells coated with FN compared to PBS. CTGF enhanced cell adhesion 2.1 ⫾ 0.3 folds, while EDTA reduced CTGF mediated cell adhesion to baseline (1.1 ⫾ 0.2). The addition of the divalent cation Mg2⫹ restored CTGF-induced adhesion, indicating involvement of integrins. Integrin alpha-5/beta-1-blocking antibodies reversed CTGF-enhanced binding (1.1 ⫾ 0.2). Consistent with the cell adhesion data, CTGFinduced migration was reduced to 1.5 ⫾ 0.3 by anti-integrin alpha5/beta-1 antibodies compared to the 2.0 ⫾ 0.6 fold increase seen with 200 ng/mL CTGF. Table. CTGF enhances keratinocyte adhesion to fibronectin and promotes migration through integrin alpha-5/beta-1 Migration (fold increase)

Control Fn FN ⫹ CTGF

1 1.5 ⫾ 0.3* 2.1 ⫾ 0.3*

FN ⫹ CTGF ⫹ EDTA FN ⫹ CTGF ⫹EDTA ⫹ Mg2⫹ FN ⫹ CTGF ⫹ antialpha-5/ beta-1 FN ⫹ CTGF ⫹ IgG

1.1 ⫾ 0.2 1.6 ⫾ 0.2* 1.1 ⫾ 0.2

1.7 ⫾ 0.4*

200 ng/m LCTGF ⫹ anti-alpha-5/ beta-1 200 ng/m LLCTGF ⫹ IgG

METHODS: High-throughput image analysis was used to reconstruct the three-dimensional anatomy and quantify morphomic measures of the zygomatic bone, temporalis muscle and temporal fat pad thickness, area and volume. These steps were completed in a semi-automated method using algorithms programmed in MATLAB v13.0. Difference of morphomic values across varying craniosynostosis types were assessed using wilcoxon nonparametric tests for both craniosynostosis patients and a control cohort of trauma patients.

1 2.3 ⫾ 0.7* 1.5 ⫾ 0.3

RESULTS: By utilizing pre-operative CT images, we captured 117 children with NSC from the University of Michigan Health System and 48 age matched control patients between 1999-2012. Results depicted in the Table indicate significant differences in CMI among the normal and NSC groups with normal patients having significantly higher CMI values than metopic, saggital and coronal synostosis patients. Additionally, significant differences were found to exist between each craniosynostosis group.

1.8 ⫾ 0.4*

Table.

Adhesion (fold increase)

Control 10 ng/m LEGF 50 ng/m LCTGF 100 ng/m LCTGF 200 ng/m LCTGF

utilized to calculate CraniofacialMorphomic Indices (CMI) which are unique to each craniosynostoses types (metopic, coronal and saggital).

2.0 ⫾ 0.6* 1.5 ⫾ 0.3

Temporalis local mean thickness Temporalis local volume Zygomatic bone thickness

1.8 ⫾ 0.5*

Values represent mean ⫾ SD of triplicate measurements from two experiments. *p⬍0.05 vs control group.

CONCLUSIONS: This study demonstrates that CTGF enhances keratinocyte adhesion to FN and promotes migration through integrin alpha-5/beta-1. CTGF has emerged as a regulator of epidermal regeneration and is a potential target for the modulation of keratinocyte motility.

Temporal fat volume Temporal mean fat thickness

Normal vs. saggital

Normal vs. metopic

Normal vs. coronal

Saggital vs. coronal

4.24 vs. 3.45 p ⬍ 0.001

4.24 vs. 4.03 p ⫽ 0.329

4.24 vs. 4.27 p ⫽ 0.665

3.45 vs. 4.27 p ⬍ 0.001

168.35 vs131.08 p ⫽ 0.018

129.59 vs 131.08 p ⫽ 0.730

1.57 vs. 1.55 p ⫽ 0.920

1.30 vs. 1.55 p ⫽ 0.010

168.35 vs. 129.59 168.35 vs. 141.69 p ⬍ 0.001 p ⫽ 0.085 1.57 vs. 1.30 p ⬍ 0.001

1.57 vs. 1.38 p ⫽ 0.023

431.59 vs. 321.58 431.59 vs. 305.31 431.59 vs. 240.39 321.58 vs. 240.39 p ⫽ 0.001 p ⫽ 0.001 p ⬍ 0.001 p ⫽ 0.001 10.69 vs. 8.63 p ⬍ 0.001

10.69 vs. 8.57 p ⫽ 0.001

10.69 vs. 7.38 p ⬍ 0.001

8.63 vs. 7.38 p ⫽ 0.006

CONCLUSIONS: In this study we demonstrate that craniosynostosis not only has an effect on cranial bone morphology, but also on the morphology of the surrounding muscle, fat and zygomatic bone; akin to the functional matrix theory espoused by Moss. This study presents a novel methodology of how to quantify CMI differences among craniosynostosis subtypes.

Novel development of craniofacial morphomic indeces to characterize variation among craniosynostosis subtypes Jacob Rinkinen, BA, Lu Wang, PhD, Peng Zhang, PhD, Binu Enchakalody, MS, Sven Holcombe, MS, Alex Dombrowski, MD, Jeffrey Lisiecki, BS, Stewart Wang, MD, PhD, Steven R Buchman, MD, FACS, Benjamin Levi, MD University of Michigan, Ann Arbor, MI

Factors associated with noncompliance with follow-up care after maxillofacial fractures Amelia W Maiga, MD, MPH, Dunya Atisha, MD, David Nolen, MD, Ryan Kellogg, MD, Brian Christie, MD, Ed Ruane, MD, Ketan Sharma, BA, MPH, Alex Allori, MD, MPH, Detlev Erdmann, MD, PhD, MHSc, Jeffrey Marcus, MD, FACS, FAAP Duke University Medical Center, Durham, NC

INTRODUCTION: Preoperative computed tomography (CT) evaluation of non-syndromic craniosynostosis (NSC) patients has focused on the bony cranial vault; conversely, the surrounding soft tissues have largely been ignored. We posit that CT derived temporal muscle, temporal fat pad and zygomatic bone morphomics can be

INTRODUCTION: There is a paucity of literature identifying maxillofacial trauma patients that are at risk for non-compliance with follow up. The process of follow-up care is complex and may be affected by the initial evaluation and management of the injury, patient demographics, and injury-specific factors.