53 Optimizing Gelatin-based Sponges as Stem-Cell Carriers for Mandibular Distraction Osteogenesis

Wednesday, March 21, 2012: 2:30 p.m. - 4 p.m.
Presentation Type: Oral Session
Z. SUN1, B.C. TEE1, K. KENNEDY2, D. KIM1, and E.N.D. LOW3, 1Orthodontics, Ohio State University, Columbus, OH, 2Oral and Maxillofacial Surgery, Ohio State University, Columbus, OH, 3Ohio State University, Columbus, OH
Objective: To optimize cell delivery for bone regeneration using gelatin-based scaffolds, this study investigated the optimal incubation time for cell-scaffold integration and preliminarily tested its in-vivo effects in a pig mandibular distraction osteogenesis model.

Method: Gelatin-based Gelfoam® sponges were cut into 10x5x7 mm3 pieces, seeded with 2x106 pig bone marrow stromal cells (pBMSCs), and incubated with serum-free regular medium (TCM) or osteogenic medium (ODM). Scaffolds were collected at day 1, 3, 5 to analyze cell integration/growth by DNA assay and histological analyses. Image series from H&E sections were captured randomly and cells were counted in a blinded fashion. For in vivo testing, bone marrow was aspirated from a 3-month-old pig, from which 100-million pBMSCs were expanded. Then bilateral mandibular osteotomies were performed and Gelfoam scaffolds (60x20x7mm3) with or without autologous BMSCs (5days in TCM) were transplanted into either osteotomy. After a 2-day latency, 10 mm-distraction (1mm/day) and 4-week-consolidation, distraction-site regenerates were analyzed by Cone-beam CT (250mm voxel-size) for remaining gap width and by micro-CT (27mm voxel-size) for stereology parameters. Bone volume fraction (BV/TV) of 6-12 3x3x3mm3 regions in the central and peripheral (near host bone) regenerates was quantified.

Result: Live cell content (DNA assay) in the Gelfoam scaffold peaked at 3 and 5 days of incubation in ODM and TCM media, respectively, with ODM being higher (119% vs. 80% of initial cell-loading number). Histology confirmed that cell density reached peaks (ANOVA, p<0.05) at 3 and 5 days for ODM (surface/interior: 2766/1633cells/mm2) and TCM (surface/interior: 2266/1126cells/mm2), respectively. In-vivo testing demonstrated that the cell-scaffold side had substantially smaller remaining gap (1.3mm vs. 3.6mm) and higher BV/TV (central/peripheral zones: 0.46/0.63) than the scaffold-only side (central/peripheral zones: 0/0.30).

Conclusion: This study established optimal incubation times for integrating/growing pBMSC on Gelfoam scaffolds in serum-free media before in-vivo transplantation, which may strongly enhance mandibular distraction osteogenesis.

This abstract is based on research that was funded entirely or partially by an outside source: National Center For Research Resources UL1RR025755; American Association of Orthodontists Foundation; Mandibular distractors were donated by KLS-Martin, LP

Keywords: Bioengineering, Bone repair, Cell culture, Distraction osteogenesis and Regeneration