Skeletal repair in rabbits using a novel biomimetic composite based on adipose-derived stem cells encapsulated in collagen I gel with PLGA-beta-TCP scaffold.

In bone tissue engineering, the cell distribution mode in the scaffold may affect in vivo osteogenesis. Therefore, we fabricated a novel biomimetic construct based on a combination of rabbit adipose-derived stem cells (rASCs) encapsulated in collagen I gel with a PLGA-beta-TCP scaffold (rASCs-COL/PLGA-beta-TCP, group A), the combination of rASCs and PLGA-beta-TCP (rASCs/PLGA-beta-TCP, group B), the combination of collagen I gel and PLGA-beta-TCP (COL/PLGA-beta-TCP, group C), and PLGA-beta-TCP scaffold (group D). The composites were implanted into a 15-mm length critical-sized segmental radial defect. The results were assessed by histology, radiographs, bone mineral density (BMD), and mechanical testing. After 24 weeks, the medullary cavity recanalized, bone was rebuilt, and molding finished, the bone contour remodeled smoothly and the scaffold degraded completely in group A. The BMDs and mechanical properties were similar to normal. However, the bone defect remained unrepaired in groups B, C, and D. Moreover, the scaffold degradation rate in group A was significantly higher than the other groups. Thus, enhanced in vivo osteogenesis of rASCs wrapped in collagen I gel combined with PLGA-beta-TCP was achieved, and the bone defect was repaired. We hope this study provides new insights into ASCs-based bone tissue engineering.