Repair of bone defects using a new biomimetic construction fabricated by adipose-derived stem cells, collagen I, and porous beta-tricalcium phosphate scaffolds.

Adipose derived stem cells (ASCs) with multilineage differentiation capacities have been demonstrated as an alternative cell candidate for in vitro and in vivo bone regeneration. This suggests that they may be a potential candidate to repair the bone defects. We attempted to demonstrate the use of new biomimetic constructions of undifferentiated rabbit adipose-derived stem cells (rASCs) with fully interconnected porous beta-tricalcium phosphate (β-TCP) scaffolds encapsulated by collagen I hydrogel in the regeneration of a critical-sized defect of rabbit radii. Critical-sized defects in the left radii of rabbits were prepared and inserted with rASCs/collagen I/β-TCP scaffold composites or collagen I/β-TCP scaffold composites. The results were evaluated by histology, radiographs, micro-CT, Emission Computed Tomography (ECT), fluorochrome labeling, western blot, and mechanical testing at 4, 8, and 12 weeks postsurgery. Twelve weeks after implantation, the defects were almost completely repaired as confirmed by the presence of the cortical bone and medullary cavity, which was evaluated through radiologic, histologic, and biomechanical examination. Biodegradation of the biomaterials may be attributed to extracellular liquid dissolution together with cell-mediated phagocytosis. Our study shows that a greater number of rASCs in the porous β-TCP scaffold encapsulated by collagen I gel enhanced osteogenesis in critical-sized defects. We hope to garner new insight into the engineering of rASCs-based bone tissue for clinical application.