Enhancement of tibial regeneration in a rat model by adipose-derived stromal cells in a PLGA scaffold

Introduction: Autologous adipose-derived stromal cells (ASCs) are an obvious source of osteogenic cells and can be easily isolated from adipose tissue. We evaluated the potential of ASCs seeded onto a scaffold to heal tibial defects. Methods: Autologous ASCs were obtained from adipose tissue by collagenase digestion. The cells were seeded in three-dimensional poly(lactic)-glycolic acid (PLGA) scaffolds and cultured in osteogenic medium for four weeks. Evidence of osteogenesis was assessed by von Kossa staining in three-dimensional cultures following osteogenic induction. The critical size tibial defects (10. mm) were created using a rat model. Defects were either left empty (sham group), treated with a PLGA scaffold alone (PLGA group), or a PLGA/ASC composite (PLGA/ASC group). Using radiologic and histologic analyses, we assessed total bone volume and vascular density. Total RNA was prepared from regenerated bone and analyzed for osteogenic marker gene expression. Results: In three-dimensional cultures, the PLGA/ASC composite showed multiple calcified extracellular matrix nodules on von Kossa staining after four weeks of differentiation. Near complete healing was observed between the PLGA/ASC engrafted tibial defects on plain radiographs and micro-CT findings. Total bone volume and mechanical strength were significantly higher in the PLGA/ASC group compared to the sham and PLGA groups. Histologic analysis revealed increased new bone formation along capillaries in the PLGA/ASC group. Real-time RT-PCR analysis revealed a significant increase in the expression of osteogenic genes in the PLGA/ASC group. Conclusions: The results showed that the repair of tibial defects was accelerated by implantation of autologous ASCs seeded onto a PLGA scaffold. Therefore, PLGA/ASC is a promising new cell-based therapy for healing critical size tibial defects.