Endothelial Progenitor Cell Therapy for Fracture Healing in a Rat Femoral Defect Model: A Dose-response Study

The use of endothelial progenitor cell (EPC) therapy for tissue regeneration is well documented across a wide array of disciplines, including orthopaedics where it has successfully been used preclinically to heal bone defects. Yet, no study has chosen to formally investigate a dose-response relationship between EPC therapy and bone healing. In an effort to optimize this cell therapy, we aimed to elucidate a dose-response relationshipâ initially hypothesizing that EPCs would augment fracture healing in a dose-dependent manner up until a plateau of effectiveness was reached. Using a rat bone defect model, we implanted varying doses of ex-vivo expanded syngeneic EPCs on a collagen scaffold and monitored bone healing for 10 weeks. Radiographic assessment revealed a positive relationship between the amount of EPCs implanted and the subsequent rate of bone healing. However, microCT and biomechanical analysis demonstrated ideal bone structure and strength at an optimal dose of 2 million EPCs.M.Sc