Delayed Endothelial Progenitor Cell Therapy Promotes Bone Defect Repair in a Pre-Clinical Rat Model

Bone defect repair remains a significant challenge for orthopaedic surgeons. Endothelial progenitor cells (EPCs) have successfully promoted the repair of acute defects in animal models; however, the ability of EPCs to induce the repair of chronic defects has not been investigated. The purpose of this study was to investigate the use of EPCs for the repair of chronic bone defects using a clinically relevant rat model. Bone marrow-derived EPCs on a Gelfoam scaffold were applied to 5mm segmental femoral defects 3 weeks post-fracture. Ten weeks post-treatment, EPC-treated defects demonstrated enhanced radiographic union, improved bone morphometry, and greater biomechanical strength and stiffness compared to defects treated with cell-free scaffolds. No differences between acute and delayed EPC treatment were observed. These results suggest that EPCs can enhance bone healing in both acute and chronic bone defect models, and that their use may represent a clinically translatable therapy for bone healing in humans.M.Sc