The osteogenic potential of human bone callus.

Bone callus, generated during fracture healing, is commonly discarded during surgical procedures. The aim of this study was to investigate the osteogenic potential of bone callus and its possible use as autograft material for patients needing bone grafts. Histology, immunohistochemistry, micro-computed tomography, and biomechanics were performed to examine osteogenic cells, osteoinductive factors, and the osteoconductive structure of bone callus. Alkaline phosphatase-positive osteoblasts, osteoinductive factors (including BMP2, FGF2, TGFB1, and IGF1), and a porous structure were found in bone callus. Early-stage callus (within 3 months after fracture) presented significantly improved osteogenic properties compared to medium- (3-9 months) and late-stage (longer than 9 months) callus. The results revealed that bone callus induced new bone formation in a nude mouse model. Early-stage callus showed better performance to medium- and late-stage callus in the induction of new bone formation at both 8 and 12 weeks. These findings indicated that bone callus, especially early-stage callus, possesses osteogenic potential and can potentially serve as an alternative source of material for bone grafts.