Promoting bone fusion, treating bone defects and repairing problematic bone fractures
that show delayed healing and nonunion currently involves an iliac crest autologous bone
graft, which can result in significant complications such as deep bone pain and chronic
infection. In this study, Gibon et al. sought to understand more about the bone
healing process, specifically whether MC3T3-E1 osteoprogenitor cells introduced by
injection in mice show systemic homing, and whether they then have any impact on bone
healing.
Analysis of induced bone defects in nude mice that were treated by injection of osteoprogenitor cells or control saline into their left ventricle demonstrated that the MC3T3-E1 cells migrated through the systemic circulation to the site of the bone defect. Once there, they differentiated into mature osteoblasts and brought about accelerated callus formation and a significant increase in bone mineral density compared to controls.
Editor's comment: In mice, injected osteoprogenitors were able to advance fracture healing, implying homing and participation of the cells in repair. This warrants further study as a potential therapy for exposed defects as systemic therapy with osteoprogenitor cells could provide a useful alternative to a traditional bone graft.