Effect of bone marrow-derived stem cells and bone morphogenetic protein-2 on treatment of osteoradionecrosis in a rat model

Purpose We investigated the effect of rat mesenchymal stem cells (rMSCs) and bone morphogenetic protein-2 (BMP-2) on the osseous healing of osteoradionecrosis in the rat mandible, depending on application time. Material and methods One week after irradiation (30 Gy) on the right mandible, all molar teeth were extracted. In Group 1 (n = 25), rMSCs and/or BMP-2 carried with hydrogel were applied immediately after surgery. In Group 2 (n = 25), application was done 4 weeks after surgery, after the occurrence of osteoradionecrosis. No hydrogel (n = 5), hydrogel alone (n = 5), hydrogel with 2 × 10⁴ rMSCs (n = 5), hydrogel with 10 μg of BMP-2 (n = 5), or hydrogel with 10 μg of BMP-2 and 2 × 10⁴ rMSCs (n = 5) was applied. Micro-CT data of bone healing were collected at 4 weeks post-application. Results In Group 1, BMP-2 was effective in increasing both bone volume (BV) and bone mineral density (BMD), whereas rMSCs were not. In Group 2, the combined application of rMSCs and BMP-2 significantly increased BMD and BV compared to values in the groups without hydrogel and with hydrogel alone. Conclusion Osseous healing after post-irradiation trauma in rats was enhanced immediately after dentoalveolar trauma by application of BMP-2, whereas the combined application of rMSCs and BMP-2 was most effective after osteoradionecrosis occurred.