Osteogenic activity of bone marrow-derived mesenchymal stem cells (BMSCs) seeded on irradiated allogenic bone

Allogenic bone grafting, a technique used in orthopaedic surgery, has several problems, including low osteogenic activity. To overcome the problem, this study aimed to determine whether in vivo osteogenesis could be enhanced using allogenic irradiated bone grafts after seeding with autologous bone marrow-derived mesenchymal stem cells (BMSCs). The allogenic bone cylinders were extracted from ACI rats and sterilized by irradiation. Donor BMSCs were obtained from fresh Fischer 344 (F344) rat bone marrow by cell culture. The allogenic bone with or without BMSCs were transplanted subcutaneously into syngeneic F344 rats. At 4 weeks after transplantation, high alkaline phosphatase (ALP) activity, bone-specific osteocalcin mRNA expression and newly formed bone were detected in the allogenic bone with BMSCs. The origin of the newly formed bone was derived from cultured donor BMSCs. However, none of these identifiers of osteogenesis were detected in either the fresh or the irradiated allogenic bone without BMSCs. These results indicate the availability of autologous BMSCs to heighten the osteogenic response of allogenic bone. Our present tissue-engineering method might contribute to a wide variety of allogenic bone grafting techniques in clinical settings.