Objectives: In this study, a group of cells that expressed both osteogenic and adipogenic characters was identified from murine adipose stromal cells.
Materials and methods: These cells could be enriched in the Sca-1-1 population and express both osteogenic and adipogenic genes. Osteogenic induction enhanced expression of osteogenic genes and inhibited expression of adipogenic genes, while adipogenic induction enhanced expression of adipogenic genes and inhibited expression of osteogenic genes. These cells have been called osteo-adipo progenitors (OAPs).
Results: OAPs expressed transcription factor runt-related transcription factor 2 (RUNX2) and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) proteins in cytoplasm. When OAPs were cultured in adipogenic medium, PPAR-gamma moved to the nucleus and the cells differentiated into adipocytes, while the RUNX2 remained in the cytoplasm. In contrast, when OAPs were cultured in osteogenic medium, RUNX2 moved to the nucleus and the cells differentiated to osteocytes, while the PPAR-gamma remained in the cytoplasm.
Conclusions: These experiments suggest that osteoblasts and adipocytes share a common predecessor, the OAP, in murine adipose stromal cells.