Objective: To investigate the effect of the supernatant of osteoclasts during bone resorption on the proliferation and differentiation of bone marrow-derived mesenchymal stem cells (BMSCs).
Methods: Spleen cells were induced into osteoclasts which were identified with tartrate-resistant acid phosphatase (TRAP) staining. The osteoclasts were cultured with bovine bone slices and the resorption pits on the slices were observed by scanning electron microscopy. The supernatant of the osteoclasts during bone absorption were taken and added into BMSCs. MTT assay was used to analyze the growth curves of BMSCs in experimental and control groups. After adipogenic induction, lipid droplets were observed by oil red O staining to compare the adipogenic potential between the two groups. After osteogenic induction, calcium nodules were observed by alizarin red staining. The expression levels of osteogenesis-related proteins RUNX2 and alkaline phosphatase (ALP), and adipogenesis-related protein PPAR-γ were measured by Western blotting.
Results: TRAP staining and scanning electron microscopy indicated that BMSCs could be differentiated into functional osteoclasts. Compared with the control group, the proliferation capacity of BMSCs in the experimental group was suppressed, the osteogenic potential was enhanced, and the adipogenic potential was weakened.
Conclusion: The supernatant of osteoclasts during bone absorption might increase the osteogenic activity of BMSCs by inhibiting proliferation and adipogenesis and promoting differentiation.