Objective: To study the effect and mechanism of mTOR signaling on adipogenesis of bone marrow mesenchymal stem cells(BM-MSCs) from aplastic anemia (AA) patients through regulation of PPARγ.
Methods: BM-MSCs were isolated from 24 newly diagnosed AA patients and 24 healthy controls. The surface antigen expression of BM-MSCs was identified by flow cytometry. The capacity of adipogenic differentiation of BM-MSCs was determined by lipid droplets based on Oil Red O staining and by the expression of FABP4 based on Western blot. Protein levels of mTOR signaling and PPARγ were tested by immunofluorescence and Western blot.
Results: AA BM-MSCs displayed an enhanced capacity of differentiating into adipocytes, compared with control BM-MSCs. It was found that mTOR was activated in AA BM-MSCs. Moreover, the expression levels of p-mTOR and PPAR-γ in AA BM-MSCs showed a parallel differentiation-dependent increase during adipogenic differentiation, which were significantly higher than that of control BM-MSCs at the same time point of adipogenic differentiation. mTOR inhibitor rapamycin did not only inhibit the adipogenic differentiation of BM-MSCs from AA pateints at the early-middle stage, but also partly reversed the adipogenic differention of BM-MSCs from AA pateints at the late stage by PPARγ regulation.
Conclusion: mTOR signaling may play a critical role in the adipogenic differentiation of BM-MSCs from AA patients by positively regulating PPARγ expression.