Effects of microgravity modeled by large gradient high magnetic field on the osteogenic initiation of human mesenchymal stem cells.

Microgravity (MG) leads to a decrease in osteogenic potential of human bone marrow-derived mesenchymal stem cells (hMSCs). In the present study, we used large gradient high magnetic field (LGHMF) produced by a superconducting magnet to model MG (LGHMF-MG) and analyzed the effects of LGHMF-MG on survival, cytoskeleton and osteogenic potential of hMSCs. Results showed that the LGHMF-MG treatment for 6 h disrupted the cytoskeleton of hMSCs, and the LGHMF-MG treatment for 24 h led to cell death. LGHMF-MG treatments for 6 h in early stages of osteogenic induction (the pre-treatment before osteogenic induction, the beginning-treatment in the beginning-stage of osteogenic induction and the middle-treatment in the middle-stage of osteogenic induction) resulted in suppression on osteogenesis of hMSCs. The suppression intensity was reduced gradually as the treatment stage of LGHMF-MG was postponed. The LGHMF-MG treatment for 6 h in the ending-stage of osteogenic induction (the ending-treatment) had no obvious effect on osteogenesis of hMSCs. These results indicated that LGHMF-MG should affect the initiation of osteogenesis. Finally, the possible mechanism for the inhibition effect of LGHMF-MG on osteogenesis of hMSCs is discussed.