ABSTRACT
OBJECTIVE To investigate the effect of tacrolimus on cell proliferation and osteoblastic differentiation of primary human bone marrow-derived mesenchymal stem cells (hBMSCs). METHODS hBMSCs were cultured with tacrolimus 0.001-5 μmol·L-1. BrdU incorporation was used to assess the cell proliferation while cellular alkaline phosphatase (ALP) activity and calcium deposition were measured to evaluate the osteoblastic differentiation of hBMSCs cultures. The calcineurin (CaN) activity was also examined using commercial CaN assay kit, and core binding factor 1 alpha subunit (Cbfα1) protein level was determined by Western blotting. RESULTSTacrolimus 0.001-0.1 μmol·L-1 promoted BrdU incorporation but had no effect on ALP activity and calcium deposition, whereas tacrolimus 0.5-5 μmol·L-1 resulted in significant decrease in both cell proliferation and osteoblastic maturation, by reducing BrdU incorporation, ALP activity, and calcium deposition of hBMSCs cultures in a concentration-dependent manner. In addition, tacrolimus 0.5-5 μmol·L-1 led to concentration-dependent decrement in CaN activity, which was consistent with down-regulated Cbfα1 protein in the tacrolimus treated cells. CONCLUSION High concentration of tacrolimus might inhibit the cell proliferation and osteoblastic differentiation of hBMSCs cultures through a CaN/Cbfα1 pathway.