Abstract
The aim of this study was to investigate the osteogenic induction by tacrolimus hydrate (FK506) of rat bone marrow‐derived mesenchymal stem cells (MSCs). MSCs were cultured in α‐MEM containing either (1) L‐ascorbic acid‐2‐phosphate (AsAP) and β‐glycerophosphate (β‐GP) as a control; (2) AsAP and β‐GP plus FK506; (3) AsAP and β‐GP plus Dex; or (4) AsAP and β‐GP plus FK506 and Dex. The concentration of FK506 was varied from 5 to 5000 n__M__ to investigate the dose–effect relationship. Sixteen days later, cells were harvested for analysis. Examination of morphology, alkaline phosphatase (APase) activity, calcium deposition, bone nodule formation, osteocalcin mRNA expression, and mineralized extracellular matrix formation showed that the osteogenic differentiation of MSCs was greatly promoted, bone nodule formation was enhanced, APase activity and the expression of osteocalcin mRNA were increased. FK506 was much more effective when combined with Dex. The best results were achieved with α‐MEM containing 0.25 m__M__ AsAP, 10 m__M__ β‐GP, 10 n__M__ Dex, and 50 n__M__ FK506. Formation of bone in vivo was also studied by transplanting MSCs‐loaded ceramic cubes subcutaneously into the back of rats. Satisfactory results were achieved at 4 and 8 weeks. FK506 should be considered for use as an osteogenic agent. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008