Identification of suitable culture condition for expansion and osteogenic differentiation of human bone marrow stem cells

This study was undertaken in order to identify the best culture strategy to expand and osteogenic differentiation of human bone marrow stem cells (hBMSCs) for subsequent bone tissue engineering. In this regard, the experiment was designed to evaluate whether it is feasible to bypass the expansion phase during hBMSCs differentiation towards osteogenic lineages by early induction, if not identification of suitable culture media for enhancement of hBMSCs expansion and osteogenic differentiation. It was found that introduction of osteogenic factors in alpha-minimum essential medium (αMEM) during expansion phase resulted in significant reduction of hBMSCs growth rate and osteogenic gene expressions. In an approach to identify suitable culture media, the growth and differentiation potential of hBMSCs were evaluated in αMEM, F12:DMEM (1:1; FD), and FD with growth factors. It was found that αMEM favors the expansion and osteogenic differentiation of hBMSCs compared to that in FD. However, supplementation of growth factors in FD, only during expansion phase, enhances the hBMSCs growth rate and significantly up-regulates the expression of CBFA-1 (the early markers of osteogenic differentiation) during expansion, and, other osteogenic genes at the end of induction compared to the cells in αMEM and FD. These results suggested that the expansion and differentiation phase of the hBMSCs should be separately and carefully timed. For bone tissue engineering, supplementation of growth factors in FD only during the expansion phase was sufficient to promote hBMSCs expansion and differentiation, and preferably the most efficient culture condition.