Effects of Basic Fibroblast Growth Factor on Proliferation of Human Mesenchymal Stem cells

Abstract

Human mesenchymal stem cells (hMSCs) are multipotent stem cells that can differentiate into several mesenchymal lineage cells. In this study, we established conditions that allowed a long term expansion of hMSCs. To search for the optimum culture condition, growth rates of hMSCs were measured in the presence of several growth factors. Hepatic growth factor (HGF) and leukemia inhibitory factor (LIF) did not facilitate proliferation of hMSCs. In contrast, basic fibroblast growth factor (bFGF) effectively promoted growth of the cells in vitro by 3 fold. The growth stimulatory effect of bFGF was dependent on the concentration. The adipogenic potential was dramatically decreased in hMSCs isolated from an aged donor whereas osteogenic potential was minimally decreased. Addition of bFGF resumed the adipogenic and osteogenic differentiation potential. Thus, the cells that expanded in the presence of bFGF retained the potential to differentiate into adipogenic, chondrogenic, or osteogenic lineage cells. MSCs could be expanded for at least 8 passages with bFGF and the resulting cells retained the normal karyotype. The cells were positive for CD9, CD13, CD15, CD90, CD137, and CD140b; but negative for CD14, CD34, and CD45. Importantly, the cells were found to express a neural stem cell marker, nestin, and a neuronal marker, β-tubulin III.

The results suggest that bFGF promote proliferation while maintaining multi-lineage differentiation potency of hMSCs. Finally, we suggest that it is critical to identify novel markers other than nestin or β-tubulin III to monitor acquisition of neuronal phenotypes by hMSCs.