Adhesion and differentiation of adipose-derived stem cells on a substrate with immobilized fibroblast growth factor

Control of cell-matrix interactions plays a role in the regulation of stem cell function. In this study basic fibroblast growth factor (bFGF) linked to maltose-binding protein (MBP) was designed as a matrix for cell adhesion. MBP-FGF was immobilized on polystyrene (PS) surfaces by spontaneous adsorption. The amount of MBP-bFGF immobilized on the PS surface increased with increasing protein concentration, being 158 ng cm^-2 at 10 μg ml^-1 protein. Human adipose-derived stem cell (hASC) adhesion to MBP-bFGF immobilized on a PS surface (PS-MBP-bFGF) was inhibited by heparin. Integrin signaling and cell spreading of hASC on PS-MBP-bFGF were down-regulated compared with those on fibronectin-coated surfaces or tissue culture polystyrene (TCP). hASC differentiated into adipocytes, which stained positive for lipid vacuoles with Oil Red, more readily on PS-MBP-bFGF than on TCP. In contrast, hASC hardly differentiated into osteoblast on PS-MBP-bFGF or on TCP. These results suggest that the mechanism of hASC adhesion to MBP-bFGF immobilized on a PS substrate is mediated by a specific interaction between bFGF and heparin, and that the adhesion mechanism might provide an insight into the design of biomaterials to control the fate of stem cells.