Attachment, morphology, and protein expression of rat marrow stromal cells cultured on charged substrate surfaces

Although surface charge has been shown to affect the adhesion and morphology of a variety of cell types, the interactions of bone marrow stromal cells with charged surfaces still remain unclear. A novel electrical stimulation system was used to investigate the interactions between rat bone marrow stromal cells and charged substrates in this study. A conductive and transparent indium tin oxide (ITO) coating was used as an electret substrate. Rat marrow stromal cells were cultured on positive, negative, and uncharged ITO surfaces. Cell attachment, morphology, alkaline phosphatase activity, and expression of osteopontin and collagen type III were assessed using histochemical staining, immunolabeling, and fluorescence microscopy. Voltages of 0.7, 0.8, 0.9, and 1.0 V applied to the substrates created surface potentials but were insufficient to decompose the media. On positively charged ITO, cell attachment was enhanced in serum-supplemented and serum-free media. Furthermore, decreases in cell spreading, alkaline phosphatase activity, and osteopontin were observed in cells grown on the positively charged ITO. These data indicate that positively charged surfaces enhance cell attachment but suppress cell spreading and differentiation of rat marrow stromal cells.