Binding and spreading of hepatocytes on synthetic galactose culture surfaces occur as distinct and separable threshold responses.

Isolated rat hepatocytes bind to synthetic flat polyacrylamide matrices containing covalently attached galactose residues in a sugar-specific and concentration-dependent manner. Cell binding is mediated by the asialoglycoprotein receptor and occurs as a threshold response at or above a critical concentration of sugar in the matrix. Hepatocytes in the presence or absence of serum were able to spread on these synthetic galactose surfaces and were morphologically similar to cells on tissue culture plastic. Cell spreading also occurred as a threshold response but at a much higher critical concentration of sugar than for the cell-binding response. Above the critical concentration for spreading, the area occupied by a cell increased as the sugar concentration increased. By manipulating the galactose content of the matrix, cell spreading and cell binding can be differentiated as independent and separable threshold responses to the extracellular substratum.