The effects of EGTA and trypsin on the serum requirements for cell attachment to collagens

Cells growing on plastic or glass surfaces in vitro may be brought into suspension by proteases (e.g. trypsin) or chelating agents (e.g. EGTA). Trypsin and EGTA remove different quantities and types of molecules from cell surfaces. Previous studies have revealed that when confluent cultures of either BHK or PyBHK cells are brought into suspension by exposure to trypsin, foetal calf serum (or fibronectin) is required for cell attachment to films of denature type I collagen, but not to 3-dimensional gels of native collagen fibres. In this communication the serum requirements for the attachment of BHK and PyBHK cells to collagen substrata have been examined as a function of (a) the method used to prepare the cell suspension (EGTA or trypsin), and (b) cell density. Data are presented consistent with the view that cell surface-associated fibronectin is able to mediate cell attachment directly to films of denatured collagen.