MECHANISMS OF RECOVERY FROM MECHANICAL INJURY OF CULTURED RAT HEPATOCYTES

The mechanism(s) whereby hepatocytes restore denuded areas remains unk nown. We therefore studied the recovery of denuded areas made in monol ayers of primary cultures of rat hepatocytes. Minimal recovery occurre d in cells plated on plastic. Plating on Matrigel produced modest reco very (25% at 24 h), whereas plating on a type I collagen substrate res ulted in > 70% recovery at 24 h. The rate of recovery on collagen coul d be attenuated by a monoclonal antibody directed against the extracel lular domain of the beta(1)-integrin subunit. Monoclonal antibodies di rected against CD44 (the hyaluron receptor) and E-cadherin did not inf luence the rate of recovery. Recovery could be stimulated, in a dose-d ependent fashion, by epidermal and hepatocyte growth factors. The effe cts of epidermal and hepatocyte growth factors to promote recovery occ urred in the absence of 5-bromo-2'-deoxyuridine uptake, suggesting a p roliferation-independent mechanism. Transforming growth factor-beta(1) inhibited recovery. Exposure to selected cytokines (interleukins 1 an d 2), an adenine nucleotide [adenosine 5'-O-(3-thiotriphosphate)], ade nosine, pertussis toxin, and selected agents that bind to fibronectin and other matrix component adhesive sites (heparin and the RGD peptide ) did not influence the rate of recovery of hepatocytes. However, the peptide DGEA, which can bind to collagen adhesive sites, attenuated re covery. These studies demonstrate that primary cultures of rat hepatoc ytes require a particular type of extracellular matrix to renew denude d areas and that the beta(1)-integrin subunit may be involved in this recovery process. Hepatocyte recovery of denuded areas can be modulate d by growth factors in both a stimulatory (epidermal and hepatocyte gr owth factors) and an inhibitory (transforming growth factor-beta(1)) f ashion.