Expression of cytoskeletal proteins in hepatic stellate cells isolated from normal and cirrhotic rat liver.

Hepatic stellate cells (HSC) are located in Disse spaces of normal rat liver. In their quiescent state they serve as a storage site for vitamin A. In fibrotic liver they become activated, proliferate and they undergo transdifferentiation into myofibroblast-like cells. Changes in the cell phenotype are accompanied by changes in the cellular cytoskeleton. We have studied the expression of alpha-smooth muscle actin and intermediate filament proteins vimentin, desmin and glial fibrillary acidic protein (GFAP) by immunocytochemistry in HSC cultured for 2 or 7 days after isolation. Normal or cirrhotic rat liver was perfused with solutions of pronase and collagenase and HSC were isolated by density gradient centrifugation of the resulting cell suspension. Liver cirrhosis was produced in rats by repeated carbon tetrachloride administration. Vimentin was detected in all cells from normal and cirrhotic liver. The concentration of desmin in the cells from cirrhotic liver was slightly higher than that in normal cells and it increased with time in culture. GFAP could be detected only in normal cells 2 days after their isolation. In contrast, alpha smooth muscle actin (alpha-SMA) was absent from normal cells at this time but its expression was pronouced later. In most cells from cirrhotic liver this antigen was already present on the second day of culture and its expression further increased.