[Contact inhibition of desmin expression in rat liver Ito cells in vitro].

The presence of desmin is used to identify the Ito cells in rat liver and to evaluate the purity of separated and cultured cells. The present study was conducted to evaluate the expression of cytoskeletal (with special emphasis on desmin) and intercellular matrix proteins in cultured rat liver Ito cells. The Ito cells were isolated by enzymatic digestion of rat liver and purified by single-step Nycodenz gradient. During the first week of culturing, the Ito cells proliferated and all of them expressed desmin and vimentin. By the end of the first week, part of them were seen to transdifferentiate into myofibroblasts. These cells expressed alpha-smooth muscle actin. The Ito cells and myofibroblasts were stained with anti-laminin, and anti-collagen I and III antibodies. The expression of desmin in myofibroblasts was less than in untransformed (stellate shaped) Ito cells. By the end of the second week the cells developed a dense monolayer and lost desmin. We suggest that repression of desmin in the cablestone-like monolayer of cells may be due to cell-to-cell contact inhibition.