The effect of retinoic acid on the re-estabishment of differentiated phenotype in primary culture

The usefulness of cultured hepatocytes is limited by the gradual loss of their typical physiological functions that occurs in vitro, mainly due to the absence of microenviromental conditions found in vivo. In this study we describe the effect of retinoic acid on the re-establishment of morphological characteristics and on the reorganization of the cytoskeletal network in cultured rat hepatocytes. Results obtained demonstrate that retinoic acid can influence hepatocyte differentiation, as regards the recovery of cell polarity, polyhedric shape and reformation of bile canaliculi and junctional complexes. The main target of this action appears to be the cytoarchitecture of cytoskeletal components, particularly cytokeratin filaments, which regain the configuration present in intact liver. The reorganization of the intermediate filaments does not seem to be dependent on the induction of higher levels of cytokeratin proteins, but rather appears to be due to post-translational regulation. The effect of retinoic acid on the cytoskeletal organization could determine the stabilization of intercellular contacts by means of junctions, leading to the appearance of morpho-functional characteristics typical of well-differentiated hepatocytes.