Dynamics of Ito cells in minimal hepatic fibrosis induced by local tissue damage

Abstract

We have found desmin, which is a cytoskeletal protein, in the cytoplasm of Ito cells (fat-storing cells) accompanied with actin, and have observed the dynamics of Ito cells by marking them with desmin in experimental fibrosis induced by the administration of carbon tetrachloride or heterogeneic serum and by local injections of high concentrations of ethanol into liver lobules. In this study we observed the relation between Ito cells and hepatic fibrosis by minimal liver damage, i.e. by injection of 0.05ml physiologic saline solution through a 27 gauge injection needle, or piercing by 27 gauge injection needle, or piercing by glass needle with the same diameter as the injection needle. In the first few days after treatment Ito cells having a swollen cytoplasm appeared around the necrotic area after injection or piercing, increased in number after mitosis, and then fibrosis appeared in the area where Ito cells gathered. On subsequent days Ito cell processes extended and attached to those of neighbouring cell, and formed fiber bundles. Ito cells decreased in number when fiber bundles formed a fibrous septa. These results strongly suggested that Ito cells had a important role in hepatic fibrosis and were precursor cells of myofibroblasts.