Dynamics of distribution of vimentin and alpha-smooth muscle actin in the liver at the stages of regeneration after chemically induced fibros

Abstract

The aim of the study was to analyze the distribution of vimentin and alpha-smooth muscle actin (α-SMA) in the liver at various stages of regeneration after chemically induced fibrosis. Material and methods. Four experimental groups of animals were formed, consisting of white male rats representing different stages of liver recovery (no recovery, 4, 8, and 12 weeks of recovery) after chemically induced liver fibrosis, and a control group of intact animals, with 8 animals in each group. The dynamics of the distribution of intermediate filaments of mesenchymal cells were analyzed on preparations stained by immunohistochemical method using antibodies to vimentin and α-SMA. Results. After chemically induced liver fibrosis, a significant increase in the specific area of vimentin and α-SMA was observed, suggesting an important role of mesenchymal cells in the remodeling of the liver parenchyma. At the 4th week, the increased number of vimentin- and α-SMA-positive cells persisted, with these cells localized along fibrous septa and around blood vessels. At this stage, regenerative rosette-like structures consisting of vimentin- and α-SMA-positive mesenchymal cells surrounded by young regenerating hepatocytes were formed. By the 8th–12th weeks of regeneration, a decrease in the specific area of these markers was noted; however, vimentin- and α-SMA-positive cells were still present near portal triads and blood vessels, indicating ongoing regeneration processes. Conclusion. Vimentin and α-SMA play a key role in the formation of the fibrous matrix and the activation of perisinusoidal cells and myofibroblasts. The observed correlation between changes in vimentin and α-SMA indicates their coordinated involvement in the processes of fibrosis and regeneration.