Immunohistochemical Identification of Alpha-Smooth Muscle Actin Positive Myofibroblasts in Toxic Hepatitis

Abstract

The crucial role played by the myofibroblast in wound healing and pathological organ remodeling is well established. Hepatic myofibroblasts constitute a heterogeneous population of pro-fibrogenic cells found in chronically injured livers. Liver fibrogenesis is sustained by populations of highly proliferative, pro-fibrogenic, pro-angiogenic and contractile myofibroblasts that, originate by a process of activation involving perisinusoidal hepatic stellate cells, portal fibroblasts, bone marrowderived mesenchimal stem cells as well as, in certain conditions, by a process of epithelial to mesenchymal transition involving hepatocytes and cholangiocytes. (Parola 2008). In this study we used 60 male Wistar rats with an average weight of 200g, who received chronic carbon tetrachloride treatment in dose of 1,2 ml/kg, two times a week, for 12 weeks. Liver samples were taken after euthanasia at 4, 8 and 12 weeks after the start of the experiment. The formalin-fixed hepatic samples were embedded in paraffin, sectioned at 4 μm, stained by Haematoxilin-Eosine and Masson's trichrome methods. Immunohistochemistry was performed, using a Rabbit polyclonal antibody to alpha smooth muscle Actin (Abcam, Cambridge, ab5694). Alpha smooth muscle actin (SMA) positive myofibroblast were localized in the expanded connective tissue around central veins, within fibrous septa, at the interface between fibrous septa and parenchyma and in the parenchyma around sinusoids (activated hepatic stellate cells).