Liver fibrosis is one of the most cruel health problems worldwide. It is a reversible wound healing reaction to acute or chronic hepatic injury. During acute injury, changes in liver structure are unpredictable. Chronic injury, On the other hand, is a progressive substitution of the liver parenchyma by scar tissue which can be irreversible1, 2.
Liver fibrosis occurs by combination of different cell types. Hepatic stellate cells (HSCs) are key starters of fibrogenesis. They coordinate with the extra cellular matrix both in fibrotic and normal liver2.
In a new study researchers clarified the ultra-structural events that govern the extra cellular matrix deposition and fibrosis series using dimethylnitrosamine (DMN) induced liver fibrosis in rat’s model3.
The experiment was performed on male rats. They were divided into 2 groups, control and DMN. In order to induce liver fibrosis, rats were administered DMN intraperitoneally for 21 days. Liver tissues were then processed for electron microscopy examination.
It was revealed that administration of DMN induced significant body weight loss and rigorous pathological modifications were also noticed. Apoptosis occurred in hepatocytes. Quiescent hepatic stellate cells (HSCs) were activated. HSCs lost their retinoid and acquired large nucleus followed by large amount of fibers attainment. In other words HSCs were transformed into myofibroblasts (MFs) phenotype which synthesized extra cellular matrix proteins and produced fibrous scar.
In addition, portal fibroblast (PFs) proliferated and produced large amount of fibers in portal and periportal area. The most characteristic trait of the cellular events of hepatic fibrosis in the study was extensive deposition of extra cellular matrix and collagens, mainly in portal and peri-portal areas, also the massive fibrous appearance of the mitochondria of the hepatocytes.
This study may not only advance understanding of this intricate mechanism but also permit one to spotlight on therapeutic molecules and inhibitors. Authors expect that future research will focus on therapeutic strategies.
Written by: Rabeeia
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17 November, 2019