Regulating effect of apoptotic rate of hepatocyte on course of hepatic regeneration

Abstract

Objective To investigate the role of different apoptotic rate induced by TGF-β1 in different stages of hepatic regeneration after partial hepatectomy(PH).Methods Rat model of 70% PH was established.Primary hepatocytes were isolated by in situ perfusion with collagenase solution from normal rats and those 1 d,3 d,5 d,7 d after PH.Flow cytometry was used to detect apoptotic rate in each group.The apoptosis of primary hepatocytes induced by TGF-β1(5 μg/L)was determined by staining with fluorescent dyes of DNA-binding Hoechst33258 and observed under fluorescent microscope.The effect of TGF-β1 on Bcl-2 expression in hepatoeytes was detected with immunocytochemistry.Results The viability of primary hepatocytes was 92%.The apoptotic rate of normal hepatocyte was 18.89%±3.14%,the apoptotic rate in 1 d was 11.85%±2.51%.After that it began to decrease,it was the lowest on the 3rd d.Then it began to increase gradually,it was 28.82%±5.53% on day 7 after PH.The apoptotic rate of normal hepatocytes induced by TGF-β1 was 58.13%±6.63%,which was higher than that in control groups(17.81%±3.19%,P＜0.05).However,the apoptotic rate of isolated primary hepatocytes had no difference between the groups induced and not induced by TGF-β1 1,3,5 d after PH.Bcl-2 expression in hepatocytes isolated in the early stage after PH was gradually increased and higher than that of normal group.The Bcl-2 expression was decreased significantly after being treated with TGF-β1.Conclusion TGF-β1 induced apoptotic rate has a marked difference in different stages of hepatic regeneration and it possesses an important regulating role for initiation and termination of hepatic regeneration. Key words: Liver regeneration; Apoptosis; TGF-β1