Characterizations Of Reelin~+ HSCs During Chronic Liver Injury

The activation of heterogeneous hepatic stellate cells（HSCs）is the main cause of liver fibrosis induced by various chronic liver diseases.Activated HSCs migrate to the site of injury,secreting a large amount of extracellular matrix（ECM）,pro-inflammatory,and profibrotic cytokines.Inhibiting HSCs activation and promoting HSCs apoptosis are the main methods for the treatment of liver fibrosis,but due to the lack of specific markers to distinguish different subtypes of HSCs,it is currently not possible to design targeted drugs to cure liver fibrosis according to the characteristics of different subsets of HSCs in different liver fibroses.Reelin is an exocrine glycoprotein and plays an important role in brain development interacting with its two receptors.Researches indicate that Reelin is associated with liver fibrosis and up-regulated in patients with liver cirrhosis in the liver and plasma.But it is not clear to the localization and function of Reelin in the liver.Whether Reelin is expressed in HSCs,or Reelin⁺HSCs are a new HSCs subset and whether HSCs could transdifferentiate into hepatocytes or cholangiocytes through mesenchymal-epithelial transition（MET）,remain to be further studied.In this study,we developed a reliable method,Reelin-Cre ERT2;Rosa26-m Tm G mouse model,demonstrating that Reelin-Cre ERT2-labled HSCs were a new HSC subset by cell lineage tracking,which owns specific characteristics in migration,activation,and proliferation.The results are as followed:1.Reelin is located in HSCs and Reelin⁺HSCs are a new HSC subset.2.In cholestatic model,Desmin⁺Reelin^-HSCs are migrated to the portal triad with a significant activation and proliferation activity,but Desmin⁺Reelin⁺HSCs do not show migration to the portal triad or proliferation,and only a small part is activated.3.In hepatotoxic model,Desmin⁺Reelin⁺HSCs share similarities with Desmin⁺Reelin^-HSCs in migration,activation,and proliferation,nonetheless,still fewer Desmin⁺Reelin⁺HSCs are activated.4.Reelin⁺HSCs do not transdifferentiate into hepatocytes or cholangiocytes through MET in cholestatic or hepatotoxic model.5.During the recovery of CCl₄-induced hepatotoxic liver fibrosis,Reelin⁺HSCs undergo apoptosis,with a significant decrease in the cell number.And Reelin⁺HSCs are more prone to apoptosis than Desmin⁺HSCs.In conclusion,we using cell lineage tracking demonstrated that Reelin-Cre ERT2-labled HSCs are a new subset,which own different properties in BDL-operated fibrotic livers and similar characteristics in CCl₄-induced fibrotic livers compared to Desmin⁺HSCs.