Resolution of fibrosis by siRNA HSP47 in vitamin A‐coupled liposomes induces regeneration of chronically injured livers

Background and Aim In chronic hepatic diseases where treatment strategies are not available, deposited fibrotic tissues deteriorate the intrinsic regeneration capacity of the liver by creating special restrictions. Thus, if the anti‐fibrosis modality is efficiently applied, the regeneration capacity of the liver should be reactivated even in such refractory hepatic diseases. Methods Rat liver fibrosis was induced by dimethyl‐nitrosamine (DMN). Another liver fibrosis model was established in CCl4 treated Sox9CreERT2ROSA26: YFP mice. To resolve hepatic fibrosis, vitamin A‐coupled liposomes containing siRNA HSP47 (VA‐liposome siHSP47) were employed. EpCAM + hepatic progenitor cells from GFP rats were transplanted to DMN rat liver to examine their trans‐differentiation into hepatic cells after resolution of liver fibrosis. Results Even under continuous exposure to such strong hepatotoxin as DMN, rats undergoing VA‐liposome siHSP47 treatment showed an increment of DNA synthesis of hepatocytes with the concomitant restoration of impaired liver weight and normalization of albumin levels. These results were consistent with the observation that GFP + EpCAM hepatic progenitor cells transplanted to DMN rat liver, trans‐differentiated into GFP + mature hepatic cells after VA‐liposome siHSP47 treatment. Another rodent model also proved regeneration potential of the fibrotic liver in CCl4 administered Sox9CreERT2ROSA26: YFP mice, VA‐liposome siHSP47 treatment‐induced restoration of liver weight and trans‐differentiation of YEP + Sox9 + cells into YFP + hepatic cells, although because of relatively mild hepatotoxicity of CCl4, undamaged hepatocytes also proliferated. Conclusions These results demonstrated that regeneration of chronically damaged liver indeed occurs after anti‐fibrosis treatment even under continuous exposure to hepatotoxin, which promises a significant benefit of the anti‐fibrosis therapy for refractory liver diseases.