Hydrodynamic‐based in vivo transfection of retinoic X receptor‐α gene can enhance vitamin A‐induced attenuation of liver fibrosis in mice

Abstract: Background/Aim: In hepatic stellate cells isolated from rat fibrotic livers, the amount of retinoid X receptor‐alpha (RXR‐α) mRNA is greatly reduced. However, the effectiveness of retinoids in the treatment of liver fibrosis is controversial. We hypothesized that increasing the expression levels of RXR‐α in livers will improve the response of liver fibrosis to retinoids treatment. Methods: pTracer‐CMV2 vector harboring both green fluorescent protein and RXR‐α genes was given to mice with carbon tetrachloride (CCl 4 )‐induced liver fibrosis, by hydrodynamic‐based in vivo transfection. Vitamin A was simultaneously administered to the mice. Sirius red staining and measurement of hydroxyproline content were performed to evaluate liver fibrosis. The incorporation of 5‐bromo‐2‐deoxyribouridine (BrdU) was carried out to determine liver cell proliferation. Results: Successful transfection and expression of exogenous RXR‐α gene in the liver was determined by observance of green fluorescence under a confocal microscope, and detection of RXR‐α protein by immunohistochemistry. Hepatic fibrosis, evaluated by both Sirius red staining with image analysis and quantity of hydroxyproline in livers of RXR‐α‐transfected group, tapered off remarkably. The hydroxyproline content and Sirius red‐positive staining area on liver sections from RXR‐α‐transfected mice decreased by 34.3% and 54.63%, respectively, compared with the control group receiving empty vector. The labeling index of BrdU in non‐parenchymal cells was much lower in livers from the RXR‐α‐transfected group than that of empty vector‐transfected group. Conclusions: Hydrodynamic‐based in vivo transfection of the RXR‐α gene can enhance the vitamin A‐induced attenuation of liver fibrosis in mice. One of the possible mechanisms of action for this gene treatment is inhibition of non‐parenchymal cell proliferation mainly composed of hepatic stellate cells in fibrotic livers.