OBJECTIVETo investigate the anti-fibrogenesis property of intraportal vein small interfering RNA (siRNA) injection targeting connective tissue growth factor (CTGF) in a rat model of liver fibrosis induced by carbon tetrachloride (CCl4) and its effect on hepatic stellate cell (HSC) activation.

METHODS24 male rats were randomly divided into four group. rats received CCl4 by subcutaneous injections every three days for 6 consecutive weeks, and meantime they also obtained either siRNA targeting CTGF (as CTGF siRNA group), saline (as model group) or a control siRNA (as control siRNA group) by intraportal vein injection to rats liver at the same approach. Other rats received saline intraportal vein injection for 6 weeks (as normal control group). The expressions of CTGF and a-SMA protein were detected by Western blot. Hepatic histology was evaluated by HE staining and Sirius red staining. The collagen staining areas were measured quantitatively using a computer-aided manipulator with slight modifications. The number of active HSC were evaluated by immunohistochemistry.

RESULTSSix weeks after CCl4 injection, prominent upregulations were observed in the expressions of CTGF and a-SMA protein in saline or control siRNA-treated rats livers. In rats with CTGF siRNA treatment, the protein expressions of CTGF and a-SMA in liver decreased by 95%+/-2% and 86%+/-11% (F=21.234 and 12.473, P<0.01) respectively, the number of active HSC in liver decreased by 76%+/-9% (F=9.179, P<0.01) as compared to the model group. The attenuation of liver fibrosis was also observed in rats with CTGF siRNA treatment.

CONCLUSIONIntraportal vein siRNA injection targeting CTGF could significantly inhibit CTGF gene expression in rats, thereby attenuate liver fibrosis by decreasing the number of active HSCs.