Abstract:Objectives: To construct recombinant adeno-associated Virus and lentivirus carrying siRNA of TIMP-1 and to investigate the antifibrotic effects of these two recombinant viruses on CCl4 induced liver fibrosis in rats. Methods: One pair of siRNA which could effectively inhibit expression of the TIMP-1 gene in HSC-T6 was screened and cloned into AAV vector and lentiviral vector to construct the recombinant AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1. AAV/EGFP and Lenti/EGFP as negative control were also obtained. Wistar rats were randomly divided into six groups: Control group, CCl4 group, AAV/EGFP, Lenti/EGFP, AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 group. After four weeks administration of CCl4, liver samples were collected for the histochemical stain and the detection of TIMP-1 expression. Results: Livers from control rats showed normal H&E and Masson staining around vessels. In contrast, livers from the model, AAV/EGFP and Lenti/EGFP groups showed severe fibrosis, including septal fibrosis, extensive bridging, fatty degeneration. The mRNA and protein expression of TIMP-1 were also elevated in the livers from these groups. Compared with the fibrosis model group, the AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 group showed good preservation of liver acini architecture and only mild bridging fibrosis, accompanied by the decreased mRNA and protein expression of TIMP-1. Semi-quantitative analysis of the fibrosis stage indicated that most rats in the model, AAV/EGFP and Lenti/EGFP groups were at S3 and S4 (80%), while 20% of rats were at S5. In contrast, most rats (90%) in the AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 group were at stages S2 and S3, with only one at S4. There was no significant difference between these recombinant virus therapy groups. Conclusions: AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 could suppress the expression of TIMP-1 in rat fibrotic liver, which may be effective antifibrotic gene therapy agents.