OBJECTIVETo investigate the effect of 90% portal branch ligation on liver regeneration and expression of metalloproteinases and tissue inhibitors of metalloproteinases in rats.

METHODSNinety-six SD rats were randomly divided into Sham-PBL group and portal vein branches ligation group. The weight of both ligated and unligated lobes of liver were measured at post operation day (POD) 0.5, 1, 3, 5, 7, 14, 21 and 28. The morphological changes of the non-ligated liver lobes were observed by microscope. The expression of PCNA, MMP2, MMP9 and TIMP2 of the non-ligated liver lobes were studied by immunohistochemistry.

RESULTS1) 95.8% rats survived from the ligation of 90% portal branch. Hepatic lobe at the ligated side diminished progressively after ligation, whereas the lobes of the unligated side underwent compensatory regeneration. The ratio of non-ligated lobes weight to the whole liver increased slowly within 1d, speeded up significantly during 1-5d period, increased slowly after POD5, and got the plateau stag at POD7; 2) PCNA index were markedly increased within POD 0.5-3 (P < 0.01). It reached the peak at POD5 and decreased slightly at POD7, but still higher than Sham-PBL group level, then gradually returned to normal. 3) The expression of MMP2,MMP9 and TIMP2 in the non-ligated liver lobes were markedly increased at 1d. It reached the peak at POD7 and gradually returned to normal within POD7-28. 4) The MMP2 and PCNA in liver had a positive correlation at POD 0.5, 1, 5, 7, 14. The expressions of MMP9 and PCNA had a positive correlation at POD 0.5, 1, 7, 21.

CONCLUSIONThe expressions of TIMP2 and PCNA had a positive correlation at POD1, 7, 14, 21. The expression of MMP2, MMP9 and TIMP2 of the non-ligated liver lobes is markedly increased at POD1. It reaches the peak at POD7, and dropped to normal level gradually. The expressions of MMP2, MMP9 and TIMP2 and PCNA were correlated in 90% portal branch Ligation rats. The expression of MMP2,MMP9 and TIMP2 may play a pivotal role in liver regeneration.