Fig. 1.

MMP-2−/− mice develop increased hepatic fibrosis in response to chronic liver injury. MMP-2+/+ and MMP-2−/− livers were harvested and sectioned, and degree of fibrosis assessed with Sirius Red staining at baseline and following chronic CCl₄ administration. Percentage overall fibrosis was subsequently calculated via histomorphometric bioquant analysis of 36 images per animal (n = 4) in a blinded fashion. Representative baseline Sirius Red staining on MMP-2+/+ (a) and MMP-2−/− (b) livers and examples of bridging fibrosis after chronic CCl₄ in MMP-2+/+ (c) and MMP-2−/− (d) mouse livers shown. Results of histomorphometric bioquant demonstrates a 1.7-and 3-fold increase in fibrosis in MMP-2+/+ and MMP-2−/− livers from untreated baseline, respectively. An almost twofold increase in fibrosis was observed in the MMP-2−/− livers as compared with the MMP-2+/+ livers after chronic CCl₄ administration (e). Representative immunoblot using whole liver protein extracted from MMP-2+/+ and MMP-2−/− mice after chronic CCl₄ administration confirms increase in collagen I expression (f). Original magnification 40×. Arrows point to areas of bridging fibrosis. Data represent means ± SEM; ** P < 0.001