Effect of pentoxifylline on stellate cell activation in human liver slices

Introduction: Precision-cut liver slices are a promising alternative to cell culture models for the study of hepatic stellate cell (HSC) activation and fibrogenesis since HSC are maintained in their original extracellular matrix and multicellular milieu. In the present study we evaluated human liver slices as a tool to study fibrogenesis and to test antifibrotic drugs. Methods: Firstly we determined whether spontaneous fibrogenesis occurred in human liver slices (250 μm thick, diameter 8 mm) during 1-48 hours of incubation and whether the anti-fibrotic compound pentoxifylline could prevent this. Secondly, the effect of pentoxifylline on carbon tetrachloride (CCl4)-induced early HSC activation was determined. To assess HSC activation and fibrogenesis mRNA expression of several markers was measured. Results: After prolonged incubation of human liver slices (> 24 hours), αSMA and procollagen 1a1 mRNA expression started to increase, which was significantly inhibited by pentoxifylline. Analysis of synaptophysin and fibulin-2 mRNA expression during incubation with or without pentoxifylline indicated that likely both HSC and other (myo)fibroblasts are involved in this fibrotic process. CCl4-induced early HSC activation, which was reflected by increased HSP47 and αB-crystallin mRNA expression, was not inhibited by pentoxifylline. Conclusions: 1) Preparation and/or culturing of human liver slices induced fibrogenesis after prolonged incubation, which may be mediated by both activated HSC and resident liver (myo)fibroblasts. 2) Our results suggest that pentoxifylline can only inhibit relatively late processes of HSC activation. 3) Human liver slices are a promising in vitro system to study both early HSC-activation and fibrogenesis, and to test anti-fibrotic drugs in a multicellular environment, closely resembling the in vivo situation in man.