Liver slices as a model to study fibrogenesis and test the effects of anti-fibrotic drugs on fibrogenic cells in human liver.

Cell culture models have contributed significantly to the study of liver fibrosis, but cannot accurately incorporate in vivo cell-cell and cell-extracellular matrix interactions or account for the heterogeneity of the fibrogenic cell population involved in fibrosis development. Thus, there persists a need for an in vitro model that mimics the in vivo situation more closely, which may be provided by using precision-cut liver slices. In the present study we evaluated human liver slices as a tool to study fibrogenesis and test anti-fibrotic drugs. In this study we examined the responses of fibrogenic cells in human liver slices during control incubation and studied the effect of the anti-fibrotic compound pentoxifylline both during control incubation and after induction of early hepatic stellate cell (HSC) activation by carbon tetrachloride. After prolonged (>24 h) incubation, alphaSMA and pro-collagen 1a1 mRNA expression in human liver slices started to increase. Analysis of synaptophysin and fibulin-2 mRNA expression indicated that both activated HSC and other (myo)fibroblasts may be involved in this process. This response of fibrogenic cells to prolonged incubation of the liver slices was accompanied by an increased collagen protein content and could be inhibited by pentoxifylline. Early HSC activation, which was reflected by increased HSP47 and alphaB-crystallin mRNA expression, was not inhibited by pentoxifylline. Preparation and/or culturing of human liver slices induces fibrogenesis, which may be mediated by both activated HSC and resident liver (myo)fibroblasts and may represent a simple and rapid method to test the effects of potential anti-fibrotic drugs on fibrogenic cells in human liver.

Liver fibrosis in vitro: cell culture models and precision-cut liver slices.

Chronic liver injury of various etiologies can cause liver fibrosis, which is characterized by the progressive accumulation of connective tissue in the liver. As no effective treatment for liver fibrosis is available yet, extensive research is ongoing to further study the mechanisms underlying the development of disease- or toxicity-induced liver fibrosis and to identify potential pro- or anti-fibrotic properties of compounds. This review gives an overview of the in vitro methods that are currently available for this purpose. The first focus is on cell culture models, since the majority of in vitro research uses these systems. Both primary cells and cell lines as well as the use of different culture matrices and co-culture models are discussed. Second, the use of precision-cut liver slices, which recently came into attention as in vitro model for the study of fibrosis, is discussed. The overview clearly shows that continuous optimization and adaptation have extended the potential of in vitro models for liver fibrosis during the past years. By combining the use of the different cell and tissue culture models, the mechanisms underlying multicellular fibrosis development can be studied in vitro and potential pro- or anti-fibrotic properties of compounds can be identified both on single liver cell types and in human liver tissue.

Human liver slices as an in vitro model to study toxicity-induced hepatic stellate cell activation in a multicellular milieu.

INTRODUCTION: Hepatic stellate cell (HSC) activation is a key event in wound healing as well as in fibrosis development in the liver. Previously we developed a technique to induce HSC activation in slices from rat liver. Although this model provides a physiologic, multicellular milieu that is not present in current in vitro models it might still be of limited predictive value for the human situation due to species-differences. Therefore, we now aimed to evaluate the applicability of human liver slices for the study of HSC activation. METHOD: Liver slices (8 mm diameter, 250 microm thickness) were generated from human liver tissue and incubated for 3 or 16 h with 0-15 microl of carbon tetrachloride (CCl4) after which ATP-content and expression levels of HSC (activation) markers was determined. RESULTS: Human liver slices remained viable during incubation as shown by constant ATP levels. Incubation with CCl(4) caused a dose-dependent decrease in viability and an increase in mRNA expression of the early HSC activation markers HSP47 and alphaB-crystallin, but not the late markers for HSC activation, alphaSMA and pro-collagen 1a1. Synaptophysin mRNA expression remained constant during incubation with or without CCl4, indicating a constant number of HSC in the liver slices. CONCLUSION: We developed a technique to induce early toxicity-induced HSC activation in human liver slices. This in vitro model provides a multicellular, physiologic milieu to study mechanisms underlying toxicity-induced HSC activation in human liver tissue.

Interactions of human immunodeficiency virus-1 proteins with neurons: possible role in the development of human immunodeficiency virus-1-associated dementia.

Human immunodeficiency virus-1 (HIV-1)-associated dementia is a severe neurological complication of HIV-1 infection that affects 15-20% of the patients in the late stages of acquired immunodeficiency syndrome. HIV-1-associated dementia is most probably a consequence of HIV-1 infection of the brain rather than of an opportunistic pathogen. The exact mechanism by which the virus causes this disorder, however, is not completely understood. A number of HIV-1 proteins have been shown to be released from HIV-1-infected cells and/or to be present in the extracellular milieu in the HIV-1-infected brain. Moreover, these proteins have been shown to possess neurotoxic and/or neuromodulatory features in vitro. This review describes the possible direct interactions of the HIV-1 proteins gp120, gp41, vpr, tat, rev, vpu and nef with neurons, which might play a role in the development of HIV-1-associated dementia in vivo.