6 ALL ORAL THERAPY WITH SOFOSBUVIR + RIBAVIRIN FOR 12 OR 16 WEEKS IN TREATMENT EXPERIENCED GT2/3 HCV-INFECTED PATIENTS: RESULTS OF THE PHASE 3 FUSION TRIAL

Abstract

functional effects of matrix on cell behaviour were studied in vitro using recombinant laminins and a line of spontaneously immortalised mouse HPCs, and in vivo using transgenic Cre-lox mouse strains that allows conditional knock-out of specific laminin or integrin subunits in HPCs. Results: The laminin alpha 5 (Lama5) chain is significantly upregulated in both models, with up to a 16-fold increase in gene expression during regeneration (p < 0.001). The Lama5 forms a basement membrane which surrounds the progenitor cells. The HPCs express the cell surface receptor alpha-6 beta-1 integrin, a binding partner of Lama5. Compared to other laminin chains, Lama5 selectively promotes HPC adhesion and spreading. These effects are partially blocked by antibodies against beta-1 integrin. Lama5 also significantly enhances HPC migration, resulting in a 2.8-fold increase in cell migration (p < 0.01). Furthermore, only Lama5 enhances HPC survival in serum-free medium, with a 3-fold increase in cell viability (p < 0.001). HPCs maintained in culture on plastic synthesise Lama5 chain. Knock-down of endogenous Lama5 production using siRNA results in hepatocytic differentiation, with increased albumin production (p < 0.001). Disruption of the laminin-integrin interaction in vivo by conditional gene knock-out alters the regenerative response, confirming the importance of this interaction. Conclusions: Laminin alpha 5-containing matrix is deposited around HPCs during liver regeneration and supports progenitor cell attachment, migration and maintenance of an undifferentiated phenotype. This work identifies a novel target for enhancing liver regeneration.