A combining method to enhance the in vitro differentiation of hepatic precursor cells.

The ideal bioartificial liver should be designed to reproduce as nearly as possible in vitro the habitat that hepatic cells find in vivo. In the present work, we investigated the in vitro perfusion condition with a view to improving the hepatic differentiation of pluripotent human liver stem cells (HLSCs) from adult liver. Tissue engineering strategies based on the cocultivation of HLSCs with hepatic stellate cells (ITO) and with several combinations of medium were applied to improve viability and differentiation. A mathematical model estimated the best flow rate for perfused cultures lasting up to 7 days. Morphological and functional assays were performed. Morphological analyses confirmed that a flow of perfusion medium (assured by the bioreactor system) enabled the in vitro organization of the cells into liver clusters even in the deeper levels of the sponge. Our results showed that, when cocultured with ITO using stem cell medium, HLSCs synthesized a large amount of albumin and the MTT test confirmed an improvement in cell proliferation. In conclusion, this study shows that our in vitro cell conditions promote the formation of clusters of HLSCs and enhance the functional differentiation into a mature hepatic population.