Browsing by Subject "3D culture"

There is a great demand of cultured human hepatocytes for hepatotoxicity studies, drug testing, disease modelling and liver transplantation purposes. The current gold standard, primary human hepatocytes (PHHs), suffer from poor availability and high variability. Furthermore, PHHs are short-lived in in vitro cultures. Pluripotent stem cell (PSC)-derived hepatocyte-like cells (HLCs) have emerged as potential substitutes for PHHs in in vitro studies. PSCs are widely available, and additionally allow studies of hepatogenesis and open possibilities for personalized medicine. However, obtaining HLCs with mature hepatocyte functions in vitro has turned out to be challenging, and the differentiated cells have remained immature compared to PHHs. In vivo, hepatic differentiation and maturation of PSCs is guided by cues from the environment. Mimicking the 3D cellular environment in vitro has already shown encouraging results, but today, HLCs are still awaiting to fulfil their promise as a new gold standard. The aim of this study was first to select a new working human PSC line for in vitro hepatic differentiation and maturation. Hepatic differentiation and maturation of the selected cell line, embryonic stem cell line ESI-017, was next studied in five different 3D culture conditions (spheroids in suspension culture, four different hydrogels: Matrigel, collagen type I, mixture of Matrigel and collagen type I and alginate) with the aim to find the most favourable culture condition for later studies. For this, the PSCs were first differentiated to definitive endoderm cells and then to hepatoblasts in 2D cultures, on Matrigel- and laminin-521-coated plates, respectively. The PSC-derived hepatoblasts were then transferred for 16 days to the different 3D culture conditions for hepatic maturation. Of the conditions, suspension culture and mixture of Matrigel and collagen type I -hydrogel were estimated most promising and were selected for further studies. Hepatic maturation of the PSC-derived HLCs was estimated by analysing protein and mRNA expression levels of key marker genes, such as CYP3A4, AAT, MRP2, HNF4A, ALB, AFP, CK-8/18 and CK-19 by immunofluorescence staining and qPCR, respectively, and by cell morphology. Based on cell morphology and noticeable level of CYP3A4 expression, suspension culture shows most potential of the studied conditions in hepatic maturation of PSC-derived hepatoblasts. However, given that expression level of many other hepatocyte marker genes in these HLCs remained low compared to PHHs or human fetal liver samples, it is evident that adjustments to protocol and culturing conditions are still needed.