Directed differentiation of human induced pluripotent stem cells to hepatic stellate cells.

Hepatic stellate cells (HSCs) are nonparenchymal liver cells responsible for extracellular matrix homeostasis and are the main cells involved in the development of liver fibrosis following injury. The lack of reliable sources of HSCs has hence limited the development of complex in vitro systems to model liver diseases and toxicity. Here we describe a protocol to differentiate human induced pluripotent stem cells (iPSCs) into hepatic stellate cells (iPSC-HSCs). The protocol is based on the addition of several growth factors important for liver development sequentially over 12 d. iPSC-HSCs present phenotypic and functional characteristics of primary HSCs and can be expanded or frozen and used to perform high-throughput in vitro studies. We also describe how to coculture iPSC-HSCs with hepatocytes, which self-assemble into three-dimensional (3D) hepatic spheroids. This protocol enables the generation of HSC-like cells for in vitro modeling and drug screening studies.