Due to the lack of appropriate culture condition and microenvironment, functional cells derived from stem cells induced differentiation in vitro are difficult to be mature and maintain their long term function. It's a long-term challenge in the research and application of regenerative medical technique. In the past few decades, people trying different method such as changing the culture materials, co-culture and three-dimensional culture, but they have never been able to establish a in vitro culture system which is efficient, stable and functional. In order to solve this problem, Deng Hongkui's research team and other research groups took the PHH which is quickly lost the function during in vitro culture the research object, screened five chemical combinations and used them successfully achieve long-term maintenance of liver cell function in vitro. during the cultivation period of more than 1 month, the combination of 5C inhibited the dedifferentiation of hepatocytes. The overall gene expression profile of the cell is highly similar to the hepatocytes in the body, and that hepatocyte secretion, urea synthesis, drug metabolism and other hepatocytes functions have been maintained for a long time. Related work was published online in Science magazine on April 26, 2019