Direct and indirect coculture of mouse hepatic progenitor cells with mouse embryonic fibroblasts for the generation of hepatocytes and cholangiocytes

The widespread use of hepatocytes and cholangiocytes for regenerative medicine and tissue engineering is restricted by the limited number of hepatocytes and cholangiocytes; a simple and effective method for the expansion and differentiation of the hepatic progenitor cells (HPCs) is required. Recent studies demonstrated that mouse embryonic fibroblasts (MEFs) play an important role in supporting the proliferation of the mouse hepatic progenitor cells (mHPCs). However, the effect of direct and indirect coculture of MEFs with mHPCs on the differentiation of mHPCs is poorly studied. Herein, we show that mHPCs rapidly proliferate and form colonies in direct or indirect contact coculture with MEFs in the serum-free medium. Importantly, after direct contact coculture of the mHPCs with MEFs for 6 days, mHPCs expressed the hepatic marker albumin (ALB) and did not express the cholangiocyte marker CK19, indicating their differentiation into hepatocytes. In contrast, after indirect contact coculture of the mHPCs with MEFs for 6 days, mHPCs expressed the cholangiocyte marker CK19 and did not express the hepatic marker ALB, indicating their differentiation into cholangiocytes. These results indicate that direct and indirect contact cocultures of the mHPCs with MEFs are useful for rapidly producing hepatocytes and cholangiocytes.