[Human fetal liver nonparenchymal mesenchymal stem cells differentiate into functional hepatocyte-like cells in vitro].

Objective: To induce nonparenchymal mesenchymal stem cells (NPMSCs) differentiating into functional hepatocyte-like cells in vitro, and to identify the molecular biology and functional characteristics of those hepatocyte-like cells.

Methods: Human NPMSCs were isolated and cultured with cell culture technique. NPMSCs were induced (on 1% Matrigel as a matrix and then submitted to 2.5 mmol/L AZA pretreatment for 10-12 h), by adding HGF 10 microg/L + FGF4 10microg/L + HGM into the culture medium. The characteristics of proliferation and growth of human NPMSCs were studied with methyl thiazolyl tetrazolium (MTT). The phenotypes of NPMSCs were identified by flow cytometry, immunohistochemistry and RT-PCR. Albumin (Alb) levels in culture supernatants were determined with ELISA. Staining for glycogen of undifferentiated NPMSCs and NPMSCs derivated hepatocyte-like cells was conducted with periodic acid-Schiff (PAS) test.

Results: Growth and division of adherent cells obtained from fetal livers were good and the amount of NPMSCs resourced from each fetus could be amplified to 109 cells after 10 serial subcultivations. The phenotype of NPMSCs was CD166 positive and CD34 negative. The shape of NPMSCs plated on Matrigel with FGF4 and HGF changed from long fusiform to polygonal or round on days 21-28. The rate of cell rounding was 40% and the ratio of dikaryocytes was 5%. Immunohistochemical and RT-PCR detection showed that undifferentiated NPMSCs expressed few alpha fetoprotein (AFP) and AFP mRNA, and did not express any of the liver-specific transcription factors or cytoplasmic markers. Many cells in early induction expressed GATA4, AFP and CK18 proteins and their mRNAs, and their expressions were reduced at the late induction, but the expressions of Alb, CK18, GST-and hepatocyte transcription factor HNF1increased gradually. The ratio of Alb and CK18 positive cells was 60%. Undifferentiated NPMSCs did not produce Alb. Alb production by induced NPMSCs increased in a time-dependent manner. Glycogen storage was first seen on day 14, and maximum levels were seen after day 28.

Conclusions: There are MSCs among nonparenchymal cells of fetal livers. A high ratio of hepatocyte-like cells was obtained under our induction condition. NPMSCs differentiate firstly into hepatocyte precursors, and then differentiate into mature hepatocytes and hepatocyte-like cells with positive hepatocyte markers. The induced NPMSCs have hepatocyte specific functional features.