[Impact of hepatitis B virus infected serum on the hepatic differentiation of human bone marrow mesenchymal stem cells].

Objective: To study the effects of hepatitis B virus (HBV) infection in vitro on differentiation of mesenchymal stem cells (MSCs) to liver cells.

Methods: MSCs were isolated from human bone marrow by density gradient centrifugation, and expanded by adherent culture. MSCs were cultured under liver-stimulating condition, and different composition of serum was added to the induced medium: Group A: 5% fetal bovine serum (FBS); Group B: 2.5% FBS+2.5% HBV-containing serum; Group C: 2.5% FBS+2.5% serum from healthy volunteers; Group D: the undifferentiated MSCs cultured in LG-DMEM+10% FBS. The expressions of a variety of hepatic lineage markers were analyzed by immunocytochemistry and immunofluorescence. The functionality of differentiated cells was assessed by their ablility to store glycogen. After 2 weeks of exposure to HBV infected serum, HBV-specific protein was also detected by immunocytochemistry.

Results: As a result of our hepatic induction, the expressions of albumin (ALB) and alpha-fetoprotein (AFP) by MSCs were observed by immunocytochemical and immunofluorescence techniques. Moreover, MSCs had acquired the ability of glycogen storage which was characteristic of liver cells. Compared with the control group, the proliferation of MSCs was inhibited greatly by the virus-containing serum. After 2 weeks of exposure to HBV infected serum, the surface antigen (HBsAg) was detected in some induced MSCs. However, after immunocytochemical stain for ALB and AFP, there was not much difference between the Group B and C. The ability of glycogen storage of two groups were almost the same. Using confocal microscopy, we found the co-expressions of ALB and HBsAg in the same differentiated cells.

Conclusion: The bone marrow MSCs have the ability to trans-differentiate into functional hepatocyte-like cells, hence may serve as a cell source for tissue engineering and cell therapy of hepatic diseases. HBV infected serum could inhibit the proliferation of MSCs in culture, but it seemed that the hepatic differentiation of the cell was unsuppressed.