ABSTRACT
<p><b>OBJECTIVE</b>To investigate the differentiation of bone marrow mesenchymal stem cells (BMSCs) and the effects of BMSCs on the proliferation of cirrhotic fat-storing cells (CFSC) and hepatocytes in vitro.</p><p><b>METHODS</b>BMSCs and hepatocytes were isolated and harvested from the bone marrow and livers of rats. A co-culture system was set up by transwell inserts in which the two chambers were separated by a semipermeable membrane. BMSCs labeled with PKH26 were cultured with hepatocytes/CFSC in the co-culture system and also in a cell-cell direct contact culture system. Anti-albumin and anti-smooth muscle alpha-actin (alpha-SMA) antibodies were tested by using fluorescence immunocytochemistry. BMSCs and hepatocytes/CFSC cultured alone served as controls. The proliferation level of hepatocytes in the co-culture system was measured. CFSC were cultured with the conditional medium of BMSCs, and their quantities were measured microscopically.</p><p><b>RESULTS</b>Expression of albumin was observed in the hepatocytes of the two culture systems after they were cultured for 72 h but the albumin levels were higher in the cell-cell direct contact culture system (P<0.01). As compared to the controls, the number of hepatocytes was larger in the co-culture system (P<0.01). No expression of alpha-SMA in CFSC was observed in either culture system. The proliferation of CFSC was inhibited by the conditional medium of BMSCs. The longer the time of the co-culturing the more significant was the CFSC growth suppression (P<0.01).</p><p><b>CONCLUSIONS</b>BMSCs can be induced into hepatocytes by a local micro-environment formed by hepatocytes. BMSCs may promote proliferation of hepatocytes and inhibit proliferation of CFSC.</p>