Objective: To investigate the expression and distribution of extracellular matrix (ECM) in the co-culture of porcine primary hepatocytes and bone marrow mesenchymal stem cells (MSCs) in vitro.
Methods: Mononuclear cells were isolated from bone marrow of swine by density gradient centrifugation. MSCs of passage 3 and primary hepatocytes harvested by a two-step in situ collagenase perfusion technique were co-cultured, and the morphological and functional changes of heterotypic interactions were characterized. Immunocytochemical analysis was performed to monitor the expression and distribution of ECM.
Results: The purity of the third passage MSCs and primary hepatocytes was more than 90% and 99%, respectively. More than 95% of the hepatocytes were viable. Compared to hepatocytes culture, co-culture with MSCs significantly enhanced hepatic function: including albumin secretion and urea synthesis (P < 0.01). The best hepatic function level was achieved on day 2 and gradually decreased in the following co-culture days. Immunocytochemical staining suggested that higher amounts of naturally occurring ECM proteins including fibronectin, laminin, and several kinds of collagens were produced in co-culture group compared to hepatocyte homo-culture (P < 0.01). RNAi experiments verified that there was a correlation between ECM and hepatic functions.
Conclusion: ECM may indeed play a key role in the up-regulation of hepatocyte functions in MSC/hepatocytes co-culture.