Heterotypic interactions in the preservation of morphology and functionality of porcine hepatocytes by bone marrow mesenchymal stem cells in vitro.

Temporary replacement of specific liver functions with extracorporeal bioartificial liver has been hampered by rapid de-differentiation of porcine hepatocytes in vitro. Co-cultivation of hepatocytes with non-parenchymal cells may be beneficial for optimizing cell functions via mimicry of physiological microenvironment consisting of endogenous matrix proteins. However, the underlying mechanisms remain to be elucidated. A randomly distributed co-culture system composed of porcine hepatocytes and bone marrow mesenchymal stem cells was generated, and the morphological and functional changes of varying degrees of heterotypic interactions were characterized. Furthermore, contributions of extracellular matrix within this co-culture were evaluated. A rapid attachment and self-organization of three-dimensional hepatocyte spheroids were encouraged. Studies on hepatocyte viability showed a metabolically active, viable cell population in all co-culture configurations with occurrence of few dead cells. The maximal induction of albumin production, urea synthesis, and cytochrome P4503A1 activities was achieved at seeding ratio of 2:1. Immunocytochemical detection of various extracellular matrix confirmed that a high level of matrix proteins synthesis within distinct cells was involved in hepatocyte homeostasis. These results demonstrate for the first time that cell-matrix has synergic effects on the preservation of hepatic morphology and functionality in the co-culture of porcine hepatocytes with mesenchymal stem cells in vitro, which could represent a promising tool for tissue engineering, cell biology, and bioartificial liver devices. (c) 2008 Wiley-Liss, Inc.