One of the greatest challenges in the attempt to create functional bioartificial liver designs is the maintenance of porcine hepatocyte differentiated functions in vitro. Co-cultivation of hepatocytes with nonparenchymal cells may be beneficial for optimizing cell functions via mimicry of physiological microenvironment. However, the underlying mechanisms remain to be elucidated. An equal number of freshly isolated porcine hepatocytes and purified bone marrow mesenchymal stem cells (MSCS) was randomly co-cultured and the morphological and functional changes of heterotypic interactions were characterized. Furthermore, contributions of soluble factors involved in the separated co-culture system were evaluated. The purity of the third-passage MSCS and primary hepatocytes was more than 90% and 99%, respectively. Hepatocyte viability was greater than 95%. A rapid attachment and self-organization of three-dimensional hepatocyte spheroids were encouraged, which was due to the supporting MSCS of high motility. The elevated induction of both albumin production and urea synthesis was achieved in co-culture (P < 0.05). Data from semipermeable membrane cultures suggested that interleukin-6 is one of the key stimulators in hepatic functional enhancement. These results demonstrate for the first time that soluble factors have beneficial effects on the preservation of hepatic morphology and functionality in the co-culture of hepatocytes with MSCS in vitro, which could represent a promising tool for tissue engineering, cell biology, and bioartificial liver devices.
Comparative analysis and characterization of soluble factors and exosomes from cultured adipose tissue and bone marrow mesenchymal stem cells in canine species
