Gene expression profiling to explore mechanisms of cell-cell interaction in hepatic co-cultures

Abstract

Cell-based therapies have the potential to replace, repair or improve tissue function. In the case of the liver, the need for liver tissue has been exacerbated by the rise in liver disease due to Hepatitis C. The number of liver transplants needed greatly outnumbers the number of donor livers available. We are interested in hepatic tissue engineering towards the creation of an extracorporeal bioartificial liver (BAL) device with functionally stabilized liver cells (hepatocytes) as a temporary hepatic support before an orthotopic liver transplantation is available. Primary hepatocytes, however, rapidly lose phenotypic functions (e.g. albumin secretion and urea synthesis) when isolated from the liver. Investigators have used various methods to stabilize the hepatocyte phenotype including: extracellular matrix manipulation, media additives, and co-cultivation with various non-parenchymal cell types. Despite the robust stabilization of hepatocyte phenotype produced by non-parenchymal cells, the molecular mechanisms involved in this cell-cell interaction remain largely unknown. Here we report the use of gene expression profiling to narrow the search space for molecules that may be involved in this response. We co-cultured primary rat hepatocytes with four highly-related murine fibroblast cell lines that induce various levels of liver-specific function. We correlated these functional response with gene expression profiles obtained using Affymetrix GeneChip™ arrays. Data filtering and microarray data analysis techniques (supervised and unsupervised) were then used to obtain a handful of candidate genes for further experimental investigations. Validation of the candidate genes will be performed both at the mRNA and protein levels. In the future, identification of a critical molecule (s) that mediate stabilization of the hepatic phenotype may have implications in hepatic tissue engineering, stem cell biology, and the pathophysiology of liver disease.