BACKGROUND: Xenogeneic hepatocytes encapsulated in semipermeable membranes could be used in the future; however, encapsulated human hepatocytes presented an early decrease of hepatocyte gene expression. The objective of this study is to investigate the immunological consequences of intraperitoneal implantation of encapsulated xenogeneic hepatocytes on gene expression. METHODS: human hepatocytes were encapsulated in hollow fibers and transplanted in the peritoneal cavity of rats. The fibers were explanted for analysis at days D3, D7 and D14 following transplantation. Morphological features under light and electron microscopies and gene expression were compared to those of non-transplanted encapsulated hepatocytes. Human albumin mRNAs were quantified by RT-PCR and Northern blot. Immunological activity against human hepatocytes was assessed by the analysis of DNA searching for nucleolar apoptosis and also by the rise on MHC class I expression. RESULTS: Transplanted hepatocytes were more than 60% viables and exhibited morphological criteria of hepatocytic differentiation up to D7. At no time cells involved with the immunological response were observed inside the fibers. Albumin transcripts were also detected up to D14. At D3 and D7, albumin mRNA levels were of 30 %, compared to control. The DNA analysis showed well preserved bands with no apoptosis at any time of evaluation. There was no rise on MHC class I expression. CONCLUSION: Human hepatocytes remain viable following encapsulation and intraperitoneal transplantation in rats. Although there is a decrease in gene expression this is not due to a host response against those cells. It seems that this effect is rather related to the process of hepatocyte isolation itself.
Live transplantation; Hepatocyte; Liver, artificial; Biocompatible materials
