In vitro transdifferentiation of mature hepatocytes into insulin-producing cells

Abstract

Adenovirus-mediated gene transfer of pancreatic duodenal homeobox transcription factor PDX-1, especially its super-active version (PDX-1/VP16), induces the expression of pancreatic hormones in murine liver and reverses streptozotocin-induced hyperglycemia. Histological analyses suggest that hepatocytes are the major source of insulin-producing cells by PDX-1 gene transfer, although the conversion of cultured hepatocytes into insulin-producing cells remains to be elucidated. The present study was conducted to address this issue. Hepatocytes were isolated from adult rats. Then, PDX-1 or PDX-1/VP16 gene was introduced by using adenovirus vector. Two days later, the expression of insulin was detected at mRNA and protein levels. Transfection of PDX-1/VP16 was more efficient in converting hepatocytes to insulin-producing cells. Immunoreactivity of albumin was downregulated in transdifferentiated cells and some of them almost completely lost albumin expression. During the course of transdifferentiation, upregulation of mRNA for CK19 and α-fetoprotein was observed. When cultured in collagen-1 gel sandwich configuration, hepatocytes maintained their mature phenotype and did not proliferate. In this condition, transfer of PDX-1/VP16 also induced the expression of insulin. These results clearly indicate that hepatocytes possess a potential to transdifferentiate into insulin-producing cells in vitro.