Retrovirus vector-mediated gene transfer into hepatocytes

Abstract

The introduction and stable expression of foreign genes in mammalian hepatocytes have recently been demonstrated by several techniques, including the use of physical approaches such as direct injection of a DNA calcium phosphate precipitate, electroporation of plasmid DNA and the exposure to liposome-erythrocyte ghost complexes as well as the biological approach of infection of primary hepatocyte cultures with retrovirus vectors. Retrovirus-mediated transduction has proven to be highly advantageous in many in vitro gene transfer studies of mammalian cells, and recent results with primary rat liver cultures have begun to define the conditions under which foreign genes can be transduced into hepatocytes in vitro. Fully differentiated hepatocytes are poorly susceptible, if at all, to infection with retroviruses, a phenomenon due at least in part to the fact that cells must undergo replication in order to retroviral integration and gene expression to occur. Hepatocytes are largely resting cells, arrested in G0. Nevertheless, primary cultures of hepatocytes are known to demonstrate a partial de-differentiation in vitro and undergo several rounds of replication. During a narrow period of time early in primary culture correlated roughly with the de-differentiation, adult hepatocytes do become susceptible to efficient infection with retrovirus vectors. In infected cells, gene expression remains relatively stable for the several week duration of the primary culture. It is not known if the restriction of virus infection in hepatocytes is a function of the state of cellular differentiation, of the availability of viral receptors or of other factors.(ABSTRACT TRUNCATED AT 250 WORDS)