FRACTIONATION OF RAT HEPATOCYTE SUBPOPULATIONS WITH VARYING METABOLICPOTENTIAL, PROLIFERATIVE CAPACITY, AND RETROVIRAL GENE-TRANSFER EFFICIENCY

The liver contains hepatocytes with varying ploidy and gene expression . To isolate cells on the basis of ploidy for analyzing mechanisms con cerning cell proliferation and differentiation, we used Percoll gradie nts to separate F344 rat hepatocyte subpopulations. Specific fractions were enriched in polyploid (H2 fraction) or diploid (H3 and H4 fracti ons) hepatocytes containing glycogen and glucose-6-phosphatase. H4 cel ls were relatively smaller with greater nuclear/cytoplasmic ratios, le ss complex cytoplasm, and higher serum albumin or ceruloplasmin biosyn thetic rates. H2 fraction cells were larger with lesser nuclear/cytopl asmic ratio, more complex cytoplasm, and more cytochrome P450 activity . Phenotypic marking showed that H4 cells originated in zone one and H 2 cells in zones two or three of the liver lobule. H4 cells showed muc h greater mitogenic responsiveness to human hepatocyte growth factor. Retroviral gene transfer, which requires both viral receptors and cell ular DNA synthesis, was significantly more efficient in H4 cells. The findings indicated that small diploid and large polyploid hepatocytes show unique biological differences. The ability to isolate hepatocytes of varying maturity is relevant for mechanisms concerning liver growt h control and hepatic gene expression. (C) 1998 Academic Press.