Heterogeneity of growth potential of adult rat hepatocytes in vitro

Nearly pure populations of small hepatocytes (SHs), parenchymal hepatocytes (PHs), and nonparenchymal cells (NPCs) were prepared from the adult rat, a nd cocultures of hepatocytes and NPCs were reconstituted from them first to obtain the direct evidence that NPCs promote the growth of hepatocytes and second to compare the growth potential between SHs and PHs, SHs and pi-Is underwent multiple divisions when cocultured with NPCs, whereas neither SHs nor PHs formed colonies at 10 days when cultured alone. Stellate cells in the NPCs were shown to be responsible for this growth promotion. SHs showed a higher growth capacity than PHs. To clearly show the relationship betwee n the growth potential and the size of hepatocytes, SHs and PI-is were furt her fractionated by a fluorescence-activated cell sorter, because the size distribution of SHs and PI-Is was half overlapped. SHs produced 2 cell popu lations, SH-R2 and SH-R3, The former showed a greater extent of granularity and autofluorescence than the latter. In contrast, PI-Is produced only 1 p opulation (PH-R2), which corresponded to the SH-R2. The size of hepatocytes of SH-R3 was smaller (17.1 +/- 0.2 mu m) than those of SH-R2 (22.6 +/- 0.5 mu m) and PH-R2 (24.1 +/- 0.1 mu m) and there was not a significant overla p in the size distribution between the 2 groups. The hepatocytes of SH-R3 w ere highly replicative and 4 or 5 times higher in their growth potential th an those of SH-R2 and PH-R2. We concluded that the growth potential of hepa tocytes is heterogeneous and is correlated with their size and the extent o f their granularity and autofluorescence.