Abstract
Two-color flow cytometric (FCM) analysis using anti-bromodeoxyuridine (BrdU) monoclonal antibody (MoAb) was used to investigate the cell kinetics of regenerating liver after 70% partial hepatectomy in rats. Three peaks were seen in DNA histograms of rat hepatocyte nuclei, corresponding to diploid(2c), tetraploid(4c), and octaploid(8c). These proportions changed in the course of regeneration which were clearly demonstrated by DNA histograms using flow cytometry. The proportion of diploid, tetraploid, and octaploid nuclei in control liver were 49.3 ± 1.6%, 45.0 ± 7.4%, and 1.7 ± 0.7%, respectively. A significant change occurred at 24 hours after hepatectomy, as FCM revealed 25.9 ± 1.1% diploid, 54.5 ± 1.2% tetraploid, and 9.0 ± 0.9% octaploid. This shift to polyploid nuclei persisted until 72 hours, and then gradually returned to the pattern of control liver. The S-phase nuclei which incorporated BrdU increased rapidly at 24 hours to a peak of 11.3 ± 0.9%, and gradually decreased to 5.8 ± 0.8%, 5.3 ± 0.8%, 2.4 ± 0.6%, 2.9 ± 1.1%, and 1.2 ± 0.6%, at 48, 72, 96, 120, and 168 hours, respectively. This 2-color FCM analysis made a detailed analysis of the cell kinetics in regenerating hepatocytes possible, and may be applied in investigations of various aspects of liver regeneration.