The natural history of liver regeneration in rats: Description of an animal model for liver regeneration studies

BACKGROUND: Rodent models have been used to evaluate aspects of liver regeneration. The aim of the present study was to investigate the natural history of liver regeneration in healthy rats. METHODS: A 70% partial hepatectomy was performed in 64 rats. The animals were randomised into 8 groups and evaluated on postoperative days one to eight. Hepatocyte proliferation was evaluated by immunohistochemistry using unbiased stereological principles. RESULTS: The mean rat body weight was 238 g (211-287). The mean weight of the resected liver was 6.3 g (5.2-7.3) and the estimated mean total liver weight was 8.9 g (7.4-10.4). Both liver weight analysis and regeneration rate showed an ascending curve, with a maximum slope on postoperative days 1-4, reaching a steady state on days 5-8. Hepatocyte proliferation (positive Ki-67 cell profiles pr. mm(2)) was high (250 cell profiles/mm(2)) on postoperative days 1-3 and tapered off on day 5. CONCLUSION: Seventy percent partial hepatectomy in healthy rats induces a rapid regenerative response and PODs 2, 4 and 8 seems optimal for assessing hepatic growth in future studies.