Liver regeneration after partial hepatectomy is non-uniform: flow cytometric bromodeoxyuridine incorporation and cell cycle studies in a porcine model

The rate of hepatocyte regeneration at different anatomical locations of th e remnant liver after partial hepatectomy was assessed in porcine hepatocyt es by bromodeoxyuridine (BrdUr) incorporation and cell cycle kinetics using now cytometric analysis. Partial hepatectomy was performed in five Yorkshi re pigs. A single intravenous injection of BrdUr at 50 mg/kg was administer ed on the 2nd post-operative day and the animals were sacrificed 1 h later. The remnant liver tissue was harvested and divided into four equal zones, from the liver periphery towards the surgical cut-edge. Biopsy samples were obtained from the centre of each of these zones and similarly from identic al anatomical locations in two control pigs that had undergone sham surgery . Hepatocyte nucleus suspension was prepared, double labelled with anti-Brd Ur and propidium iodide and analysed by a flow cytometer. The cells in S-ph ase was used as the parameter to measure the regeneration status. A gradien t increase in S-phase from the periphery to the cut edge was observed in al l five pigs that had undergone partial hepatectomy. The percentage of S-pha se cells in all four zones from the hepatectomy group was significantly hig her when compared with that in the controls. Liver regeneration after parti al hepatectomy was not uniform but was greatest adjacent to the surgical cu t edge and decreased towards the periphery of the liver.