Application of human amniotic membrane on rat liver following left hepatectomy : evaluation of liver reaction

Over past decades, the numerous unique characteristics of human amniotic membrane (hAM), such as its anti-inflammatory and antifibrotic properties, justified the frequent use of this material in human reparative surgery and experimental animal disease models. In order to investigate the potential of amniotic membrane to promote hepatic regeneration, we applied the membrane to the external surface of hepatectomized rat livers and assessed hepatocyte proliferation rate and tissue reaction at 1, 3, 7 and 14 days after surgery. Clinical and histopathological data were collected and compared with hepatectomized control rats which received no hAM transplantation and were sacrificed at the same intervals. In both control and hAM-transplanted animals, a rapid rise in mitotic activity was first observed near the resection, followed by a higher peak in mitoses at day 3 in distant areas. The number of binucleated cells, which decreased after partial hepatectomy, increased during liver regeneration, and this was observed more so in hAM transplanted animals. In this group, at day 7, hAM was adherent to the liver capsule in association with interposed palisades of tightly packed fibroblast-like cells. Discrete areas of partial resorption of hAM were observed at day 14. The parenchyma did not show any morphologically appreciable signs of degeneration or inflammatory infiltration in hAM-transplanted animals. Our data suggest that application of hAM membrane to the surface of resected rat livers does not impede normal recovery and actually induces a slight improvement in hepatocyte proliferation without any evident signs of rejection against xenogeneic human transplanted membrane