Autologous transplanted hepatocytes: depletion of recipient leukocytes prevents in vivo lysis

Transplantation of hepatocytes: Temporary elimination of scavenger cells prevents early loss of grafted cells

Transplants of isolated syngeneic and allogeneic hepatocytes are rapidly disintegrated, irrespective of the site of engraftment; be it spleen, liver, portal vein, peritoneum, or subcutaneous tissue. Host scavenger cells are responsible for this reaction. We designed a method overcoming early disintegration of the grafted hepatocytes. It consisted of administration of anti-asialoGM1 antiserum eliminating natural killer cells; sublethal whole body irradiation; and reconstitution with syngeneic bone marrow cells, ligation of host bile duct, intrasplenic hepatocyte transplantation, and three consecutive partial hepatectomies. Six months after transplantation a glycogen-rich, trabeculae-forming, dividing hepatocytes, situated along strands of newly-formed fibrous tissue and numerous dilated blind bile cannaliculae were observed. There was evidently more bile canaliculae in hosts with ligated bile duct than nonligated controls. This is the first study showing fibrous tissue formed at the site of hepatocyte implantation, and stellate cells are presumably involved in this process.

Clinical and experimental transplantation of isolated organ or tissue cells indications problems from the Polish perspective

Clinical cell transplantation remains as a clinical experiment. Morphologically intact and functional cells transplanted into their tissue of origin undergo rapid disintegration by attacking granulocytes and macrophages, leading to the so-called early graft dysfunction. When transplanted to sites remote from their origin, the process of elimination is even faster. Among millions of transplanted cells, only a few survive in an autologous or syngeneic recipient, not to mention an allogeneic combination. What is the mechanism of elimination of the majority of transplanted cells? Which cells survive and what is their genotype and phenotype? There are several problems that should be investigated: (1) the mechanism of anoikis, namely, detachment-induced apoptosis, (2) the reaction of the innate immune system to transplanted cells, (3) the microchimerism created by the transplanted cells, and (4) the "niche" for transplanted cells within the local cell chemical environment and signalling. Our experience with transplantation of hepatocytes illustrates current problems in isolated cell grafting. Proposals to increase the in vivo survival rate of transplanted syngeneic hepatocytes are essential to the vision of the future of cell transplantation.

Transplantation of hepatocytes: elimination of recipient natural killer cells with irradiation and bone marrow reconstitution prevent early graft dysfunction

Transplanted isolated syngeneic and allogeneic hepatocytes rapidly disintegrate, irrespective of the origin or the site of engraftment namely spleen, liver, portal vein, peritoneum, or subcutaneous tissues. Although various methods have been applied to attenuate this reaction, none have been found effective. We applied a combined protocol consisting of administration of anti-asialoGM1 antiserum (eliminating NK cells), sublethal whole-body irradiation, and reconstitution with syngeneic bone marrow cells to intrasplenic hepatocyte transplantation and 3 consecutive partial hepatectomies. This method overcame the early disintegration of grafted hepatocytes. Ninety days after transplantation numerous hepatocyte clusters and dilated bile canaliculae, occupying two thirds of the spleen, were observed, with some hepatocytes adhering to the bile ducts forming Hering's canals. Mitotic figures were noticed. There were no recipient mononuclear infiltrates around the hepatocyte clusters.