In vivo selection of liver cells in a model of allogeneic bone-marrow-transplantation

K. Streetz; R. Doyonnas; D. Jenkins; S. Perryman; S. Lin; C. Trautwein; J. Shizuru; H. Blau; K. Sylvester; M. Kay

doi:10.1055/s-2006-950752

Zeitschrift für Gastroenterologie, Table of Contents

In vivo selection of liver cells in a model of allogeneic bone-marrow-transplantation

K Streetz ¹, R Doyonnas ², D Jenkins ³, S Perryman ³, S Lin ⁴, C Trautwein ¹, J Shizuru ⁴, H Blau ², K Sylvester ³, M Kay ⁵

¹University Hospital of Aachen, Dept. of Medicine 3, Aachen, Germany
²Stanford University, Dept. of Microbiology and Immunology, Stanford, United States of America
³Stanford University, Dept. of Surgery, Stanford, United States of America
⁴Stanford University, Dept. of Bone-Marrow-Transplantation, Stanford, United States of America
⁵Stanford University, Dept. Pediatrics and Genetics, Stanford, United States of America

Abstract

Aims: Expansion of transplanted cells is a common goal for cellular therapies. As the available amount of liver cells for transplantation is limited we aimed to explore new resources for replacement therapies, such as intra- and extrahepatic stem cells.

Methods: We performed allogeneic Bone-marrow-transplantation (BMT) in balb/c mice. Hepatocyte transplantation was carried out subsequently. Transgenic FVB-mice expressing human alpha-1-antitrypsin (hAAT) under the liver specific hAAT-promoter were used as BM and hepatocyte donors.

Results: After subsequent allogeneic BM and hAAT(+) hepatocyte transplantation we observed a complete liver repopulation of transplanted balb/c mice over time. We noticed mononuclear infiltrates, slight histological changes and an enhanced p21 activation in livers of allogeneic BM transplanted balb/c mice. In contrast, all these changes appeared at a much lesser degree in fully hepatocyte repopulated animals. Infiltrates were mostly CD4(+) cells. Experiments using blocking antibodies revealed further, that in vivo selection of hepatocytes was abrogated in mice, which had received anti-CD4 rather then anti-CD8 or NK cell antibodies. Furthermore, using hAAT(+) BM as the source for immune-reconstitution we also observed the appearance and selection of hAAT(+) hepatocytes within our model. This could be demonstrated by the detection of clusters of hAAT(+) hepatocytes in mice, which had received hAAT(+) BM alone (and no further hepatocytes). These cells could be further expanded in secondary recipients after hepatocyte transplantation.

Conclusions: We could demonstrate the effective in vivo selection of transplanted primary hepatocytes and of hepatocytes expressing a BM transferred liver specific markergen (most likely a result of a fusion event) after allogeneic transplantation. Mechanistically based on the BMT related irradiation induced liver injury an allogeneic inflammatory response, mediated predominantly by CD4(+) cells, favors the proliferation of the transplanted cells. Thus, we first demonstrate a new mechanism for in vivo expansion of transplanted hepatocytes. Additionally this is one of the few reports about the selection of liver cells expressing a hepatocyte specific, BM transferred gene in mice.