title: Disappearance of GFP-positive hepatocytes transplanted into the liver of syngeneic wild-type rats pretreated with retrorsine.
abstract: OBJECTIVE
  Green fluorescent protein (GFP) is a widely used molecular tag to trace transplanted cells in rodent liver injury models. The differing results from various previously reported studies using GFP could be attributed to the immunogenicity of GFP.
  
  
  METHODS
  Hepatocytes were obtained from GFP-expressing transgenic (Tg) Lewis rats and were transplanted into the livers of wild-type Lewis rats after they had undergone a partial hepatectomy. The proliferation of endogenous hepatocytes in recipient rats was inhibited by pretreatment with retrorsine to enhance the proliferation of the transplanted hepatocytes. Transplantation of wild-type hepatocytes into GFP-Tg rat liver was also performed for comparison.
  
  
  RESULTS
  All biopsy specimens taken seven days after transplantation showed engraftment of transplanted hepatocytes, with the numbers of transplanted hepatocytes increasing until day 14. GFP-positive hepatocytes in wild-type rat livers were decreased by day 28 and could not be detected on day 42, whereas the number of wild-type hepatocytes steadily increased in GFP-Tg rat liver. Histological examination showed degenerative change of GFP-positive hepatocytes and the accumulation of infiltrating cells on day 28. PCR analysis for the GFP transgene suggested that transplanted hepatocytes were eliminated rather than being retained along with the loss of GFP expression. Both modification of the immunological response using tacrolimus and bone marrow transplantation prolonged the survival of GFP-positive hepatocytes. In contrast, host immunization with GFP-positive hepatocytes led to complete loss of GFP-positive hepatocytes by day 14.
  
  
  CONCLUSIONS
  GFP-positive hepatocytes isolated from GFP-Tg Lewis rats did not survive long term in the livers of retrorsine-pretreated wild-type Lewis rats. The mechanism underlying this phenomenon most likely involves an immunological reaction against GFP. The influence of GFP immunogenicity on cell transplantation models should be considered in planning in vivo experiments using GFP and in interpreting their results.
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America; Department of Surgery, Kochi Medical School, Nankoku, Kochi, Japan; Cancer Treatment Center, Kochi Medical School, Nankoku, Kochi, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Maeda
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Shigoka
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Yongchun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Yingxin
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Russell N
authors.initials: RN
authors.lastname: Wesson
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lin
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Montgomery
authors.affiliation: Diagnostic Pathology, Chikamori Hospital, Kochi, Kochi, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Enzan
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Zhaoli
authors.initials: Z
authors.lastname: Sun
mesh_terms: D000818:Animals; D017690:Cell Transplantation; D006084:Graft Rejection / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D006085:Graft Survival / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology / Q000637:transplantation; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011917:Rats, Inbred Lew; D055647:Rats, Transgenic; D016559:Tacrolimus / Q000494:pharmacology; D013997:Time Factors; D019076:Transgenes; D014185:Transplantation, Isogeneic
chemical_list: D007166:Immunosuppressive Agents; D049452:Green Fluorescent Proteins; D016559:Tacrolimus