Cardiomyocyte-targeted HIF-1alpha gene therapy inhibits cardiomyocyte apoptosis and cardiac allograft vasculopathy in the rat.
BACKGROUND
Hypoxia-inducible factor-1 (HIF-1), a key transcription factor in hypoxia, affects a wide range of adaptive cell functions. We examined the kinetics of endogenous HIF-1alpha during acute and chronic rejection, and the effect of exogenous HIF-1alpha in chronically rejecting rat cardiac allografts.


METHODS
Heterotopic cardiac transplantations were performed between major MHC-mismatched Dark Agouti and Wistar-Furth rats. Cyclosporine A (CsA) was used to prevent acute rejection in the chronic rejection model. The effect of HIF-1alpha overexpression was investigated by adeno-assocated virus 2 (AAV2)-mediated gene transfer of a constitutively stabilized form of mouse HIF-1alpha (AAV-HIF-1alpha). The analysis of allografts was based on histology, immunohistochemistry and quantitative reverse transcript-polymerase chain reaction (RT-PCR).


RESULTS
Acute and chronic rejection significantly induced HIF-1alpha mRNA in rat cardiac allografts when compared with syngeneic controls. Immunohistochemistry localized significantly increased HIF-1alpha immunoreactivity to vascular smooth muscle cells, vascular endothelial cells, post-capillary venules and graft-infiltrating mononuclear inflammatory cells of the allograft, whereas expression in cardiomyocytes remained unchanged. Regression analysis revealed a linear correlation between the progression of cardiac allograft vasculopathy (CAV) and HIF-1alpha immunoreactivity in post-capillary venules and graft-infiltrating mononuclear inflammatory cells in chronically rejecting rat cardiac allografts. AAV-HIF-1alpha enhanced cardiomyocyte HIF-1alpha production and significantly reduced cardiomyocyte apoptosis and the development of CAV in chronically rejecting rat cardiac allografts.


CONCLUSIONS
We found that acute and chronic rejection increased HIF-1alpha mRNA and protein levels in rat cardiac allografts. On the other hand, cardiomyocyte-targeted HIF-1alpha gene transfer inhibited cardiomyocyte apoptosis and the development of CAV, suggesting a novel therapeutic strategy for HIF-1alpha in cardiac allografts.
Keränen
Mikko A I
MA
Cardiopulmonary Research Group, Transplantation Laboratory, Haartman Institute, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
Nykänen
Antti I
AI
Krebs
Rainer
R
Pajusola
Katri
K
Tuuminen
Raimo
R
Alitalo
Kari
K
Lemström
Karl B
KB
D000005:Abdomen; D000818:Animals; D017209:Apoptosis; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000378:metabolism; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D006084:Graft Rejection / Q000473:pathology; D016027:Heart Transplantation / Q000276:immunology / Q000379:methods / Q000473:pathology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000473:pathology; D011183:Postoperative Complications / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D011920:Rats, Inbred WF; D016042:Transplantation, Heterotopic; D014184:Transplantation, Homologous / Q000276:immunology / Q000473:pathology
C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; C526285:Ca9 protein, rat; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases