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Liver‐restricted expression of the canine factor VIII gene facilitates prevention of inhibitor formation in factor VIII‐deficient mice
Author(s) -
Ishiwata Akira,
Mimuro Jun,
Mizukami Hiroaki,
Kashiwakura Yuji,
Takano Katsuhiro,
Ohmori Tsukasa,
Madoiwa Seiji,
Ozawa Keiya,
Sakata Yoichi
Publication year - 2009
Publication title -
the journal of gene medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 91
eISSN - 1521-2254
pISSN - 1099-498X
DOI - 10.1002/jgm.1391
Subject(s) - enhancer , transgene , biology , microbiology and biotechnology , genetic enhancement , antibody , viral vector , virology , gene expression , promoter , genetically modified mouse , gene , recombinant dna , immunology , genetics
Background Gene therapy for hemophilia A with adeno‐associated virus (AAV) vectors involves difficulties in the efficient expression of factor VIII (FVIII) and in antibody formation against transgene‐derived FVIII. Methods AAV8 vectors carrying the canine B domain deleted FVIII (cFVIII) gene under the control of the ubiquitous β‐actin promoter, the liver‐specific human α1 anti‐trypsin promoter (HAAT) and the liver‐specific hepatic control region (HCR) enhancer/human α1 anti‐trypsin promoter complex (HCRHAAT) were used for the expression of cFVIII in FVIII deficient ( fviii −/− ) mice. Results Addition of the hepatic control region enhancer element to the HAAT promoter successfully augmented HAAT promoter activity without loss of liver‐specificity in vivo . Using this enhancer/promoter complex, a high cFVIII transgene expression was achieved, resulting in increased blood cFVIII activities to more than 100% of the normal canine FVIII levels in fviii −/− mice at a 1 : 10 lower dose of the AAV8 vector carrying the cFVIII gene driven by the HAAT promoter. Under short‐term immunosuppression, neutralizing antibodies against cFVIII developed in only one out of six mice when the HAAT promoter was used for cFVIII expression, whereas all the mice developed neutralizing antibodies against cFVIII when the β‐actin promoter was used for cFVIII expression. No neutralizing antibodies against cFVIII developed in fviii −/− mice that received the AAV8 vector carrying the cFVIII gene driven by the HCRHAAT enhancer/promoter complex without immunosuppression. Conclusions These data suggest that AAV8 vector‐mediated liver‐restricted cFVIII gene expression is sufficient for immune hypo‐responsiveness to transgene‐derived cFVIII in fviii −/− mice. Copyright © 2009 John Wiley & Sons, Ltd.