Hemophilia B occurs in 1:30,000 males and is associated with a life-long bleeding diathesis. Although IV injection of Factor IX can prevent or stop bleeding, this treatment is inconvenient, expensive, and can transmit infections. Hepatic gene therapy could permanently correct the clinical manifestations of hemophilia. Retroviral vectors (RV) can result in long-term and therapeutic levels of expression of coagulation factors from the liver in rodents, and are currently being used in a clinical trial for Hemophilia A in humans. However, there are two major problems that must be solved before RV-mediated hepatic gene therapy will be used routinely: 1) identify ways to achieve a higher efficiency of stable gene transfer without major toxicity; and 2) identify methods for blocking an immune response to the therapeutic gene in the context of RV-mediated hepatic gene therapy. This project will address both of these issues.
The first aim i s to determine if delivery of an RV expressing the canine Factor IX (cFIX) cDNA into the liver can reduce the bleeding manifestations of Hemophilia B dogs obtained from a colony that rarely makes antibodies to the canine protein. This should allow us to quantify gene expression without the confounding issue of an immune response. Initial studies will use neonatal dogs, as their high baseline level of hepatocyte replication allows transduction of 9 percent of liver cells. Subsequent studies will use hepatocyte growth factor to induce replication in young adult dogs. Animals will be evaluated for cFIX levels, development of antibodies, bleeding, and for other adverse effects.
The second aim will address the second major problem of RV-mediated hepatic gene therapy, that of immune responses to the therapeutic gene product. In this aim, we will try to block immune responses to the de novo expression of a transgene from an RV in mice by either performing neonatal gene transfer, or by injecting immunoinhibitory agents at the time of gene therapy in young adults. Although mice are optimal for initial studies due to cost considerations, approaches that function in inbred mice sometimes fail in outbred larger animals. We will therefore test any immunomodulatory approaches that function in mice for their efficacy in normal and Hemophilia B dogs in Aim III. Success in this project might lead to a safe, effective, and permanent therapy for Hemophilia B.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK048028-08
Application #
6687743
Study Section
Special Emphasis Panel (ZRG1-SSS-2 (01))
Program Officer
Mckeon, Catherine T
Project Start
2003-09-01
Project End
2005-12-31
Budget Start
2004-01-01
Budget End
2004-12-31
Support Year
8
Fiscal Year
2004
Total Cost
$266,804
Indirect Cost
Name
Washington University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
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Xu, L; Mei, M; Ma, X et al. (2007) High expression reduces an antibody response after neonatal gene therapy with B domain-deleted human factor VIII in mice. J Thromb Haemost 5:1805-12
Xu, Lingfei; Nichols, Timothy C; Sarkar, Rita et al. (2005) Absence of a desmopressin response after therapeutic expression of factor VIII in hemophilia A dogs with liver-directed neonatal gene therapy. Proc Natl Acad Sci U S A 102:6080-5
Zhang, Jun; Xu, Lingfei; Haskins, Mark E et al. (2004) Neonatal gene transfer with a retroviral vector results in tolerance to human factor IX in mice and dogs. Blood 103:143-51
Xu, Lingfei; Gao, Cuihua; Sands, Mark S et al. (2003) Neonatal or hepatocyte growth factor-potentiated adult gene therapy with a retroviral vector results in therapeutic levels of canine factor IX for hemophilia B. Blood 101:3924-32
Xu, Lingfei; Haskins, Mark E; Melniczek, John R et al. (2002) Transduction of hepatocytes after neonatal delivery of a Moloney murine leukemia virus based retroviral vector results in long-term expression of beta-glucuronidase in mucopolysaccharidosis VII dogs. Mol Ther 5:141-53
Xu, L; Daly, T; Gao, C et al. (2001) CMV-beta-actin promoter directs higher expression from an adeno-associated viral vector in the liver than the cytomegalovirus or elongation factor 1 alpha promoter and results in therapeutic levels of human factor X in mice. Hum Gene Ther 12:563-73
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Gao, C; Sands, M S; Haskins, M E et al. (2000) Delivery of a retroviral vector expressing human beta-glucuronidase to the liver and spleen decreases lysosomal storage in mucopolysaccharidosis VII mice. Mol Ther 2:233-44
Gao, C; Jokerst, R; Gondipalli, P et al. (1999) Lipopolysaccharide potentiates the effect of hepatocyte growth factor on hepatocyte replication in rats by augmenting AP-1 activity. Hepatology 30:1405-16

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