: The genetic treatment of X-linked severe combined immunodeficiency (XSCID) and most immune and hematological disorders will require the transduction of pluripotent, self-renewing hematopoietic stem cells (HSCs) rather than their progenitors in order to achieve enduring production of genetically corrected cells and durable immune reconstitution. Gene-corrected HSCs will have to compete not only with the defective host cells but also with a significant number of uncorrected HSCs depending upon the transduction efficiency. In XSCID, the selective advantage of T cells expressing a normal common gamma chain (gamma c) gene means that transduction of small numbers of immature progenitor cells may produce clinically significant numbers of mature T cells. However, the lack of a selective advantage in the B cell lineage means that reconstitution of normal B cells may depend on transduction of a large number of immature progenitors and/or HSCs. The results of the recent successful retroviral gene therapy trial for human XSCID suggest that the number of transduced cells will be important for the quality and durability of immune reconstitution following treatment. Although all successfully treated patients developed normal levels of T cells following treatment, they developed few, if any, gene-corrected B cells. However the oldest patient is showing decline in the number of T cells raising questions of the durability of T cell reconstitution. In addition, one of the patients recently developed a T cell leukemia as a result of the gene therapy. The overall hypothesis of this competitive renewal is that increasing the number of genetically corrected HSCs and/or progenitors will result in improved quality and durability of immune reconstitution. The general prediction is that the vectors that give the highest rate of HSC transduction will produce more B cells and better humoral function as well as produce a more durable T cell reconstitution. Therefore, the major focus of the proposed studies is to evaluate strategies for improving gene delivery to increase the number of gene-corrected cells. Special emphasis will be placed upon lentiviral vectors that, unlike retroviral vectors, can transduce non-cycling cells that should result in increased numbers of gene-corrected HSCs. We will also evaluate strategies for enhancing the selective advantage of gene corrected cells using either nonmyeloablative conditioning or in vivo selection of genetically corrected cells. Since higher transduction efficiencies and/or enhanced engraftment of transduced cells may lead to an overall higher number of transgene insertions increasing the potential risk of insertional mutagenesis, we will perform longitudinal integration site analyses to determine whether clonality changes over time and for risk assessment of side effects related to transgene integration and expression. Canine XSCID has an identical immunologic phenotype as human XSCID making it an ideal large-animal model in which to perform these studies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI043745-07
Application #
6797842
Study Section
Immunobiology Study Section (IMB)
Program Officer
Wedgwood, Josiah F
Project Start
1998-05-01
Project End
2007-12-31
Budget Start
2004-01-01
Budget End
2004-12-31
Support Year
7
Fiscal Year
2004
Total Cost
$534,319
Indirect Cost
Name
University of Pennsylvania
Department
Other Clinical Sciences
Type
Schools of Veterinary Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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Luff, Jennifer A; Yuan, Hang; Kennedy, Douglas et al. (2014) Keratinocyte antiviral response to Poly(dA:dT) stimulation and papillomavirus infection in a canine model of X-linked severe combined immunodeficiency. PLoS One 9:e102033
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Vernau, William; Hartnett, Brian J; Kennedy, Douglas R et al. (2007) T cell repertoire development in XSCID dogs following nonconditioned allogeneic bone marrow transplantation. Biol Blood Marrow Transplant 13:1005-15
Suter, Steven E; Gouthro, Terry A; O'Malley, Thomas et al. (2007) Marking of peripheral T-lymphocytes by retroviral transduction and transplantation of CD34+ cells in a canine X-linked severe combined immunodeficiency model. Vet Immunol Immunopathol 117:183-96
Goldschmidt, Michael H; Kennedy, Jeffrey S; Kennedy, Douglas R et al. (2006) Severe papillomavirus infection progressing to metastatic squamous cell carcinoma in bone marrow-transplanted X-linked SCID dogs. J Virol 80:6621-8
Swerdlow, Mathew P; Kennedy, Douglas R; Kennedy, Jeffrey S et al. (2006) Expression and function of TLR2, TLR4, and Nod2 in primary canine colonic epithelial cells. Vet Immunol Immunopathol 114:313-9
Ting-De Ravin, Suk See; Kennedy, Douglas R; Naumann, Nora et al. (2006) Correction of canine X-linked severe combined immunodeficiency by in vivo retroviral gene therapy. Blood 107:3091-7
Suter, S E; Gouthro, T A; McSweeney, P A et al. (2006) Optimized transduction of canine paediatric CD34(+) cells using an MSCV-based bicistronic vector. Vet Res Commun 30:881-901

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