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In vivo protection of activated Tyr22‐dihydrofolate reductase gene‐modified canine T lymphocytes from methotrexate
Author(s) -
Gori Jennifer L.,
Beard Brian C.,
Williams Nathaniel P.,
Ironside Christina,
Swanson Debra,
Scott McIvor R.,
Kiem HansPeter
Publication year - 2013
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.2713
Subject(s) - dihydrofolate reductase , methotrexate , transplantation , immunology , biology , haematopoiesis , immunosuppression , bone marrow , immune system , genetic enhancement , cancer research , microbiology and biotechnology , medicine , stem cell , gene , biochemistry
Abstract Background Nonmyeloablative allogeneic hematopoietic stem cell (HSC) transplantation can cure malignant and nonmalignant diseases affecting the hematopoietic system, such as severe combined immunodeficiencies, aplastic anemia and hemoglobinopathies. Although nonmyeloablative is favored over myeloablative transplantation for many patients, graft rejection remains problematic. One strategy for decreasing rejection is to protect donor activated T cells in the graft from methotrexate (MTX) by genetically modifying the cells to express MTX‐resistant dihydrofolate reductase (Tyr22‐DHFR), leaving the immunosuppressive effects of MTX to act solely on activated host T lymphocytes, shifting the balance to favor allogeneic engraftment. Methods To evaluate MTX resistance of Tyr22‐DHFR + T lymphocytes in vivo , we transplanted dogs with autologous CD34 + cells modified with yellow fluorescent protein (YFP) and DHFR‐green fluorescent protein (GFP) lentivirus vectors. Dogs were then treated with a standard MTX regimen days 1, 3, 6 and 11) following immune activation with a foreign antigen as a surrogate assay to mimic early transplantation. Results DHFR‐GFP + gene marking was maintained in CD3 + CD25 + and CD4 + T lymphocytes after MTX treatment, whereas the level of T lymphocytes that expressed only a fluorescent reporter (YFP + ) decreased. These data show that Tyr22‐DHFR expression protects T lymphocytes from MTX toxicity in dogs, highlighting a clinically relevant application for preserving donor T lymphocytes during post‐transplantation immunosuppression. Conclusions The findings of the present study have implications for the clinical translation of MTX‐resistant T cells to facilitate engraftment of allogeneic cells following nonmyeloablative conditioning and to minimize the risk of rejection. In summary, Tyr22‐DHFR expression in T lymphocytes provides chemoprotection from MTX‐mediated elimination in the context of immune activation in vivo . Copyright © 2013 John Wiley & Sons, Ltd.