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G‐CSF‐lentivirus administration in rats provided sustained elevated neutrophil counts and subsequent EPO‐lentivirus administration increased hematocrits
Author(s) -
Brzezinski Margaret,
Yanay Ofer,
Waldron Lanaya,
Barry Simon C.,
Osborne William R. A.
Publication year - 2007
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.1050
Subject(s) - lentivirus , virus , neutropenia , virology , granulocyte colony stimulating factor , microbiology and biotechnology , biology , medicine , immunology , andrology , chemotherapy , viral disease
Background Towards gene therapy treatment of patients with neutropenia, characterized by neutrophil counts < 500 cells/µl, we investigated the ability of lentivirus vectors to provide sustained granulocyte colony‐stimulating factor (G‐CSF) delivery and to permit transgene expression from a second virus administration in a preclinical rat model. Methods Rats were injected intramuscularly (IM) with 24 × 10 6 and 9 × 10 6 infectious units (IU) of a VSV‐G‐pseudotyped self‐inactivating (SIN) lentivirus encoding rat G‐CSF cDNA and containing cPPT and PRE elements. To determine the effectiveness of a second virus administration treated rats and a naïve rat received erythropoietin (EPO)‐lentivirus IM. Rats were monitored for neutrophil and red blood cell production. Lentivirus antibodies were assayed by virus‐neutralizing assay and ELISA. Results High and low dose virus administration increased neutrophil counts to 5660 ± 930 cells/µl (mean ± SD) and 4010 ± 850 cells/µl, respectively, that were sustained for > 17 months and were significantly higher than controls counts of 1890 ± 570 cells/µl ( p ⩽0.0002). Rats treated with EPO‐virus produced significantly increased hematocrits (HCT) (63.1 ± 4.3% vs. 46.0 ± 3.2%, p < 0.0001) without effect on G‐CSF‐virus‐mediated neutrophil production. Antivirus antibodies were not detectable at serum dilutions ≥1:10 by virus neutralization or ELISA. Lymphocytes and platelets were not significantly different between control and treated animals ( p > 0.1). Only genomic DNA from muscle at injection sites was positive for provirus suggesting lack of virus spread. Conclusions G‐CSF‐lentivirus administered IM provided elevated, sustained neutrophil counts that were unchanged by subsequent EPO‐lentivirus administration. Significantly increased hematocrits were obtained following EPO‐lentivirus delivery. These data support the treatment of patients with severe chronic neutropenia by dosed lentivirus delivery IM. Copyright © 2007 John Wiley & Sons, Ltd.