Brzezinski, M.Yanay, O.Waldron, L.Barry, S.Osborne, W.2008-04-142008-04-142007Journal of Gene Medicine, 2007; 9(7):571-5781099-498X1521-2254http://hdl.handle.net/2440/41981<h4>Background</h4>Towards gene therapy treatment of patients with neutropenia, characterized by neutrophil counts < 500 cells/microl, 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.<h4>Methods</h4>Rats were injected intramuscularly (IM) with 24 x 10(6) and 9 x 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.<h4>Results</h4>High and low dose virus administration increased neutrophil counts to 5660 +/- 930 cells/microl (mean +/- SD) and 4010 +/- 850 cells/microl, respectively, that were sustained for > 17 months and were significantly higher than controls counts of 1890 +/- 570 cells/microl (p< or =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 > or =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.<h4>Conclusions</h4>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.enNeutrophilsHela CellsAnimalsRats, Inbred F344HumansRatsProvirusesLentivirusErythropoietinGranulocyte Colony-Stimulating FactorDNAAntibodies, ViralBlood Cell CountHematocritGenomeMaleGenetic TherapyJournal article002007421810.1002/jgm.10500002481625000032-s2.0-3444756833246492Barry, S. [0000-0002-0597-7609]