Preventive and therapeutic effects of gene therapy using silica nanoparticles–binding of GM-CSF gene on white blood cell production in dogs with leukopenia

Objective Our previous study has shown that granulocyte-macrophage colony-stimulating factor (GM-CSF) gene/silica nanoparticles have a leukocytosis effect in normal dogs. Therefore, this study was conducted to determine whether treatment of canine GM-CSF gene/silica nanoparticles has preventive or therapeutic effects in dogs with leukopenia. Materials and Methods To induce leukopenia, vinblastine was administered intravenously at a dose of 2 mg/m2 of body surface area on day 0. Then 7.5 μg GM-CSF/nanoparticles (1:100, w/w) were administered intravenously to each of four dogs in the prevention group on day 2 and an equivalent amount of GM-CSF/nanoparticles was administered to the post-nadir group on day 4 (other groups were administered phosphate-buffered saline intravenously). Results Therapeutic GM-CSF gene was expressed in peripheral blood mononuclear cells for 10 days and both the prevention and post-nadir groups showed significant increases in white blood cell counts when compared with the control group, as confirmed by complete blood count, differential count, and flow cytometry. Conclusions GM-CSF/nanoparticles can be useful for correction of acute leukopenia, such as chemotherapy-induced myelosuppression, without developing neutralizing antibodies.