Systemic Hematological Effects of Granulocyte Colony-Stimulating Factor Produced by Irradiated Gene-Transfected Fibroblasts

Abstract

Although long-term expression of therapeutic molecules is necessary for the treatment of permanent deficiencies, short-term expression of therapeutic molecules inducing local or systemic effects is preferable in clinical situations where temporary substitution is the goal. One such clinical setting is the administration of hematopoietic growth factors in cancer chemotherapy-induced myelosuppression. Several plasmid vectors containing the human granulocyte colony-stimulating factor (G-CSF) gene under transcriptional control of different regulatory elements were constructed. In vitro production of G-CSF by nonvirally transfected murine fibroblast clones initially increased after lethal irradiation and was detectable for at least 12 days. We also demonstrate that a single injection of irradiated G-CSF-secreting fibroblasts leads to accelerated hematopoietic recovery and mobilization of committed peripheral blood progenitor cells equivalent to that achieved by twice daily s.c. administration of high doses of recombinant human G-CSF. Using dicistronic vectors, high levels of G-CSF secretion were also obtained in human fibroblasts.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) secreted by cDNA-transfected tumor cells induces a more potent antitumor response than exogenous GM-CSF

“…Data show the mean levels of mGM-CSF in a vaccination site (a standard 1.5 ϫ 1.5 cm 2 full thickness skin biopsy). long-lasting although transient 19 production of GM-CSF by irradiated tumor cells was consistent with data reported by Rosenthal et al, 37 who showed that irradiated gene-transfected fibroblasts produced a detectable level of G-CSF for 12 days and had systemic hematological effects. mGM-CSF was detected at both the injection site of i.d.…”

Systemic Production of Human Granulocyte Colony-Stimulating Factor in Nonhuman Primates by Transplantation of Genetically Modified Myoblasts

“…Ex vivo gene therapy offers the following advantages over direct gene therapy: (1) cells are transduced in vitro, and thus no immune response against the viral capsid proteins should be observed; (2) variable amounts of secreting cells can be transplanted into the patient for accurate dosage of hG-CSF; and (3) no professional antigen-presentin g cells such as resident macrophages should be exposed to viral antigens, thus lowering the chance of immune responses against the transgene. Transplantation of hG-CSF-secreting cells has been perform ed successfully in other studies using fibroblast cell lines (Tani et al, 1989;Rosenthal et al, 1996) and primary muscle cells (Bonham et al, 1996;Lejnieks et al, 1996). Moreover, in the Bonham and colleagues study, hG-CSF could be detected at a stable level in the treated animal sera over a period of 6 months (Bonham et al, 1996).…”

Cytokine gene transfer in cancer therapy

“…In a preclinical murine model, a single injection of irradiated GM-CSF-transduced fibrosarcoma cells was shown to be equally efficacious as twice daily S.C. injections for seven days of the recombinant protein [75]. A single injection of irradiated G-CSF-secreting fibroblasts also leads to accelerated hematopoietic recovery as well as a mobilization of hematopoietic progenitor cells into the peripheral blood [76]. These results indicate that irradiated cytokine gene-transfected cells which have lost proliferation capability in vivo, retain the ability to secrete biologically active levels of cytokines over several days to weeks, periods sufficient for many clinical applications.…”