title: In vitro exploration of a myeloid-derived suppressor cell line as vehicle for cancer gene therapy.
abstract: Recent research indicates that cell-mediated gene therapy can be an interesting method to obtain intratumoral expression of therapeutic proteins. This paper explores the possibility of using transfected myeloid-derived suppressor cells (MDSCs), derived from a murine cell line, as cellular vehicles for transporting plasmid DNA (pDNA) encoding interleukin-12 (IL-12) to tumors. Transfecting these cells via electroporation caused massive cell death. This was not due to electroporation-induced cell damage, but was mainly the result of the intracellular presence of plasmids. In contrast, pDNA transfection using Lipofectamine 2000 (LF2000) did not result in a significant loss of viability. Differences in delivery mechanism may explain the distinctive effects on cell viability. Indeed, electroporation is expected to cause a rapid and massive influx of pDNA resulting in cytosolic pDNA levels that most likely surpass the activation threshold of the intracellular DNA sensors leading to cell death. In contrast, a more sustained intracellular release of the pDNA is expected with LF2000. After lipofection with LF2000, 56% of the MDSCs were transfected and transgene expression lasted for at least 24 h. Moreover, biologically relevant amounts of IL-12 were produced by the MDSCs after lipofection with an IL-12 encoding pDNA. In addition, IL-12 transfection caused a significant upregulation of CD80 and considerably reduced the immunosuppressive capacity of the MDSCs. IL-12-transfected MDSCs were still able to migrate to tumor cells, albeit that lipofection of the MDSCs seemed to slightly decrease their migration capacity.
authors.affiliation: Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Denies
authors.affiliation: Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.|Cancer Research Institute Ghent (CRIG), Ghent, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Combes
authors.affiliation: Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Ghekiere
authors.affiliation: Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.|Cancer Research Institute Ghent (CRIG), Ghent, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Mc Cafferty
authors.affiliation: Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Cicchelero
authors.affiliation: Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.|Cancer Research Institute Ghent (CRIG), Ghent, Belgium.
authors.forename: N N
authors.initials: NN
authors.lastname: Sanders
mesh_terms: D000818:Animals; D002460:Cell Line; D018274:Electroporation; D015316:Genetic Therapy / Q000379:methods*; D018664:Interleukin-12 / Q000235:genetics / Q000276:immunology; D051379:Mice; D022423:Myeloid Cells / Q000276:immunology*; D009369:Neoplasms / Q000235:genetics / Q000276:immunology / Q000628:therapy
chemical_list: D018664:Interleukin-12