gms | German Medical Science

Various physical technologies are employed to deliver naked DNA into the desired cells or tissues in vitro and in vivo, such as simple needle injection, ballistic transfer, in vivo electroporation or jet-injection. Among the various nonviral gene delivery technologies jet-injection is gaining increasing acceptance, since this technique allows gene transfer into different tissues with deep penetration of the applied naked DNA. The jet-injection is based on jets of high velocity (>300m/s) possessing the force to penetrate skin and underlaying tissues leading to transfection of the affected area. In cooperation with EMS Medical Systems, SA (Nyon, Switzerland) a jet-injector prototype was created and tested for efficient in vivo gene transfer using small volumes of DNA-solutions. The beta-galactosidase (LacZ), green fluorescence protein (GFP) reporter gene constructs and tumor necrosis factor alpha (TNF) gene expressing vector were successfully jet-injected into different syngeneic mouse tumor models and xenotransplanted human tumor models of colon- or mammary carcinoma. Qualitative and quantitative expression analysis of jet-injected tumor tissues at mRNA and at protein level revealed the efficient intratumoral expression of these genes. The essential parameters of efficient in vivo jet-injection such as jet-injection volume, applied pressure, jet-penetration into the tumor tissue, DNA stability and biodistribution have been analyzed and optimized for nonviral in vivo gene transfer. Therapeutic in vivo experiments using the jet-injection transfer of a cytosine deaminase (CD) suicide gene expessing vector in patient-derived xenotransplanted colon carcinoma models demonstrated antitumor effects after the single application of the CD-expressing vector. The observed suicide gene mediated growth inhibitory effect lasted for the entire observation time and showed significant growth inhibition of the jet-injected colon carcinomas compared to the non-transduced 5-fluorouracil (5-FU) treated animals. Based on our detailed in vivo experiments a phase I gene therapy study has started at the Robert-Rössle-Clinic, Charité to evaluate the feasibility and safety of jet-injection aided LacZ reporter gene transfer in patients with human colon- and mammary tumors.