Background: Gene Electro Transfer (GET) is a promising method for therapeutic
purposes. Intratumoral GET has reached clinical evaluation for antitumor treatment.
An increasing number of studies suggests that antitumor effectiveness not only
depends on the transfection efficiency, but also on the induction of immune responses and vascular effects that result in
the nonspecific induction of cell death. Real time noninvasive optical imaging methods allow longitudinal studies of these
dynamic biological processes. Objective: In the present study, a noninvasive bioluminescence technology was used to further
explore the phenomena associated with GET to tumors by a real time monitoring of the transfection efficiency as well
as cell death following the treatment. Method: By using transgenic light-producing tumors, tumor growth was visualized,
and since dead cells stop producing light, effectiveness of the treatment or the emergence of necrotic areas in the tumors
was followed visually. The transfection efficiency of reporter genes (iRFP protein and luciferase) in the subcutaneous tumors
was also evaluated. Results: Our results showed that the GET of a reporter gene can lead to nonspecific antitumor
effectiveness and even complete regression of tumors. Using light-producing tumors, we were also able to indirectly visualize
the previously described vascular effects of electroporation. Additionally, using the intratumoral GET of a luciferase
encoding plasmid, we localized the source of the expression mainly in the peritumoral and not in the tumoral region.
Conclusion: The data obtained provide new insights into some of the phenomena associated with GET to tumors, which
should be taken into account when designing improved and more effective cancer gene therapy, in order to accelerate the
transfer of the technology into clinical trials.
Keywords: Electroporation, Gene electrotransfer, Bioluminescence, Tumor, Fluorescence, Transfection, In vivo imaging.
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