Electroporation is a technique, which employs pulsed electric fields to create pores across cell membranes. Reversible pore formation has been recognized as a powerful means to introduce macromolecules into cells, while maintaining cell viability. Recently, irreversible electroporation (IRE), which results in cell death, has been used for the ablation of undesirable tissue. Results indicate that due to its non-thermal nature, IRE preserves important tissue components, such as the extracellular matrix, major blood vessels, and nerves. This project will investigate whether IRE protocols can be adapted for the ablation of Glioblastoma Multiforme (GBM) tumors. Despite recent advancements in brain cancer therapies, the median survival for people diagnosed with GBM is only 15 months. One of the reasons for poor survival is that glioma cells typically infiltrate up to 2 cm beyond the volume of the visible tumor. Dissipation of the electric field during IRE gives rise to regions of reversibly electroporated cells outside the ablation zone that may be more susceptible to the uptake of drugs. This proposal will assess IRE's capacity to treat infiltrative cells within the zone of reversible electroporation when combined with chemotherapeutic agents. Treatment of malignant gliomas is also limited by insufficient delivery of drugs due to the blood-brain-barrier (BBB). Therefore, this plan will also investigate whether IRE can be applied to mediate BBB disruption to aid in the delivery of chemotherapeutic agents. A combination of experiments and modeling on the molecular, cellular, and tissue levels will be used to determine the mechanism of IRE and deepen scientific understanding of the effects of electric fields in the brain. Specifically, strength-duration relationships of the electric field for reversible and irreversible electroporation will be determined for individual cells in a micro-electroporation device, cells in suspension, and in vivo brain tissue. For each preparation, numerical models will compute electrical and thermal quantities measured during the experiments, and they will make the connection between subcellular-level, cellular-level, and tissue-level responses. Specifically, this proposal aims to: 1) Develop a quantitative understanding of electroporation at the cellular level and the mechanism of both IRE-induced cell death and chemotherapy mediated cell death in electroporated cells. 2) Create a multi-scale numerical model of BBB disruption and IRE focal ablation regions along with regions of reversible electroporation for predictive treatment planning. 3) Quantify the in vivo effects of IRE for GBM ablation, BBB disruption, and infiltrative cell death using a rat model. The intellectual merit of this proposal will be the resolution of the longstanding controversy regarding the mechanism of cell death induced by IRE. Gaining knowledge of the electric field, temperature, and conductivity distributions throughout IRE both in vitro and in vivo will help us pinpoint whether membrane rupture, excessive leakage through pores, or intracellular thermal effects are responsible for cell death. For the first time, temperature will be measured in real-time in order to assess and validate the theory that IRE protocols generate cell death without inducing thermal damage. Additionally, this information will tremendously improve one's ability to design effective IRE treatment planning models. A multi-scale model that captures the dynamic changes in the membrane will be constructed and can ultimately be translated to any type of therapy involving pulsed electric fields. This research will culminate in the development of a non-thermal technique for ablating aggressive, infiltrative tumors in the brain, and the improvement of uptake of anti-cancer agents beyond the tumor margin utilizing IRE mediated BBB disruption. The broader impacts of this proposal include the development of a method of non-thermal ablation that will allow us not only to fight numerous types of cancer, but other pathologies, such as cardiac arrhythmias. Integration of IRE into mainstream medicine will have enormous socioeconomic benefits and dramatically enhance the quality and length of life for millions of patients. It will also impact other emerging applications of electroporation in tissue engineering, gene therapy, DNA vaccination, medicine, industry, and biodefense. In education, this project will create a Biomedical Engineering Minor for students at Oakwood University, in which the students would spend two summers taking classes and conducting research at Virginia Tech. The students would have the opportunity to work on elements of the proposed research as well as a variety of other bioengineering projects.
