Sukhendu B. Dev

Sustained local delivery of heparin to the rabbit arterial wall with an electroporation catheter

Current methods of local drug delivery frequently fail to achieve a prolonged therapeutically effective tissue drug level without producing vascular trauma. A novel double-balloon catheter system, incorporating electroporation technology, has been designed and tested to deliver heparin into rabbit carotid arteries in an overstretch balloon injury model in vivo. Following arterial injury, fluoresceinated heparin was delivered into the volume between the two inflated balloons, and the artery was subjected to an electrical pulse. Catheter deployment and endovascular electrical pulsing were well-tolerated in all animals (N = 21) without adverse hemodynamic and histological changes. Periodic arterial blood samples revealed no abnormalities in the clotting profile or any gross morphological changes in the blood cells up to 8 hr after treatment. Much stronger heparin fluorescence was detected throughout the vessel layers for at least 12 hr in the pulsed samples compared to the control. Histochemical staining of the tissue showed intracellular localization of heparin. Endovascular electroporation may provide better retention and higher therapeutic efficacy than can be achieved by conventional systemic delivery of heparin at clinically safe concentrations.

Intratumoral Delivery of Interleukin 12 Expression Plasmids with In Vivo Electroporation Is Effective for Colon and Renal Cancer

We report on an antitumor treatment involving electrogene therapy (EGT), a newly developed in vivo gene transfer method using electroporation. We carried out in vivo EGT in a subcutaneous model of CT26 colon carcinoma cells, using plasmid DNAs encoding interleukin 12 (IL-12) subunits. For this purpose, we developed two IL-12 expression systems: a cotransfer system using a plasmid encoding the IL-12 p40 subunit and a plasmid encoding the IL-12 p35 subunit, and a single-vector system using a plasmid expressing a p40-p35 fusion protein. Both transfer systems significantly inhibited the growth of CT26 tumor. Immunohistochemical analysis of IL-12 EGT-treated tumors revealed enhanced infiltration of CD8(+) cells into the tumor tissue, while reverse transcriptase-polymerase chain reaction confirmed the increased expression of interferon gamma within treated tumors. The same IL-12 EGT applied to the nude mouse model was not effective, suggesting the critical role of T cell infiltration in this treatment. The inhibitory effects revealed in experiments in which previously treated mice were rechallenged with a second inoculation of CT26 tumor cells suggested that IL-12 EGT may also establish partial systemic antitumor immunity. The growth of IL-12 EGT-treated Renca tumors, a renal cell carcinoma, was also significantly inhibited. These findings suggest that EGT of the IL-12 gene has the potential to be an effective anticancer gene therapy.

Treatment of human pancreatic tumors xenografted in nude mice by chemotherapy combined with pulsed electric fields.

Cancer of the pancreas is currently the fifth leading cause of cancer related deaths with a five year survival of less than 1% In the United States (1). It is one of the most difficult cancers to treat, since it is hard to detect in the early stages. The patients remain asymptomatic until late in the course of the disease. An excellent review of pancreatic carcinoma has appeared (2). Despite the progress made in our understanding of the biology of this cancer (3), the final outcome for this disease has remained extremely poor. Conventional chemotherapeutic agents have not been very effective for human pancreatic adenocarcinoma (4). Use of intratumoral chemotherapy in combination with monoclonal antibodies have been reported to produce better response rate and also reduced toxicity (5,6). Smith and colleagues (7) have recently shown that an injectable gel with a sustained release profile can inhibit tumor growth in vivo in human pancreatic cancer xenografts. This was demonstrated in nude mice with BxPC-3 xenografts using fluorouracil, cisplatin, and doxorubicin with a consequent size reduction of the tumors between 72% and 79%, compared to the controls at day 28 after the first treatment. Although these figures are impressive, by any standard, no cure was reported.