Abstract A119: Assessment and optimization of electroporation assisted tumoral nanoparticle uptake in a pancreatic adenocarcinoma nude mouse model
Authors: West Derek Lamont , White Sarah , Zhang Zhuoli , Larson Andrew , Omary Reed 
Published: October 2015

Summary: Pancreatic ductal adenocarcinoma (PDAC) is a particularly lethal form of cancer. In 2012, the incidence of PDAC was 43,920. Five year survival for patients with PDAC was 6%, regardless of staging, making PDAC one of the deadliest forms of cancer. One reason for such dismal prognosis is chemoresistance to the current first-line therapy of choice, gemcitabine. There are multiple factors which contribute to chemoresistance observed in pancreatic cancer. Among them, desmoplasia has been increasingly seen as a significant contributor to chemoresistance in PDAC. To overcome desmoplastic chemoresistance, several novel methods of treatment have been developed. Electroporation is one such novel treatment. High electrical fields are applied to cells to create pores which increase the cell permeability. It has been previously demonstrated that electroporation enhances therapeutic efficacy of anticancer drugs in pancreatic tumor models. Nanoparticle-based drug delivery systems constitute a second novel method to overcome desmoplastic chemoresistance. Due to their intrinsic design advantages, nanoparticles have been shown to increase effectiveness of chemotherapeutic agents, while further reducing or even eliminating side effects. To date, there have been no studies to evaluate the cumulative effect of combining both nanoparticle and electroporation strategies to overcome chemoresistance in PDAC.

Objective: Our laboratory conducted preliminary studies using a panc-1 athymic nude mouse model to assess doxorubicin iron oxide nanoparticle uptake as a function of electroporation voltage and timing. Our studies showed that electroporation with iron oxide doxorubicin nanoparticle administration increases nanoparticle uptake in panc-1 cell line athymic nude mouse models of PDAC.

Methods: Our experiment first assessed the in vitro uptake of doxorubicin-iron oxide nanoparticles and cell viability in panc-1 cells, to optimized electroporation voltage setting to maximize iron uptake without excessive cell death. 2 million panc-1 cells were placed in 1 ml of DMEM with or without 100 nM of iron oxide doxorubicin nanoparticles. Each plate of cells were individually electroporated at voltages from 0 to 1500. The cells were then incubated for another 24 hours. Cells were trypsonized and evaluated for cell viability and iron uptake by flow cytometry and inductively coupled plasma mass spectrometry, respectively.

For our in vivo study, mouse xenograft models were inoculated with 5x106 panc-1 human PDAC cell line into the left and right flank tissues to grow tumors roughly 10 mm in size. Once the tumors reached 10mm, the mice were anesthetized. The mice were then randomized into electroporation-nanoparticle administration timing study limbs ranging from electroporation 12 minutes before nanoparticle administration to electroporation 12 minutes after nanoparticle administration. One hour after the administration of nanoparticles, the mice were euthanized and the tumors were excised. Iron content for each tumor sample was analyzed quantitatively and qualitatively, using ICP-MS and H&E staining with Prussian Blue.

Results: From our in vitro study, we found that voltage setting of 400V optimally allowed reversible electroporation without excessive cell death. Our in vivo study demonstrated that electroporation 3 minutes after administration of intravenous nanoparticles provided the greatest degree of intratumoral particle uptake.

Conclusions: Significant improvement in chemotherapeutic uptake can be achieved, using optimized nanoparticle and electroporation settings to overcome the intrinsic chemoresistance in PDAC.

Citation Format: Derek Lamont West, Sarah White, Zhuoli Zhang, Andrew Larson, Reed Omary. Assessment and optimization of electroporation assisted tumoral nanoparticle uptake in a pancreatic adenocarcinoma nude mouse model. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A119.