Treatment of pancreatic cancer cells in vitro using ultrasound, microbubbles, and gemicitabine

Julia Christine Mariglia

doi:10.32920/ryerson.14651550

Abstract

Ultrasonically stimulated microbubbles can enhance the localized delivery and cytotoxic effects of chemotherapy drugs to cells by transient permeabilization of cell membranes in a process called sonoporation. However, there is insufficient data investigating whether ultrasound and microbubbles (USMB) enhances the delivery and cytotoxicity of the nucleoside analog (NA) gemcitabine. To address this gap in the literature, cancer cells were sonicated using low frequency ultrasound in combination with Definity® microbubbles in the presence of NAs. Viability analyses show that gemcitabine in combination with USMB additively enhanced cell death, suggesting that these two therapies mediate cell death independent of one another. This was confirmed when USMB treatment did not enhance (nor impair) the retention of a radiolabeled NA molecule. Altogether, these data suggest that the laws of diffusion forcing small molecules across a barrier cannot solely describe the efficacy of sonoporation; there are obviously important biological factors specific to the molecule intended to be delivered to consider as well.

Highlights

1.1 Rationale guiding this researchIn the last twenty years, scientists have been reporting on the use of ultrasound as a tool to enhance the delivery of drugs[1–3], gene products[4–8], and fluorescent markers[5,9] into cells by transient permeabilization of cell membranes
The data produced in this study support the contention that ultrasound and microbubble (USMB) in combination with gemcitabine (GEM) resulted in an additive cytotoxic effect in BxPC3 pancreatic cancer cells
These ultrasound settings were sufficient to induce sonoporation of a fluorescent molecule (10 kDa Fluorescein isothiocyanate (FITC)-dextran), USMB therapy did not enhance the intracellular concentration of the radiolabeled nucleoside analogs (NA) 2-Chloroadenosine

Summary

Introduction

1.1 Rationale guiding this researchIn the last twenty years, scientists have been reporting on the use of ultrasound as a tool to enhance the delivery of drugs[1–3], gene products[4–8], and fluorescent markers[5,9] into cells by transient permeabilization of cell membranes. The ultrasound parameters partly dictate the acoustic response of MBs, which in turn dictates the bioeffects induced on cells that enhance molecular uptake[10] The potential for this approach to enhance drug delivery is the focus of this research. Studies have shown that ultrasound and microbubble (USMB) therapy can be focused with millimeter precision[11,12] to enhance the localized uptake of chemotherapy drugs and representative fluorescent markers in vitro[1,9,13,14] and in vivo[15– 17], paving the way for clinical studies employing this therapy to enhance drug delivery[18,19] Despite these studies, there is insufficient data on the effect of USMB therapy on enhancing the delivery of a major class anti-cancer, anti-viral, and antiparasitic drugs: the nucleoside analogs (NA) and in particular, the widely used anticancer drug, gemcitabine

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