Effect of molecular weight on sonoporation-mediated uptake in human cardiac cells

Abstract

Sonoporation of cells induced by ultrasound-driven microbubble cavitation has been utilized for intracellular delivery of molecular therapeutics. The molecular weight of therapeutic agents can vary significantly, with DNA plasmids often larger than 5 MDa, siRNAs and miRNAs ~10 kDa, and other drugs often less than 1 kDa. Some studies have suggested that sonoporation-mediated uptake may decrease at higher molecular weights due to slower diffusion rates, but experiments with equal molar concentrations have not been reported. Therefore, the objective of this study was to explore the effect of molecular weight on sonoporation-mediated uptake of fluorescein (0.33 kDa) or fluorescent dextrans (10 kDa, 2 MDa) using equal molar concentrations (100 nM). Sonoporation was induced in cultured human cardiac mesenchymal cells using lipid microbubbles and 2.5 MHz B-mode ultrasound (P4-1 transducer, Verasonics Vantage ultrasound system) and uptake by viable cells was measured with flow cytometry. No significant differences in sonoporation-mediated uptake were measured between molecules of different sizes at equal molar concentrations (ANOVA p = 0.92). However, significant differences in uptake were observed at different molar concentrations and acoustic pressures (ANOVA p = 0.02). In summary, these results suggest that the effect of molecular weight on sonoporation-mediated uptake is minimal compared to drug concentration or acoustic pressure.