Enhancement effect of ultrasound-induced microbubble cavitation on branched polyethylenimine-mediated Vascular Endothelial Growth Factor 165 (VEGF165)transfection

Abstract

Angiogenesis is a complex process mediated by growth factor. One isoform of vascular endothelial growth factor, VEGF165, is reported to be a dominant regulator of angiogenic process. Branched polyethylenimine (bPEI) is a widely used non-viral delivery vector for gene therapy. HEK 293T cells, mixed with bPEI:VEGF165 at different nitrogen:DNA phosphate (N/P) ratios, were exposed to 1-MHz ultrasound (US) pulses. The enhancement effect of microbubble inertial cavitation (IC) on bPEI-mediated VEGF165 transfection was systemically investigated, in an effort to optimize transfection efficiency using low N/P ratios. The results show that: (1) Microbubble IC activity can be quantified as an IC "dose" (ICD) that is affected by US parameters; (2) DNA transfection efficiency initially increases with the increasing ICD, then tends to saturate; (3) the measured ICD, sonopration pore size, and cell viability exhibit high correlation among each other; and (4) IC activity has less cytotoxicity than bPEI, although a combinatorial effect of IC activity and bPEI can be observed on cell viability. The results indicated that ICD could be used as an effective tool to monitor US-mediated gene/drug delivery, and it is possible to optimize bPEI-mediated VEGF transfection efficiency with relatively low N/P ratios by employing appropriate US parameters.