Enhancement effect of ultrasound-induced microbubble cavitation on branched polyethylenimine-mediated vascular endothelial growth factor 165 (VEGF165) transfection

Abstract

Angiogenesis is a complex process that is mediated by growth factor. One isoform of the vascular endothelial growth factor, VEGF165, has been reported to be a dominant mediator and regulator of angiogenic process. Branched polyethylenimine (bPEI) has been widely used as a non-viral delivery vector for gene therapy. HEK 293T cells, mixed with bPEI:VEGF165 complexes with different 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 nitrogen:DNA phosphate (N/P) ratios. The results show that: (1) Microbubble IC activity can be quantified as an IC “dose” (ICD) and will be affected by US parameters; (2) DNA transfection efficiency initially increases with the increasing ICD, then tends to saturate instead of achieving a maximum value while ICD keeps going up; (3) the measured ICD, sonopration pore size, and cell viability exhibit high correlation among each other; and (4) microbubble IC activity has less cytotoxicity than bPEI, although a combinatorial effect of IC activity and bPEI can be observed on cell viability. All the results indicated that ICD could be used as an effective tool to monitor and control US-mediated gene/drug delivery effect, and it is possible to optimize bPEI-mediated VEGF transfection efficiency with relatively low N/P ratios by employing appropriate US parameters.