Sonoporation, a redefined ultrasound modality as therapeutic aid: A review

Traditionally a diagnostic modality, ultrasound is emerging as a promising tool for non-invasive therapy, drug delivery, and gene therapy. The ultrasound is a mechanical wave energy generated in a medium as oscillating pressure in space and time at frequencies above 20 kHz, beyond the audible range. The ultrasound exposure generates bioeffects resulting in tissue heating, shear stress, and cavitation, which have been exploited for therapeutic applications. Ultrasound cavitation, enhanced by injected micro bubbles, perturbs cell membrane structures to cause sonoporation and increases the permeability to bioactive materials. Ultrasound-mediated gene delivery has been applied to heart, blood vessel, lung, kidney, muscle, head and neck tumour with enhanced gene transfection efficiency. The genes can be incorporated into microbubbles which in turn can target a specific disease site. Local drug delivery ensures sufficient drug concentration at the diseased region while limiting toxicity for healthy tissues. Nevertheless, it has only recently become popular as a technique to enhance drug release from drug delivery systems. This review presents the main findings in the field of sonoporation, namely drug delivery, gene delivery and DNA transfer.