Membrane effects from ultrasound interactions with microbubbles—From drug delivery to mechanotransduction

Abstract

Ultrasound is an ideal modality to interact noninvasively with tissues deep within the body because of its significant penetration depth. However, noninvasive low intensity ultrasound on its own has difficulty creating mechanical forces necessary for localized activation of cells through mechanotransduction or rupture of non-echogenic drug delivery vehicles. Lipid-coated microbubbles are particles that provide a high-level of impedance contrast with the surrounding tissue and undergo significant size oscillations when exposed to ultrasound. This imparts mechanical forces on nearby lipid membranes which can be used for a variety of applications. Here, I will discuss the mechanical forces that are created by ultrasound/microbubble interactions that can be used to transduce mechanical forces across intact membranes for cellular activation, and to rupture membranes of drug delivery vehicles. I will also discuss the interaction of lipid debris left over from by microbubble destruction with cell membranes. The cell activation and vehicle release show promise for clinical applications including neuromodulation and cancer chemotherapy delivery.