Activation of Piezo1 mechanosensitive ion channel in HEK293T cells by 30 MHz vertically deployed surface acoustic waves

Abstract

Ultrasound (US) has emerged as a promising noninvasive modality for neuromodulation. Despite previous evidence that US may mediate cellular response by activating mechanosensitive ion channels embedded in the cell membrane, the underlying mechanism is not well understood. In this work, we developed a vertically deployed surface acoustic wave (VD-SAW) platform that generates 30 MHz focused ultrasound wave for mechanical stimulation of single cells. We investigated the role of Piezo1 in mediating the intracellular calcium response ([Ca2+]i) of HEK293T cells in response to pulsed US operated at a peak pressure of 1.6 MPa with 20% duty cycle, and a total treatment time of 60 s. We observed that the elicited calcium response depends critically on the pulse repetition frequency (PRF) or burst duration of the US, as well as the presence of the Piezo1. Significantly higher [Ca2+]i increase was produced in the Piezo1-transfected (P1TF) than in the Piezo1-knockout (P1KO) HEK293T cells. Furthermore, higher calcium response probability, stronger and faster [Ca2+]i increase, and greater cell displacement were produced at 2 Hz PRF with 100 ms burst duration than 200 Hz PRF with 1 ms burst duration. Altogether, we have demonstrated that the VD-SAW platform provides a unique and versatile tool for investigating US-induced mechanotransduction at the single cell level.