Ultrasound effect on vascular smooth muscle cells in vitro: A preliminary parametric study

High incidence of intra-stent restenosis (ISR) remains a troublesome issue after endovascular treatment for arteriosclerosis obliterans. ISR is mainly caused by neointimal hyperplasia, which refers to proliferation and migration of vascular smooth muscle cells (VSMCs). Previous studies showed that sonotherapy might reduce neointimal hyperplasia through inhibiting VSMC proliferation and migration in vivo. However, there is still no consensus on the sonication parameters. This study is aimed to evaluate the effect of sonication parameters on VSMCs in vitro, including frequency, acoustic intensity and duration. Sonications were exposed to cultured human VSMCs. Frequency varied from 0.497MHz to 2.718MHz while duration varied from 1min to 20mins, and the maximum of acoustic intensity was 0.675W/cm2. The post-sonication cell number was measured through cell counting kit-8, and the cell apoptosis was evaluated using trypan blue staining. Moreover, the thermal effect on VSMC proliferation was assessed. After the comparison of results from sonication parameter settings, the following parameters could be recommended for the inhibition of VSMCs proliferation: frequency is 0.7–0.8MHz, acoustic intensity is about 0.5W/cm2 and duration is 5–8 mins.