Study for prevention of proliferation of smooth muscle cells after balloon angioplasty using Ho:YAG laser-induced acoustic wave

We designed the method for prevention of restenosis after balloon angioplasty using laser-induced bubble-collapse acoustic wave. This study was performed to evaluate the effect on smooth muscle cells (SMCs) by Ho:YAG laser (lambda=2.10mum)-induced acoustic wave, in vitro and in vivo. The laser energy was delivered by a silica glass fiber into water. Sound pressure was measured with a hydrophone changing the laser energy. The laser-induced acoustic wave was loaded to SMCs in vitro. This acoustic effect on SMCs was measured by MTT assay. The acoustic wave loaded SMCs were controllably injured with the laser energy and laser shots. The balloon denudated rabbit aorta was used to evaluate in vivo effect. The laser-induced acoustic wave loaded aorta was extracted at 42 days after the laser irradiation, and was examined by Hematoxylin-Eosin staining. We found that the laser irradiation of 20 pulses with 60mJ/pulse prevented SMCs proliferation. We think the mechanism of this effect might be same as brachytherapy. We demonstrated the applicability of Ho:YAG laser-induced acoustic wave against vascular restenosis after balloon angioplasty.