In vivo experimental investigation on multi-pulse Nd:YAG laser-induced vesicle embolization of vascular lesions

Abstract

Laser therapy is the most effective clinical treatment to dermal vascular malformations, such as port wine stains (PWSs). Recently, a development-stage treatment modality based on photothermal-activatable liposomal drug delivery systems has been proposed to enhance post-irradiation vascular occlusion of PWSs. However, safety and effectiveness of this method still requires validation. Few studies have reported whether polymer-modified liposomes can be actuated to aggregate and promote vessel occlusion under multi-pulse neodymium-doped yttrium aluminum garnet (Nd:YAG) laser heating. In this study, multi-pulse Nd:YAG laser-induced small polyethylene glycosylated liposome vesicles aggregated to form large vesicles was observed in in vivo animal experiments performed on a rat dorsal skin chamber model. Energy threshold of large vesicle generation measured 47 J/cm2. The probability of vesicle formation reached 53% in the presence of liposomes in the blood and at moderate laser fluence. In the experiments, the formed large vesicles experienced surface tension-dominated coalescence and finally occluded the target vessels. Vesicle occlusion lasted for several hours and may result in lesion blanching caused by ischemia and chronic inflammation. In conjunction with liposome injection, multi-pulse Nd:YAG laser features potential as a safe curative strategy for PWS treatment.