Photodynamic and Plasmonic Photothermal Combination Therapy of Transplanted Tumors of a Rat Model

Abstract

The aim of this study was to develop a combined technology of plasmon photothermal therapy and photodynamic therapy of transplanted cholangiocarcinoma PC-1 in rats. For photodynamic therapy, rats were intratumorally administered with indocyanine green diluted in polyethylene glycol at a ratio of 1 : 100 at a dose of 2 mg/kg. For plasmon photothermal therapy, gold nanorods diluted in polyethylene glycol (400 μg/mL) were intratumorally injected in a volume of 30% of the tumor volume. At 1 h after injection, the tumor was percutaneously irradiated with a diode infrared laser with a wavelength of 808 nm at a power density of 2.3 W/cm² for 15 min. The animals were removed from the experiment 72 h and 21 days after therapy. Morphological studies of the tumor were performed on sections stained with standard and immunohistochemical methods. A significant increase in tumor temperature was noted, up to 60.0 ± 4.1°C with combined plasmon photothermal and photodynamic therapy. After 72 h, pronounced necrotic changes were observed in the tumor tissue and intact tumor cells were observed only on the periphery of the tumor. At 21 days after therapy, a significant inhibition of tumor growth was noted; the inhibition index by tumor mass was 77.4%.