Photodynamic therapy using nanoparticle loaded with indocyanine green for experimental peritoneal dissemination of gastric cancer

Although there have been multiple advances in the development of novel anticancer agents and operative procedures, prognosis of patients with advanced gastric cancer remains poor, especially in patients with peritoneal metastasis. In this study, we established nanoparticles loaded with indocyanine green (ICG) derivatives: ICG loaded lactosomes (ICGm) and investigated the diagnostic and therapeutic value of photodynamic therapy (PDT) using ICGm for experimental peritoneal dissemination of gastric cancer. Experimental peritoneal disseminated xenografts of human gastric cancer were established in nude mice. Three weeks after intraperitoneal injection of the cancer cells, either ICGm (ICGm‐treated mice) or ICG solution (ICG‐treated mice) was injected through the tail vein. Forty‐eight hours after injection of the photosensitizer, in vivo and ex vivo imaging was carried out. For PDT, 48 h after injection of the photosensitizer, other mice were irradiated through the abdominal wall, and the body weight and survival rate were monitored. In vivo imaging revealed that peritoneal tumors were visualized through the abdominal wall in ICGm‐treated mice, whereas only non‐specific fluorescence was observed in ICG‐treated mice. The PDT reduced the total weight of the disseminated nodules and significantly improved weight loss and survival rate in ICGm‐treated mice. In conclusion, ICGm can be used as a novel diagnostic and therapeutic nanodevice in peritoneal dissemination of gastric cancer.