The efficacy and mechanism of thoracic photodynamic therapy mediated by hematoporphyrin injection on disseminated pleural malignancies of Lewis lung carcinoma in mice.

In order to avoid the problems of long exposure time and high incidence of photosensitivity by intravenous injection of photosensitizer, our study explore the safety, efficacy, and possible mechanisms of photodynamic therapy (PDT) by intrathoracic administration of hematoporphyrin injection in the treatment of disseminated pleural malignancies of Lewis lung carcinoma in mice to provide a theoretical basis for thoracic PDT in the clinic. Hematoporphyrin was administered into the thoracic cavity of tumor-bearing mice, and the concentrations of hematoporphyrin in normal and tumor pleural tissues were detected by high-performance liquid chromatography. The tumor-bearing mice were randomly divided into four groups: model control, pure laser irradiation, PDT low-dose, and PDT high-dose groups. Hematoxylin and eosin (H&E) staining was used to observe the histological changes in normal pleural tissue. H&E and DNA in situ nick end-labeling staining were used to detect necrosis and apoptosis in the tumor tissues. The tumor volume in each group from high to low was as follows: model control group > pure laser irradiation group > PDT low-dose group > PDT high-dose group. Inflammatory cells infiltrated the normal pleural tissue of the PDT group. Necrosis was observed to different extents in the tumor tissues of the PDT group. The apoptosis index of each group from high to low was as follows: PDT high-dose group > PDT low-dose group > pure laser irradiation group > model control group. The differences were statistically significant (P<0.05). Hematoporphyrin selectively accumulated in tumor pleural tissues. PDT with intrathoracic administration of hematoporphyrin injection could inhibit the thoracic implant tumors in mice by inducing necrosis and apoptosis.