Photodynamic Therapy using Talaporfin Sodium (Laserphyrin^®) on Malignant Tumors in Orthopaedics: in vitro and in vivo Study

Abstract

The first choice for treatment to osteoskeletal malignant tumor is mainly surgical resection. Thanks to taking these pre-operational chemotherapies, the survival rate has recently improved and excellent limb functions in patients have been restored. However some tumors do not respond to any current chemotherapy or radiotherapy. Therefore, a new treatment for osteoskeletal malignant tumor that can be performed under such conditions has been pursued. In the present study, we investigated the anti-tumor effect of PDT using talaporfin sodium (laserphyrin) on several osteoskeletal malignant tumors in in vitro and in vivo. In in vitro, we measured cell viability and demonstrated the cell death pattern, apoptosis or necrosis, after PDT. In in vivo, we measured the size of the tumor grafted SCID mice for 3 weeks after PDT and the PDT effect on the tumor cells was evaluated histologically. In addition, we detected the ¹O₂ production during the PDT. PDT was effective, both in in vitro and in vivo, for all cell lines in the study. In in vitro, the cell death patterns by PDT were mainly apoptosis on the condition of 50 % cell death and mainly necrosis on the condition of 90 % cell death. In in vivo, the local recurrence rates obviously were dependent on the dose of the drug and the amount of laser energy. Histological evaluation after PDT revealed a necrosis area and an apoptosis area on all tumors. The necrosis area was found near the incidence of the laser and the apoptosis area was found outside the necrosis area. The ratios of ¹O₂ production of tumors treated by irradiation with the photosensitizer to that of tumors treated by irradiation without the photosensitizer exhibited extremely high values about 20 - 60 times. PDT using talaporfin sodium was effective on osteoskeletal malignant tumor and might be innovative surgical modalities.