Photodynamic Therapy of Intestinal Tumors with Mono-L-aspartyl Chlorin e6 (NPe6): A Basic Study

Background: To clarify the usefulness of the second-generation photosensitizer, mono-L-aspartyl chlorin e6 (NPe6), we examined the possibility of photodynamic diagnosis and photodynamic therapy for intestinal tumors in a mouse model. Materials and Methods: NPe6 was intravenously administered to the tumor-bearing mice through the tail vein. The intestinal tumor sites were irradiated with a 664-nm diode laser at constant intervals after the administration of photosensitizers. The tumors were excised and fluorescence was observed in frozen sections by microscope. Results: We observed the fluorescent image and calculated that the mean fluorescence intensity was significantly higher in the tumors than the normal mucosa during 6 hours (p<0.05). The fluorescence of NPe6 was chiefly accumulated in the intestinal tumors as red fluorescence on the fluorescent microphotographic image. Conclusion: We conclude that NPe6 may be a valuable photosensitizer for the photodynamic diagnosis and photodynamic therapy of intestinal tumors.