Effect of Photosensitizer Delivery System and Irradiation Parameters on the Efficiency of Photodynamic Therapy of B16 Pigmented Melanoma in Mice |
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| Authors: | Roberta Biolo Giulio Jori Marina Soncin Boris Rihter Malcolm E Kenney Michael A J Rodgers |
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| Institution: | Department of Biology, University of Padova, Italy;Department of Chemistry, Case Western Reserve University, Cleveland, OH, USA;Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH, USA |
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| Abstract: | Abstract— Previous studies (Biolo et al., Photochem. Photobiol. 59, 362-365, 1994) showed that liposome-delivered Si(IV)-na-phthalocyanine (SiNc) photosensitizes B16 pigmented melanoma subcutaneously transplanted in C57 mice to the action of 776 nm light. However, the efficacy of the phototreatment was limited by a lack of selectivity of tumor targeting by SiNc as well as by incomplete necrosis of the neoplastic mass. The present investigations show that the use of a different delivery system (Cremophor emulsion vs liposomes of dipalmitoylphosphatidylcholine) causes no significant increase in the selectivity of tumor targeting for three injected doses of SiNc (0.5, 1, 2 mg/kg). However, upon 776 nm light irradiation (300 mW/cm2; 520 J/cm2), the delay in the rate of tumor growth was maximal (7-8 days) for the highest naphthalocyanine dose. On the other hand, a remarkable improvement in the tumor response was obtained by inducing an intratumoral temperature increase to 44°C immediately after PDT. The thermal effect appeared to be due to photoexcitation of melanin by 776 nm light (550 mW/cm2; 520 J/cm2) and subsequent partial conversion of absorbed energy into heat. |
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