Effect of photosensitizer delivery system and irradiation parameters on the efficiency of photodynamic therapy of B16 pigmented melanoma in mice.
Previous studies (Biolo et al., Photochem. Photobiol. 59, 362-365, 1994) showed that liposome-delivered Si(IV)-naphthalocyanine (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 degrees 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.
Biolo
R
R
Department of Biology, University of Padova, Italy. valduga/cribi 1.bio.unipd.it
Jori
G
G
Soncin
M
M
Rihter
B
B
Kenney
M E
ME
Rodgers
M A
MA
D000818:Animals; D004337:Drug Carriers; D005260:Female; D008081:Liposomes; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics
D004337:Drug Carriers; D008081:Liposomes; D017319:Photosensitizing Agents