Liposomal delivery of ferrous chlorophyllin: A novel third generation photosensitizer for in vitro PDT of melanoma

Background Cutaneous melanoma (CM) has substantially increased among Caucasian populations in the past few decades. This increased the number of CM deaths throughout the world. Pigmentation of melanoma reduces the efficacy of photodynamic therapy (PDT). Third generation photosensitizers (PSs) are characterized by improved targeting to the diseased tissue and reduced systemic side effects. This study is directed towards synthesis and characterization of liposomes encapsulating sodium ferrous chlorophyllin (Fe-CHL) and assessing its efficacy as a PS in PDT of melanoma. Methods Phenylthiourea (PTU) was used as a melanin synthesis inhibitor. PDT has been applied on de-pigmented melanoma cells using liposomes-encapsulated Fe-CHL. Cell death mechanisms after PDT were evaluated. Results Treatment of melanoma cells with 200μM of PTU for 48h provided 49.9% melanin inhibition without significant cytotoxicity. Transmission electron microscope (TEM) results proved an increase in the cellular uptake of liposomes by increasing incubation period from 6 to 24h via endocytosis with preferential accumulation in the mitochondria and the nucleus. Following de-pigmentation, PDT was applied resulting in LC50 of 18.20 and 1.77μM after 24 and 48h incubation with liposomes-encapsulated Fe-CHL respectively and exposure to 56.2J/cm2 monochromatic red laser of wavelength of 652nm. Mechanism of cell death of Fe-CHL mediated PDT was found to be a combination of both apoptosis and necrosis. Conclusions Liposomes could be efficiently employed as a potential sustained release delivery system in the Fe-CHL-mediated PDT of de-pigmented melanoma.