Do folate-receptor targeted liposomal photosensitizers enhance photodynamic therapy selectivity?

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Cancer Therapy

Background:

• Photodynamic therapy (PDT) aims to improve tumor targeting to reduce side effects.
• Folate receptor-mediated delivery systems are a key strategy for targeted cancer therapy.
• Liposomal formulations offer a versatile platform for drug delivery.

Purpose of the Study:

• To evaluate the efficacy of folate-targeted liposomes carrying a photosensitizer (ZnTPP) for enhanced tumor cell targeting in PDT.
• To investigate the selectivity of folate-targeted liposomes compared to non-targeted liposomes in vitro.
• To assess the impact of folate receptor expression on liposomal uptake and photocytotoxicity.

Main Methods:

• Incorporation of a model photosensitizer (ZnTPP) into folate-targeted and non-targeted liposomes.
• In vitro studies using folate receptor-positive (HeLa) and folate receptor-deficient (A549) cancer cell lines.
• Measurement of liposomal uptake, photocytotoxicity, and singlet oxygen kinetics.

Main Results:

• Folate-targeted liposomes exhibited a 2-fold higher uptake in HeLa cells compared to non-targeted liposomes.
• Photocytotoxicity was significantly improved with folate-targeted liposomes in folate receptor-positive cells.
• Targeting selectivity was inhibited by excess folic acid, confirming receptor-mediated uptake.
• Similar liposomal incorporation was observed in A549 cells, indicating involvement of non-specific pathways.
• Both liposome types localized in acidic lysosomes, suggesting adsorptive endocytosis.

Conclusions:

• Folate-targeted liposomes enhance selective uptake and photocytotoxicity in cancer cells, offering a promising strategy for PDT.
• While folate receptor targeting is effective, non-specific uptake pathways also contribute to liposome localization.
• Further optimization is needed to maximize targeting specificity and therapeutic outcomes in PDT.