title: Encapsulation of p-THPP into nanoparticles: cellular uptake, subcellular localization and effect of serum on photodynamic activity.
abstract: The cellular uptake, localization and efflux of meso-tetra-(4-hydroxyphenyl)porphyrin (p-THPP)-loaded nanoparticles have been studied in EMT-6 tumor cells. The effect of blood serum on photocytotoxicity has also been evaluated. Sub-130 nm nanoparticles based on poly(D,L-lactide-co-glycolide) (PLGA) (50:50 PLGA and 75:25 PLGA) and poly(D,L-lactide) (PLA) have been examined in comparison with free p-THPP. For all formulations tested, uptake of photosensitizer into cells was dependent on concentration, time and temperature. All nanoparticulate formulations accumulated within the cells to a greater extent relative to free drug. Indeed, the fluorescence intensities measured on EMT-6 cells treated with p-THPP-loaded nanoparticulate formulations were at least two-fold higher than those obtained with free dye. Furthermore, the highest accumulation level was found with PLGA nanoparticles. Fluorescence microscopy revealed that endocytosis is a major intracellular sequestration mechanism of these p-THPP formulations and that these were localized into early and late endosomes. The efflux study performed on both nonirradiated and irradiated cells indicated that free and p-THPP-loaded nanoparticles gradually escaped from EMT-6 cells as a function of time. This was more pronounced when cells were treated with nanoparticles and irradiated, reflecting important photodamage. It was also found that regardless of the nanoparticulate formulations tested, p-THPP photocytotoxicity was influenced by the concentration of the serum.
authors.affiliation: School of Pharmacy, University of Geneva, Geneva, Switzerland.
authors.forename: Y N
authors.initials: YN
authors.lastname: Konan
authors.forename: J
authors.initials: J
authors.lastname: Chevallier
authors.forename: R
authors.initials: R
authors.lastname: Gurny
authors.forename: E
authors.initials: E
authors.lastname: Allémann
mesh_terms: D000818:Animals; D001692:Biological Transport; D004305:Dose-Response Relationship, Drug; D005453:Fluorescence; D019344:Lactic Acid / Q000737:chemistry; D015674:Mammary Neoplasms, Animal / Q000188:drug therapy / Q000378:metabolism; D051379:Mice; D036103:Nanotechnology; D010777:Photochemistry; D011091:Polyesters / Q000737:chemistry; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry; D011166:Porphyrins / Q000378:metabolism* / Q000627:therapeutic use / Q000633:toxicity; D044967:Serum / Q000378:metabolism*; D013696:Temperature; D014407:Tumor Cells, Cultured
chemical_list: D011091:Polyesters; D011108:Polymers; D011166:Porphyrins; C481734:meso-tetra-(4-hydroxyphenyl)porphyrin; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)