title: Comparative characterization of the cellular uptake and photodynamic efficiency of Foscan® and Fospeg in a human prostate cancer cell line.
abstract: BACKGROUND
  m-THPC (Foscan(®)) is one of the most potent second generation photosensitizers used in photodynamic therapy, photoactivated at higher wavelengths (652 nm). However, its strongly hydrophobic nature causes aggregation of the molecules and prevents its unbiased bioavailability in the biological media, resulting in lower accumulation in the tumor cells. Several strategies have been adopted to improve the photodynamic characteristics of the photosensitizer. Among them, very promising seems to be the encapsulation of the molecule into liposomes, due to the superior properties of liposomes as drug carriers.
  
  
  METHODS
  In this paper the photodynamic characteristics of the PEGylated liposomal formulation of m-THPC, Fospeg, using the human prostate cancer cell line LNCaP, as an in vitro model, were investigated. In addition the spectral characteristics, cellular uptake and localization, dark and light induced cytotoxicity and photodynamic efficacy of Foscan(®) and Fospeg were compared.
  
  
  RESULTS
  Fospeg, compared with Foscan, showed higher intracellular uptake at any concentration and incubation time. Regarding PDT efficacy, Fospeg produced more severe cytotoxicity than Foscan(®) at any concentration and energy dose. Using Fospeg, the lowest concentration (0.22 μM) and energy dose (180 mJ/cm(2)) was adequate to result in the death of 50% of the cells 24h post PDT while an approximately 10 times higher Foscan(®) concentration (1.8 μM) was needed to result in the same cytotoxicity.
  
  
  CONCLUSIONS
  The use of the PEGylated liposomal formulation of m-THPC resulted in the improvement of its intracellular uptake and the enhancement of its photodynamic activity. Fospeg, compared to Foscan(®), proved to be a more advantageous photosensitizer for photodynamic therapy.
authors.affiliation: Laboratory of Biomedical Optics and Applied Biophysics, School of Electrical and Computer Engineering, National Technical University of Athens, Iroon Politechniou 9, Zografou Campus, 157 80 Athens, Greece. aspetri@mail.ntua.gr
authors.forename: Aspasia
authors.initials: A
authors.lastname: Petri
authors.forename: Dido
authors.initials: D
authors.lastname: Yova
authors.forename: Eleni
authors.initials: E
authors.lastname: Alexandratou
authors.forename: Maria
authors.initials: M
authors.lastname: Kyriazi
authors.forename: Michail
authors.initials: M
authors.lastname: Rallis
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D008081:Liposomes / Q000737:chemistry; D008297:Male; D008652:Mesoporphyrins / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000737:chemistry; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism
chemical_list: D008081:Liposomes; D008652:Mesoporphyrins; D017319:Photosensitizing Agents; D011092:Polyethylene Glycols; C072269:temoporfin