Influence of incubation time and sensitizer localization on meta-tetra(hydroxyphenyl)chlorin (mTHPC)-induced photoinactivation of cells.
Fiche publication
Date publication
août 2007
Journal
Radiation research
Auteurs
Membres identifiés du Cancéropôle Est :
Dr BEZDETNAYA-BOLOTINE Lina, Dr DUMAS Dominique
Tous les auteurs :
Sasnouski S, Pic E, Dumas D, Zorin V, D'Hallewin MA, Guillemin F, Bezdetnaya L
Lien Pubmed
Résumé
The present study addresses the impact of different aggregation states of meta-tetra(hydroxyphenyl)chlorin (mTHPC) on the photoinactivation of cells. Measurements of the photophysical properties of mTHPC in MCF-7 cells showed progressive sensitizer aggregation with increasing incubation time. Reconstructed absorption spectra of intracellular mTHPC showed a significant decrease in the molar extinction coefficient and broadening of the Soret band at 24 h incubation compared to 3 h. Intracellular photobleaching of mTHPC slowed down, and the profile changed from mono- to bi-exponential upon incubation. Fluorescence lifetime imaging (FLIM) measurements revealed a substantial decrease in the lifetime of mTHPC fluorescence at 24 h compared to 3 h. In addition, the intracellular localization of mTHPC as observed by fluorescence microscopy changed from a diffuse homogeneous fluorescence pattern at short incubation times to a punctiform pattern at 24 h. The efficiency of photodynamic therapy (PDT) assessed by a clonogenic assay was three times greater at 24 h. However, when the survival curves were replotted as a function of the number of absorbed photons, the efficiency was 1.8 times greater at 3 h than at 24 h. The loss of photosensitizing efficiency at higher mTHPC concentrations was attributed to self-quenching of the triplet states of the sensitizers.
Mots clés
Absorption, Cell Line, Tumor, Humans, Mesoporphyrins, pharmacokinetics, Photochemotherapy, Photosensitizing Agents, pharmacology, Time Factors
Référence
Radiat. Res.. 2007 Aug;168(2):209-17