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Hexyl‐aminolevulinate‐mediated photodynamic therapy: How to spare normal urothelium. An in vitro approach
Author(s) -
Vaucher Laurent,
Jichlinski Patrice,
Lange Norbert,
RitterSchenk Céline,
van den Bergh Hubert,
Kucera Pavel
Publication year - 2007
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20416
Subject(s) - urothelium , photodynamic therapy , photobleaching , protoporphyrin ix , phototoxicity , in vivo , chemistry , reactive oxygen species , photosensitizer , pathology , biophysics , in vitro , medicine , fluorescence , urinary bladder , biology , urology , photochemistry , biochemistry , optics , physics , microbiology and biotechnology , organic chemistry
Background and Objectives Photodynamic therapy (PDT) of superficial bladder cancer may cause damages to the normal surrounding bladder wall. Prevention of these is important for bladder healing. We studied the influence of photosensitizer concentration, irradiation parameters, and production of reactive oxygen species (ROS) on the photodynamically induced damage in the porcine urothelium invitro. The aim was to determine the threshold conditions for the cell survival. Methods Living porcine bladder mucosae were incubated with solution of hexylester of 5‐aminolevulinic acid (HAL). The mucosae were irradiated with increasing doses and cell alterations were evaluated by scanning electron microscopy and by Sytox green fluorescence. The urothelial survival score was correlated with Protoporphyrin IX (PpIX) photobleaching and intracellular fluorescence of Rhodamine 123 reflecting the ROS production. Results The mortality ratio was dependent on PpIX concentration. After 3 hours of incubation, the threshold radiant exposures for blue light were 0.15 and 0.75 J/cm 2 (irradiance 30 and 75 mW/cm 2 , respectively) and for white light 0.55 J/cm 2 (irradiance 30 mW/cm 2 ). Photobleaching rate increased with decreasing irradiance. Interestingly, the DHR123/R123 reporter system correlated well with the threshold exposures under all conditions used. Conclusions We have determined radiant exposures sparing half of normal urothelial cells. We propose that the use of low irradiance combined with systems reporting the ROS production in the irradiated tissue could improve the in vivo dosimetry and optimize the PDT. Lasers Surg. Med. © 2006 Wiley‐Liss, Inc.