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Phototoxicity is not associated with photochemical tissue bonding of skin
Author(s) -
Yao Min,
Yaroslavsky Anna,
Henry Frank P.,
Redmond Robert W.,
Kochevar Irene E.
Publication year - 2010
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.20869
Subject(s) - phototoxicity , rose bengal , dermis , chemistry , ex vivo , in vivo , wound healing , confocal microscopy , acellular dermis , biophysics , pathology , in vitro , surgery , medicine , optics , biology , implant , biochemistry , physics , microbiology and biotechnology , organic chemistry
Background and Objective We have developed a light‐activated method called photochemical tissue bonding (PTB) for closing wounds using green light and a photosensitizing dye (Rose Bengal—RB) to initiate photochemical crosslinking of wound surface proteins. These studies were designed to determine whether RB causes phototoxicity during closure of skin incisions with PTB. Study Design/Materials and Methods RB phototoxicity was evaluated after sealing incisions in porcine skin ex vivo and rabbit skin in vivo using PTB (1 mM RB, 100 J/cm 2 , 532 nm, 0.3 or 0.5 W/cm 2 .) Dead cells were identified by pyknotic nuclei and eosinophilic cytoplasm on H&E‐stained sections. The influence on RB phototoxicity of penetration of RB into the wound wall (by confocal microscopy), RB concentration in the tissue (by extraction), and fluence of 532 nm reaching depths in skin (calculated from skin optical properties) were investigated. Results No significant differences were found in the percent dead cells in PTB‐treated and control incisions in porcine skin at 24 hours or in rabbit skin at 2 hours and 3 and 7 days after surgery. RB was retained in a ∼100 µm wide band next to the wound wall. The mean RB concentration within this band was 0.42±0.03 mM. Monte Carlo modeling of light distribution indicated that the fluence rate decreased from the subsurface peak to 0.5 W/cm 2 in the mid‐dermis (∼350 µm.) In vitro RB phototoxicity to dermal fibroblasts yielded an LD 50 of 0.50±0.09 J/cm 2 when the cells contained 0.46 mM RB. Conclusions PTB does not cause phototoxicity when used to repair skin wounds even though the RB concentration and 532 nm fluence in the mid‐dermis during PTB are much greater than the LD 50 for RB phototoxicity in vitro. These results indicate that phototoxicity is not a concern when using PTB for tissue repair. Lasers Surg. Med. 42:123–131, 2010. © 2009 Wiley‐Liss, Inc.