TY - JOUR
T1 - Wavelength and fluence effect on vascular damage with photodynamic therapy on skin
AU - Tsoukas, Maria M.
AU - González, Salvador
AU - Flotte, Thomas J.
AU - Rox Anderson, R.
AU - Sherwood, Margaret E.
AU - Kollias, Nikiforos
PY - 2000
Y1 - 2000
N2 - Normal skin phototoxicity is clinically predictable during photodynamic therapy with light at 690 and 458 nm wavelengths, in the first 5 h after intravenous bolus infusion of benzoporphyrin derivative mono-acid ring A. This study goal was to determine histologic milestones that lead to tissue necrosis with exposure to red (690nm) and blue (458nm) light. The threshold doses for skin necrosis on rabbits were equal at both wavelengths. Lower, equal to, and higher than threshold fluences were delivered in duplicates at hourly intervals, with 40% increments, at constant irradiance. Pathology specimens from irradiated and control sites, were collected at 0, 2, 7, 24, 48 h, and 2 wk after treatment and were paired to equivalent treated sites for clinical evaluation. Immediately after irradiation, at 690 and 458nm thresholds, light microscopy showed stasis and inflammatory infiltrate in the papillary dermis, respectively; electron microscopy demonstrated pericyte and endothelial cell damage - greater at 690 than 458nm. At day 1, vascular stasis in the dermis showed a steeper dose-response with red than blue light, and led to necrosis of skin appendages (day 1) and epidermis (days 1-2) at both wavelengths. Subthreshold fluences induced similar, but significantly milder (p <0.05) changes and epidermis recovered. Skin necrosis, at threshold fluences in photodynamic therapy with benzoporphyrin derivative mono-acid ring A, was primarily due to vascular compromise to a depth potentially reaching the subcutaneous muscle at 690nm, whereas at 458nm vascular damage was confined to upper dermis. This system facilitates selective destruction of skin vasculature, sparing normal epidermis.
AB - Normal skin phototoxicity is clinically predictable during photodynamic therapy with light at 690 and 458 nm wavelengths, in the first 5 h after intravenous bolus infusion of benzoporphyrin derivative mono-acid ring A. This study goal was to determine histologic milestones that lead to tissue necrosis with exposure to red (690nm) and blue (458nm) light. The threshold doses for skin necrosis on rabbits were equal at both wavelengths. Lower, equal to, and higher than threshold fluences were delivered in duplicates at hourly intervals, with 40% increments, at constant irradiance. Pathology specimens from irradiated and control sites, were collected at 0, 2, 7, 24, 48 h, and 2 wk after treatment and were paired to equivalent treated sites for clinical evaluation. Immediately after irradiation, at 690 and 458nm thresholds, light microscopy showed stasis and inflammatory infiltrate in the papillary dermis, respectively; electron microscopy demonstrated pericyte and endothelial cell damage - greater at 690 than 458nm. At day 1, vascular stasis in the dermis showed a steeper dose-response with red than blue light, and led to necrosis of skin appendages (day 1) and epidermis (days 1-2) at both wavelengths. Subthreshold fluences induced similar, but significantly milder (p <0.05) changes and epidermis recovered. Skin necrosis, at threshold fluences in photodynamic therapy with benzoporphyrin derivative mono-acid ring A, was primarily due to vascular compromise to a depth potentially reaching the subcutaneous muscle at 690nm, whereas at 458nm vascular damage was confined to upper dermis. This system facilitates selective destruction of skin vasculature, sparing normal epidermis.
KW - Benzoporphyrin derivative monoacid ring A
KW - Phototoxicity
KW - Skin histology
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U2 - 10.1046/j.1523-1747.2000.00872.x
DO - 10.1046/j.1523-1747.2000.00872.x
M3 - Article
C2 - 10651990
AN - SCOPUS:1642633547
SN - 0022-202X
VL - 114
SP - 303
EP - 308
JO - Journal of Investigative Dermatology
JF - Journal of Investigative Dermatology
IS - 2
ER -