Chronic UVB exposure enhances in vitro percutaneous penetration of 5-aminulevulinic acid in hairless mouse skin.
OBJECTIVE
(Pre)cancerous skin lesions accumulate more protoporphyrin IX (PpIX) upon topical application of 5-aminolevulinic acid (ALA) than the surrounding normal skin. This might be the result of a higher percutaneous penetration of ALA into (pre)cancerous skin.


METHODS
ALA penetration through (1) healthy skin with intact stratum corneum, (2) healthy skin with reduced stratum corneum (i.e. tape stripped skin) and (3) diseased skin with dysplastic and thickened epidermis (chronically UVB-exposed skin) was determined in an in vitro model with hairless mouse skin.


RESULTS
More ALA had penetrated through chronically UVB-exposed skin than through normal non-exposed skin after 8 hours ALA application. The amount of ALA penetrated through chronically UVB-exposed skin was smaller than through tape stripped skin.


CONCLUSIONS
The stratum corneum barrier function is less effective in chronically UVB-exposed skin than in normal non-exposed skin, but more effective than in tape stripped skin. A higher penetration rate of ALA into (pre)cancerous lesions may be (partly) responsible for the greater accumulation of PpIX in such lesions.
School of Biochemistry and Molecular Biology, University of Leeds, Leeds, United Kingdom.
Johanna T H M
JT
van den Akker
J Andrew
JA
Holroyd
David I
DI
Vernon
Henricus J C M
HJ
Sterenborg
Stanley B
SB
Brown
D000622:Aminolevulinic Acid / Q000493:pharmacokinetics*; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D066298:In Vitro Techniques; D051379:Mice; D008812:Mice, Hairless; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D017319:Photosensitizing Agents / Q000493:pharmacokinetics*; D011230:Precancerous Conditions / Q000378:metabolism; D012867:Skin / Q000378:metabolism* / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000209:etiology; D014466:Ultraviolet Rays / Q000009:adverse effects*
D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid