title: Ultrastructural alteration of tape-stripped normal human skin after photodynamic therapy.
abstract: The effect of photodynamic therapy on tape-stripped normal human skin was explored ultrastructurally. Back skin areas of 3 healthy Caucasian volunteers, 2 men and 1 woman, were tape-stripped 10 consecutive times followed by topical treatment with 5-aminolevulinic acid (20%, w/w) for 4 hours under occlusion (Tegaderm). Then the areas were irradiated for 30 minutes with Waldman PDT 1200 lamp (570-650 nm) with a total dose of 70 J/cm(2). Full-thickness punch biopsies were taken immediately after irradiation, and at 3 and 24 hours for electron microscopy examination. Photodynamic therapy caused morphological alterations mainly in the epidermis. Keratinocytes became oedematous and tonofilament bundles were split, but desmosomes remained normal. Many keratinocytes contained large intracellular vacuoles and extremely electronlucent cytoplasm implying cell damage. Although the majority of Langerhans cells were unaffected isolated Langerhans cells became apoptotic at 3 hours. The melanocytes preserved their normal morphology. The epidermal alterations recovered 24 hours after the irradiation. Inflammatory cell infiltrates were evident at 3 and 24 hours but no other dermal changes were observed. In conclusion, photodynamic therapy with 5-aminolevulinic acid affects mainly keratinocytes and can trigger apoptosis in Langerhans cells while melanocytes appear refractory, at least morphologically, to photodynamic therapy.
authors.affiliation: Department of Dermatology D92, University of Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: Jacek
authors.initials: J
authors.lastname: Bartosik
authors.forename: Ida-Marie
authors.initials: IM
authors.lastname: Stender
authors.forename: Takasi
authors.initials: T
authors.lastname: Kobayasi
authors.forename: Magnus S
authors.initials: MS
authors.lastname: Agren
mesh_terms: D000328:Adult; D000622:Aminolevulinic Acid / Q000008:administration & dosage; D001706:Biopsy / Q000379:methods; D020405:Dermis / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D005260:Female; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D007801:Langerhans Cells / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D008297:Male; D008544:Melanocytes / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000008:administration & dosage; D012016:Reference Values; D012867:Skin / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure*
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid