title: Histological responses of cutaneous vascular lesions following photodynamic therapy with talaporfin sodium: a chicken comb model.
abstract: BACKGROUND
  Mono-L-aspartyl chlorin e6 (Talaporfin sodium) is a novel photosensitizer, and is currently being used in photodynamic therapy for various malignant tumors in combination with irradiation with a 664 nm laser. An interesting characteristic of Talaporfin sodium is that the skin photosensitivity after injection of this agent disappears faster than any other existing photosensitizers. This study examined the vascular events that occurred postirradiation in the chicken comb as a capillary malformation model after photosensitization with Talaporfin sodium.
  
  
  METHODS
  A single intravenous bolus injections of Talaporfin sodium was administered to the chickens, and a 1 cm diameter area of the comb of each animal was irradiated with a 664 nm visible red laser. The gross changes in the chicken combs were recorded for 7-14 days after photodynamic therapy. For the histological examination, HE, PTAH and Azan stained sections were analyzed.
  
  
  RESULTS
  All treated chicken combs had blanched after photodynamic therapy. Microscopy demonstrated an absence of erythrocytes and the vessel lumina were obliterated, leaving the normal overlying epidermis completely intact. Concomitantly with selective destruction of the capillaries in the target area, moderate invasion of inflammatory cells and a slight increase in the stroma were observed.
  
  
  CONCLUSIONS
  In the chicken comb model, photodynamic therapy with Talaporfin sodium effectively achieved selective destruction of the microvasculature while leaving the epidermis intact. Our results strongly suggest that photodynamic therapy with Talaporfin sodium could be a feasible method to treat dermal hypervascular lesions.
authors.affiliation: Department of Plastic and Reconstructive Surgery, School of Medicine, Keio University, Tokyo, Japan. ttoo@ohshiro.com
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ohshiro
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Nakajima
authors.forename: Hisao
authors.initials: H
authors.lastname: Ogata
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kishi
mesh_terms: D000818:Animals; D002196:Capillaries; D002645:Chickens; D002735:Chlorophyllides; D003129:Comb and Wattles / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects*; D004912:Erythrocytes / Q000378:metabolism; D007249:Inflammation; D008297:Male; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology; D011166:Porphyrins / Q000494:pharmacology*; D019339:Port-Wine Stain / Q000188:drug therapy / Q000532:radiotherapy; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D012867:Skin / Q000473:pathology; D012871:Skin Diseases / Q000188:drug therapy* / Q000532:radiotherapy*
chemical_list: D002735:Chlorophyllides; D017319:Photosensitizing Agents; D011166:Porphyrins; D011838:Radiation-Sensitizing Agents; C062985:phytochlorin; C053434:Talaporfin