title: In vitro and in vivo photosensitizing capabilities of 5-ALA in vascular endothelial cells.
abstract: BACKGROUND
  The object of our study is to evaluate the feasibility of photodynamic therapy for complicated hemangiomas. We studied the effect of the photosensitizing agent 5-aminolevulinic acid (5-ALA) in both in vitro and in vivo models.
  
  
  METHODS
  The in vitro photosensitizing activity of 5-ALA was examined in a microvascular endothelial cell (MEC) culture system. 5-ALA was added in various concentrations and the cells were illuminated at 630 nm. The percentage of MEC killed was measured by either a Live/Dead assay or an lactate dehydrogenase (LDH) assay. The effect of varying the light energy dose delivered at 630 nm after the administration of 5-ALA was studied by determining the amount of necrosis produced in chicken combs.
  
  
  RESULTS
  The combination of 5-ALA at a concentration of 35 micrograms/ml, and illumination by 100 mW/cm2 of laser light at 630 nm wavelength, caused 50% cell kill in the MEC culture system. Chicken combs of animals that received 200 mg/kg of 5-ALA and illumination at a power density of 80 mW/cm2 had a depth of injury of 362.5 +/- 27.6 microns upon histological examination. Those combs that received 100 or 120 mW/cm2 showed a depth of injury of 732.5 +/- 29.1 and 792.5 +/- 36.0 microns respectively.
  
  
  CONCLUSIONS
  5-ALA is effective in sensitizing human MEC to laser illumination. However, the degree of absorption and tissue destruction in different anatomical structures should be considered in future clinical studies.
authors.affiliation: Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Taipei, Taiwan, R.O.C. chengjen@adm.cgmh.com.tw
authors.forename: C J
authors.initials: CJ
authors.lastname: Chang
authors.forename: S F
authors.initials: SF
authors.lastname: Ma
authors.forename: F C
authors.initials: FC
authors.lastname: Wei
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D004730:Endothelium, Vascular / Q000187:drug effects*; D006801:Humans; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid