title: Restoration of collagen formation in photodamaged human skin by tretinoin (retinoic acid)
abstract: BACKGROUND
  Topical tretinoin (retinoic acid) modifies fine wrinkles and certain other features of human skin damaged by exposure to the sun (photodamage), but histologic changes do not account for this improvement. In mice with photodamage induced by ultraviolet light, effacement of fine wrinkles by tretinoin is correlated with dermal collagen synthesis but not with histologic changes. We investigated whether collagen synthesis was reduced in photodamaged human skin and, if so, whether it could be restored by treatment with topical tretinoin.
  
  
  METHODS
  Biopsies of photodamaged skin from the extensor aspect of the forearm and skin from the buttocks, which had been protected from the sun, were performed on 26 healthy subjects. In addition, 29 patients with photodamaged skin were treated for 10 to 12 months with a daily application of 0.1 percent tretinoin cream (15 patients) or vehicle cream (14 patients). Skin-biopsy specimens obtained at base line and after treatment were assessed immunohistologically for evidence of dermal collagen I formation (collagen synthesis).
  
  
  RESULTS
  Collagen I formation was 56 percent less in the papillary dermis of photodamaged skin than in skin protected from the sun (P < 0.001) and was correlated with the clinical severity of photodamage (r = -0.58, P = 0.002). Treatment of photodamaged skin with tretinoin produced an 80 percent increase in collagen I formation, as compared with a 14 percent decrease in collagen formation with the use of vehicle alone (P = 0.006).
  
  
  CONCLUSIONS
  The formation of collagen I is significantly decreased in photodamaged human skin, and this process is partly restored by treatment with tretinoin.
authors.affiliation: Department of Dermatology, University of Michigan Medical Center, Ann Arbor 48109-0314.
authors.forename: C E
authors.initials: CE
authors.lastname: Griffiths
authors.forename: A N
authors.initials: AN
authors.lastname: Russman
authors.forename: G
authors.initials: G
authors.lastname: Majmudar
authors.forename: R S
authors.initials: RS
authors.lastname: Singer
authors.forename: T A
authors.initials: TA
authors.lastname: Hamilton
authors.forename: J J
authors.initials: JJ
authors.lastname: Voorhees
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003094:Collagen / Q000096:biosynthesis*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009824:Ointments; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D015595:Skin Aging / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D014212:Tretinoin / Q000627:therapeutic use*
chemical_list: D009824:Ointments; D014212:Tretinoin; D003094:Collagen