title: In vivo histological evaluation of a novel ablative fractional resurfacing device.
abstract: OBJECTIVE
  A novel carbon dioxide (CO(2)) laser device employing ablative fractional resurfacing was tested on human skin in vivo for the first time.
  
  
  METHODS
  An investigational 30 W, 10.6 microm CO(2) laser system was focused to a 1/e(2) spot size of 120 microm to generate an array of microscopic treatment zones (MTZ) in human forearm skin. A range of pulse energies between 5 and 40 mJ was tested and lesion dimensions were assessed histologically using hematoxylin and eosin. Wound healing of the MTZ's was assessed immediately-, 2-day, 7-day, 1-month, and 3-month post treatment. The role of heat shock proteins was examined by immunohistochemistry.
  
  
  RESULTS
  The investigational CO(2) laser system created a microscopic pattern of ablative and thermal injury in human skin. The epidermis and part of the dermis demonstrated columns of thermal coagulation that surrounded tapering ablative zones lined by a thin eschar layer. Changing the pulse energy from 5 to 30 mJ resulted in a greater than threefold increase in lesion depth and twofold increase in width. Expression of heat shock protein (hsp)72 was detected as early as 2 days post-treatment and diminished significantly by 3 months. In contrast, increased expression of hsp47 was first detected at 7 days and persisted at 3 months post-treatment.
  
  
  CONCLUSIONS
  The thermal effects of a novel investigational ablative CO(2) laser system utilizing fractional resurfacing were characterized in human forearm skin. We confirmed our previous ex vivo findings and show for the first time in-vivo, that a controlled array of microscopic treatment zones of ablation and coagulation could be deposited in human skin by varying treatment pulse energy. Immunohistochemical studies of heat shock proteins revealed a persistent collagen remodeling response lasting at least 3 months. We successfully demonstrated the first in-vivo use of ablative fractional resurfacing (AFR) treatment on human skin.
authors.affiliation: Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Basil M
authors.initials: BM
authors.lastname: Hantash
authors.forename: Vikramaditya P
authors.initials: VP
authors.lastname: Bedi
authors.forename: Bhumika
authors.initials: B
authors.lastname: Kapadia
authors.forename: Zakia
authors.initials: Z
authors.lastname: Rahman
authors.forename: Kerrie
authors.initials: K
authors.lastname: Jiang
authors.forename: Heather
authors.initials: H
authors.lastname: Tanner
authors.forename: Kin Foong
authors.initials: KF
authors.lastname: Chan
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Zachary
mesh_terms: D001706:Biopsy; D002245:Carbon Dioxide; D003880:Dermatology / Q000295:instrumentation*; D019583:Dose Fractionation, Radiation; D004847:Epithelial Cells; D005542:Forearm; D050884:HSP72 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007834:Lasers; D012867:Skin / Q000293:injuries / Q000473:pathology / Q000528:radiation effects*; D014945:Wound Healing / Q000528:radiation effects
chemical_list: D050884:HSP72 Heat-Shock Proteins; D002245:Carbon Dioxide