To quantitatively examine the dynamics of molecular alterations involved in dermal remodeling after carbon dioxide (CO2) laser resurfacing of photodamaged human skin.
Serial in vivo biochemical analyses after laser therapy.
Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor.
Volunteer sample of 28 adults, 48 to 76 years old, with clinically evident photodamage of the forearms.
Focal CO2 laser resurfacing of photodamaged forearms and serial biopsies at baseline and various times after treatment.
Main Outcome Measures
Reverse transcriptase real-time polymerase chain reaction technology and immunohistochemistry were used to assess levels of type I and type III procollagens; matrix metalloproteinases (MMPs) 1, 3, 9, and 13; tropoelastin; fibrillin; primary cytokines interleukin 1β and tumor necrosis factor α; and profibrotic cytokine transforming growth factor β1.
Production of type I procollagen and type III procollagen messenger RNA peaked at 7.5 and 8.9 times baseline levels, respectively, 21 days after treatment and remained elevated for at least 6 months. Increases in messenger RNA levels of several cytokines (interleukin 1β, tumor necrosis factor α, and transforming growth factor β1) preceded and/or accompanied changes in collagen levels. Marked increases in messenger RNA levels of MMP-1 (39 130-fold), MMP-3 (1041-fold), MMP-9 (75-fold), and MMP-13 (767-fold) were noted. Levels of fibrillin and tropoelastin rose in a delayed fashion several weeks after treatment.
The biochemical changes seen after CO2 laser resurfacing proceed through a well-organized and highly reproducible wound healing response that results in marked alterations in dermal structure. These quantitative changes may serve as a means for comparison as other therapeutic modalities meant to improve the appearance of photodamaged skin are evaluated.