In photodynamic therapy, a light-activated medication is exposed to a light source. Photodynamic therapy for aesthetic treatments typically involves application of a topical medication, such as 5-aminolevulinic acid (5-ALA).
In this study, Dr. Jeffrey S. Orringer and colleagues at the University of Michigan Medical School in Ann Arbor, used photodynamic therapy to treat 25 people, aged 54 to 83, with sun-damaged skin on their forearms.
Prior to treatment, the patients' degree of skin damage was rated, and tissue samples were taken from their forearms. A solution containing 5-ALA was applied to the damaged skin and left on for three hours. The skin was then cleaned and treated with a pulsed-dye laser. The patients were re-examined four to five times over the following six months.
Tissue samples showed that treatment resulted in a fivefold increase in levels of a protein called Ki67, believed to play an important role in the growth and development of new skin cells. In addition, there was a 1.4-fold increase in the thickness of the skin's outer layer (epidermis) and higher levels of enzymes and other compounds associated with the production of collagen, the main structural protein in skin.
The findings were published in the October issue of the Archives of Dermatology.
"Photodynamic therapy with the specific treatment regimen employed produces statistically significant quantitative cutaneous molecular changes [e.g., production of types I and III collagen] that are associated with improved appearance of the skin," the researchers wrote.
The findings suggest that use of a photosensitive compound such as 5-ALA in combination with pulsed-dye laser therapy prompts more beneficial changes in skin than laser therapy alone.
"Although our molecular measurements cannot yet precisely predict clinical outcomes for a single given patient, taken together they are very much in keeping with the bulk of the clinical literature and thus lend substantial support to the conclusions reached by other researchers who have published purely clinically oriented work in this field," the study authors concluded.
"We believe that the quantitative amount of dermal repair and regeneration induced by a specific therapeutic intervention very likely underlies the degree of clinical rejuvenation produced." they wrote. "Thus, it is our hope that, with further development, our working molecular model may one day be used to predict the clinical value of new technologies in aesthetic dermatology."
More information
The National Institute on Aging has more about skin care and aging.
SOURCE: JAMA/Archives journals, news release, Oct. 20, 2008
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