Light-activated therapy may change skin at molecular level

Oct 20, 2008

Photodynamic therapy—which involves a light-activated medication and exposure to a light source—appears to produce changes at the molecular level in aging skin, according to a report in the October issue of Archives of Dermatology, one of the JAMA/Archives journals. These changes are consistent with increased collagen production and improved appearance of the skin.

"The deleterious effects of exposure of the skin to UV irradiation are well established," the authors write as background information in the article. "Alternatively, several visible and infrared lasers and light sources have been reported to produce various positive changes in the clinical and histologic [microscopic] appearance of the skin. In recent years, the concept of employing a photosensitizing compound to enhance the effects of some light-based therapies has been espoused."

For aesthetic treatments, this type of photodynamic therapy typically involves application of a topical medication, such as 5-aminolevulinic acid (5-ALA), that is activated by exposure to light. Jeffrey S. Orringer, M.D., and colleagues at the University of Michigan Medical School, Ann Arbor, studied this treatment in 25 adults age 54 to 83 with sun-damaged skin on their forearms. Before treatment, the degree of skin damage was rated and a biopsy (tissue sample) was taken from the forearm. A solution containing 5-ALA was applied to the treatment site and left on for three hours; the skin was then washed with cleanser and treated with a pulsed-dye laser. Participants returned for re-examination and to provide additional biopsy samples four to five times during the six months following treatment.

After photodynamic therapy, tissue samples demonstrated a five-fold increase in levels of Ki67, a protein thought to play a fundamental role in the growth and development of new skin cells. The epidermis (skin's outer layer) increased in thickness 1.4-fold. Levels of enzymes and other compounds associated with the production of collagen, the main structural protein in the skin, also were increased.

"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 authors conclude. When compared with previous data regarding the effectiveness of pulsed-dye laser therapy alone, these results suggest that using a photosensitive compound such as 5-ALA enhances changes in the skin.

"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 authors conclude. "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. 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."

Source: JAMA and Archives Journals

Explore further: New research demonstrates benefits of national and international device registries

add to favorites email to friend print save as pdf

Related Stories

March of the penguin genomes

Dec 11, 2014

Two penguin genomes have been sequenced and analyzed for the first time in the open access, open data journal GigaScience. Timely for the holiday season, the study reveals insights into how these birds have b ...

What is heat conduction?

Dec 09, 2014

Heat is an interesting form of energy. Not only does it sustain life, make us comfortable and help us prepare our food, but understanding its properties is key to many fields of scientific research. For example, ...

Recommended for you

New approach to particle therapy dosimetry

Dec 19, 2014

Researchers at the National Physical Laboratory (NPL), in collaboration with EMRP partners, are working towards a universal approach to particle beam therapy dosimetry.

Supplement maker admits lying about ingredients

Dec 17, 2014

Federal prosecutors say the owner and president of a dietary supplement company has admitted his role in the sale of diluted and adulterated dietary ingredients and supplements sold by his company.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.