Sun-damaged skin responds well to laser treatment

Oct 20 2008

Researchers at the University of Michigan Health System Department of Dermatology have found scientific evidence that the appearance of sun-damaged skin may be improved by treatment with a topical product that increases the skin's sensitivity to light, followed by laser therapy.

In the new study, participants whose skin was sun-damaged - or photodamaged - were treated with a topical photosensitizer called 5-aminolevulinic acid (5-ALA) and then with a pulsed dye laser. This type of treatment, known as photodynamic therapy, increased collagen levels in the skin and also produced other skin changes that are known to improve its appearance.

The results also suggest that skin with the worst sun damage may respond particularly well to this treatment.

"This is new scientific evidence that photodynamic therapy may in fact be a useful tool to improve the appearance of the skin. This type of therapy has been performed in clinical practice for the past few years, but we've never had detailed molecular evidence for why it may work," says lead author Jeffrey S. Orringer, M.D., associate professor of dermatology at the U-M Health System and director of U-M's Cosmetic Dermatology and Laser Center. The study appears in the October issue of the Archives of Dermatology.

The study looked at 24 adults, ages 54 to 83, all of whom had significant photodamage on the forearm skin. They received a three-hour application of 5-ALA followed by pulsed dye laser therapy. Researchers examined biopsies taken before and at several times after the treatments, and they recorded the molecular changes in the participants' skin at various stages.

Among many other molecular changes, levels of the proteins procollagen I and procollagen III increased after treatment. For instance, one month after treatment, levels of procollagen I peaked with an increase of 2.65 times the pre-treatment levels. Procollagen III peaked one month after treatment with an increase of 3.32 times the pre-treatment levels. Other protein levels molecular markers also increased.

The study represents the latest example of U-M's human appearance research program's unraveling of the mechanisms by which popular treatments improve the appearance of the skin, Orringer notes.

The group has studied the treatment of sun-damaged skin with estrogen, the science behind wrinkle treatments, the effects of smoking on aging skin, and more.

Photodynamic therapy has been used as a treatment for precancerous lesions called actinic keratoses and for some types of skin cancer, but little scientific research has been conducted about its use in appearance-oriented dermatology.

Future studies are needed to gauge whether the improvements shown in the forearm skin in this study can be replicated on facial skin.

Authors: In addition to Orringer, authors of the paper - all from the U-M Department of Dermatology - were senior author John J. Voorhees, M.D., FRCP, Duncan and Ella Poth Distinguished Professor and chairman of the Department of Dermatology; Craig Hammerberg, Ph.D., laboratory manager; Ted Hamilton, M.S., senior research associate; Timothy M. Johnson, M.D., professor and director of the Cutaneous Surgery and Oncology Unit and the Melanoma Clinic; Sewon Kang, M.D., formerly a professor of dermatology at U-M; Dana L. Sachs, M.D., associate professor; and Gary Fisher, Ph.D., Harry Helfman Professor of Molecular Dermatology.

Funding: The study was funded by the Human Appearance Research Program (HARP) of the U-M Department of Dermatology.

Reference: Archives of Dermatology, Vol. 144, No. 10, October 2008, "Molecular Effects of Photodynamic Therapy for Photoaging."