Gene repair may help restore color of gray hair

NEW YORK, Jan 05 (Reuters Health) — It won't be on the drugstore shelf any time soon, but a type of gene therapy called gene repair could one day replace coloring as a way to cover up gray hair, US researchers suggest.

According to a report in the January issue of Nature Biotechnology, altering a mutation in a gene in the hair follicle restored pigmentation to the hairs of albino mice. The study is the first to demonstrate that genetic manipulation can correct a damaged gene sequence in the hair follicle, the authors write.

"Gene therapy has just taken a cosmetic step forward,'' Robert M. Hoffman, president of AntiCancer, Inc., a San Diego, California-based biotechnology company that develops products to diagnose and treat cancer, stated in an editorial.

While the study results suggest that certain molecules made up of a corrective DNA sequence may help to restore pigmentation in mice, similar studies have not been conducted on humans, according to the research team from Thomas Jefferson University and Jefferson Medical College and the University of Pennsylvania in Philadelphia.

Kyonggeun Yoon, an associate professor in the department of dermatology and cutaneous biology at Jefferson Medical College, and one of the study's authors, explained the technique. "The albino mouse has a mutation in tyrosinase, a key enzyme involved in melanin synthesis. Graying hairs are caused by loss of melanocytes due to the aging process,'' Yoon told Reuters Health.

The investigators applied molecules, known as chimeric oligonucleotides, to albino mice that had had their hair removed. The molecules were applied topically to 4 mice and or injected into the skin of 11 mice.

A few weeks after treatment, a small number of pigmented hairs grew in the areas that were exposed to the oligonucleotides. Tests revealed that a key DNA sequence had been repaired and key enzyme activity had been restored, although the mechanism of gene correction has not been shown, Yoon said.

Color was found in only a small number of hairs and lasted just 3 months after the last application, however. The authors explain that enhancing DNA delivery to the hair follicle, correcting the mutation in the correct stage of hair growth cycle or correcting stem cells in the skin, could lead to more permanent results.

The researchers had previously shown that gene repair could be used to restore the pigmentation of albino cultured mouse skin cells by correcting a mutation in the enzyme responsible for producing the pigment melanin.

In his editorial, Hoffman notes that the study offers ''exciting possibilities... for modifying hair features.'' The hair follicle "stands as one of the most promising targets for effective, useful, safe and lucrative gene therapy,'' he adds. SOURCE: Nature Biotechnology 2000;18:20-21, 43-47.