A new study by a team of Cornell researchers indicates that a revolutionary gene transfer technique may be able to speed the regrowth of hair that has been lost during chemotherapy.

Hair loss occurs in an estimated 85% of chemotherapy patients, depending on their treatment regimen. Regrowth of the lost hair can take from 3 to 6 months, and a small percentage of patients never completely recover their hair. Chemotherapy-induced hair loss can be particularly devastating because it is an outward sign of disease, leading some patients to refuse systemic chemotherapy altogether.

Drs. Noboru Sato, Philip Leopold and Ronald Crystal of the Weill Medical College of Cornell University in New York investigated hair growth in mouse models and its association with the Sonic hedgehog (Shh) gene. The Shh gene is involved in the formation of vertebrate organs, including the brain, heart, lung, and skeleton. It also appears to play an important role as an initiator of hair follicle growth.

Writing in the Journal of the National Cancer Institute, the investigators suggested that delivery of this gene into the skin through an "adenovirus vector" shows significant potential as a future treatment for accelerating hair regrowth after chemotherapy.

The Shh gene controls production of a protein that is part of the normal hair growth regulation cycle. The researchers inserted the Shh gene into an adenovirus vector, which was then introduced into the skin of mice that had lost hair after injection of the cancer drug cyclophosphamide. Two weeks after the gene was introduced, the mice that received it showed large hair follicles in an active growth phase. In mice receiving an unmodified vector after chemotherapy-induced hair loss, or no treatment at all, the skin showed only damaged hair follicles.

The authors said that their data support the idea that the Shh signaling pathway acts as a biologic switch that accelerates the initiation of the hair growth phase. Therefore, they concluded, the use of this gene transfer technique may prove to be a useful technology for learning about the mechanisms controlling hair regeneration in a variety of disease treatments, including chemotherapy-induced hair loss.

Ultimately, a combination of treatments that prevent hair loss and accelerate hair follicle recovery may prove to be the most effective for chemotherapy patients, they wrote.

SOURCE:
Journal of the National Cancer Institute, December 19, 2001; 93:1858-1864