Scientists grow hair on bald mice

By Dr. Ananya Mandal, MDApr 22 2012

Japanese researchers have successfully regrown hair on a bald mouse. This could mean hair related solutions for many men and women with baldness in future.

Not only were Japanese scientists able to regrow hair in the study, which was published April 17 in Nature Communications, but they were able to manipulate the density and colour of the hair as well. “Our study provides a substantial contribution to the development of bioengineering technologies that will enable future regenerative therapy for hair loss caused by injury or by diseases such as alopecia and androgenic alopecia,” researchers wrote in the study.

Hair loss may affect two-thirds of American men by age of 35 according to the American Hair Loss Association. At 50, 85 percent of men will have significantly thinning hair. Thought typically considered to be a male disease, 40 percent of women make up hair loss sufferers. The disease is not life-threatening, but it can cause many emotional problems because of the physical changes.

For the experiment the researchers cultivated two different kinds of mice hair follicles and transplanted them on a mouse. Three weeks later, 74 percent of the hair follicles had grown into black hair. When human hair follicles cells were transplanted, human hair grew. The hair continued to regenerate after it fell out due to normal growth cycles.

Unlike current hair transplant methods, which simply move existing hair follicles from one area of the scalp to another to cover a bald region, the approach would spur the creation of new hair follicles from existing cells say researchers. “It’s exciting because it shows a cell-based approach for treating hair loss is maybe feasible,” says George Cotsarelis, a dermatologist at the University of Pennsylvania in Philadelphia.

Hair follicles develop when two different types of cells - epithelial and mesenchymal cells - interact with each other. Epithelial cells grow very quickly and shed, while mesenchymal cells direct epithelial cells to make a follicle. Previously, Tsuji and colleagues had bioengineered follicles and hair shafts in the lab using epithelial and mesenchymal cells from mouse embryos. Until now, it was unclear whether these organized clusters of cells would make normal hair if inserted into mouse skin.

Importantly, the researchers were able to ensure hair didn’t become ingrown or point in the wrong direction by attaching a nylon thread to the engineered follicles and guiding the hair to grow outward. “You have to make hair that is positioned right,” says Cheng-Ming Chuong, a stem cell and regeneration researcher at the University of Southern California in Los Angeles. Chuong notes that the new study succeeded in getting the follicles to grow in an organized way. Previous studies involving transplanted follicles produced hair that grew in random directions or formed cysts, which isn’t very useful clinically.

The results also mark a step forward in efforts to regenerate organs such as salivary glands that form in a process similar to hair early in their development, says study co-author Takashi Tsuji of Tokyo University of Science in Chiba, Japan.

Hair has been regenerated in mice in previous research, such as experiments conducted by scientists at the University of California, Los Angeles and the Veterans Administration in 2011, and by the Kennedy Krieger Institute and Johns Hopkins in 2005. But, unlike the Tokyo University of Science study, those experiments focused on determining the genetic roots of baldness and the role of stress hormones in inhibiting growth.