June 15, 2011

Why Does Our Hair Turn Gray?

According to a new study published in the journal Cell, Wnt signaling, already known to control many biological processes, between hair follicles and melanocyte stem cells can determine hair pigmentation.

The research at NYU Langone Medical Center was led by Mayumi Ito, PhD, assistant professor at the Ronald O. Pereleman Department of Dermatology at NYU.

"We have known for decades that hair follicle stem cells and pigment-producing melanocyte cells collaborate to produce colored hair, but the underlying reasons were unknown," said Ito. "We discovered Wnt signaling is essential for coordinated actions of these two stem cell lineages and critical for hair pigmentation."

Ito and colleagues suggest that the manipulation of Wnt signaling may be a fresh strategy for targeting pigmentation such as graying hair. The researchers also found a possible model for tissue regeneration with their studies.

"The human body has many types of stem cells that have the potential to regenerate other organs," said Ito. "The methods behind communication between stem cells of hair and color during hair replacement may give us important clues to regenerate complex organs containing many different types of cells."

The team used genetic mouse models to examine how Wnt signaling pathways enabled both hair follicle stem cells and melanocyte stem cells to cooperate to generate hair growth and produce hair color.

The research also showed the abnormal Wnt signaling in hair follicle stem cells not only inhibits hair re-growth but also prevents melanocyte stem cell activation required for producing hair color. The lack of Wnt activation in melanocyte stem cells leads to de-pigmented or gray hair.

The study suggests that Wnt signaling is vital for regulation of melanocyte stem cells and shows how melanocyte behavior is linked with hair regeneration.

This study provides a better understanding of diseases in which melanocyte stem cells are either appropriately lost through hair graying or undergo uncontrolled cell growth such as with melanoma.


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