New study decodes biological cell mechanisms behind gray hair

When these McSCs move into the hair follicle compartment, they are exposed to "different levels of maturity-influencing protein signals," which aid cell proliferation.

In this continuous back-and-forth movement between the compartment, the cell's state changes from primitive to mature — known as the transit-amplifying state. 

However, as people age, these cells lose motility and become stuck in the developing hair follicle compartment. As a result, they miss the signal to mature, move, or multiply. Because they cannot return to the germ compartment, the cells cannot regenerate the pigment.

Eventually, this causes graying in areas of hair where cell movement stops. The hair, on the other hand, continues to grow as the hair follicle develops. There are some hair locations where the cell movement continues to work normally. Thus the hair retains the pigment. That is why graying occurs in different places.

Simply put, for normal hair color, these cells must be active; that is, they must constantly be moving back and forth on the maturity axis. 

“Our study adds to our basic understanding of how melanocyte stem cells work to color hair. The newfound mechanisms raise the possibility that the same fixed-positioning of melanocyte stem cells may exist in humans. If so, it presents a potential pathway for reversing or preventing the graying of human hair by helping jammed cells to move again between developing hair follicle compartments,” said Qi Sun, a postdoctoral fellow at NYU Langone Health, in a statement. 

The team is working to find a way to restore these cells' motility. This biological function was closely monitored on mouse skin cells. They also used 3D intravenous imaging and scRNA sequencing to track cell movement in real time.  

The findings were published in the journal Nature.