Why hair turns grey with old age, scientists have a new reason

It is a widely known scientific fact that human hair turns grey as people get older because the production of pigment declines. But scientists have found a clearer answer.

It is because melanocyte stem cells get stuck inside the hair follicle and become unable to produce pigment. The pigment-producing part of a stem cell changes as you get older. "The melanocyte stem cell system fails earlier than other adult stem cell populations, which leads to hair greying in most humans and mice," says the study published in the journal Nature.

Researchers tracked individual cells in the fur of mice for two years to discover how hair turns grey. They also used special scans and lab techniques to study the cell-ageing process.

The report in the New York Post said that when hair ages, sheds, and grows back, the melanocyte stem cells get stuck in a part of the hair follicle called the hair follicle bulge. When stem cells stop roaming around the follicle and become fixed, they can no longer mature into fully-fledged melanocytes.

"This is a really big step forward in understanding why we grey. It is the loss of chameleon-like function in melanocyte stem cells that may be responsible for greying and loss of hair colour," said author and dermatology professor Mayumi Ito.

"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 greying of human hair by helping jammed cells to move again between developing hair follicle compartments," said lead investigator Qi Sun.