Hair follicles contain several different types of cells, including melanocyte stem cells (McSCs) which generate cells that produce the pigment melanin – responsible for hair colour.
A new US study in mice found these McSCs migrate between two sites at the base of each hair follicle during each cycle of hair growth and shedding – from a site where they produce the pigment for hair colour to another where they produce stem cells.
The study, published in the journal Nature, found ageing results in a greater portion of these McSCs becoming stuck at the site where they produce stem cells, which leaves a smaller portion of stem cells to generate melanin- producing cells – resulting in greying of hair.
While it was previously thought that once McSCs differentiated into melanocytes, the process was irreversible, the new study suggests McSCs ‘can migrate back and forth between the two locations, differentiating to produce hair pigment-producing melanocytes in the hair germ area and then transcending to the other site and de-differentiating to ensure the maintenance of an adequate supply of stem cells’, explained medicalnewstoday.com.
‘In other words, during each growth cycle, the McSCs can differentiate into a pigment-producing partially differentiated state and then revert back to an undifferentiated state.’
Study author Dr Mayumi Ito from New York University commented: ‘Our analysis revealed melanocyte stem cells are more dynamic/mobile than previously thought.
‘We revealed that as melanocyte stem cells move within the hair follicle, stem cells can reversibly alter cell state from immature to mature state, and this reversibility is critical for the proper maintenance of these stem cells.
‘Our study suggests melanocyte stem cell localisation may be altered during the course of ageing. Moving melanocytes to a proper location within the hair follicle may help prevent hair greying.’
