A recent study conducted by researchers from NYU Grossman School of Medicine has uncovered how certain stem cells, known as melanocyte stem cells (McSCs), play a crucial role in maintaining hair color and how their behavior changes with age. The study, published in the journal Nature, focused on both mice and humans.

The researchers found that McSCs exhibit remarkable plasticity, continually transitioning between their primitive stem cell state and a more mature transit-amplifying state, depending on their location within the developing hair follicle. However, as hair ages, more McSCs become trapped in the stem cell compartment known as the hair follicle bulge. These trapped cells do not mature and fail to return to their original location, where they would regenerate into pigment-producing cells in response to WNT proteins.