The ability of hair to grow depends on activators that wake up cells and inhibitors that calm them down, according to research presented at the annual meeting of the American Society for Cell Biology and reported by the University of Southern California.

To prove their hypothesis, USC scientists teamed with Oxford University mathematicians to build a model that showed hair follicle behavior. Researchers found that each hair follicle took its hair growth cue from inner signals without being influenced by other nearby follicles.

What’s more, scientists noticed that changing the follicle environment either stimulated hair growth or stopped it. For example, researchers found that the winter season as well as puberty could regenerate hair stem cell activity in each follicle. In other seasons or life stages, individual hair follicles could stay in the resting phase (called telogen) and simply not grow.

These finding are important because they suggest it might be easier to treat hair loss and encourage growth by improving the  hair follicle environment rather than by implanting stem cells.

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