Hair Growth at a Solid-Liquid Interface as a Protein Crystal Without Cell Division

The study proposed a novel understanding of hair growth, suggesting it occurred at a solid-liquid interface without cell division, akin to inorganic crystal growth. Using X-ray fluorescence analysis, researchers found that hair growth was driven by a chemical potential gradient, with serum proteins flowing into the hair bulb and forming keratin without new protein formation by gene expression. The hair bulb was in a liquid state, and element segregation, such as Ca and Sr, occurred at the interface, reflecting the flow of substances from blood to hair. This process was described as "protein-melt growth," challenging traditional views of hair growth involving cell proliferation. The study involved analysis of hair roots from thousands of people, providing a comprehensive examination of the hair growth mechanism.