Characterization of Hair Damage at the Molecular Level through Proteomics

Overall protein integrity is an important hallmark of healthy hair and has a great impact on the cosmetic value of the hair shaft. Hair is comprised of ~80% protein (predominantly αkeratin) and is not regenerative after it exits the scalp. Therefore, protection of the native hair structure on the protein and fiber levels is critical to ensure good cosmetic properties of the hair. Consumer practices such as grooming and chemical treatments can impact the structural integrity of the hair. The accumulation of damage from these factors ultimately weakens the hair fibers and leads to consumer-noticeable changes such as breakage or split ends. At the molecular level, damage to the hair shaft can lead to the breakdown and/or release of proteins from the hair, which can provide an early diagnostic for damage before it is manifested at the macro-structural level. We have deployed the use of 2-dimensional gel electrophoresis (2DGE) coupled with mass spectrometry (MS) to evaluate the integrity of hair shaft proteins after different types of insult. This work has enabled us to localize damage at the sub-fiber and molecular levels, and the identification of peptide biomarkers for hair damage. Understanding how the hair shaft is damaged at the proteome level has provided new insights into hair structure and the how protein changes impact the mechanical and cosmetic value of the hair shaft.