A New Ex Vivo Model to Evaluate the Hair Protective Effect of a Biomimetic Exopolysaccharide against Water Pollution

As an external appendage, hair is exposed to multiple stresses of different origins such as particles and gases in air, or heavy metals and chemicals in water. So far, little research has addressed the impact of water pollution on hair. The present study describes a new ex vivo model that allowed us to document the adverse effects of water pollutants on the structure of hair proteins, as well as the protective potential of active cosmetic ingredients derived from a biomimetic exopolysaccharide (EPS). The impact of water pollution was evaluated on hair from a Caucasian donor repeatedly immersed in heavy metal-containing water. Heavy metal retention in and on hair was then quantified using Inductively Coupled Plasma Spectrometry (ICP/MS). The adverse effects of heavy metals on the internal structure of hair and its prevention by the EPS were assessed through measurement of keratin birefringence. Notably, the method allows the monitoring of the organization of keratin fibers and therefore the initial change on it in order to modulate the global damage in the hair. Results revealed an increasing amount of lead, cadmium and copper, following multiple exposures to polluted water. In parallel, the structure of keratin was also altered with exposures. However, heavy metal-induced keratin fiber damage could be prevented in the presence of the tested EPS, avoiding more drastic hair problems, such as lack of shine, or decrease in strength, due to damage accumulation.