Hyaluronic Acid in Topical Applications: The Various Forms and Biological Effects of a Hero Molecule in the Cosmetics...

Hyaluronan, or hyaluronic acid (HA), is a glycosaminoglycan with structural and signaling functions playing key roles in human skin homeostasis. It ensures hydration and biomechanical properties of this tissue as well as regulates cell adhesion, migration, proliferation, and inflammation. Its biocompatibility, viscoelastic properties, biological functions, and large-scale sustainable bioproduction made this polysaccharide a hero molecule of the cosmetic industry.

A literature search was conducted to discuss the skin and hair benefits of the external use of HA and its derivatives. Four main questions were addressed: What are the different forms of HA in cosmetic formulations? What about their safety? Does HA penetrate human skin and hair? What are the benefits and mode of actions of HA, and its derivatives, in the fields of cosmetic and dermatology?

The analysis revealed HA below 100 kDa to penetrate skin, and lower molecular weight being able to reach the dermis. The safety of HA-containing formulations has been evaluated in several clinical trials and is supported by independent reports of commercial ingredients. We described HA molecules having beneficial effects on skin and hair, as well as their mode of action.

This review provides comprehensive information on the nature and efficacy of topical HA, and its derivatives, in cosmetic applications, with an emphasis on hair care. New areas of research were highlighted as the vectorization of high-molecular-weight HA.