Hyaluronic Acid (HA) is a unique, naturally occurring polysaccharide. It is unique due to various physicochemical properties that enable high degrees of modulation targeted for specific uses cases. Hyaluronic Acid is naturally occurring in the human body, at concentrations ranging from 10 to 100 ug/L in circulating serum.
Chemical and Physiochemical Properties
HA is a negatively charged polysaccharide commonly known as a glycosaminoglycan (GAG). Their monomeric unit is disaccharide in nature and is known to form very stable tertiary structures. Due to its high degree of modularity, factors such as pH, salt concentration, molecular weight of the HA itself, and the presence of other ionic components all dictate the formation of the final tertiary structure. Furthermore, the differences in these formation and shape of these tertiary structure affect the rheological properties of the final solution. HA takes on large volumes of water even at extremely low concentrations, resulting in exponential relationships between concentration of HA and the viscosity of solution.
In-Vivo Occurrence and Support Function
HA is abundant in the skin, the vitreous of the eye, the umbilical cord, and synovial fluid. The skin specifically holds most of the HA of the entire body, accounting for nearly 50% of the total body HA. The main function of HA is to serve as scaffolding and support material for various processes. It provides hydration to the skin, as it takes on water volume and has a “storing” effect that decreases trans epidermal water loss through the skin.
Skin Function
Skin hydration relies on HA-bound water in the dermis and vital epidermis, while maintenance of hydration depends on the stratum granulosum. Dermal fibroblasts play a crucial role in synthesizing HA, and efforts to enhance skin hydration should target these cells, considering challenges related to exogenous HA clearance and degradation.
References
Hyaluronic acid: A key molecule in skin aging