Hyaluronic acid (HA) is a polysaccharide (a sugar) distributed widely throughout connective, epithelial, and neural tissues. The average 70 kg person has roughly 15 grams of HA in their body, one-third of which is turned over (degraded and synthesised) every day. HA in the skin is produced by the epithelial cells and is a polymer of disaccharides. It can be 25000 repeats in length.
Hyaluronidase is the natural enzyme which breaks down HA. There are 7 known hyaluronidases in the body.
Hyaluronic acid is a major component of skin, where it is involved in tissue repair. It is also a powerful humectant (aka moisture-binding ingredient) that keeps skin plump and hydrated. It is a common ingredient in moisturisers, especially those that are oil-free. As HA is an important component of articular cartilage, HA injections are also used to treat arthritis.
Recent studies have found that HA content increases in the presence of retinoic acid (vitamin A). The proposed effects of retinoic acid against skin photo-damage and aging may be correlated, at least in part, with an increase of skin HA content, giving rise to an increase in tissue hydration. It has been suggested that the free-radical scavenging property of HA contributes to protection against solar radiation.
Stabilised (cross-linked) HA is used as a dermal filler (the cross-linkage significantly improves its properties and longevity); whereas unstabilised HA, using multiple intradermal injections is used to hydrate the skin. These treatments can be further individualised and boosted by adding the patient’s own platelet-rich plasma (PRP) which is rich in growth factors. Adding a small amount of muscle relaxant to the HA injections helps to ‘unyawn pores’ and reduce excessive oil production.
Dr Julie Bradford