The skin's healing process following trauma is not flawless, and it is common for scars to persist, which can be both unsightly and uncomfortable. Acne scars, chickenpox marks, stretch marks, cuts... There are many types. They all share one thing in common: they are difficult to treat. Could hyaluronic acid, one of the most frequently used active ingredients in the field of cosmetics, be of help?
Scars: Can Hyaluronic Acid Fade Them?
Summary
Published on May 14, 2024, by Pauline, Chemical Engineer — 6 min of reading
Themes:
Healing: What is the mechanism of action of hyaluronic acid?
An essential constituent of the extracellular matrix of the dermis, hyaluronic acid plays a significant role in numerous embryological, physiological, and pathological processes, including wound healing. It notably possesses angiogenic properties, demonstrated during in vitro tests, meaning it stimulates the formation of new blood vessels from a pre-existing network. Furthermore, hyaluronic acid alters vascular permeability by activating endothelial cells, which are involved in initiating the wound healing process. Finally, this molecule facilitates the binding between certain microbial membrane factors and Toll-like receptors, thereby promoting wound healing.
The effects of hyaluronic acid on healing vary according to its molecular weight. Indeed, high molecular weight hyaluronic acid plays a crucial structural role within the extracellular matrices of tissues by regulating their hydration and plasticity. It also protects cells from enzymatic, viral or bacterial attacks, which could potentially disrupt the healing process. When it is hydrolysed or its molecular weight is lower, hyaluronic acid acts as a signalling molecule during angiogenesis and tissue repair.
Hyaluronic Acid and Healing: A Closer Look at Clinical Studies.
To diminish the appearance of scars, hyaluronic acid can be used either topically or through injection, each method having its own distinct advantages and disadvantages.
The efficacy of hyaluronic acid in topical application for diminishing scars has been demonstrated in several clinical studies, conducted on volunteers with various types of scars. The results, compiled in the table below, seem to indicate that hyaluronic acid is a genuine aid in the re-epithelialisation of the skin.
| Study | Number of Participants | Type of Scar | Protocol | Results |
|---|---|---|---|---|
| ERDEI & al. (2012) | 60 | Partial thickness burn (on average 3% of the total body surface area) | Daily application of a gel containing hyaluronic acid and zinc | Average wound reduction of 50% by the 5th day and complete epithelialisation in 56 patients by the 21st day |
| SCUDERI & al. (2013) | 40 | Persistent leg ulcer | Daily application of a cream containing hyaluronic acid and collagenase | No improvement for 4 patients, moderate improvement for 4, good improvement for 32 |
| ALLAERT & al. (2013) | 38 | Ulcer | Daily application of a hyaluronic acid compress | After 45 days, there was an average reduction in ulcer size of 73% |
When it comes to the effects of hyaluronic acid injections on scars, the evidence is more abundant and concrete. Their effectiveness is based on the filling effect of the active ingredient: by slightly elevating the skin at the scar site, it helps to make it less visible. However, while hyaluronic acid injections are useful for treating indented scars, their effectiveness is limited on hypertrophic scars, which present an overgrowth of skin tissue. It is also important to bear in mind that hyaluronic acid injections carry risks of side effects (infections, allergic reactions, oedema, inflammation...) and should not be undertaken lightly.
| Study | Number of Participants | Type of Scar | Protocol | Results |
|---|---|---|---|---|
| BLOMSTER & al. (2018) | 12 | Atrophic acne scars | 3 injections of hyaluronic acid at 4-week intervals | No improvement for 1 patient, moderate improvement for 1, good for 9 and very good for 1 |
| DE FRANCESCO & al. (2019) | 41 | Hypertrophic Scars | 2 injections of hyaluronic acid at 2 weeks interval | Average improvement in the appearance of scars quantified at 22% |
| FRIEDMAN & al. (2019) | 12 | Atrophic acne scars | 2 injections of hyaluronic acid at 4-week intervals | Minimal improvement for 2 patients, moderate for 8 and significant for 2 |
| NOBILE & co. (2024) | 32 | Stretch Marks | 4 injections of 10 mL of low molecular weight hyaluronic acid + 6 amino acids at 2-week intervals | Average improvement in participants' quality of life assessed at 19% |
Sources
GALL Y. Hyaluronic Acid: Structure, Metabolism and Implication in Wound Healing. Annals of Dermatology (2010).
ERDEI I. & al. Treatment of partial thickness burns with Zn-hyaluronan: insights from a clinical pilot study. Annals of burns and fire disasters (2012).
SCUDERI N. & al. A novel correlation between hyaluronic acid and collagenase in wound healing: an open study. European review for medical and pharmaceutical sciences (2013).
ALLAERT F. A. & co. Efficacy and safety of a gauze pad imbued with hyaluronic acid for the treatment of leg ulcers of venous or mixed origin: a double-blind, randomised, controlled trial. International Wound Journal (2013).
BLOMSTER S. & al. Efficacy and Safety of Acne Scar Treatment Using Nonanimal Stabilised Hyaluronic Acid Gel. Dermatologic Surgery (2018).
DE FRANCESCO F. & al. Managing Pathological Scars through the Injection of Auto-Cross-Linked Hyaluronic Acid: An Initial Prospective Clinical Study. Aesthetic Plastic Surgery (2019).
FRIEDMAN O. & al. Dual-plane hyaluronic acid treatment for atrophic acne scars. Journal of Cosmetic Dermatology (2019).
NOBILE V. & al. The addition of low molecular weight hyaluronic acid to six specific amino acids in the treatment of striae alba (SA): An observational study. Aesthetic Plastic Surgery (2024).
