Cosmetic scientists strive to unpack skin regeneration

When it comes to treating sun damage, acne scars, wrinkles and abnormal pigmentation, two procedures are increasingly popular. Microneedling involves making tiny holes in the outermost layer of skin, while laser therapy uses intensely focused beams of light to heat the skin.

Both treatments are thought to work by stimulating skin regeneration as part of normal healing, but the precise mechanisms remain unclear. To further optimize treatments, cosmetic researchers need a deeper understanding of what’s happening.

With that goal, researchers at L’Oréal have developed human-skin models to allow standardized testing of cosmetic products. They have also clinically tested a variety of ingredients designed to improve recovery from microneedling and lasering. “There is still a significant gap in understanding how these procedures drive skin regeneration, what the side effects are, and how to enhance the effects of these procedures,” says skin scientist, Charbel Bouez, Global Head of Regenerative Beauty, Research and Innovation, L’Oréal, in the United States.

Regenerative dermatology is a key research area at L’Oréal. Founded in 1909, the company has a presence in 150 countries and a workforce of more than 88,000, including approximately 4,000 people dedicated to research. Annually, L’Oréal invests more than $1.2 billion in research and innovation, leading to 561 international and national patents in 2022 alone.

Several significant patents have come from the La Roche Posay skincare laboratory in Paris, France, which is part of L’Oréal’s Dermatological Beauty Division.

“Developing scientifically relevant models helps us understand the effects of aesthetic procedures like lasers and microneedling on the skin,” says I-Chien Liao, director of Advanced Research, North America, L’Oréal.

Aesthetic models

In one model, L’Oréal researchers used skin removed during abdominoplasty or ‘tummy tucks’ ¹ and kept alive in the lab. Unlike earlier models that used reconstructed skin or lab animals, such ‘real-world skin’ includes all skin cell types and immune cells, Bouez says.

L’Oréal studies using the model were among the first to show tissue regeneration in microneedled skin in the lab. “We demonstrated that skin goes through the hallmark signs of epidermal regeneration through morphological and molecular changes after the treatment,” says Bouez.

Microneedling of the skin model was found to stimulate the production of keratinocytes, the primary cell type found in the outermost layer of the skin. The cells migrated to the skin surface. Proteins such as vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor and insulin were also activated. That is typical of the early stages of tissue repair.

A second skin model has been used to study healing after laser resurfacing. It is constructed from layers of human fibroblasts, the primary cell type in connective tissue, and keratinocytes².

“To our knowledge, this is the first work in vitro to cover the dynamic changes to the skin following aesthetic laser treatment,” Liao says. “The reconstructed skin behaved very similarly to skin undergoing the key stages of wound healing.”

This included inflammation, characterized by an increase in cytokines. There was also an increase in the skin regeneration biomarkers Ki67, a protein associated with cell proliferation, and filaggrin, a protein that binds to keratin fibres in epithelial cells.

As wounds heal following microneedling and laser treatments, people can experience temporary redness, swelling, itching and burning — and sometimes permanent unwanted pigmentation and even scarring.

“The management of barrier restoration and inflammation likely helps the skin to recover from procedures,” Liao says. With that in mind, L’Oréal’s research also focuses on post-procedure care that could reduce recovery times and improve aesthetic outcomes.

For example, in one double-blinded, randomized controlled trial, a cream developed by La Roche-Posay and L’Oréal China that contains 5% panthenol was used to treat one side of the face of 43 women who had received a type of laser treatment called fractional CO₂ laser resurfacing. The other side was treated with a hospital-made wound healing cream³.

Skin recovery

Three days after treatment, the researchers measured redness and swelling, comparing the two sides of the face. A week later, they measured loss of moisture from the skin as an indicator of the integrity of the skin.

In a second trial, L’Oréal researchers monitored redness and swelling following laser treatment in people with acne scars on both cheeks. Twenty participants received L’Oréal’s 5% panthenol cream on one side of their face, and a cream containing 0.02% triamcinolone acetonide (a synthetic corticosteroid medication) on the other side⁴.

L’Oréal scientists are now conducting research to understand better why people with deeper skin tones are more prone to developing of post-inflammatory hyperpigmentation after aesthetic procedures such as microneedling and lasering.

Such trials, and the insights gained from them, help L’Oréal’s researchers optimize their product formulations.

“Understanding the biological pathways induced after a procedure, and the efficacy of core ingredients, allow us to design the optimal approach to targeting regenerative pathways, including effective delivery systems for those active ingredients,” says Frédérique Labatut, research director of the La Roche-Posay skincare laboratory in Paris, France.

Global team

L’Oréal’s science-led approach is evident in a wound-healing cream, which combines a proprietary xylose-derived sugar protein with niacinamide and panthenol. The formula is trademarked as REGENAMIDE-22. It could, the scientists say, help to heal and enhance the regenerative effects after aesthetic procedures. According to Bouez, the product was made possible by more than 50 lab studies and four clinical studies performed in China, France, and the United States.

During that research, L’Oréal examined the ability of its sugar protein to help skin retain water and support the skin structural proteins collagen and elastin. They also examined keratinocyte migration and the strengthening of the dermal-epidermal junction.

Guided by studies, L’Oréal researchers married their formula with a proprietary delivery system designed to trap moisture and encourage wound healing.

Bouez argues that the scientific grounding has allowed L’Oréal to innovate around “skin wound healing, and as a result, enhance the regenerative effects of aesthetic procedures.”

The xylose-derived sugar protein, niacinamide and panthenol formula has also been incorporated into another cream that includes a swelling gel and ‘multilamellar vesicles’ — tiny spheres made of multiple layers like an onion — which are intended to store water and active compounds and enhance penetration within the skin. This cream is designed to mimic a medical wound dressing that traps moisture, Bouez says.

Results of research on the formula and laser technology related to wrinkles, fine lines, and skin smoothness were presented at the 25th World Conference of Dermatology in Singapore in July 2023.

“L’Oréal’s research group has a strong interest in leveraging regenerative medicine concepts and advances to create the future of beauty, which we believe will be regenerative,” Bouez says. “Aesthetic procedures like microneedling and laser therapy are the perfect examples of regenerative medicine being applied for skin beauty.”