Imagine a skin cream that heals damage occurring throughout the day when your skin is exposed to sunlight or environmental toxins. That’s the potential of a synthetic, biomimetic melanin developed by scientists at Northwestern University.
In a new study, the scientists show that their synthetic melanin, mimicking the natural melanin in human skin, can be applied topically to injured skin, where it accelerates wound healing. These effects occur both in the skin itself and systemically in the body.
When applied in a cream, the synthetic melanin can protect skin from sun exposure and heals skin injured by sun damage or chemical burns, the scientists said. The technology works by scavenging free radicals, which are produced by injured skin such as a sunburn. Left unchecked, free radical activity damages cells and ultimately may result in skin aging and skin cancer.
Melanin in humans and animals provides pigmentation to the skin, eyes and hair. The substance protects your cells from sun damage with increased pigmentation in response to sunlight — a process commonly referred to as tanning. That same pigment in your skin also naturally scavenges free radicals in response to damaging environmental pollution from industrial sources and automobile exhaust fumes.
Everyday injury to your skin
“People don’t think of their everyday life as an injury to their skin,” said co-corresponding author Dr. Kurt Lu, the Eugene and Gloria Bauer Professor of Dermatology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine dermatologist. “If you walk barefaced every day in the sun, you suffer a low-grade, constant bombardment of ultraviolet light. This is worsened during peak mid-day hours and the summer season. We know sun-exposed skin ages versus skin protected by clothing, which doesn’t show age nearly as much.”
The skin also ages due to chronological aging and external environmental factors, including environmental pollution.
“All those insults to the skin lead to free radicals which cause inflammation and break down the collagen,” Lu said. “That’s one of the reasons older skin looks very different from younger skin.”
When the scientists created the synthetic melanin engineered nanoparticles, they modified the melanin structure to have higher free radical scavenging capacity.
“The synthetic melanin is capable of scavenging more radicals per gram compared to human melanin,” said co-corresponding author Nathan Gianneschi, the Jacob and Rosaline Cohn Professor of Chemistry, Materials Science & Engineering, Biomedical Engineering and Pharmacology at Northwestern. “It’s like super melanin. It’s biocompatible, degradable,nontoxic and clear when rubbed onto the skin. In our studies, it acts as an efficient sponge, removing damaging factors and protecting the skin.”
Once applied to the skin, the melanin sits on the surface and is not absorbed into the layers below.
“The synthetic melanin stabilizes and sets the skin on a healing pathway, which we see in both the top layers and throughout the body,” Gianneschi said.
Both Lu and Gianneschi are members of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
Topical cream quiets immune system
The scientists, who have been studying melanin for nearly 10 years, first tested their synthetic melanin as a sunscreen.
“It protected the skin and skin cells from damage,” Gianneschi said. “Next, we wondered if the synthetic melanin, which functions primarily to soak up radicals, could be applied topically after a skin injury and have a healing effect on the skin? It turns out to work exactly that way.”
Lu envisions the synthetic melanin cream being used as a sunscreen booster for added protection and as an enhancer in moisturizer to promote skin repair.
“You could put it on before you go out in the sun and after you have been in the sun,” Lu said. “In both cases, we showed reduction in skin damage and inflammation. You are protecting the skin and repairing it simultaneously. It’s continuous repair.”
The cream could also potentially be used for blisters and open sores, Lu said.
Gianneschi and Lu discovered that the synthetic melanin cream, by soaking up the free radicals after an injury, quieted the immune system. The stratum corneum, the outer layer of mature skin cells, communicates with the epidermis below. It is the surface layer, receiving signals from the body and from the outside world. By calming the destructive inflammation at that surface, the body can begin healing instead of becoming even more inflamed.
“The epidermis and the upper layers are in communication with the entire body,” Lu said. “This means that stabilizing those upper layers can lead to a process of active healing.”