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Nov. 2 (UPI) -- Scientists at Northwestern University say they have developed a synthetic melanin cream that repairs injured skin as well as protecting against sun damage. In a new study published Thursday in the journal Nature, the research team found their man-made melanin mimicking the natural melanin in human skin, accelerates wound healing with the therapeutic effects seen in the skin and systemically, inside the body.
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Applied directly to the skin, the "super melanin" can protect skin from sun exposure and heal skin injured by sun damage or chemical burns, said the scientists who carried out the research with the help of a National Institute of Arthritis and Musculoskeletal and Skin Diseases grant.
Skin damaged by sunburn or other injuries produces free radicals and the cream works by "scavenging" up these molecules which damage cells if allowed free rein potentially causing skin aging and skin cancer. Natural melanin in human and animal skin does the same, but the Northwestern scientists modified the structure of the synthetic melanin-engineered nanoparticles so that they had a greater capacity to soak up free radicals.
"The synthetic melanin is capable of scavenging more radicals per gram compared to human melanin," said joint-lead 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.
"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.
Melanin is responsible for the protective tanning response of skin when exposed to sunlight. That pigmentation protects skin from sun damage but it also scavenges free radicals produced in skin cells by industrial and traffic pollution.
"People don't think of their everyday life as an injury to their skin," said joint lead author Dr. Kurt Lu, the Eugene and Gloria Bauer Professor of Dermatology at Northwestern University Feinberg School of Medicine who is also a 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 passage of time and environmental factors including pollution also take their toll, Lu said, with collagen paying the price of the free radicals-induced inflammation from accumulated assaults on the skin.
"That's one of the reasons older skin looks very different from younger skin."
After initial tests found the synthetic melanin prevented damage to skin and skin cells the scientists decided to try to find out whether it would promote healing when applied directly on injured skin.
"It turns out to work exactly that way," Gianneschi said.
Lu believes the melanin could be utilized to double up the protection from regular sunscreen and added to moisturizer as a skin repair agent.
"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."
Gianneschi and Lu also found in laboratory testing that the synthetic melanin cream reduced the damage triggered by free radicals by calming down the immune system's inflammatory response. Calming the inflammation and reducing the "damage" markers sent from the outer layer of mature skin cells to the epidermis beneath.
"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."
The team applied a chemical to two human skin tissue samples causing the skin to become swollen and blistered. The sample treated with the cream saw an immune response helping the skin's own radical scavenging enzymes to recover and halting the production of inflammatory proteins, leading to further responses, including preservation of healthy lower skin layers.
The untreated skin, by contrast, failed to heal.
"The treatment has the effect of setting the skin on a cycle of healing and repair, orchestrated by the immune system," Lu said.
Gianneschi and Lu, who have also been looking into the wider applications of the technology with funding from the National Institutes of Health and the Department of Defense, have discovered melanin could provide protection from heavy metals and toxins, particularly nerve gas.
They demonstrated how a uniform treated with a specially engineered melanin dye absorbed the gas and believe synthetic melanin could also be used to treat burns from radiation, with positive future implications for cancer patients receiving radiotherapy.
Following a recent trial that showed that the synthetic melanins are non-irritating to human skin, the scientists are pursuing clinical translation and trials testing to establish its efficacy.
