Tag: melanin

New Synthetic Melanin Cream Could Boost Skin’s Natural Healing Process

The synthetic melanin is being applied to inflamed skin. Just under the surface of the skin are green free radicals, also known as reactive oxygen species (ROS). Credit: Yu Chen, Northwestern University

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, published in Nature npj Regenerative Medicine, 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, protecting cells from sun damage with increased pigmentation in response to sunlight. That same pigment in skin also naturally scavenges free radicals in response to damaging environmental pollution from industrial sources and automobile exhaust fumes.

Everyday skin injury

“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 stabilises 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 moisturiser 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 stabilising those upper layers can lead to a process of active healing.”

The scientists used a chemical to create a blistering reaction to a human skin tissue sample in a dish. The blistering appeared as a separation of the upper layers of the skin from each other.

“It was very inflamed, like a poison ivy reaction,” Lu said.

They waited a few hours, then applied their topical melanin cream to the injured skin. Within the first few days, the cream facilitated an immune response by initially helping the skin’s own radical scavenging enzymes to recover, then by halting the production of inflammatory proteins. This initiated a cascade of responses in which they observed greatly increased rates of healing. This included the preservation of healthy skin layers underneath. In samples that did not have the melanin cream treatment, the blistering persisted.

“The treatment has the effect of setting the skin on a cycle of healing and repair, orchestrated by the immune system,” Lu said.

Melanin could protect from toxins including nerve gas

Gianneschi and Lu are studying melanin as part of US government-funded research, which has included looking at melanin as a dye for clothing that would also act as an absorbent for toxins in the environment, particularly nerve gas. They showed they could dye a military uniform black with the melanin, and that it would absorb the nerve gas.

Melanin also absorbs heavy metals and toxins. “Although it can act this way naturally, we have engineered it to optimise absorption of these toxic molecules with our synthetic version,” Gianneschi said.  

The scientists are pursuing clinical translation and trials testing for efficacy of the synthetic melanin cream. In an initial step, the scientists recently completed a trial showing that the synthetic melanins are non-irritating to human skin.

Given their observation that melanin protects biologic tissue from high energy radiation, they surmise that this could be an effective treatment for skin burns from radiation exposure.

The promising work may well provide treatment options for cancer patients in the future, undergoing radiation therapy.

Source:

New Technique Enhances Clarity of Photoacoustic Imaging in Dark Skin

Photo by Nsey Benajah on Unsplash

In photoacoustic imaging, laser light is pulsed through the skin into tissues, which release ultrasound signals with which the internal structure can be imaged. This works well for people with light skin but has trouble getting clear pictures from patients with darker skin. A Johns Hopkins University-led team found a way to deliver clear pictures of internal anatomy, regardless of skin tone. Their technique is described in the journal Photoacoustics.

In experiments the new imaging technique produced significantly sharper images for all people – and excelled with darker skin tones. It produced much clearer images of arteries running through the forearms of all participants, compared to standard imaging methods where it was nearly impossible to distinguish the arteries in darker-skinned individuals.

“When you’re imaging through skin with light, it’s kind of like the elephant in the room that there are important biases and challenges for people with darker skin compared to those with lighter skin tones,” said co-senior author Muyinatu “Bisi” Bell, Associate Professor at Johns Hopkins. “Our work demonstrates that equitable imaging technology is possible.”

“We show not only there is a problem with current methods but, more importantly, what we can do to reduce this bias,” Bell said.

The findings advance a 2020 report that showed pulse oximeters, which measure oxygen rates in the blood, have higher error rates in Black patients.

“There were patients with darker skin tones who were basically being sent home to die because the sensor wasn’t calibrated toward their skin tone,” Bell said.

Bell’s team created a new algorithm to process information from photoacoustic imaging, a method that combines ultrasound and light waves to render medical images. Body tissue absorbing this light expands, producing subtle sound waves that ultrasound devices turn into images of blood vessels, tumours, and other internal structures. But in people with darker skin tones, melanin absorbs more of this light, which yields cluttered or noisy signals for ultrasound machines.

The team was able to filter the unwanted signals from images of darker skin, in the way a camera filter sharpens a blurry picture, to provide more accurate details about the location and presence of internal biological structures.

The researchers are now working to apply the new findings to breast cancer imaging, since blood vessels can accumulate in and around tumours. Bell believes the work will improve surgical navigation as well as medical diagnostics.

“We’re aiming to mitigate, and ideally eliminate, bias in imaging technologies by considering a wider diversity of people, whether it’s skin tones, breast densities, body mass indexes – these are currently outliers for standard imaging techniques,” Bell said. “Our goal is to maximise the capabilities of our imaging systems for a wider range of our patient population.”

Source: John Hopkins University

Ultra-protective Sunscreens May One Day be Based on Our Own Melanin

Photo by Rfstudio on Pexels

Our body’s own melanin has long held potential as an inspiration for ultra-protective sunscreens, but has been too unstable to properly study. In Nature Chemistry, researchers report a major advance in understanding the fundamental structure of melanin and one of its subunits that turns light into heat, protecting the body from sun damage.

Melanin is the body’s natural pigment that is its first and best natural defence against the damaging effect of ultraviolet radiation. Cosmetics companies have long tried to harness the protective powers of natural and synthetic melanin for use in chemical sunscreens and other personal care products. For example, melanin could, in theory, be used to produce a radiation barrier that augments skin care products by matching a more diverse range of natural skin tones. But melanin is so notoriously unstable and difficult to study that, thus far, scientists have not been able to see what it looks like at the molecular level, resulting in a slow, trial-and-error approach to its potential use in personal care products.

“As we gain a better understanding of the structure of melanin, we should be able to predictably make alternatives that perform better than what is currently available,” said Jean-Philip Lumb, one of the lead authors of the paper. The study found that the melanin component converted light into heat from all wavelengths, spanning the ultraviolet to the infrared, offering a broad spectrum of protection. The molecule was also remarkably small, which the researchers say has practical benefits because the number of atoms needed to provide this level of sun protection is fewer than anything reported up to now. “We’ve taken a major step forward in understanding a new mechanism for how melanin can serve as a sunscreen,” Lumb said.

Source: McGill University

People with Blue Eyes Share a Single Ancestor

Eye
Source: Daniil Kuzelev on Unsplash

New research published in Human Genetics shows that people with blue eyes trace their ancestry back to a single individual. Researchers tracked down a genetic mutation which took place 6–10 000 years ago and is the cause of the eye colour of all blue-eyed humans without albinism alive on the planet today.

While blue eyes evolved only once, blonde hair has evolved at least twice: in Melanesian populations, blonde hair evolved independently to European populations, involving a mutation in a different gene.

“Originally, we all had brown eyes,” said Professor Hans Eiberg from the University of Copenhagen. “But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a ‘switch’, which literally ‘turned off’ the ability to produce brown eyes.” The OCA2 gene codes for the P protein, which is involved melanin production. This ‘switch’, located in the gene next to OCA2, does not completely shut off production but instead is limited to reducing the production of melanin in the iris, effectively ‘diluting’ brown eyes to blue. The switch’s effect on OCA2 is very specific therefore. If the OCA2 gene is completely destroyed or turned off, albinism would be the result.

Eye colours from brown to green depend on the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes. “From this we can conclude that all blue-eyed individuals are linked to the same ancestor,” said Professor Eiberg. “They have all inherited the same switch at exactly the same spot in their DNA.” Brown-eyed individuals, by contrast, have considerable individual variation in the area of their DNA that controls melanin production.

Professor Eiberg and his team studied mitochondrial DNA and compared the eye colour of blue-eyed individuals in countries as diverse as Jordan, Denmark and Turkey. His research stretches back to 1996, when he first implicated the OCA2 gene as being responsible for eye colour.

The mutation of brown to blue eyes does not confer any evolutionary advantage, as with others such as hair colour.

As Professor Eiberg explained, “it simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so.”

Source: University of Copenhagen