Scientists are a step closer to creating a natural sunscreen that mimics the body’s own protection mechanisms.
In a paper published in the American Chemical Society journal, ACS Central Science, scientists from the University of California San Diego (UCSD) described their development of nanoparticles that mimic the way the human body naturally develops sunscreen in the skin.
Melanosomes are cell structures that produce melanin, the pigment that gives human skin, hair, and eyes their color, and also offers some protection from the sun.
"Basically, we succeeded in making a synthetic version of the nanoparticles that our skin uses to produce and store melanin, and demonstrated in experiments in skin cells that they mimic the behavior of natural melanosomes," said Nathan Gianneschi, PhD, a professor of chemistry and biochemistry, materials science and engineering, and nanoengineering at UCSD, who headed the team of researchers, in a press release.
Using melanin as sunscreen
In humans, melanin is made in different parts of the body.
In the skin, melanin is excreted by cells called melanocytes and then consumed by keratinocytes. Keratinocytes then “tan” and use the melanin to make tiny umbrellas to shield their nuclei from the sun.
“These are interesting as the ‘screen’ is inside cells, not just on the surface. The term for the melanin-based screen in our skin cells is ‘microparasol’. I very much like that term, as it nicely captures how these look if you look at cells with high-resolution methods,” Gianneschi told Healthline.
An absence of melanin from the skin makes an individual more susceptible to damage from the sun’s radiation. Those living with vitiligo and albinism are at particular risk.
Vitiligo causes a loss of color in the skin in blotches. It occurs when the cells that produce melanin die or stop functioning.
Albinism is a genetic condition that reduces the amount of pigment in the skin, eyes, and hair.
Hoping for new treatments
The scientists from UCSD hope their synthetic nanoparticles will be able to create new treatments for melanin-defective diseases.
“These systems have potential as artificial melanosomes for the development of novel therapies, possibly supplementing the biological functions of natural melanins,” the researchers said in their paper.
Dr. Adam Friedman, an associate professor of dermatology at the George Washington University School of Medicine and Health Sciences, said it is an interesting concept.
“They have their work cut out for them, but this is a great example of how nanotechnology can help us overcome many of the limitations preventing us from translating biology into bold new drugs,” Friedman told Healthline.
“This research focuses on the end product of melanin being made, packaged, and sent off to the other skin cells. So in essence, you would be bypassing the problems if the nanoparticles could actually get into the skin,” he said.
Gianneschi said if the synthetic nanoparticles were developed to a point where they could then be used as a cream, the benefits could be significant.
“If it could indeed pass across the skin having been topically applied. It could be a way to give the skin some natural protection, and the appearance of tanning. This could be valuable from a UV protection standpoint in the skin, but also elsewhere including in the eyes,” he told Healthline.
Possible uses, obstacles
It’s possible the invention could also be used for general sun protection and, Gianneschi said, even in cosmetics.
“If this could work by topical application, then I think you could view this as a way to protect you from longer-term damage from the sun. Beyond the medical benefit, one could also imagine desirable properties as a cosmetic. A cosmetic that would give one a natural looking tan, but also skin protection,” he said.
But it could be a long way off before such a topical cream is created.
Friedman said it may be too early to get excited about the work.
“Until these nanoparticles are evaluated in either a 3-D (not 2-D) skin model or more importantly, a living thing [pig skin is the most analogous to human skin], then all the press and excitement is a bunch of social media overstated hype,” he said.
Gianneschi concedes far more research into the nanoparticles is necessary.
“Our study was basic science, and in cells only, not in real tissues. Getting them [the nanoparticles] across the skin and into skin cells is not trivial. It will require more research and development. What we have done is a proof of concept in monolayer cell culture only. Not in an organism, where the system is far more complex,” he said.