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A $2.99 tube of moisturizer from your neighborhood drugstore could soon deliver gene-regulation technology for treating skin cancer and other ailments, according to a team of researchers from Northwestern University. Because the skin’s formidable defenses make it difficult for drugs to penetrate deep into cells below, scientists enlisted a nanostructure with the unique ability to break past those barriers. Normal, linear nucleic acids cannot get into cells, but the nanoparticle’s unique spherical shape and densely packed orientation of nucleotides can. At one-thousandth the diameter of a human hair, the structure is able to permeate through several layers of skin, allowing small interfering RNA molecules on its periphery to target and “switch off” disease-causing genes.
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Led by Amy S. Paller, chair of dermatology and professor of pediatrics at Northwestern University Feinberg School of Medicine, and Chad Mirkin, the director of Northwestern’s International Institute for Nanotechnology, the study could redefine the field of gene regulation. “[The technology] allows us to treat a skin problem precisely where it is manifesting—on the skin,” Paller says. “We can target our therapy to the drivers of disease, at a level so minute that it can distinguish mutant genes from normal genes.”
Early targets include melanoma and squamous cell carcinoma, two of the most common types of skin cancer.
By combining the nanostructures with commercial moisturizer, researchers created a therapeutic ointment that they used to target melanoma and squamous cell carcinoma (two of the most common types of skin cancer), psoriasis, diabetic wound healing, and a rare genetic skin disorder known as epidermolytic ichthyosis. Future targets could include wrinkles caused by aging.
It was Mirkin who first developed the nanostructure platform in 1996. Since cleared by the U.S. Food and Drug Administration, the technology is now the cornerstone of some of the most powerful commercial medical-diagnostic tools. The Northwestern study, however, is the first time the nanostructures have been used to deliver a large payload of therapeutics through the skin.
Because the treatment is skin specific, it doesn’t interfere with other cells. Nor have tests demonstrated any side effects.
“We now can go after a whole new set of diseases,” Mirkin says. “Thanks to the Human Genome Project and all of the genomics research over the last two decades, we have an enormous number of known targets. And we can use the same tool for each, the spherical nucleic acid. We simply change the sequence to match the target gene. That’s the power of gene-regulation technology.”
Because the treatment is skin-specific, it doesn’t interfere with other cells. Tests on mice and human epidermis also showed no evidence of side effects, any inappropriate triggering of the immune system, or the accumulation of the nanoparticles in organs. “This study is a landmark achievement in the area of gene regulation,” Mirkin adds. “I believe our work has a chance to positively and irreversibly change the field.”