JUL-AUG 2019

MedEsthetics—business education for medical practitioners—provides the latest noninvasive cosmetic procedures, treatment trends, product and equipment reviews, legal issues and medical aesthetics industry news.

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Page 31 of 68 | JULY/AUGUST 2019 29 © GETTY IMAGES Yarosh, who is the inventor of a DNA liposomal repair technology for use in topical skin care, did his postdoctoral research in the late 1970s on using bacterial DNA repair enzymes as reagents to fi x damaged DNA in human cells. "Although we could do it, the early methods were crude and toxic to the cells," he says. "I searched for safer and more effective methods than the chemicals we were using, and after reading about liposome drug delivery, I decided to try it with enzymes on skin. I started a biotech company to do this, and after a few years we patented a liposome method to get DNA repair enzymes into the skin and then the cells without toxicity." His own work was inspired by Tomas Lindahl, Paul Modrich and Aziz Sancar, who jointly won the 2015 Nobel Prize in Chemistry for their decades of research on "mechanistic studies of DNA repair." " "They each studied a different type of DNA repair, demonstrating how it happens and which enzymes are involved," says Yarosh. "Their discoveries allowed me to design and engineer a practical way to use these enzymes in human health." For example, sun exposure causes a very specifi c chemical change in DNA, in which two DNA bases are linked together, interfering with the coding information. "DNA repair enzymes recognize this altered change and start the process of reversing the damage," explains Yarosh. "Some repair enzymes trigger the removal of the damaged bases and re-synthesis using the opposite strand as a template. Others directly split the fused bases without DNA strand cutting." In a paper published in The Lancet on March 24, 2001, Yarosh and his team showed that DNA repair enzymes extracted from plankton reduced skin cancers by 30 percent and precancers by 68 percent. The placebo- controlled study included 30 patients with xeroderma pigmentosum, a rare disease in which sufferers cannot tolerate sunlight becasue they lack DNA repair enzymes. Previous research had shown that DNA repair enzyme T4 endonuclease V—when delivered intracellularly— increased the rate of repair of sunlight-induced DNA damage in human cells. For their 2001 paper, Yarosh and his colleagues used a liposomal delivery vehicle to apply the enzyme topically. Twenty patients received the active and 10 received a placebo lotion daily for one year and were followed every three months. At each visit, the rates of new actinic keratoses and basal-cell carcinomas were signifi cantly lower in the treatment group. Yarosh notes that the same DNA lesions that the en- zymes recognize are the ones that lead to mutations that cause skin cancer, so removing the lesions should reduce skin cancer risk. "In animal studies, UV-induced skin can- cers were prevented by treating the animals topically with DNA repair enzymes," he says. "In several human studies, these DNA repair enzymes have reduced the rate of actinic keratosis. And in a few studies in patients with compro- mised DNA repair and very high rates of skin cancer, these DNA repair enzymes have lowered skin cancer rates." "In animal studies, UV-induced skin cancers were prevented by treating the animals topically with DNA repair enzymes."

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