For years I suffered from hay fever, with swollen eyes, fatigue and a runny nose that made my head feel like a stuffed balloon. Then I got pregnant and they went away. Go figure. But little did I know when I was cursing late summer and those waving golden rods along the side of the road, the runny nose and its “mucosal secretions,” or mucus, were helping me keep viruses and other bad microbes away from my body.
Unfortunately, they also water down any medication, taken to treat “infections and inflammation that occur when an infectious agent…penetrates the body's defenses,” according to a story by Larry Greenemeier of Scientific American.
Since even nanoscale particles of medicine (smaller than a grain of salt) can be flushed away by layers of mucus before they can treat an illness, a team of Johns Hopkins University scientists decided to see if they couldn’t find something that could still get deeply into the body’s defense system that wouldn’t be washed away. They developed “specially coated nanoparticles that can penetrate deep into the body's defenses and remain long enough kill harmful microbes,” according to Greenemeier. The organ they used was one you might be surprised to know.
Greenemeier reports that the researchers broke up the herpes-fighting drug acyclovir (which heals sores or blisters) into nanosize units “coated with low–molecular weight polyethylene glycol (PEG)” and then applied them to female mice in a vaginal gel.The PEG-coated acyclovir particles – only slightly larger than a virus – penetrated the cervico-vaginal mouse mucus and remained in the vaginal folds for 24 hours.
Less than half the mice receiving this treatment were infected with herpes simplex virus while 84 percent of mice given the same concentration of acyclovir but using uncoated nanoparticles were infected, the researchers reported Wednesday in Science Translational Medicine.
Greenemeier quoted Justin Hanes, a project researcher and director of the Center for Nanomedicine at the Johns Hopkins University School of Medicine, as saying this is the first time the researchers can report a successful nanomedical herpes treatment in living animals.
The researchers picked the vagina to experiment on because it’s one of the places microbicides fail, as the vagina has deep folds, allowing it to expand during childbirth or intercourse, and they can’t penetrate the body deeply enough, Hanes said.
Hanes is also a co-founder of Kala Pharmaceuticals, a Waltham, Mass.–based company he formed with MIT Professor Robert Langer to develop mucus-penetrating nanoparticles for treating diseases in the eyes and lungs.In many parts of the body, as well as the sinuses, the body clears mucus layers every few minutes. "We needed to design a system that, like some viruses capable of infecting humans at mucosal surfaces, would allow treatment to penetrate deep into the mucus layer where they would not be cleared as rapidly by the body," Hanes told Greenemeier.
"Our goal was to coat and line the epithelium with particles [of acyclovir] and then have them stay there with a uniform distribution and release the drug over a longer period of time than you'd have if you administered the treatment in a standard gel preparation that uses uncoated nanoparticles."Greenemeier also interviewed Paula Hammond, a chemical engineering professor at M.I.T. Hammond, who did not participate in the Johns Hopkins research. "The use of a nanoscale delivery vehicle with this type of surface functionality is key to this advance,” she said.
Hammond is also studying PEG-coated nanoparticles to penetrate and treat cancerous tumors. "The work shows the relevance of nanomedicine not only for treatment of diseases such as cancer, but for a breadth of other medical applications,” she told Greenemeier.Hanes and his colleagues are also studying other illnesses that might be treated with their “stealthy nanoparticles,” as Hammond calls them, including those of the eyes, and cancers of the lung and cervix, as well as an HIV drug, tenofovir, to try to make it more effective.
The team is not the only one looking for ways nanoparticles can penetrate the body to heal. University of Texas at Arlington researchers are using magnetic carbon nanoparticles to target and destroy cancer cells through laser therapy – a treatment that also might be applicable to skin and other cancers without damaging surrounding healthy cells.
Researchers at MIT and Harvard Medical School have built targeted nanoparticles “that can cling to artery walls and slowly release medicine, an advance that potentially provides an alternative to drug-releasing stents in some patients with cardiovascular disease,” according to the source.
Edited by
Braden Becker
