Researchers have already demonstrated in the lab that the materials the body uses to make proteins can also successfully suppress several different types of viruses, including HIV and influenza A, by disrupting the formation of viral proteins. Less clear, however, was how to get these virus-busting molecules where they needed to be in the body in order to keep viruses from spreading. Now a team of Yale University researchers believe they have found an effective way of delivering these special, short-interfering RNA (siRNA) molecules to specific locations within the body's biological battlefield.
The key is hitching siRNA molecules (a class of double-stranded RNA molecules that cells can use to control protein production) to microscopic particles of a biodegradable polymer known as polylactic-co-glycolic acid (PLGA) that can ferry these virus fighters to the site of the infection, according to a report published online today in Nature Materials. While this approach is at a very early stage, researchers report being able to use the PLGA particles deliver siRNAs to tissue lining the female mouse reproductive tract, which resembles that of the female reproductive system. Once there, the siRNAs penetrate to reach cells below the surface of the mucosa, and distribute the molecules throughout the vaginal, cervical, and uterine regions. Beyond reaching their intended target, the siRNAs reportedly remained in the tissues (effectively disrupting virus activity) for up to 14 days. It's important to note that the experiment has been successful in cell cultures, as opposed to live mice.
The researchers, lead by Kim Woodrow, a Yale postdoctoral fellow in the School of Engineering & Applied Science, were looking for a way to deliver siRNAs with a material approved by the U.S. Food and Drug Administration (FDA). The FDA has already approved PLGA for use in grafts, sutures, prosthetics and other therapeutic devices due to its biodegradability and biocompatibility. The PLGA approach to delivering siRNA could, Woodrow said in a statement, allow people to protect themselves using antimicrobial treatments (most likely via prescription) that they administer themselves, rather than relying on an injection administered by a physician. Her research was funded by grants from the National Institutes of Health and fellowship support from the L'Oreal-Unesco's For Women in Science (FWIS) program.
SiRNA has shown potential to also disrupt the spread of the influenza A virus, according to a 2003 study conducted by Massachusetts Institute of Technology (M.I.T.) researchers at the Center for Cancer Research and the school's Department of Biology. Meanwhile, new uses for nanomaterials continue to emerge. ScientificAmerican.com reported last year on the study of nanoparticles as drug carriers.
Image of Kim Woodrow © Yale
Image of distribution of nanoparticles seen by fluorescence throughout mouse reproductive tract © Woodrow/Yale