from Scientific American by Amanda B. Keener
In exosomes, our bodies have an efficient means of transmitting RNA information. Researchers want to use it to deliver drugs.
When Lydia Alvarez-Erviti started her postdoctoral studies at the University of Oxford, UK, in 2008, her goal was to develop gene therapies for neurodegenerative diseases. She had identified her target—α-synuclein, a protein that accumulates in the brains of people with Parkinson’s disease—and designed a short interfering RNA (siRNA) to reduce the amount of α-synuclein made in mice. But she needed to get the siRNA into the brain. The method would have to protect the RNA, cross the barrier between circulating blood and the brain, and be safe enough to use repeatedly. Fortuitously, a colleague had begun studying something that could work—naturally occurring, nano-sized vesicles called exosomes.
Exosomes are 30–100-nanometre-wide lipid spheres that are used by cells throughout the body to transfer small molecules such as microRNA (miRNA). Optimized to travel in the body without attracting undue attention from the immune system, each tiny package is “an ideal drug carrier”, says Juliane Nguyen, a bioengineer at the University of North Carolina at Chapel Hill.