Nanoparticles Treat Muscular Dystrophy in Mice
Researchers at Washington University School of Medicine in St. Louis have demonstrated a new approach to treating muscular dystrophy. Mice with a form of this muscle-weakening disease showed improved strength and heart function when treated with nanoparticles loaded with rapamycin, an immunosuppressive drug recently found to improve recycling of cellular waste. The investigators, including Kristin P. Bibee, MD, PhD, looked at a mouse model of Duchenne muscular dystrophy, the most severe inherited form of the disease. Duchenne exclusively affects boys who have to rely on wheelchairs by age 12 and die from heart or respiratory failure in their 20s. When treated with rapamycin nanoparticles, the mice showed a 30 percent increase in grip strength and a significant improvement in cardiac function, based on an increase in the volume of blood the heart pumped. The nanoparticle used in the study consists of an inert core made of perfluorocarbon, originally designed as a blood substitute. The particles are about 200 nanometers in diameter—500 times smaller than the thickness of a human hair. The surface of the nanoparticle is coated with rapamycin, which suppresses the immune system. The drug typically is used to help prevent organ rejection in transplant patients. It is known for its anti-inflammatory properties and, more recently, for its role in activating autophagy.