Biomedical research is breaking ground in finding ways to help the more than 250,000 Americans paralyzed from spinal cord injuries (SCIs) gain better access to everyday life. Researchers at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have successfully developed a wireless device that allows monkeys with lower body paralysis due to SCIs, gain movement in their lower limbs. Although more research is needed before the study results can be applied to humans, the information may someday provide better rehabilitation and improve the overall quality of life for people who are paralyzed, including those suffering from paraplegia and quadriplegia. This development is significant, since just a few decades ago many scientists believed that paralysis due to SCIs was irreversible.
Paralysis, which is often caused by damage to the spinal cord, can also result from genetic abnormalities and various brain-related illnesses. A package of nerve cells and fibers that extends from the brain to the lower back functions mainly to transmit information from the brain to other parts of the body. In order for humans and animals to walk, our brains communicate with our spinal cords by sending messages that tell us to move the muscles in our limbs. However, when the spinal cord is damaged, those signals are not able to pass from the brain to the spine, and ultimately—to the muscles. This damage often can result in impaired movement of the lower limbs, reduced bladder control and paralysis. Injuries to the spinal cord are commonly caused by falls, sports injuries, motor vehicle accidents, and violent acts like gunfire or IED’s on battlefronts. Complications from diseases like arthritis and cancer can also cause paralysis.
Rhesus Macaque Monkeys
The EPFL-developed device was tested in rhesus macaque monkeys, a species of non-human primates (NHPs) which have contributed enormously to medical research, and even preceded man in space. By connecting nodes and prompting nerve signals sent from the brain through the point of lesion in the spinal cord, muscle movement was stimulated. The equipment contains two pieces: an implant consisting of 100 electrodes that is placed over the portion of the brain that controls voluntary movements, and a second implant near the point of lesion in the spine. When the brain releases signals that would normally travel to the spine, they are instead re-routed to a computer, which then signals to the second implant that the leg would like to move. This transmission of information allows nerves that activate muscles in the legs to move, and even walk. The monkeys involved in this study were paralyzed in one leg, but with the device they were able to walk within just two weeks.
Promising Future Built on Past Discoveries
This exciting new study certainly holds promise for the future, however, we cannot overlook the building blocks of past findings biomedical researchers have discovered throughout the last decade. Prior to this study, years of research had been performed with rodents to prepare and gather data for testing in primates. Results from previous animal research have given paralyzed humans the ability to experience the sense of touch with a robotic arm controlled by the mind, restored a quadriplegic person’s control over a brain implant and electronic sleeve, and given paralyzed rats the ability to walk again.
Non-human primates are invaluable to biomedical research, and essential in paralysis studies because of the sophistication and similarities of their nervous systems to humans. Looking to the future, researchers hope further studies will allow people suffering from paralysis to function more independently and experience a better quality of life.
*Additional information about the contribution of primates to the advancement of biomedical technologies can be found in our white paper, “The Critical Role of Nonhuman Primates in Medical Research”.
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