Non-invasive neuromodulation techniques - A new era for the treatment of Parkinson’s disease
There is still no treatment that can reverse the effects of Parkinson’s disease, a condition estimated to affect 10 million people worldwide. As life expectancy increases, the number of people suffering from this disease is set to rise in the future, making the need for effective treatment a priority. Doctors prescribe oral medication to alleviate the main symptoms and, for a few patients, use deep brain stimulation. The electrodes stimulate the affected areas and relieve the reactions induced by the disease such as tremor or rigidity. However, this technique presents significant challenges because surgeons have to drill a hole in the skull to implant the electrodes. But what if we could control the neurons without the need of this invasive and expensive procedure? This is the question some scientists asked themselves a few decades ago, opening the doors to what are known as non-invasive neuromodulation techniques. Although manipulating neurons without touching them was regarded as science fiction, this method gained a lot of popularity, and several groups of researchers worldwide jumped onto investigating it for a wide variety of conditions, including Parkinson’s disease. In 2004, one of those techniques, named optogenetics, was described for the first time, revolutionising the field of neuroscience. It consists of genetically modifying the brain cells to express proteins sensitive to light, meaning that a neuron’s activity can be controlled using light pulses. Until last year, this procedure was still considered invasive, as getting the pulses of light inside the brain to control cells required implants. However, this changed last October when a group of researchers from Stanford University reported having successfully developed an implant-free version of the technique, making deep brain optogenetics without surgery possible in mice. Following the principles of optogenetics, a new technique called sonogenetics was proposed in 2015. “We discovered a new set of proteins, which are not normally expressed in the cells that we are trying to control. And the special thing about these proteins is that they are sensitive to ultrasound,” explains Sreekanth Chalasani, associate professor at the Salk Institute for Biological Studies, in the US, and the first who described sonogenetics. “By delivering these proteins to the affected cells, they become responsive to ultrasound,” he says. “You don’t need any surgery, you stick your transducer on the skull, and you deliver the ultrasound to control the cells”. Besides the fact that surgery is not needed, one of the main advantages of this technique is its safety, as Chalasani points out. “Ultrasound is sound waves with frequencies higher than what humans can hear. It is safe, non-invasive, and we have a lot of experience with it. For decades, we’ve been using ultrasound to image babies, and to relieve pain,” he explains. Moreover, ultrasound goes through skin and bone. Because of this, “the transducer that produces the ultrasound can be outside of the body and still target structures that are deep in the brain, as is required to alleviate symptoms of Parkinson’s disease,” adds Chalasani. Although a lot has been accomplished since 2015, some questions remain unsolved. On the one hand, scientists need to find a reliable way to introduce light- and ultrasound-sensitive proteins to the human body. “At the moment, we don’t have a way of delivering genes to a specific targets in the human brain,” says Chalasani. “We need a way to express a protein just in the desired cells, and not anywhere else.” Read the full article on: http://www.fetfx.eu/story/non-invasive-neuromodulation-techniques-new-era-treatment-parkinsons-disease/
Keywords
diseases, neuromodulation, treatment, Parkinson, optogenetics, ultrasound, cells, human body, magnetogenetics, nanoparticles