Paraplegic rat, with spinal cord completely split in two, walks fluently and even jumps over obstacles.
Scientists have made a paraplegic rat, with its spinal cord completely split in two, walk with amazing fluidity on a treadmill and even jump over obstacles.
Upright on her hind legs thanks to a harness that works like a mother helping her child walk , she is capable of taking more than 1,000 steps in 25 minutes, without fail, despite having cut the cord, the cable that connects the brain with the legs. The password to watch the video before its official publication was illustrative: “Usain Bolt”, as the fastest runner in the world.
The rodent’s movements, however, are not voluntary. The five protagonist rats in the experiment are like puppets moved by invisible strings: two flexible electrodes that transmit electrical impulses over their spinal cord. Behind these invisible threads is the Spanish neuroengineer Eduardo Martín Moraud and his team from the Federal Polytechnic School of Lausanne (Switzerland).
” We have placed electrodes in the neuronal circuits of the spinal cord, below the lesion, and replaced the electrical signals that should come from the brain , ”he explains by phone. The technique, known as epidural electrical stimulation, is not new. In 2009, the American neuroscientist Reggie Edgerton demonstrated that paraplegic rats could take more or less coordinated steps after receiving electrical impulses in an injured spinal
cord.Reactivating the spinal cordThis
same 2014, also thanks to Edgerton’s team, four men who had been paraplegic for years were able to voluntarily move their hips, ankles and toes thanks to continuous electrical stimulation on your spinal cord.The four young people suffered a partial spinal cord injury, typical in traffic accidents. Thanks to the electricity, the spinal cord reactivated the residual neural circuits that connected it to the brain, and the boys were able to move some of their muscles voluntarily again.
But the new study in Switzerland “goes further”, in the words of the Spanish neuroengineer. Thanks to a network of cameras and a sophisticated mathematical algorithm that monitors the movements of the rats, the system self-modulates and optimizes the electrical impulses that the rodents receive., so that your steps and jumps are perfect. “Not only is the spinal cord reactivated, but it can be modulated in real time,” says Martín. By increasing the frequency of electrical impulses, the legs rise higher. The system takes advantage of this feature to adapt in real time the progress of the rats to the obstacles they find in their path, without the need for human intervention. “ The rats have walked without fail for 25 minutes on a treadmill without us touching anything ,” stresses the Spanish scientist, a 30-year-old telecommunications engineer who studied at the Polytechnic University of Madrid but has researched outside of Spain from the beginning. .
The authors of the work, published a few days ago in the journal Science Translational Medicine, believe that this strategy could be used in the future to improve rehabilitation programs for people with spinal cord injuries , preventing loss of muscle mass and facilitating the recovery of locomotion. “You must not create false expectations. We are where we are and the rest are assumptions”, warns Martín.먹튀검증
Achilles’ heel
The main person in charge of the new study, the French neuroscientist Grégoire Courtine, maintains that the technique could be applied to a dozen volunteers from the summer of 2015, if the Swiss authorities approve the clinical trials.The facilities to carry them out are ready, in a 100-square-meter room at the Lausanne University Hospital. The plan is part of the European NEUWalk project, financed with nine million euros from the EU.
The Achilles heel of the research, Courtine admits, is that the success in rats has been due in part to injecting a cocktail of drugs that facilitates the action of electrical stimulation into the paralyzed legs of rodents.“The pharmacological components are not yet ready to be transferred to humans,” acknowledges the neuroscientist, who in 2013 gave a successful talk at the annual congress of the TED organization in Edinburgh (United Kingdom), entitled “The paralyzed rat that walked.” The conference summarized his previous research, in which rodents took steps, but without the perfection provided by the new self-modulation technique.
Courtine’s team is also now working on what is now science fiction. “We are implanting probes in the motor cortex of the [rat’s] brain to decode their movement intentions and use this activity to regulate spinal cord stimulation,” he explains.The system, in a very experimental phase, would allow an external device to connect the brain and legs even with a spinal cord split in two.
The pioneer of the technique, Reggie Edgerton, of the University of California, Los Angeles, applauds the therapeutic potential of the new work, in which he was not involved. “ This strategy may allow a person to carry out a task, such as walking, in a more automatic way, reducing the burden of having to consciously control these arousal properties, ” he opines.
In his opinion, the start of clinical trials in humans in 2015 would be “encouraging”, but he calls for caution: “It must be clear that we are taking the first steps to understand how to take advantage of the residual function of the spinal cord that persists in many people with injuries serious”.