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Paralyzed Rats Walk, Even Sprint After Rehab


This is SCIENCE FRIDAY. I'm Ira Flatow. Journalists should shy away from using the word breakthrough; it is a very rare event. But it's hard to ignore that word when you hear about this experimental rehab technique used in rats.

Rats paralyzed after severe spinal cord injury were able to walk, they could sprint upstairs and even avoid obstacles after a combination of therapies. In a study published in Science, Swiss researchers began by electrically and chemically stimulating the rats' spinal cords. Next, they strapped the rats into a robotic harness for support, and they left the rats to will themselves toward a treat. There's a treat, I'm going to get that treat.

And after six weeks of that training, the rats learned to walk and even run again, and what the team observed was that new neural connections had formed between the brain and the spinal cord, bypassing the injury. Wow.

Dr. Moses Chao is professor of cell biology, physiology and neuroscience at New York University School of Medicine. He's also president of the Society for Neuroscience and was part of the advisory board for the Christopher and Dana Reeve Foundation. He's not affiliated with the study, and he joins us from Washington to comment on its significance. Welcome to SCIENCE FRIDAY.

MOSES CHAO: Thank you, Ira, it's a pleasure to be here.

FLATOW: Is this as surprising to you as it sounds to us?

CHAO: Well, the success of the recovery from spinal cord injury is quite a surprise, but the findings are really built on many basic research work in the last decade.

FLATOW: Describe it to us, what kind of injury that the rats had and what actually happened in the treatment.

CHAO: So this was an injury that was in the spinal cord, the lower spinal cord, and it was actually two different lesions. They were pretty close together. It's not a complete lesion of the spinal cord, so these are really incomplete injuries, but it was enough to cause paralysis in these animals.

FLATOW: And so they electrochemically stimulated the rat's spinal cord.

CHAO: That's right. The treatment was quite interesting because the investigators combined three different methods. One is the electrical stimulation. And the second was treadmill training. They had taken these rats and put harnesses on them and induced them to go through a treadmill. And the third treatment was use of a number of chemicals, neurotransmitters, to really elicit locomotion of the spinal cord.

FLATOW: And the rats were stimulated to go after a piece of chocolate?

CHAO: Yes, either chocolate or cheese. This was to try to induce voluntary movement on the animal's part.

FLATOW: And that seemed to be a critical part of the success here.

CHAO: Yes, that's part of it, surely. Besides the three methods, I think the rats were induced to take part in more voluntary movements.

FLATOW: And the rats that had no goal, had no enticement, they did not do as well.

CHAO: That's correct.

FLATOW: Wow, and so just by willing themselves to go after this, they could help regenerate some of those nerve cells?

CHAO: That's right. So we don't know how much regeneration there was, but certainly signals from the brain to the spinal cord were involved in this - in these new connections, and some of the signals from the brain have to involve voluntary decision-making on the part of the animal. So that's quite an impressive result, that is the brain, the brain's plasticity or ability to change or change its movements was certainly part of the treatment here.

FLATOW: So there was a connection between the willing part of the brain and the growing part of it.

CHAO: There probably is, yeah. We - that was not really investigated, but it was shown in experiments by this group that was reported in Science that stimulation of neurons in the brain could have effects on muscle in these animals. So there was a definite connection between signals in the brain and the spinal cord and also muscle.

FLATOW: Of course the next question I'm going to ask you is the $64 question, and that is: What about humans?

CHAO: Yeah, so that's going to be very interesting. There's already a lot of training on treadmills of patients in rehab that's been carried out for many years at UCLA and also at Louisville. In general, the training is in patients where the injury is not very severe, it's a mild injury to the spinal cord.

But in these human trials, it's very clear that treadmill training can improve locomotion in these patients. So that's been going on for a number of years. For this study, though, the injury was more severe, it was not a complete injury, as I mentioned, but the hope is that by stimulating some of the connections that were perhaps lost, together with the treadmill training and the neurotransmitters, you could get recovery in terms of locomotion.

FLATOW: In other words don't give up so quickly on the more severely injured people.

CHAO: Exactly.

FLATOW: And do you have to create a support system for people, like you have literally a support system to hold the rats up?

CHAO: Yes, in fact, the treadmill training that's usually carried out is with a harness or, in the case of Christopher Reeve, who went through some of this training, he went in a swimming pool and tried to move his legs. So people are immobilized during this kind of training. But in recent work, it's been found that the patients do improve.

FLATOW: So where to go next with this kind of work?

CHAO: Well, I think the fact that these neurotransmitters and the electrical stimulation give these positive effects means there must be a lot of actions through the electrical stimulation and the neurotransmitters to facilitate locomotion and to activate the motor system.

And we need to know a little bit more about the mechanism by which electrical stimulation and these neurotransmitters can sort of awaken these networks of neurons in the spinal cord. But there's a lot of work going on right now, and I'm very hopeful that we'll be able to understand these mechanisms.

FLATOW: Dr. Chao, thank you for taking time to be with us today.

CHAO: Well, thank you.

FLATOW: Dr. Moses Chao professor of cell biology, physiology and neuroscience at New York University School of Medicine and president of the Society for Neuroscience. Transcript provided by NPR, Copyright NPR.