Dogs that had lost the use of their back legs as a result of spinal injuries were able to walk again after a revolutionary transplant operation that might also benefit paralysed patients, scientists said.
The pet dogs had all suffered serious accidental damage to their spinal cords which had left them paralysed and unable to walk normally with their hind limbs.
Following the transplant of specialised cells from the dogs’ noses to the damaged nerves most of the pets recovered their lost mobility and some were able to walk and even run on all four legs, according to a study published today.
Scientists believe the results show that people paralysed with spinal injuries could be treated with the same transplant technique which involves transferring olfactory ensheathing cells from the nasal cavity to the spinal cord.
“Our findings are extremely exciting because they show for the first time that transplanting these types of cell into a severely damaged spinal cord can bring about significant improvement,” said Professor Robin Franklin of the University of Cambridge.
“We’re confident that the technique might be able to restore at least a small amount of movement in human patients with spinal cord injuries but that’s a long way from saying that they might be able to regain all lost functions,” Professor Franklin said.
“It’s more likely that this procedure might one day be used as part of a combination of treatments, alongside drug and physical therapies, for example,” he said.
The study, published in the journal Brain, involved 34 pet dogs that had suffered a severe spinal injury, such as a slipped disc which, in dogs, often results in paralysis.
Scientists transplanted olfactory cells in 23 of the dogs, with the remaining 11 used as controls to see if the treatment had any effect. In order to eliminate experimental bias, the study was a “blind” trial meaning that neither the scientists nor the pet owners knew until the experiment was over which dogs were treated.
All of the dogs had suffered the initial spinal injury at least a year before the study had started and in addition to being unable to use their back legs, they were unable to feel pain in their hindquarters.
Following the treatment, all the dogs were tested on a treadmill to see whether they were able to coordinate the movements of the front and back legs while being supported by a harness.
Professor Franklin said the dogs that received the transplant of olfactory ensheathing cells showed a significant improvement in mobility, which was not seen in the control group of dogs.
“These dogs went from being paraplegic to being able to walk, which is terrific. It absolutely shows that these cells are worth transplanting. It suggests there will be benefit to human patients when applied in a clinical context,” Professor Franklin said.
The normal function of olfactory ensheathing cells is to protect the regrowth of nerve cells in the olfactory centre just below the brain. These nerve cells need to be able to regenerate because they are exposed to regular damage from the outside environment, he said.
The study, funded by the Wellcome Trust and the Medical Research Council, will be used as the basis for phase 2 clinical trials on human patients, which will test the efficacy of the treatment. Phase 1 toxicity trials have already shown that the procedure is safe, Professor Franklin said.
However, the researchers emphasised that the cell transplants are only likely to stimulate the regrowth of spinal nerve cells over short distances. Nerve regeneration over longer distances is unlikely, which means the technique would probably not help to restore lost control over hand movements, sexual function and bladder and bowel movements, the scientists said.
Professor Geoffrey Raisman, chair of neural regeneration at University College London, said: “This is not a cure for spinal cord injury in humans – that could still be a long way off. But this is the most encouraging advance for some years and is a significant step on the road towards it.”