The pets had all suffered spinal injuries which prevented them from using their back legs.
The Cambridge University team is cautiously optimistic the technique could eventually have a role in the treatment of human patients.
The dogs had olfactory ensheathing cells from the lining of their nose removed.
These were grown and expanded for several weeks in the laboratory.
Of 34 pet dogs on the proof of concept trial, 23 had the cells transplanted into the injury site – the rest were injected with a neutral fluid.
Many of the dogs that received the transplant showed considerable improvement and were able to walk on a treadmill with the support of a harness.
Professor Robin Franklin, a regeneration biologist at the Wellcome Trust-MRC Stem Cell Institute and report co-author, said: ‘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.
“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 they might be able to regain all lost function. ‘
Prof Franklin said the procedure might be used alongside drug treatments to promote nerve fibre regeneration and bioengineering to substitute damaged neural networks.
The researchers say the transplanted cells regenerated nerve fibres across the damaged region of the spinal cord. This enabled the dogs to regain the use of their back legs and coordinate movement with their front limbs.
The new nerve connections did not occur over the long distances required to connect the brain to the spinal cord. The MRC scientists say in humans this would be vital for spinal injury patients who had lost sexual function and bowel and bladder control.
Prof Geoffrey Raisman, chair of Neural Regeneration at University College London, who discovered olfactory ensheathing cells in 1985 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.”
He said the clinical benefits were still limited: “This procedure has enabled an injured dog to step with its hind legs, but the much harder range of higher functions lost in spinal cord injury – hand function, bladder function, temperature regulation, for example – are yet more complicated and still a long way away.”
ABSTRACT – This study was designed to determine whether an intervention proven effective in the laboratory to ameliorate the effects of experimental spinal cord injury could provide sufficient benefit to be of value to clinical cases. Intraspinal olfactory ensheathing cell transplantation improves locomotor outcome after spinal cord injury in ‘proof of principle’ experiments in rodents, suggesting the possibility of efficacy in human patients. However, laboratory animal spinal cord injury cannot accurately model the inherent heterogeneity of clinical patient cohorts, nor are all aspects of their spinal cord function readily amenable to objective evaluation. Here, we measured the effects of intraspinal transplantation of cells derived from olfactory mucosal cultures (containing a mean of ∼50% olfactory ensheathing cells) in a population of spinal cord–injured companion dogs that accurately model many of the potential obstacles involved in transition from laboratory to clinic. Dogs with severe chronic thoracolumbar spinal cord injuries (equivalent to ASIA grade ‘A’ human patients at ∼12 months after injury) were entered into a randomized double-blinded clinical trial in which they were allocated to receive either intraspinal autologous cells derived from olfactory mucosal cultures or injection of cell transport medium alone. Recipients of olfactory mucosal cell transplants gained significantly better fore–hind coordination than those dogs receiving cell transport medium alone. There were no significant differences in outcome between treatment groups in measures of long tract functionality. We conclude that intraspinal olfactory mucosal cell transplantation improves communication across the damaged region of the injured spinal cord, even in chronically injured individuals. However, we find no evidence for concomitant improvement in long tract function.