Randomised controlled trial showing spinal cord regeneration (in dogs)

A research team in Cambridge recently undertook the first double blind trial (neither the researchers or the pet owners knew which pets were receiving the real treatment) to test a transplant technique involving olfactory ensheathing cells in "real-life" spinal injuries suffered by dogs. Real life in the sense that the dogs were injured spontaneously and accidentally rather than in the controlled environment of a laboratory. The treatment was also given sometime after the injury occurred.

The transplant consisted of olfactory ensheathing cells* being removed from the lining of the nose. These were then grown and expanded for several weeks in the laboratory.

*The only part of the body where nerve fibres continue to grow in adults is the olfactory (smell) system. Olfactory ensheathing cells (OEC) which are found in the back of the nasal cavity surround the receptor neurones that enable us to smell and convey these signals to the brain. These nerve cells need constant replacement which is promoted by the OEC.

It has been thought for some time that OEC may be useful in spinal chord repair and this recent study supports this.

The trial provides "proof of concept", of the 34 dogs involved 23 had OEC transplanted into their injury site - the remainder were injected with a neutral fluid (a placebo). The results were positive, many of the dogs which received transplant cells showed considerable improvement and were able to walk on a treadmill with the support of a harness. As expected no improvement was seen in the control group.

The transplanted cells regenerated nerve fibres across the damaged region of the spinal cord. As a consequence the dogs were able to regain the use of their back legs and more importantly co-ordinate movement with their front limbs.

However these new nerve connections did not occur over the long distances that would be required to connect the brain to the spinal cord, something which would be crucial for human spinal injury patients who had lost sexual function and bowel/bladder control. Given that in a survey of spinal injury patients these two factors were rated higher in importance than improved mobility.

So how significant is this research and what are its possible clinical implications/benefits for the future? Well, Prof. Geoffrey Raisman 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." Furthermore despite the recovery seen amongst the dogs in the trial, in humans "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."

(Source: BBC Health News - also click here to see a video of the transformation from immobility to unassisted mobility in one of the dogs)