'Bionic' spinal implant helped paralysed rats walk

"Elastic implant 'restores movement' in paralysed rats," BBC News reports after researchers developed an implant that can be used to treat damaged spinal cords in rats.

The spinal cord, which is present in all mammals, is a bundle of nerves that runs from the brain through the spine, before branching off to different parts of the body.

It is the main "communication route" the brain uses to control the body, so damage usually results in some degree of paralysis or sensory loss, depending on the extent of the injury.

This promising research developed a novel spinal cord implant that has been able to restore movement in paralysed rats. The implant is made of a flexible material that is able to integrate and move with the spinal cord.

This overcomes problems found with previously tested rigid and inflexible implants, which have caused inflammation and quickly stopped working.

The implant works by delivering both electrical and chemical signals, and enabled the rats to walk again for the six weeks of testing.

However, the research is mainly "proof of concept" at this stage, showing the technique works in animals – at least in the short term. It remains to be seen whether implants are safe and effective at restoring movement in people with paralysis. 

Where did the story come from?

The study was carried out by researchers from École Polytechnique Fédérale de Lausanne in Switzerland and other institutions in Switzerland, Russia, Italy and the US.

Financial support was provided by various organisations, including the Bertarelli Foundation, the International Paraplegic Foundation, and the European Research Council.

It was published in the peer-reviewed journal, Science Magazine. 

Of all the UK coverage, BBC News reported the research most accurately, and included quotes about the promising nature of the research, but also due caution about the long timeline ahead before it is known whether such implants could be used in people.

Other headlines, such as that in The Times, arguably offer premature hope of a new treatment that can help the paralysed walk again. 

What kind of research was this?

This animal research aimed to develop a new flexible spinal implant to restore movement after a spinal cord injury.

Implants are just one of the ways medical science is exploring how to help people who have spine injuries regain sensation and movement.

In the past, electrical implants for the spinal cord encountered problems because spinal cord tissue is soft and flexible, while the implants of old were often rigid and inflexible.

The researchers expected implants with mechanical properties matching those of the host tissue would work better and for longer.

Here, they designed and developed a new soft electrical implant, which has the shape and elasticity of the dura mater, the outermost layer of the protective membranes (meninges) that cover the brain and spinal cord.

The device was tested in paralysed rats. Animal studies are a valuable first step in the development of treatments that may one day be used in people.

However, the road ahead is a long one in terms of developing the treatment for testing in people, hopefully followed by trials of its safety and effectiveness.

What did the research involve?

The researchers developed a silicone implant they called electronic dura mater, or e-dura. This implant has interconnecting channels that transmit electrical signals and can also deliver drugs. It was made for surgical insertion just beneath the dura mater layer.

They first tested the long-term functionality of this soft implant compared with conventional stiff implants. Long-term meant testing the device for six weeks.

Each type of implant was inserted into the lower part of the spinal cord of healthy rats. The rats were then assessed using specialised movement recordings, and the rats with the soft spinal implant were able to behave and move as normal.

However, rats with the stiff implants started to demonstrate problems with their movement one to two weeks after surgery, which only deteriorated further up to six weeks.

When examining the rats' spinal cords after the implants were removed at six weeks, the researchers found rats with the stiff implants displayed significant deformity and inflammation in the spinal cord. None of these adverse effects were observed in those who had the soft implant.

They followed this with a series of further tests of the mechanics and functioning of the soft implant, both in the laboratory using a model of spinal cord tissue and in further tests in healthy rats.

The researchers also examined the ability of e-dura to restore movement after spinal cord injury.

The rats received a spinal cord injury that led to permanent paralysis of both hind legs. The e-dura implant was then surgically inserted in the spinal cord, and drug therapy and electrical stimulation were delivered through the electrode to see how it worked. 

What were the basic results?

Most of the results in the publication relate to the initial developmental stages of the device. When it came to the paralysed rats, relatively little was said.

However, what the researchers did say is the combination of electrical and chemical stimulation through the implant enabled the paralysed rats to move both of their hind legs again and walk, apparently as normal (though this isn't specifically stated).

The e-dura implant was able to bring about these effects for the six-week period it was tested. 

How did the researchers interpret the results?

The researchers concluded they have developed a soft implant that shows long-term biointegration and functioning with the spinal cord.

The implants met the demanding mechanical properties of the spinal tissue, with a limited inflammatory reaction that has been seen with other implants.

When used in paralysed rats, the implant allowed for electrical and chemical stimulation to restore movement deficits over an extended period of time.

Conclusion

This is promising research that demonstrates how a new spinal cord implant has been able to restore movement in paralysed rats.

The e-dura implant is a breakthrough in that it overcomes a lot of the problems presented by previous rigid and inflexible implants. Instead, it is made of a flexible material that is able to integrate with spinal cord tissue.

The study demonstrated long-term functionality in rats and few side effects over the six-week testing period.

Rats given a serious spinal cord injury, who were consequently permanently paralysed, were able to walk again after the implant was surgically placed in their spinal cord. The implant works by delivering both electrical and chemical signals.

However, this research is still in the very early stages. While the findings are promising, there is a long way to go before we know whether these implants can be developed to successfully help humans with spinal injuries.

If the implants were developed for human testing, they would need to go through several stages of safety and effectiveness testing to see whether they worked at restoring movement in paralysed people.

It also needs to be seen how they would function in the much longer term, beyond just a few weeks.

Loss of movement is only one of the ways a person can be affected by permanent paralysis of both legs.

We do not know whether this implant would have any effect on loss of bladder, bowel or sexual function, for example.

These effects can have as much of a detrimental effect on quality of life as loss of physical movement.

But, overall, this is promising early-stage research and future developments are awaited with anticipation.