An end to paralysis from spinal cord injury?

A new drug could help end paralysis in people who suffer spinal cord injuries.

Researchers from Boston Children’s Hospital have been able to revive nerve pathway circuits in paralyzed mice so they can walk again by injecting a compound.

This compound helps produce more of a protein that sends signals to muscles which excite neurons, in turn activating leg muscles.

With a limited number of viable treatments available for paralysis from spinal cord injuries, the team hopes their drug could be a new form of therapy that will help maximize recovery.

Researchers from Boston Children’s Hospital have been able to revive nerve pathway circuits in paralyzed mice by injecting a compound that helps produce more of a protein. This protein sends signals to muscles which excite neurons, in turn activating leg muscles (file image)

The spinal cord carries nerve impulses to and from the brain throughout the body.

A spinal cord injury results in a partial or total loss of feeling and/or mobility.

The chances of recovery and the ability to walk again depend on the extent of the injury.

According to a study on spinal cord injuries in Colorado, one in seven who had complete paralysis upon their injury gained ‘a significant amount of movement back’, reported Craig Hospital in Englewood, Colorado.

In injuries that do not cause total paralysis, such as those who retained some movement in their legs immediately after their injury, three out of four patients regained the ability to walk. 

According to the Shepherd Center, about 17,500 Americans sustain spinal cord injuries every year. 

Previous research to reverse paralysis has focused on regenerating axons, which are nerve fibers that conduct electrical impulses to other cells.

The lab at Boston Children’s Hospital has achieved such regeneration, as well as growing new axons from healthy ones, but haven’t achieved much success in reversing paralysis. 

For this study, the researchers decided to use a treatment that administers electric currents around the injured spinal cord.

When combined with rehabilitation training, spinal cord injury patients have been able to regain some movement. 

The team wanted to see if any drugs might be able to imitate the stimulation but have a longer-lasting effect.

Two groups of mice, one that was treated with the drug and one a control group, were treated for eight to 10 weeks.

Following four to five weeks of treatment, 80 percent of mice receiving the compound regained their stepping ability after two groups of back limb muscles were activated. 

The compound used is called CLP209, which is known to excite neurons. The key is that it activates a protein called KCC2, which is crucial for sending signals from our spinal circuit.

To help us walk, the spinal cord sends two types of signals to the muscles, one that fires up the neurons, which is ChR2, and one that inhibits them, KCC2.

When our spinal cord is injured, not enough KCC2 is produced and our spinal circuit is only sending inhibitory signals to these muscles.

When the mice were injected with the compound, it rose the levels of KCC2 being produced.

The neurons were then receiving an even mix of the signals that tell them to inhibit movement and to excite them.

‘Too much excitation is not good, and too much inhibition is not good either,’ said lead author Dr Zhigang He, a professor of neurology and opthamology at Harvard Medical School.  

‘You really need to get a balance. This hasn’t been demonstrated in a rigorous way in spinal cord injury before.’

Dr He says that he hopes combining this therapy with electrical stimulation could help patients maximize recovery from spinal cord injuries one day.

‘We are very excited by this direction,’ Dr He said.

‘We want to test this kind of treatment in a more clinically relevant model of spinal cord injury and better understand how KCC2 agonists work.’