New Drug Relieves Paralysis in Rat Model

Mouse model
Mouse model
A new drug tested in a rat model of spinal cord injury showed improved movement and bladder function.

A new drug developed in a rat model of spinal cord injury may help restore movement and function in paralysis.

The study, which was partly funded by the National Institutes of Health, showed that there is possibility of axon regrowth after spinal cord injury, where the axons of the spinal cord nerve cells are crushed or severed, leading to paralysis. Axon regrowth is normally stymied by scarring from the spinal cord injury when the tyrosine phosphate sigma (PTP sigma) enzyme found in axons interacts with chondroitin sulfate proteoglycans, a sugary protein that fills the scars.

Bradley Lang, PhD, of Case Western Reserve University School of Medicine, and colleagues designed a drug, ISP, that blocks the enzyme and allows for the drug’s entry into the brain and spinal cord. In the rat model, the researchers injected the drug under the skin of paralyzed rats near the site of injury. They observed axon regeneration and improved movement and bladder function in the animals.

Upon further examination of the rats’ spinal cords, researcher found that the new axons sprouted below the injury site and were the type that uses serotonin to communicate. The researchers further tested this by giving some of the rats a serotonin blocker, which partially reversed some of the beneficial effects of the ISP injections.  However, the drug did not cause new axons to reconnect with brain neurons above the injury site, which may indicate that the recovery was due to an ISP-induced stronger signal from the remaining axons.

Lang and colleagues plan to test the ISP drug in preclinical trials. 


  1. News Release: Barrier-Breaking Drug May Lead to Spinal Cord Injury Treatments. National Institutes of Health. Available here: