NurExone's Rat Results Aren't a Human Treatment

NurExone says its experimental treatment helped rats regain motor function after their spinal cords were completely severed. The treatment hasn't been tested in people. That boundary matters: the company’s CEO calls the result dramatic, but the evidence described so far comes from animal experiments.

A result with limits

The Israeli biotech company is developing an exosome-based treatment intended to encourage damaged nerve cells to regrow. In the rat experiment, researchers administered the treatment after spinal cord injury and observed rats regain motor function. Asked whether rats that had been unable to walk started walking again, NurExone CEO Dr. Lior Shaltiel answered: “Correct. It's really binary.” He called the result “hugely dramatic” and “very, very strong proof of concept.” Those are his descriptions of the findings, not evidence of a treatment tested in patients.

The treatment was administered through nasal drops, which Shaltiel described as non-invasive. The report says the particles reached the spinal cord injury site. NurExone is also testing the approach in relation to optic nerve injuries, but the account's specific description of rats walking again concerns the spinal cord experiment. The treatment's stated goal is to restore some motor and sensory function.

What the particles carry

Exosomes are vesicles released by cells that can carry proteins and RNA molecules and affect other cells. NurExone produces them in laboratory containers, then adds molecular cargo intended to prompt repair. Shaltiel compared them to “packages from Amazon, containing lots of good things that can help damaged tissue.” He said the company adds cargo to give a stronger boost to regeneration and repair.

That cargo is a small RNA fragment called siRNA, designed to reduce production of PTEN at the injury site. PTEN helps regulate cell growth and prevent uncontrolled cell division and cancerous tumors; the same system also limits mature nerve cells' ability to regrow extensions. Shaltiel likened PTEN to “a police officer inside the cell,” operating within mechanisms that determine whether a cell can grow and develop.

The intervention is meant to be targeted and temporary, the company says. “We don't want to reduce this protein over the long term,” Shaltiel said. “The idea is to administer the treatment at the injury site, for a short period.” The account doesn't report results in people or establish that the approach is safe or effective for them.

From research to treatment

The development grew from research led by Prof. Shulamit Levenberg of the Technion and Prof. Daniel Offen of Tel Aviv University, with other researchers. They investigated whether the body's natural growth mechanisms could encourage repair at a spinal cord injury site without tissue transplantation, described in the report as complex and invasive in a particularly sensitive area.

The biological obstacle is substantial: mature nerve cells in the brain, spinal cord and optic nerve struggle to regrow extensions after injury, unlike skin that heals after a cut or a broken bone that mends. NurExone's approach attempts to alter one part of that process, not erase the distinction between a laboratory result and a clinical treatment. For now, the walking rats are a preclinical finding, and people have not received the treatment.