Spinal cord injuries have long been regarded as largely permanent: once the nerve pathways between brain and legs are destroyed, almost nothing regrows in the central nervous system. A research team at Cologne University Hospital is now showing a way to break that rule — and has given paralysed mice back the ability to move on their own legs.
At the heart of the work is a laboratory-designed molecule called hyper-interleukin-6 (hIL-6). Rather than inject the finished protein into the injured tissue, the researchers around Prof. Dietmar Fischer take a detour through the brain: a previously disarmed carrier virus delivers the genetic blueprint for hIL-6 into nerve cells of the motor cortex, the region of the cerebral cortex that plans and triggers voluntary movement. The cells then produce the protein themselves.
The real trick lies in the transport. hIL-6 travels along existing nerve fibres from the cortex down into deeper relay centres in the brainstem, reaching areas that would otherwise be almost inaccessible. There it sets a rebuilding process in motion: both injured and intact nerve cells grow new extensions, branch out and forge fresh connections. It is this rewiring of the descending motor pathways that restores function.
In the current study, published in the journal Neurobiology of Disease, the team tested the approach in mice with contusion injuries of the spinal cord — the form of injury most common in humans as well. Animals that had been paralysed were able to walk in a coordinated way again after a few weeks. The method builds on earlier work by the same group, in which hIL-6 had already enabled movement after even more severe spinal cord damage.
Encouraging as the results are, those involved urge patience. What works in a mouse model is still far from a treatment for people: questions of safety, correct dosage and possible side effects remain open and must be resolved in further studies. Yet the work brings closer a goal long considered unreachable — nerve pathways that repair themselves again after paralysis.