Scientists have sought a means to regenerate spinal cord injuries which leaves patients paraplegic or quadriplegic – and now a breakthrough by researchers at Ruhr-University Bochum, Germany, may see that dream realised.
By the time humans reach adulthood, after an injury they can no longer regenerate the axons which transfer nerve impulses from brain to muscles. In 2013, the researchers discovered that a cytokine called interleukin-6 (IL-6) promoted the regeneration of optic axon fibres in vitro. IL-6 was known to be involved in nerve regeneration as well as in neuropathic pain from peripheral nerve injuries. As promising as this experiment was, delivery of the cytokine to the injury location deep in the body was an obstacles, as was the fact that it had a fairly weak effect on stimulating nerve tissue regrowth.
The team subsequently developed hyper-IL-6, an artificial variant of IL-6 that was far more potent than its natural counterpart. However, the “designer” cytokine still could not be delivered to the injured tissue where it was needed. To get around this, the researchers turned to a somewhat novel delivery method: gene therapy. A few motor neurons in the brain’s sensorimotor cortex are altered via engineered viruses to produce hyper-IL-6, which is then distributed along the axon’s length to the injury site.
“Thus, gene therapy treatment of only a few nerve cells stimulated the axonal regeneration of various nerve cells in the brain and several motor tracts in the spinal cord simultaneously,” explained senior author Dr Dietmar Fischer.
After a single injection of the engineered virus and its hyper-IL-6 payload, mice with severed spinal cords were able to walk again after two to three weeks.
“This came as a great surprise to us at the beginning, as it had never been shown to be possible before after full paraplegia,” said Dr. Fischer.
Following the success of these experiments, Dr. Fischer’s team is looking at combining the engineered cytokine treatment to other promising applications, such as tissue grafts. Additionally, they are investigating whether the hyper-IL-6 treatment can regenerate spinal cord damage that occurred weeks beforehand.
“This aspect would be particularly relevant for application in humans. We are now breaking new scientific ground. These further experiments will show, among other things, whether it will be possible to transfer these new approaches to humans in the future.”
However, adapting this designer cytokine treatment to be one that is safe for humans will take several years.
Source: Medical News Today
