Using a cytokine-based gene therapy, researchers have successfully allowed previously paralysed mice to walk again.
Designer Cytokine
To date, paralysis resulting from spinal cord damage has been irreparable, as severed axons fail to regenerate. However, scientists from Ruhr-Universität Bochum, Germany, have developed a new therapeutic approach allowing paralysed mice to walk again.
The key protein underlying this therapy is hyper-interleukin-6, which stimulates nerve cells to regenerate. This “designer” cytokine was produced via genetic engineering and had previously been used to efficiently stimulate nerve cell regeneration in the visual system. Find their recent paper here.
Gene Therapy
In the current study, the team induced nerve cells in the motor-sensory cortex to produce hyper-interleukin-6 themselves. This was achieved using gene therapy.
First, small viruses carrying the blueprint for the production of hyper-interleukin-6 were injected into the target brain region. There, these viruses delivered the blueprint into specific neurons, called motor neurons. Motor neurons have extensive connections to other nerve cells required for movement. Therefore, hyper-interleukin-6 was automatically transported into these nerve cells and released in a controlled manner.
Although this gene therapy only targeted a small population of cells in the brain, it was able to stimulate the axonal regeneration of various nerve cells in the brain and several motor tracts in the spinal cord simultaneously. Ultimately, this allowed previously paralysed mice to walk again, after just 2-3 weeks of treatment. This has never before been possible following full paraplegia.
Future Directions
The team is now investigating whether this approach can be combined with other measures, to optimise administration of hyper-interleukin-6 and achieve additional functional improvements. They are also exploring whether hyper-interleukin-6 shows positive effects in mice, even if the injury occurred several weeks prior. This aspect would be particularly relevant to humans. Future experiments will reveal whether these approaches are transferable to humans in the near future.
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