A study in the UK and the Netherlands has uncovered how early nerve damage can sometimes lead to self-repair. It used zebrafish, mice and brain tissue from people with multiple sclerosis (MS). 

MS is a chronic disease in which the immune system attacks myelin, the protective coating around nerve fibres, in the brain and spinal cord, disrupting communication between nerve cells. Early damage often appears as swelling of the myelin sheath, previously thought to precede the formation of larger lesions. 

Using advanced microscopy – two-photon microscopy – to observe living zebrafish brains and thin mouse brain slices over time, researchers at the University of Edinburgh and EARA member the Netherlands Institute for Neuroscience found that some myelin swellings shrank or resolved completely, rather than progressing to permanent damage. 

By altering nerve cell activity in genetically modified zebrafish and mice using light-based techniques, like optogenetics, the team observed that increasing nerve cell activity worsened myelin swelling, while reducing it decreased swelling. The results indicate that nerve cell activity plays a role in early myelin damage and recovery. 

Analysis of postmortem brain tissue from people with MS confirmed that myelin swelling was more common in active lesions and could also change over time in human tissue. 

“These findings suggest that intervening during this early swelling phase could protect myelin before it is lost, offering us the opportunity to explore potential new treatment routes,” said David Lyons, from the University of Edinburgh and senior author of the study published in Science.