Scientists partially reinsulated ravaged nerves in mouse models of multiple sclerosis and restored limb mobility by treating the animals with a small non-coding RNA called a microRNA. They argue that their findings may lead to a multipoint treatment strategy for people with MS.
 
Researchers at Cincinnati Children’s Hospital Medical Center report that treatment with a microRNA called miR-219 restarted production of myelin. They administered miR-219 into the spinal columns and cerebrospinal fluid of mice with nerve coatings damaged by a mouse model of MS. Treatment with miR-219 reinvigorated the function of damaged oligodendrocytes, which produce myelin, allowing the substance to reform and reinsulate nerves.
 
MicroRNAs are short segments of RNA encoded on the chromosomes of cells. They regulate gene expression in cells by acting as molecular silencers, essentially blocking gene expression in certain situations.
 
The study authors deleted miR-219 in mice to test the effect this had on myelin-forming oligodendrocyte cells. The absence of miR-219 allowed a surge of activity by several inhibitors of nerve re-myelination – including a protein called Lingo1. Further testing revealed that miR-219 is an essential part of a network that targets and blocks molecules that inhibit the ability of oligodendrocytes to form myelin. This prompted the researchers to test treatment with miR-219 For this they used a miR-219 mimic – a synthesized version of the microRNA. After administering the mimic, the researchers noted improved limb function and regeneration of the myelin coating on nerves.
 
The authors stress that because their study was conducted in laboratory mouse models of disease, their data cannot at this stage be applied to clinical treatment in humans. The authors are now trying to develop additional mimics of miR-219 and therapeutically effective formulations of the microRNA to ease its delivery – particularly into brain tissue.
 
The study was published in the journal Developmental Cell.