The surprise discovery could pave the way to ground-breaking new therapies for the devastating auto-immune disease which affects around 100,000 people in the UK.
Scientists found that the anti-fungal agent miconazole and the steroid clobetasol both restored movement to mice paralysed by a rodent version of MS.
In laboratory tests, they prompted inactive mouse and human stem cells to regenerate myelin, the protective insulation-like coating around nerve fibres that is destroyed by the disease.
Dr Robert Miller, a member of the US team from Case Western Reserve University whose findings appear in the journal Nature, said: “It was a striking reversal of disease severity in the mice.
“The drugs that we identified are able to enhance the regenerative capacity of stem cells in the adult nervous system. This truly represents a paradigm shift in how we think about restoring function to multiple sclerosis patients.”
Although both drugs are widely used, a way must be found to use them safely as internal human treatments rather than creams or ointments before clinical trials can be considered. The researchers are confidant this problem can be solved, but have warned patients not to jump the gun by using the drugs prematurely.
Lead scientist Professor Paul Tesar, from Case Western Reserve School of Medicine, said: “We appreciate that some patients or their families feel they cannot wait for the development of specific approved medications, but off-label use of the current forms of these drugs is more likely to increase other health concerns than alleviate multiple sclerosis symptoms.”
MS occurs when the immune system attacks myelin, thereby disrupting the passage of nerve signals. As the disease progresses, it produces symptoms ranging from mild numbness or tingling to full-blown paralysis. It can also prove fatal.
Although current treatments can slow progression of MS and reduce its symptoms, the disease remains incurable.
One new approach is to focus on special stem cells called oligodendrocyte progenitor cells (OPCs) that mature into myelin-producing cells.
While other scientists have looked at ways of replacing lost stem cells using transplantation techniques, the Case Western team set out to find a way of stimulating existing, but inactive, OPCs.
After screening 727 potential drug candidates, they identified two – miconazole and clobetasol – that coaxed the OPCs to form oligodendrocytes and repair nerve fibres stripped of myelin.
“We know that there are stem cells throughout the adult nervous system that are capable of repairing the damage caused by multiple sclerosis but until now we had no way to direct them to act,” said Prof Tesar.
“Our approach was to find drugs that could catalyse the body’s own stem cells to replace the cells lost in multiple sclerosis.”
As well as testing the drugs on mice affected by MS, the scientists also observed their effect on human OPCs in the laboratory. The response was similar to that seen in mouse cells.