Nanoparticles show potential for treating MS
19th November 2012 - Researchers say they've been able to use nanoparticles to stop multiple sclerosis (MS) in mice that are bred to have the disease.
The particles are about 200 times smaller than the thickness of a human hair. They are made from the same material that's used to create dissolving stitches.
When researchers attach specific proteins to the particles, they say they are able to teach the body not to attack its own tissues.
If the approach succeeds in human studies, it may one day lead to more targeted treatments not only for multiple sclerosis but also for other kinds of autoimmune disorders, including type 1 diabetes and rheumatoid arthritis.
The research is published in the journal Nature Biotechnology. The study was funded by grants from the US National Institutes of Health, the Myelin Repair Foundation, the Juvenile Diabetes Foundation, and the Australian government.
Turning down an autoimmune attack
In multiple sclerosis, the body attacks its own myelin. Like the insulation around electric wires, myelin is a material that coats nerve fibres, allowing them to effectively carry signals that power the body.
Over time, people with MS may develop a host of problems related to myelin damage, including trouble with muscle coordination, movement, numbness, pain and vision problems. About 80% of people with MS have the relapsing-remitting form. The mice in this study were bred to have this type of MS.
Researchers wondered if they could stop that process by making use of the body's 'waste disposal system'. In addition to protecting the body from foreign invaders, an important role of the immune system is getting rid of dead cells.
When dead or dying cells pass through the spleen, big white blood cells called macrophages gobble them up. As part of this process the macrophages send signals to other parts of the immune system, letting them know that the dying cells aren't dangerous, just routine bits of rubbish that need to go.
Years ago, researcher Stephen Miller, an immunologist at Northwestern University, Chicago, US, found that it might be possible to hijack this rubbish removal system and get the body to recognise - and then ignore - proteins it was mistaking for threats.
"What we've done is simply tap into a system that the immune system was smart enough to evolve millions of years ago to get rid of dead and dying cells," Stephen Miller tells us.
He's already tried the approach in humans using white blood cells that were first collected and then killed. He then attached proteins to the dying cells and infused them into the body. In an early safety trial, he says that approach appeared to be well tolerated.
"There [were no side effects], there was no re-triggering of disease, and we actually showed that immune responses in patients were decreased," Stephen Miller says.
However, other immune responses, such as protection against certain infections, remained strong. That suggests that patients treated this way would not see the kind of general immune suppression that happens with current treatments for autoimmune diseases.