New method carries Alzheimer's drugs directly to brainDrugs delivered across blood-brain barrier
UK scientists have found a new way of delivering drugs directly to the brain.
The discovery could lead to more effective treatments for conditions such as Alzheimer's, motor neurone disease and muscular dystrophy.
Treating diseases such as these has proved to be difficult, partly because of the difficulty of getting new drugs across the normally impermeable blood-brain barrier.
"The major barrier for these drugs is delivery," said study leader Dr Matthew Wood of Oxford University.
"This problem becomes even greater when you want to reach the brain. The blood-brain barrier – which stops most things in the blood stream from crossing to our brains – is much too great an obstacle."
The scientists managed to overcome this by using used exosomes - tiny particles naturally secreted by cells - to carry drugs across the blood-brain barrier to the brain, where it is needed.
The team purified naturally occurring exosomes from mouse cells, which they then modified to carry a piece of genetic material, RNA.
The surface coat of the exosomes was also changed to incorporate proteins from the rabies virus which targets brain cells.
When injected into mice, the exosomes successfully crossed the blood-brain barrier and reached the brain. The RNA within the exosomes switched off a gene, BACE1, leading to a 60 per cent reduction in an enzyme linked to plaque formation in Alzheimer's disease.
Dr Wood said: "These are dramatic and exciting results. It’s the first time new 'biological' medicines have been delivered effectively across the blood-brain-barrier to the brain."
The treatment may also help other conditions where drugs or gene therapy needs to cross the blood-brain barrier.
"We’ve shown that a natural system could be exploited to deliver drugs across the blood-brain barrier," said Dr Wood. "We believe we can use this same technology for Alzheimer’s, motor neuron disease, Parkinson’s and Huntington’s. All we need is a different RNA each time."
He also added that more research would be needed before exosomes could be tested in humans.
Dr Susanne Sorensen, head of research at the Alzheimer's Society, said: "In this exciting study, researchers may have overcome a major barrier to the delivery of potential new drugs for many neurological diseases including Alzheimer’s.
"If this delivery method proves safe in humans, then we may see more effective drugs being made available for people with Alzheimer’s in the future."
The findings are published in Nature Biotechnology.
This article was published on Mon 21 March 2011
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