Canadian Scientists have developed a filter system that can clean blood of the prion protein that causes variant CJD (mad cow disease or BSE), potentially making blood donations much safer.
Since a paper published in the Lancet in 2000 confirmed the worst fears of doctors and public health officials - that BSE could be experimentally transmitted (amongst sheep in this case) by blood transfusion - researchers have been looking for ways to ensure that human blood products are safe. Part of the problem is that their is no clinical test for the abnormal prion protein that causes the disease, and patients can be infectious for the condition yet apparently healthy for long periods before any symptoms appear. To avoid accidental transmission of the incurable brain disease some countries like the UK are importing blood products from overseas, at significant cost, but this doesn't totally abolish the risk.
The new system, which was announced this week at the American Chemical Society Meeting in New Orleans, has been developed by Quebec-based company Prometic Life Sciences. Researcher Patrick Gurgel and his colleagues spent 5 years screening millions of tiny molecules to find one with the highest affinity for binding onto prion proteins in blood. The best performer was a small protein, which they attach to sheets of resin, multiple layers of which are then stacked side by side, each separated by a layer of membrane. Blood is then passed over the membranes and any prions present are grabbed by the proteins. Tests using prion-infected hamsters showed that their filtered blood could be injected into disease-free animals without ill-effects.
The disposable filter takes about an hour to process a single human blood donation. It's now been approved for sale in Europe and is currently undergoing evaluation by health services in the UK and Ireland. The predicted cost to roll it out nationwide in the UK is in excess of 100 million pounds. But government ministers will doubtless be asking themselves whether they can afford not to use it...