Saturday, April 12, 2008
Amid concern that recipients of certain blood transfusions may risk infection with a deadly protein responsible for the human form of mad cow disease, researchers in Canada now report development of a special filter that quickly and effectively removes the protein from blood. In addition to causing mad cow disease, these so-called prion proteins cause a variant form of the human neurological disorder, Creutzfeldt-Jakob disease. Termed variant Creutzfeldt-Jakob Disease (vCJD), its emergence triggered recent bans on exportation of beef from Europe. Variant CJD also can be transmitted in blood transfusions. "The use of the device will significantly decrease the risk of acquiring vCJD through blood transfusions," co-author Patrick V. Gurgel, Ph.D., reported at the 235th national meeting of the American Chemical Society. The device has been approved for use in Europe "and has no competitor at the moment," said Gurgel. About the size of a person's hand, the device contains a specially-designed material that recognizes and binds to prions. "This technology adds a needed layer of protection against the transmission of vCJD through blood transfusion," said Gurgel, senior research scientist at ProMetic Life Sciences in Mont-Royal, Quebec, Canada. "Our research shows that it works." The new filter can remove prions from red blood cell concentrate in less than an hour. Transfusions of red blood cells go to thousands of patients with chronic anemia resulting from kidney failure, cancer, gastrointestinal bleeding, and acute blood loss resulting from trauma. The researchers needed five years to develop the device and are now working on ways to remove prion proteins from other blood components, including plasma and plasma proteins, Gurgel said. In previous studies, the scientists showed that the device could successfully remove prions from the blood of infected hamsters and that the disinfected blood could be injected into healthy hamsters without causing disease. More recently, the researchers demonstrated that the device can also filter healthy human blood without damaging the red blood cells and other blood components, a finding that demonstrates that the technique is safe for use on human blood, they said. Human clinical studies using the device, called the P-Capt® Prion Capture Filter, are now underway in Europe, where it has received approval for commercialization, the scientists say. The first commercialization will be in Ireland and the United Kingdom (UK) and is expected in mid 2008, in an effort to help safeguard blood supplies, Gurgel suggested. Experts believe that vCJD is acquired from eating beef from prion-infected cattle. As in cows, the disease is characterized by a slow destruction of the brain tissue, which results in nerve damage, paralysis, and eventually death. So far, vCJD has killed at least 200 people in Europe alone. Health officials are increasingly concerned that the disease may spread elsewhere, including the United States, through blood transfusions from infected individuals. There is currently no reliable blood test for detecting the disease or a way of destroying the infectious prion proteins in blood. As a result, blood donation centers in the U.S. have imposed restrictions on blood donations from individuals who have lived in Europe for at least five years, particularly in the UK, where most vCJD cases have occurred.