Prion-like features and possible hazards of amyloid-β-, tauand α-synuclein aggregates Increasing evidence suggests that the misfolding and aggregation of different disease-associated proteins such as amyloid-β (Aβ) and tau in Alzheimer’s disease (AD), α-synuclein in Parkinson’s Disease (PD) and dementia with Lewy bodies (DLB), or prion protein (PrP) in prion diseases is based on a common molecular mechanism of nucleation-dependent protein polymerization [1-3]. Consistent with this concept it has been recently demonstrated that the aggregation and deposition of Aβ, tau, and α-synuclein in the brain can be stimulated in animal models by injection of inocula that contain aggregated forms of these proteins (for a review see: [4]). Additionally, intracerebral implantation of stainless steel wires previously contaminated with Aβ-containing brain extract was found to stimulate cerebral beta-amyloidosis in APP23 transgenic mice [5], and Aβ aggregates resisted inactivation of nucleating (“seeding”) activity by boiling [5] or formaldehyde [6]. Taken together, these findings raised concerns that the transmission of pathological protein particles from common neurodegenerative diseases may possibly pose a risk to patient safety, e.g. in transfusion medicine or surgery. However, so far neither experimental nor epidemiological studies provided evidence for a transmission of severe or even fatal disease by Aβ-, tauor αsynuclein aggregates [4]. Yet, stimulation of cerebral protein aggregation by iatrogenically transmitted Aβ-, tauor α-synuclein particles could possibly have harmful effects below full-blown disease transmission. For αsynuclein such scenarios have been experimentally exemplified. Intracerebrally or intramuscularly injected samples
