Blood-Based Nanoparticle-Enhanced Quaking-Induced Conversion (Nano-QuIC): Inhibitor-Resistant Detection of Seeding Activity in Patients Diagnosed with Parkinson’s Disease
Peter R. Christenson, Hyeonjeong Jeong, Manci Li, Hyerim Ahn, Ann M. Schmeichel, Pinaki Misra, Danni Li, Rodolfo Savica, Phillip A. Low, Wolfgang Singer, Peter A. Larsen, Hye Yoon Park, Sang‐Hyun Oh
Abstract
A hallmark of α-synucleinopathies (e.g., Parkinson's disease) is the misfolding and aggregation of α-synuclein in tissues and biological fluids. Protein amplification assays like real-time quaking-induced conversion (RT-QuIC) are sensitive yet currently limited to semi-invasive sample types such as cerebrospinal fluid because more accessible samples, such as blood, contain inhibitors. Here, we show that Nanoparticle-enhanced Quaking-induced Conversion (Nano-QuIC) can double the speed of reactions spiked with misfolded α-synuclein while increasing sensitivity 100-fold in human plasma. Nano-QuIC detected spike concentrations down to 90 pg/mL in lysed whole blood, while reactions without nanoparticles (RT-QuIC) failed to have any detection due to the presence of strong inhibitors. Moreover, Nano-QuIC showed increased seeding activity in plasma samples from Parkinson's patients (n = 4) versus healthy controls (n = 4). This sets the groundwork for the noninvasive diagnostic use of Nano-QuIC, potentially enabling early disease detection and management through blood-based testing.