In vivo visualization of propagating α-synuclein pathologies in mouse and marmoset models by a bimodal imaging probe, C05-05

Deposition of intracellular α-synuclein fibrils is implicated in neurodegenerative parkinsonian disorders, while high-contrast in vivo detection of α-synuclein depositions has been unsuccessful in animal models and humans. Here, we have developed a bimodal imaging probe, C05-05, for visualizing α-synuclein inclusions in the brains of living animals modeling α-synuclein propagation. In vivo optical and PET imaging of a mouse model demonstrated visualization of α-synuclein aggregates by C05-05, revealing a dynamic propagation of fibrillogenesis along neural pathways followed by disruptions of these structures. Moreover, longitudinal 18F-C05-05-PET of a marmoset model captured widespread dissemination of fibrillary pathologies accompanied by neurodegeneration detected by dopamine transporter PET. In addition, in vitro assays demonstrated the high-affinity binding of 18F-C05-05 to α-synuclein versus other protein pathologies in human brain tissues. Collectively, we propose a new imaging technology enabling etiological and therapeutic assessments of α-synuclein pathogenesis at non-clinical levels, highlighting the applicability of C05-05 to clinical PET. ### Competing Interest Statement The authors have declared no competing interest.