Optimal Preservation of PFFs in Glycerol Enhances Suitability for Modeling Parkinson's Disease

Injecting α-synuclein pre-formed fibrils (αSyn PFFs) into various tissues and organs involves converting monomeric αSyn into a fibrillar form, inducing extensive αSyn pathology that effectively models Parkinson's disease (PD). However, the distinct physicochemical properties of αSyn amyloid fibrils can potentially reduce their seeding activity, especially during storage. In this study, it is demonstrated that αSyn PFFs exhibit significant sensitivity to low temperatures, with notable denaturation occurring between -20 and 4 °C, and gradual disassembly persisted even under storage conditions at -80 °C. To mitigate this issue, a commonly used protein stabilizer, glycerol is introduced, which significantly reverses the cold-induced disassembly of PFFs. Remarkably, storing PFFs with 20% glycerol at -80 °C for a month preserved their morphology and seeding activity as freshly prepared PFFs. Glycerol-stabilized αSyn PFFs resulted in compromised neuronal survival, with the extent of these impairments correlating with the formation of αSyn pathology both in vivo and in vitro, indistinguishable from freshly prepared PFFs. Storing sonicated PFFs with 20% glycerol at -80 °C provides an optimal storage method, as sonication is necessary for activating their seeding potential. This approach reduces the frequency of sonication, simplifies handling, and ultimately lowers the overall workload, enhancing the practicality of using PFFs.