Detecting Alpha Synuclein Seeding Activity in Formaldehyde-Fixed MSA Patient Tissue by PMCA.

Area of Science:

• Neuroscience
• Biochemistry
• Pathology

Background:

• Alpha synuclein (α-syn) aggregation is central to synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA).
• The prion-like hypothesis suggests aggregated α-syn seeds pathology, but a suitable assay for biomarker development is lacking.
• Current diagnostic and progression tracking methods for synucleinopathies are limited by the absence of reliable biochemical markers for α-syn aggregates.

Purpose of the Study:

• To adapt and optimize the Protein Misfolding Cyclic Amplification (PMCA) technique for sensitive detection of α-syn seeding activity.
• To establish whether formaldehyde-fixed brain tissue from patients with synucleinopathies retains detectable α-syn seeding activity.
• To evaluate the potential of PMCA as a quantitative method for detecting α-syn aggregates as biomarkers for synucleinopathies.

Main Methods:

• Adapted Protein Misfolding Cyclic Amplification (PMCA) technique for detecting α-syn seeding activity.
• Extensively optimized PMCA parameters to achieve high sensitivity and quantitative detection.
• Tested the developed protocol on formaldehyde-fixed brain samples from patients with multiple system atrophy (MSA) and control subjects.

Main Results:

• Developed a highly sensitive PMCA protocol capable of detecting as little as 100 attomoles (10^-16 mol) of α-syn aggregate.
• Successfully detected α-syn seeding activity in a histologically positive, formaldehyde-fixed MSA brain sample.
• Confirmed that α-syn seeding activity persists in fixed brain tissue, demonstrating the robustness of the method.

Conclusions:

• The optimized PMCA protocol is a sensitive and quantitative method for detecting α-syn seeding activity.
• α-syn aggregates in MSA patient brains retain seeding activity even after formaldehyde fixation.
• This PMCA-based assay holds promise for adaptation to accessible patient samples for biomarker development in synucleinopathies.