Abstract
Alzheimer's disease (AD) is a debilitating neurodegenerative disorder characterized by the accumulation of β-amyloid (Aβ) peptides and phosphorylated tau (P-tau) proteins in the brain, leading to cognitive decline and memory impairment. Despite extensive research, the exact mechanisms of AD pathogenesis remain elusive, and reliable biomarkers for early diagnosis and disease monitoring are still needed. Extracellular vesicles (EVs), including exosomes (∼50–150 nm diameter) and microvesicles (~0.1–1.0 μm diameter), are considered multifunctional molecular complexes that act as mediators of intercellular communication, with roles in maintaining homeostasis and facilitating the exchange of information in both physiological and pathological conditions. Furthermore, EVs have emerged as potential biomarkers due to their ability to carry proteins related to the key pathologies in AD, such as P-tau and Aβ. EVs may facilitate the spread of these proteins between cells, potentially propagating pathological changes throughout the brain. While numerous studies have examined plasma-derived EVs in AD, limited research has focused on cerebrospinal fluid (CSF)-derived EVs, which may more closely reflect brain changes.
Therefore, this study aims to isolate EVs from CSF using a novel acoustic trapping method and to characterize their content for AD-related biomarkers. We included CSF samples from 20 patients with AD and 20 cognitively unimpaired (CU) individuals. The setup (AcouTrap 2, AcouSort AB) was employed to isolate EVs from minimal volumes (75 µL) of CSF, and then isolation of EVs was confirmed through transmission electron microscopy (TEM) and the presence of EV-specific markers such as CD9, CD63, CD81 and ATP1A3 (a marker specific for brain-derived EVs) and nanoparticle tracking analysis (NTA) for size and concentration. For Meso Scale Discovery immunoassays, the EVs were lysed and their content in the form of levels of two variants of P-tau: P-tau181 and P-tau217 were measured.
Our findings demonstrate that EVs can be efficiently isolated from CSF using acoustic isolation, providing a sample suitable for further analysis, without other fragments. Although there were no significant differences in counts or size between EVs isolated from AD and CU CSF, the results revealed that AD patients exhibited higher levels of P-tau181 and lower levels of P-tau217 in CSF-derived EVs compared to CU individuals. This differential presence of P-tau variants opens for future studies of tau biology in AD. It suggests that the ratio of P-tau181 to P-tau217 within EVs could serve as a novel biomarker for AD.
Additionally, this study is the first to utilize acoustic trapping for EV isolation from CSF, which may have advantages over traditional methods such as ultracentrifugation, including higher throughput, reduced sample requirements, and enhanced purity. This innovative approach could significantly impact clinical practices by providing a more practical and reliable method for EV-based biomarker discovery. Overall, this research shows distinct differences in P-tau variants within EVs from AD patients compared to CU individuals, highlighting the potential of EVs as biomarkers for AD and suggesting a new way to investigate AD pathophysiology.
Therefore, this study aims to isolate EVs from CSF using a novel acoustic trapping method and to characterize their content for AD-related biomarkers. We included CSF samples from 20 patients with AD and 20 cognitively unimpaired (CU) individuals. The setup (AcouTrap 2, AcouSort AB) was employed to isolate EVs from minimal volumes (75 µL) of CSF, and then isolation of EVs was confirmed through transmission electron microscopy (TEM) and the presence of EV-specific markers such as CD9, CD63, CD81 and ATP1A3 (a marker specific for brain-derived EVs) and nanoparticle tracking analysis (NTA) for size and concentration. For Meso Scale Discovery immunoassays, the EVs were lysed and their content in the form of levels of two variants of P-tau: P-tau181 and P-tau217 were measured.
Our findings demonstrate that EVs can be efficiently isolated from CSF using acoustic isolation, providing a sample suitable for further analysis, without other fragments. Although there were no significant differences in counts or size between EVs isolated from AD and CU CSF, the results revealed that AD patients exhibited higher levels of P-tau181 and lower levels of P-tau217 in CSF-derived EVs compared to CU individuals. This differential presence of P-tau variants opens for future studies of tau biology in AD. It suggests that the ratio of P-tau181 to P-tau217 within EVs could serve as a novel biomarker for AD.
Additionally, this study is the first to utilize acoustic trapping for EV isolation from CSF, which may have advantages over traditional methods such as ultracentrifugation, including higher throughput, reduced sample requirements, and enhanced purity. This innovative approach could significantly impact clinical practices by providing a more practical and reliable method for EV-based biomarker discovery. Overall, this research shows distinct differences in P-tau variants within EVs from AD patients compared to CU individuals, highlighting the potential of EVs as biomarkers for AD and suggesting a new way to investigate AD pathophysiology.
Original language | English |
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Qualification | Licentiate |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 2024 Sept 13 |
Place of Publication | Lund |
Publisher | |
ISBN (Print) | 978-91-8021-618-0 |
Publication status | Published - 2024 |
Bibliographical note
Defence detailsDate: 2024-09-13
Time: 13:00
Place: Dora Jacobsohn, BMC D15, Klinikgatan 32 i Lund
External reviewer(s)
Name: Schedin Weiss, Sophia
Title: docent
Affiliation: Karolinska Institutet
Subject classification (UKÄ)
- Neurosciences
Free keywords
- Alzheimer's disease
- Extracellular vesicles
- P-tau181
- P-tau217
- Acoustic trapping