Investigating small extracellular vesicle miRNA as biomarkers for Alzheimer’s disease

Aarons, Toby

Abstract

Alzheimer’s disease (AD) is the leading cause of dementia, a syndrome impacting over 900,000 people in the UK alone. There are currently no disease modifying treatments for AD, which is largely attributable to the heterogenous basis of the disease which is known to have multiple genetic and environmental contributors. Early identification of the pathogenic drivers of disease could help with both the diagnosis of specific dementia subtypes and the development of more targeted, personalised, therapeutic interventions.
Extracellular vesicles (EVs) can cross the blood-brain-barrier and have been shown to carry AD associated cargoes, including amyloid-β and tau. EV miRNA presents a promising avenue for biomarkers for AD. Within this project, EVs were isolated from fibroblasts, hydrogen peroxide treated SH-SY5Y cells and human brain tissue, by sequential centrifugation and separation by size exclusion chromatography. Isolated EVs were characterised using western blotting, fluorescence nanoparticle tracking analysis, and transmission electron microscopy. MiRNA analysis was performed using qPCR and small RNA sequencing.
Isolated EVs displayed size ranges in line with small EVs (< 150 nm) and expressed EV associated proteins, including tetraspanins CD9, CD63 and CD81, while not expressing cellular associated markers. Small RNA sequencing identified a panel of upregulated (miR-203a, miR-141, miR-361, miR-30a, and miR-125b-1) and downregulated (miR-582 and miR-1248) miRNAs in brain derived EVs (BDEVs) in AD. In fibroblast derived EVs, miR-146, miR-92a and miR-134 were upregulated in both qPCR and RNA sequencing, while miR-134 was downregulated in SH-SY5Y EVs. When stratified for females, miR-27a and miR-668 displayed increased dysregulation in BDEVs in AD. miR-185, miR-132 and miR-660 showed converse patterns of dysregulation in AD, between fibroblast derived and brain derived EVs. In both, fibroblast derived and brain derived EVs, miR-660 was inversely dysregulated in AD between males and females.
Combined we highlight a panel of EV miRNAs that show promise as biomarkers for AD that express centrally and peripherally, that can support early intervention of disease.
Key words: Alzheimer’s disease, extracellular vesicles, miRNA, fibroblast, brain tissue, SH-SY5Y, biomarkers

Citation

Aarons, T. (2023). Investigating small extracellular vesicle miRNA as biomarkers for Alzheimer’s disease. (Thesis). University of Salford

• Thesis Type: Thesis
• Publicly Available Date: Jul 3, 2023
• Award Date: Jun 2, 2023