DATE: November 14, 2017
TIME: 12:00pm PST, 03:00pm EST

Learning Objectives:

• How to maximise RNA yield and extraction from exosomes and biological fluids
• How to construct small RNA libraries from low RNA yields
• How to analyze your small RNA reads to select a list of biomarker candidates for validation

Alzheimer’s disease (AD) affects more than 55 million people worldwide and is expected to double every 20 years in the absence of disease-modifying drugs. Future therapeutic strategies aimed at limiting neurodegeneration require methods to diagnose the disease in preclinical patients. Several blood-based tests have been explored to detect AD however, evidence is required to determine whether blood sampling is an appropriate specimen to diagnose brain diseases. Previously we isolated serum exosomes from AD patients which displayed an abnormal composition of 16 specific microRNA (miRNA) biomarkers compared to controls. To provide evidence that our serum exosomal miRNA biomarkers are suitable for the detection of a brain condition, we also profiled exosomes isolated from post-mortem human AD and control brain tissues. Exosomes were extensively characterised to meet the minimal experiments requirements set out by The International Society for Extracellular Vesicles to be defined as exosomes and small RNA profiling was performed by next-generation sequencing.

The Ion Torrent Ion S5 and Ion Chef system was used to perform small RNA deep sequencing of the brain and serum exosome samples. Brain derived exosomes (BDEs) were found to contain a unique profile of small RNA, including miRNA, compared to whole tissue samples. Furthermore, all 16 serum biomarkers, identified in our previous study, were detected in BDEs including a panel of BDE specific miRNA that target genes involved in AD pathology. This work has identified a highly specific panel of miRNA that is both present in the brain and blood of AD patient samples. In the future, the miRNA candidates could be used to develop a blood-based diagnostic test highly relevant to a brain disease, equivalent to non-invasive brain biopsy. Furthermore, this biomarker discovery pipeline could be used to identify exosomal miRNA biomarkers for other diseases and conditions.

For Research Only. Not for use in diagnostic procedures