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Page 48 Extracell Vesicles Circ Nucleic Acids 2020;1:20-56 I http://dx.doi.org/10.20517/evcna.2020.10

from virtually all cell types and can traffic RNA between cells, and are touted as a bio- inspired delivery
vehicle. However, doses of siRNA used to suppress targets in many published studies using sEVs far exceed
those of other delivery vehicles. This suggests that sEVs are quantitatively poor at delivering cargoes into
target cells and questions the model in which the principal role of sEVs is intercellular delivery of cargoes.
We demonstrate that sEVs naturally contain thirty copies or less of specific miRNA per sEV. Nonetheless,
pre-miR-451 derivatives are enriched by 1,000-fold in sEVs produced by many cell types. Reprogramming
the unique Dicer- independent pre-miR-451 secondary structure with new siRNA sequences enables
robust siRNA enrichment in sEVs and these sEVs reduce siRNA target expression in mouse liver, intestine
and kidney podocytes with doses of siRNA that are at least 10-fold lower than lipid nanoparticles. The
capacity of sEVs to deliver siRNA is abrogated when their membranes are disrupted by electroporation.
This demonstrates that intact sEVs can be highly efficient at RNA delivery and provides an RNA stem-loop
to harness this by enabling robust, scalable packaging of siRNA into sEVs.

37. Cell type-specific and disease-associated protein networks in extracellular vesicles
isolated from human iPSC-derived neural cells and Alzheimer’s disease brain tissues

2
1
3
1
1
Authors: Yang You , Satoshi Muraoka , Mark P. Jedrychowski , Jianqiao Hu , Amanda K. McQuade ,
3
3
5,6
4
5,6
Tracy Young-Pearse , Roshanak Aslebagh , Scott A. Shaffer , Mathew Blurton-Jones , Wayne W. Poon ,
2
Steven P. Gygi , Tsuneya Ikezu 1,7,8
E-mail: tikezu@bu.edu
Affiliations:
1 Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine,
Boston, MA, USA.
2 Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
3 Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological
Disorders, University of California, Irvine, CA, USA.
4 Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA.
5 Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School,
Worcester, MA, USA.
6 Mass Spectrometry Facility, University of Massachusetts Medical School, Shrewsbury, MA USA.
7 Department of Neurology, Alzheimer’s Disease Center, Boston University School of Medicine, Boston,
MA, USA.
8 Center for Systems Neuroscience, Boston University, Boston, MA, USA.

Abstracts: Extracellular vesicles (EVs) have gathered great interest in studying neurodegenerative diseases
with the capability of transferring pathogenic molecules and the source of liquid biopsies. Here we
performed combined label-free and tandem mass tag-labeling based quantitative mass-spectrometry of EVs
isolated from human induced pluripotent stem cells (hiPSCs) and Alzheimer’s disease (AD) brain tissues
to conduct a comprehensive EV proteomics study on AD. Cell type-specific EV protein signatures were
identified from hiPSC-derived excitatory neurons, astrocytes, microglia-like cells and oligodendrocytes.
Furthermore, a whole protein co-expression network analysis identified a module most significantly
associated with AD pathology and cognitive function and enriched in astrocytic markers, particularly
reactive astrocytes. Proteins within this module were regulated by pro-inflammatory molecules for the
inflammatory processes. Our study presents unique human neural cell type-specific EV markers and their
application for liquid biopsy-based EV AD biomarkers and disease monitoring.