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Extracell Vesicles Circ Nucleic Acids 2020;1:20-56 I http://dx.doi.org/10.20517/evcna.2020.10 Page 23

2. Super-resolution microscopy-based resolving of membrane-associated proteins on
extracellular vesicles

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Authors: Ryan P. McNamara 1,2,* , Yijun Zhou , Meredith G. Chambers , Anthony. B. Eason ,
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Justin T. Landis , Brian Yang , Blossom A. Damania , Dirk P. Dittmer 1,2
E-mail: ryanpm@email.unc.edu
Affiliations:
1 Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel
Hill, NC, USA.
2 Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill,
NC, USA.
*Presenting Author
Abstracts: Extracellular vesicles (EV) are secreted from most cell types and are intimately involved in
homeostasis. Given that their size can drop well beneath the limit of diffraction of typical light microscopy
[< 250 nanometers (nm)], direct visualizations and characterizations of single EV have proven daunting.
Conventional approaches to their visualization include light scattering methods such as nanoparticle
tracking analysis, transmission and scanning electron microscopy (EM), and highly sensitive nanoscale
flow cytometry. Super-resolution microscopy, such as direct stochastic optical reconstruction microscopy
(dSTORM) has also been recently employed to view EV. Here, we show that dSTORM can be employed in
multiple channels to resolve membrane-associated proteins to nanometer precision. Our dSTORM- based
characterizations of EV typically had resolutions of ± 20 nm on the XY axis using excitation lasers of 473
and 640 nm. Size distributions of EV were consistent with other methods of measurement such as light
scattering and resistive pulse sensing and were independent of the excitation laser. Moreover, we were able
to resolve tetraspanins on the membrane of an individual EV, both by conjugation to- mCherry or through
indirect antibody-mediated detection. In conclusion, we have rendered individual EV to nanometer
detail through super-resolution microscopy and confirmed the presence of tetraspanin molecules on their
surface. We propose that a highly sensitive analysis like this could be adapted to rapidly scan for rare- event
biomarkers of disease through fluorescence-based machine learning.

3. Exosomal carboxypeptidase econfers and CPE-shRNA loaded exosomes inhibit
tumorigenesis

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Authors: Sangeetha Hareendran , Bassam Albraidy , Xuyu Yang , Aiyi Liu , Anne Breggia , Clark C Chen ,
Y Peng Loh 1
E-mail: lohp@mail.nih.gov
Affiliations:
1 Section on Cellular Neurobiology.
2 Biostatistics&Bioinformatics Branch, National Institute of Child Health and Human Development, NIH,
Bethesda, MD, USA.
3 Maine Medical Center BioBank, Portland, ME, USA.
4 Department of Neurosurgery, University of Minnesota Medical School, MN, USA.
Abstracts: Carboxypeptidase E (CPE) and its splice variant CPE- N has been shown to promote cancer
growth and metastasis in various cancer types. Exosomes carry biomolecules (proteins, DNA, mRNA and