Cryo-electron microscopy of extracellular vesicles from cerebrospinal fluid

Extracellular vesicles (EVs) are membrane-enclosed vesicles which play important role for cell communication and physiology. EVs are found in many human biological fluids, including blood, breast milk, urine, cerebrospinal fluid (CSF), ejaculate, saliva etc. These nano-sized vesicles contain proteins, mRNAs, microRNAs, non-coding RNAs and lipids that are derived from producing cells. EVs deliver complex sets of biological information to recipient cells thereby modulating their behaviors by their molecular cargo. In this way EVs are involved in the pathological development and progression of many human disorders, including neurodegenerative diseases.

Researchers from the Petersburg Nuclear Physics Institute characterized EVs purified by ultracentrifugation from CSF of patients with Parkinson’s disease (PD) and individuals of the comparison group using nanoparticle tracking analysis, flow cytometry and cryo-electron microscopy. Vesicular size and the presence of exosomal marker CD9 on the surface provided evidence that most of the EVs were exosome-like vesicles. Cryo-electron microscopy allowed us to visualize a large spectrum of extracellular vesicles of various size and morphology with lipid bilayers and vesicular internal structures. Thus, we described the diversity and new characteristics of the vesicles from CSF suggesting that subpopulations of EVs with different and specific functions may exist.

Cryo-EM images of EVs isolated from pooled CSF of Parkinson’s disease patients

exosomes

(A) Single vesicles; (B, K) double vesicles; (C, L) double-membrane vesicles; (C-F, L) multilayer vesicles; (G-J, L) vesicles with electron dense cargo in lumen; (K, M) vesicles with broken membrane. The arrows point to vesicle with double membrane (black arrow) and “bowling pin” vesicle (white arrow). Scale bars are 50 nm.

Emelyanov A, Shtam T, Kamyshinsky R, Garaeva L, Verlov N, Miliukhina I, et al. (2020) Cryo-electron microscopy of extracellular vesicles from cerebrospinal fluid. PLoS ONE 15(1): e0227949. [abstract]

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