The presented work was supported by the Ministe&#768;re de L&#8217;Education Nationale, de L&#8217;Enseignement Supe&#769;rieur et de la Recherche and INSERM. We gratefully acknowledge the BICeL- Campus Scientific City Facility for access to instruments and technical advices. We gratefully acknowledge Jean-Pascal Gimeno, Soulaimane Aboulouard and Isabelle Fournier for the Mass spectrometry assistance. We gratefully acknowledge Tanina Arab, Christelle van Camp, Francoise le Marrec-Croq, Jacopo Vizioli and Pierre-Eric Sauti&#232;re for their strong contribution to the scientific and technical developments.

1. Primary Culture of Microglia/Macrophages
<ol>
	<li>Primary culture of microglia
	<ol>
		<li>Culture commercial rat primary microglia (2 x 106 cells) (see the Table of Materials) in Dulbecco&#39;s modified Eagle medium (DMEM) supplemented with 10% exosome-free serum, 100 U/mL of penicillin, 100 &#181;g/mL streptomycin, and 9.0 g/L glucose at 37 &#176;C and 5% CO2.</li>
		<li>Collect the conditioned medium after a 48 h culture and proceed to the isolation of EVs....

The central nervous system (CNS) is a complex tissue in which cell-to-cell communication regulates normal neuronal functions necessary for homeostasis30. EVs are now widely studied and described as important molecular cargos for cell-to-cell communication31. They specifically deliver a cocktail of mediators to recipient cells thereby affecting their functions in healthy and pathological conditions32. Recent studies indicate that EVs play a crucial ro...

Many neuropathologies are related to the neuro-inflammatory state which is a complex mechanism that is increasingly considered, but still poorly understood because the immune processes are diverse and depend upon the cell environment. Indeed, the CNS disorders do not systematically involve the same activation signals and immune cell populations and thus the pro- or anti-inflammatory responses are difficult to evaluate as causes or consequences of pathologies. The brain resident macrophages called &#8220;microglia&#8221; appear to be at the interface between the nervous and immune systems1. Microglia have a myeloid origin and are derived from the yolk sac during primitive hematopoiesis to colonize the brain, whereas peripheral macrophages are derived from the fetal liver during definitive hematopoiesis to become peripheral macrophages2. The microglia cells communicate with neurons and neuron-derived glial cells such as astrocytes and oligodendrocytes3. Several recent studies have demonstrated that microglia are involved in neuronal plasticity during CNS development and adult tissue homeostasis, and also in the inflammatory state associated with neurodegenerative diseases4,5. Otherwise, the integrity of the blood brain barrier can be compromised in other CNS pathologies. The immune responses, especially in the glioblastoma multiforme cancer, are not supported only by microglia cells as the blood brain barrier is reorganized through angiogenic processes and the presence of lymphatic vessels6,7. Therefore, a large bone marrow-derived macrophages (BMDMs) infiltration occurs in the brain tumor throughout tumor-dependent angiogenesis mechanisms8. The cancer cells exert a significant influence on infiltrated BMDMs leading to immunosuppressive properties and tumor growth9. Thus the communication between the immune cells and their brain microenvironment is difficult to understand as the cell origin and activation signals are diverse10,11. It is thus interesting to apprehend the functions of immune cell-associated molecular signatures in physiological conditions. In this regard, the cell-cell communication between immune cells and cell microenvironment can be studied through the release of extracellular vesicles (EVs).
The EVs are being studied more and more in the regulation of immune functions in healthy as well as pathological conditions12,13. Two populations, exosomes and microvesicles, can be taken into account. They present different biogenesis and size ranges. The exosomes are vesicles of ~30&#8211;150 nm diameter and are generated from the endosomal system and secreted during fusion of multivesicular bodies (MVBs) with the plasma membrane. The microvesicles are about 100&#8211;1,000 nm in diameter and are generated by an outward budding from the cell plasma membrane14. Because the exosome versus microvesicle discrimination is still difficult to realize according to the size and molecular patterns, we will only use the term EVs in the present report. The EV-associated communication in the CNS represents an ancestral mechanism since studies showed their involvement in invertebrate species including nematodes, insects or annelids15,16. Moreover, the results showing that EVs can communicate with cells from different species demonstrate this mechanism to be a key-lock system, based first on surface-molecule recognition between vesicles and recipient cells and then allowing the uptake of mediators16,17. Indeed, the EVs contain many molecules like proteins (e.g., enzymes, signal transduction, biogenesis factor), lipids (e.g., ceramide, cholesterol) or nucleic acids (e.g., DNA, mRNA or miRNAs) acting as direct or indirect regulators of the recipient cell activities14. That is why methodological studies were also performed on immune cells to isolate EVs and fully characterize their protein signatures18,19.
The earliest studies demonstrated the release of exosomes from primary cultured rat microglia as an inducible mechanism following a Wnt3a- or serotonin-dependent activation20,21. Functionally in the CNS, microglia-derived EVs regulate the synaptic vesicle release by presynaptic terminals in neurons contributing to the control of the neuronal excitability22,23. Microglia-derived EVs could also propagate cytokines-mediated inflammatory response in large brain regions24,25. Importantly, the diverse ligands for toll-like receptor family might activate specific productions of EVs in the microglia26. For example, in vitro studies show that LPS-activated microglia BV2 cell lines produce differential EV contents including pro-inflammatory cytokines27. Therefore, the functional diversity of immune cell subpopulations in the CNS, microglia and infiltrating BMDMs, might be evaluated through their own EV populations including the EV impact on recipient cells and the identification of EV contents.
We previously described methods to evaluate the functional properties of microglia- and BMDM-derived EVs after their isolation16,19. In the present report, we propose to independently evaluate the effect of microglia-derived EVs on neurite outgrowth, and the effect of macrophage-derived EVs on the control of glioma cell aggregates. This study also proposes a wide proteomic analysis of the EV fractions in order to validate the EV isolation procedure as well as identify the biologically active protein signatures. The beneficial effects and the molecular deciphering of EV contents could help their possible manipulation and use as therapeutic agents in brain disorders.

<table>
<tbody>
<tr>
<td>12% Mini-PROTEAN&nbsp;TGX Precast Protein Gels</td>
<td>Bio-rad</td>
<td>4561045EDU</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Acetonitrile</td>
<td>Fisher Chemicals</td>
<td>A955-1</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Amicon 50 kDa centrifugal filter</td>
<td>Merck</td>
<td>UFC505024</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ammonium bicarbonate</td>
<td>Sigma-Aldrich</td>
<td>9830</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>HSP90 &alpha;/&beta; antibody (RRID: AB_675659)</td>
<td>Santa-cruz</td>
<td>sc-13119</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>B27 Plus supplement</td>
<td>Gibco</td>
<td>A3582801</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>BenchMixer V2 Vortex Mixer</td>
<td>Benchmark Scientific</td>
<td>BV1003</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Bio-Rad Protein Assay Dye Reagent Concentrate (Bradford)</td>
<td>Bio-Rad</td>
<td>5000006</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>C18 ZipTips</td>
<td>Merck Millipore</td>
<td>ZTC18S096</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>C6 rat glioma cell</td>
<td>ATCC</td>
<td>ATCC CCL-107</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Canonical tubes</td>
<td>Sarstedt</td>
<td>62.554.002</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Centrifuge</td>
<td>Eppendorf</td>
<td>5804000010</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>CO2 Incubator</td>
<td>ThermoFisher</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Confocal microscope LSM880</td>
<td>Carl Zeiss</td>
<td>LSM880</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Cover glass</td>
<td>Marienfeld</td>
<td>111580</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Culture Dish (60 mm)</td>
<td>Sarstedt</td>
<td>82.1473</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Dithiothreitol</td>
<td>Sigma-Aldrich</td>
<td>43819</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>DMEM</td>
<td>Gibco</td>
<td>41966029</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>EASY-nLC 1000 Liquid Chromatograph</td>
<td>ThermoFisher</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Electron microscope JEM-2100</td>
<td>JEOL</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ethylene glycol-bis(2-aminoethylether)-N,N,N&prime;,N&prime;-tetraacetic acid</td>
<td>Sigma-Aldrich</td>
<td>03777-10G</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ethylenediaminetetraacetic acid</td>
<td>Sigma-Aldrich</td>
<td>ED-100G</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Exo-FBS</td>
<td>Ozyme</td>
<td>EXO-FBS-50A-1</td>
<td>Exosome depleted FBS</td>
</tr>
<tr>
<td>ExoCarta database (top 100 proteins of Evs)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>http://www.exocarta.org/</td>
</tr>
<tr>
<td>Fetal Bovine Serum</td>
<td>Gibco</td>
<td>16140071</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Fetal Horse Serum</td>
<td>Biowest</td>
<td>S0960-500</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Filtropur S 0.2</td>
<td>Sarstedt</td>
<td>83.1826.001</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Fisherbrand&nbsp;Q500 Sonicator with Probe</td>
<td>Fisherbrand</td>
<td>12893543</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>FlexAnalysis</td>
<td>Brucker</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Fluorescence mounting medium</td>
<td>Agilent</td>
<td>S3023</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Formic Acid</td>
<td>Sigma-Aldrich</td>
<td>695076</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Formvar-carbon coated copper grids</td>
<td>Agar scientific Ltd</td>
<td>AGS162-3</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Glucose</td>
<td>Sigma-Aldrich</td>
<td>G8769</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Glutaraldehyde</td>
<td>Sigma-Aldrich</td>
<td>340855</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Hoechst 33342</td>
<td>Euromedex</td>
<td>17535-AAT</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Idoacetamide</td>
<td>Sigma-Aldrich</td>
<td>I1149</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>InstantBlue Coomassie Protein Stain</td>
<td>Expedeon</td>
<td>ISB1L</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invert light microscope CKX53</td>
<td>Olympus</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>L-glutamine</td>
<td>Gibco</td>
<td>25030-024</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>LabTek II 8 wells</td>
<td>&nbsp;Nunc</td>
<td>154534</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Laemmli 2X</td>
<td>Bio-Rad</td>
<td>1610737</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Laminin</td>
<td>Corning</td>
<td>354232</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>MaxQuant software (proteins identification software)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>https://maxquant.net/maxquant/</td>
</tr>
<tr>
<td>MBT Polish stell</td>
<td>Brucker</td>
<td>8268711</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>MEM 10X</td>
<td>Gibco</td>
<td>21090-022</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Methylcellulose</td>
<td>Sigma-Aldrich</td>
<td>M6385-100G</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>MiliQ water</td>
<td>Merck Millipore</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Milk</td>
<td>Regilait</td>
<td>REGILAIT300</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Mini PROTEAN Vertical Electrophoresis Cell</td>
<td>Bio-Rad</td>
<td>1658000FC</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>MonoP FPLC column</td>
<td>GE Healthcare</td>
<td>&nbsp;</td>
<td>no longer available</td>
</tr>
<tr>
<td>Nanosight NS300</td>
<td>Malvern Panalytical</td>
<td>NS300</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>NanoSight NTA software v3.2</td>
<td>Malvern Panalytical</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>NanoSight syringe pump</td>
<td>Malvern Panalytical</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Neurobasal</td>
<td>Gibco</td>
<td>21103-049</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Nitrocellulose membrane</td>
<td>GE Healthcare</td>
<td>10600007</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Nonidet P-40</td>
<td>Fluka</td>
<td>56741</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Nunc multidish 24 wells</td>
<td>ThermoFisher</td>
<td>82.1473</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Paraformaldehyde</td>
<td>Electro microscopy Science</td>
<td>15713</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>PC-12 cell line</td>
<td>ATCC</td>
<td>ATCC CRL-1721</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Penicillin-Streptomycin</td>
<td>Gibco</td>
<td>15140-122</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Peptide calibration mix</td>
<td>LaserBio Labs</td>
<td>C101</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Peroxidase AffiniPure Goat Anti-Mouse IgG (H+L)</td>
<td>Jackson ImmunoResearch</td>
<td>115-035-003</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Perseus software (Processing of identified proteins)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>https://maxquant.net/perseus/</td>
</tr>
<tr>
<td>Phalloidin-tetramethylrhodamine conjugate</td>
<td>Santa-cruz</td>
<td>sc-362065</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Phenylmethanesulfonyl fluoride</td>
<td>Sigma-Aldrich</td>
<td>78830</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Phosphate Buffer Saline</td>
<td>Invitrogen</td>
<td>14190094</td>
<td>no calcium, no magnesium</td>
</tr>
<tr>
<td>pluriStrainer M/ 60 &micro;m</td>
<td>pluriSelect</td>
<td>43-50060</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Poly-D-lysine</td>
<td>Sigma-Aldrich</td>
<td>P6407</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Polycarbonate centrifuge tubes</td>
<td>Beckman Coulter</td>
<td>355651</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Protease Inhibitor</td>
<td>Sigma-Aldrich</td>
<td>S8830-20TAB</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>PureCol</td>
<td>Cell Systems</td>
<td>5005</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Q-Exactive mass spectrometer</td>
<td>ThermoFisher</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>rapifleX mass spectrometer</td>
<td>Brucker</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Rat cortical neurons</td>
<td>Cell Applications</td>
<td>R882N-20</td>
<td>Cell origin : Derived from cerebral cortices of day 18 embryonic Sprague Dawley rat brains</td>
</tr>
<tr>
<td>Rat Macrophage &amp; Microglia Culture Medium</td>
<td>Cell Applications</td>
<td>R620K-100</td>
<td>Cell orgin : Normal healthy Rat bone marrow</td>
</tr>
<tr>
<td>Rat primary macrophages</td>
<td>Cell Applications</td>
<td>R8818-10a</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Rat primary microglia</td>
<td>Lonza</td>
<td>RG535</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sepharose CL-2B</td>
<td>GE Healthcare</td>
<td>17014001</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sequencing Grade Modified Trypsin</td>
<td>Promega</td>
<td>V5111</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Slide</td>
<td>Dustsher</td>
<td>100204</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sodium Chloride</td>
<td>Scharlau</td>
<td>SO0227</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sodium Dodecyl Sulfate</td>
<td>Sigma-Aldrich</td>
<td>L3771</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sodium Fluoride</td>
<td>Sigma-Aldrich</td>
<td>S7920-100G</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sodium hydroxide</td>
<td>Scharlab</td>
<td>SO0420005P</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Sodium pyrophosphate</td>
<td>Sigma-Aldrich</td>
<td>S6422-100G</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>SpeedVac Vacuum Concentrator</td>
<td>ThermoFisher</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>String software (functional protein association networks)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>https://string-db.org/</td>
</tr>
<tr>
<td>SuperSignal West Dura extended Duration Substrate</td>
<td>ThermoFisher</td>
<td>34075</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Syringe 1.0 mL</td>
<td>Terumo</td>
<td>8SS01H1</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Trans-Blot SD Semi-Dry Transfer cell</td>
<td>Bio-Rad</td>
<td>1703940</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Trifluoroacetic acid</td>
<td>Sigma-Aldrich</td>
<td>T6508</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Tris</td>
<td>Interchim</td>
<td>UP031657</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Tris-Glycine</td>
<td>Euromedex</td>
<td>EU0550</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Tween 20</td>
<td>Sigma-Aldrich</td>
<td>P2287</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ultracentrifuge</td>
<td>Beckman Coulter</td>
<td>A95765</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ultracentrifuge Rotor 70.1 Ti</td>
<td>Beckman Coulter</td>
<td>342184</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Uranyl acetate</td>
<td>Agar Scientific Ltd</td>
<td>AGR1260A</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Whatman filter paper</td>
<td>Sigma-Aldrich</td>
<td>WHA10347510</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>&alpha;-Cyano-4-hydroxycinnamic acid</td>
<td>Sigma-Aldrich</td>
<td>C2020-25G</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>

characterization of immune cell-derived extracellular vesicles and studying functional impact on cell environment

The neuroinflammatory state of the central nervous system (CNS) plays a key role in physiological and pathological conditions. Microglia, the resident immune cells in the brain, and sometimes the infiltrating bone marrow-derived macrophages (BMDMs), regulate the inflammatory profile of their microenvironment in the CNS. It is now accepted that the extracellular vesicle (EV) populations from immune cells act as immune mediators. Thus, their collection and isolation are important to identify their contents but also evaluate their biological effects on recipient cells. The present data highlight chronological requirements for EV isolation from microglia cells or blood macrophages including the ultracentrifugation and size-exclusion chromatography (SEC) steps. A non-targeted proteomic analysis permitted the validation of protein signatures as EV markers and characterized the biologically active EV contents. Microglia-derived EVs were also functionally used on primary culture of neurons to assess their importance as immune mediators in the neurite outgrowth. The results showed that microglia-derived EVs contribute to facilitate the neurite outgrowth in vitro. In parallel, blood macrophage-derived EVs were functionally used as immune mediators in spheroid cultures of C6 glioma cells, the results showing that these EVs control the glioma cell invasion in vitro. This report highlights the possibility to evaluate the EV-mediated immune cell functions but also understand the molecular bases of such a communication. This deciphering could promote the use of natural vesicles and/or the in vitro preparation of therapeutic vesicles in order to mimic immune properties in the microenvironment of CNS pathologies.

One of the main challenges to attributing biologicals effects to extracellular vesicles (EVs) is the ability to isolate the EVs from the whole culture medium. In this report, we present a method using ultracentrifugation (UC) and size-exclusion chromatography (SEC) which is coupled to the large-scale analysis of protein signatures to validate EV markers and identify bioactive compounds. The macrophage- or microglia-derived EVs were isolated from the conditioned medium after a 24 h or 48 h culture respectively (<strong cl...

Watch this Scientific Journal Video about Characterization of Immune Cell-derived Extracellular Vesicles and Studying Functional Impact on Cell Environment at JoVE.com

Characterization of Immune Cell-derived Extracellular Vesicles and Studying Functional Impact on Cell Environment

The present report highlights chronological requirements for extracellular vesicle (EV) isolation from microglia or blood macrophages. Microglia-derived EVs were evaluated as regulators of the neurite outgrowth while blood macrophage-derived EVs were studied in the control of C6 glioma cell invasion in in vitro assays. The goal is to better understand these EV functions as immune mediators in specific microenvironments.

The neuroinflammatory state of the central nervous system (CNS) plays a key role in physiological and pathological conditions. Microglia, the resident ...

This protocol makes it possible to guarantee a good isolation of extracellular vesicles and notification of a higher number of EBDF proteins. Compared to other isolation techniques, this one maintains that it is more integrity and vertical activities. EVs are being studied more and more in LC as well as pathological conditions.This method can be applied to any systems that we choose to characterize and study the EVs. For that content or the biological ethics special attention is required when iterating EVs, as in the culture results in the following experiments. A visual demonstration is critical to host specific equipment such as a homemade size exclusion chromatography column as well as the involvement of nanoparticle counter and mass spectrometer.Helping to demonstrate the procedure will be Antonella Raffo-Romero, a from the laboratory. Start by pre-isolating extracellular vesicles, or EVs, from condition medium. Transfer the condition to culture medium from microglia or macrophage cultures into a conical tube and centrifuge it at 1, 200 times G for 10 minutes to pellet the cells.Transfer the supernatant into a new conical tube and centrifuge for another 20 minutes to eliminate apoptotic bodies. Then transfer the supernatant into a 10.4 milliliter polycarbonate tube. Place the tube into a 70.1 TI rotor and ultra centrifuge at at 100, 000 times G for 90 minutes at four degrees Celsius to pellet the EVs.After centrifugation, discard the supernatant and resuspend the pellet in 200 microliters of 0.2 micrometer filtered PBS. To isolate the EVs, prepare a homemade size exclusion chromatography column by washing and sterilizing a glass chromatography column, and placing a 60 microliter filter at the bottom. Stack the column with cross-linked agarose gel filtration base matrix to create a stationary phase of 0.6 centimeters in diameter and 20 centimeters in height.Then rinse the phase with 50 milliliters of 0.2 micro meter filtered PBS. If necessary, store the column at four degrees Celsius for later use. Place the resuspended EV pellet on top of the stationary phase and collect 20 sequential fractions of 250 microliters while continuing to add PBS to the top of the stationary phase.The fractions can be stored at minus 20 degrees Celsius. To perform a nanoparticle tracking analysis, make a dilution of each fraction with 0.2 micrometer filtered PBS and vortex it to eliminate aggregates. Put the solution in a one milliliter syringe and place it in the automated syringe pump.Next, adjust the camera settings to the appropriate screen gain level and camera level and click on Run. Load the sample in the analysis chamber with an infusion rate of 1000 for 15 seconds. Then decrease and stabilize the speed flow for video recording to an infusion rate of 25 for 15 seconds.Capture a three consecutive 60 second videos of the particle flow. Then adjust the camera level and the detection threshold before video analysis. Click on Settings OK to start the analysis, and click on Export when done.Wash the system with one milliliter of 0.2 micrometer filtered PBS between each fraction. If performing electron microscopy analysis, use a 50 kilodalton centrifugal filter to concentrate the size exclusion chromatography fractions of interest. For protein extraction, mix 50 microliters of RIPA buffer with the EV sample for five minutes on ice.Sonicate the samples three times at 500 Watts and 20 kilohertz for five seconds. Then remove vesicular debris by centrifuging at 20, 000 times G for 10 minutes at four degrees Celsius. After isolating the proteins, perform protein migration in the stacking gel of a 12%polyacrylic gel.Mix the proteins in the gel with Coomassie Blue for 20 minutes at room temperature. Then excise each colored gel piece and cut it into small pieces. Put the gel pieces through a series of successive washes as described in the manuscript.Then dry them completely with a vacuum concentrator. After drying perform protein reduction with 100 microliters of 100 millimolar ammonium bicarbonate containing 10 millimolar Dithiothreitol for one hour at 56 degrees Celsius. Next perform protein alkylation with 100 microliters of 100 millimolar ammonium bicarbonate containing 50 millimolar iodoacetamide for 45 minutes in the dark.Wash the gel pieces according to manuscript directions and completely dry them on the vacuum concentrator. Perform protein digestion with 50 microliters of trypsin in 20 millimolar ammonium bicarbonate at 37 degrees Celsius overnight. On the next day, extract the digested proteins from the gel with 50 microliters of 100%ACN for 30 minutes at 37 degrees Celsius and then 15 minutes at room temperature with continuous stirring.Then extract the proteins twice with 50 microliters of 5%TFA in 20 millimolar ammonium bicarbonate, while stirring continuously for 20 minutes. Add 100 microliters of ACN and continue stirring for 10 minutes. Afterwards, dry the proteins and resuspend them in 20 microliters of 0.1%TFA.Desalt the sample using a 10 microliter pipette tip with C 18 reverse phase media for desalting and concentrating peptides. Then elute them with ACN and 0.1%formic acid. Completely dry the sample with a vacuum concentrator and resuspend it in 20 microliters of ACN and 0.1%formic acid for liquid chromatography tandem mass spectrometry, or LC-MS.Load the digested peptides into the instrument and perform a sample analysis. To confirm EV isolation, each SCC fraction was subjected to a nanoparticle tracking analysis. The particle number was significantly higher in fractions five, six, and seven.These fractions were pooled into one sample 2F-EV positive, and compared with EV negative fractions, 1F-EV negative and 3F-EV negative, using Western blot analysis. The results showed the presence of heat shock protein 90 in the EV positive sample and in the cell lysate control. Electron microscopy of the EV positive sample showed EVs in a size range around 100 nanometers and 400 nanometers.Proteomics analysis was performed in order to identify contaminant proteins in EV negative samples and characterize the protein contents of EVs. The identified proteins were compared between 1F-EV negative and a 2F-EV positive samples, as well as between 2F-EV positive and a 3F-EV negative samples. Using this non-targeted method, a pool of 536 proteins were submitted to the ExoCarta database and led to the identification of 86 EV associated proteins.In addition, this pool also allowed for the identifying of protein interactions and their associated biological functions. It was found that the proteins from the EV positive sample played roles in immune and neuroprotective pathways. The effects of microglia-derived EVs were evaluated on neurite outgrowth with PC 12 cells and rat primary neurons.Significant outgrowth increase was observed under EVs compared to control. Macrophage-derived EVs were evaluated on glioma cell invasion. It was found that EVs impaired the growth and invasion of glioma spheroids.The most important thing to remember is to really carefully discard the supernatant of the ultracentrifugation step in order to prevent the loss of EVs in this procedure. We favor a large scale and non-targeted approach to focus on the whole protein content and then the vertical effect of EVs. so contents in nucleic acids can be associated using analysis.With this approach from a primary culture, we are able to discriminate between EV proteins and free proteins that are outside of variety. So the question remains whether this coagulation is artifactual or rather some other real

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JoVE Journal

Neuroscience

6.7K Views.  Univ. Lille, INSERM. This protocol makes it possible to guarantee a good isolation of extracellular vesicles and notification of a higher number of EBDF proteins. Compared to other isolation techniques, this one maintains that it is more integrity and vertical activities. EVs are being studied more and more in LC as well as pathological conditions.This method can be applied to any systems that we choose to characterize and study the EVs. For that content or the biological ethics special attention is requir...

Video: Characterization of Immune Cell-derived Extracellular Vesicles and Studying Functional Impact on Cell Environment

The present report highlights chronological requirements for extracellular vesicle (EV) isolation from microglia or blood macrophages. Microglia-derived EVs were evaluated as regulators of the neurite outgrowth while blood macrophage-derived EVs were studied in the control of C6 glioma cell invasion in in vitro assays. The goal is to better understand these EV functions as immune mediators in specific...

sec-based isolation of microglia-derived extracellular vesicles: a technique to isolate extracellular vesicles from microglia conditioned culture media

This video describes a method based on size-exclusion chromatography (SEC) to isolate extracellular vesicles or EVs derived from the brain immune cells&#8213;the microglia. The EVs act as molecular cargo to deliver mediators, which regulate an immune response. Therefore, the isolated EVs can be used as an in vitro model to study the microglia-neuron crosstalk during a neuronal immune...

SEC-based Isolation of Microglia-derived Extracellular Vesicles: A Technique to Isolate Extracellular Vesicles from Microglia Conditioned Culture Media

sds-page based extraction of extracellular vesicles associated proteins: a procedure to extract proteins from evs and prepare them for in-gel digestion

In this video, we demonstrate the SDS-PAGE in-gel digestion method for protein extraction from extracellular vesicles or EVs. Once isolated, the obtained protein fragments can be used for proteomic...

SDS-PAGE Based Extraction of Extracellular Vesicles Associated Proteins: A Procedure to Extract Proteins from EVs and Prepare Them for In-Gel Digestion

scalable biomanufacturing workflow to produce and isolate natural killer cell-derived extracellular vesicle-based cancer biotherapeutics

Author Spotlight: Scalable Isolation and Production of Therapeutic Immune Cell-Derived Vesicles for Solid Tumor Treatment

Natural killer cell-derived extracellular vesicles (NK-EVs) hold promising potential as cancer biotherapeutics. This methodology-based study presents a scalable closed-loop biomanufacturing workflow designed to continuously produce and isolate large quantities of high-purity NK-EVs. In-process control testing is performed throughout the biomanufacturing workflow, ensuring the EVs meet quality standards for product release.

Biomanufacturing and Characterization of NK-Extracellular Vesicles

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isolation, characterization and functional examination of the gingival immune cell network

Isolation, Characterization and Functional Examination of the Gingival Immune Cell Network

We have established a technique for the isolation, phenotypic characterization and functional analysis of immune cells from murine...

isolation of low endotoxin content extracellular vesicles derived from cancer cell lines

Isolation of Low Endotoxin Content Extracellular Vesicles Derived from Cancer Cell Lines

The proposed protocol includes guidelines on how to avoid contamination with endotoxin during the isolation of extracellular vesicles from cell culture supernatants, and how to properly evaluate...

isolation and characterization of human adipocyte-derived extracellular vesicles using filtration and ultracentrifugation

Isolation and Characterization of Human Adipocyte-Derived Extracellular Vesicles using Filtration and Ultracentrifugation

We describe the isolation of human adipocyte-derived extracellular vesicles (EVs) from gluteal and abdominal adipose tissue using filtration and ultracentrifugation. We characterize the isolated adipocyte-derived EVs by determining their size and concentration by Nanoparticle Tracking Analysis and by western blotting for the presence of EV-protein tumor susceptibility gene 101...

isolation and characterization of cyanobacterial extracellular vesicles

Isolation and Characterization of Cyanobacterial Extracellular Vesicles

The present protocol providesdetailed descriptions for isolation, concentration,and characterization of extracellular vesicles from cyanobacterial cultures. Approaches for purifying vesicles from cultures at different scales, trade-offs among methodologies, and considerations for working with field samples are also...

purification and characterization of extracellular vesicles from human adipose-derived mesenchymal stem cells

Author Spotlight: Standardizing and Improving the Extraction and Purification of Extracellular Vesicles from Human ADSCs

This protocol describes all procedures, from culturing human adipose-derived mesenchymal stem cells (ADSCs) and collecting supernatant to extracting extracellular vesicles (EVs) using...

Purification and Characterization of Extracellular Vesicles from Human Adipose-Derived Mesenchymal Stem Cells

extracting extracellular vesicles (evs) from adipose-derived mesenchymal stem cell culture

Extracting Extracellular Vesicles (EVs) from Adipose-Derived Mesenchymal Stem Cell Culture

isolation and characterization of extracellular vesicles from adult schistosoma japonicum

Isolation and Characterization of Extracellular Vesicles from Adult Schistosoma japonicum

Here, we present a protocol to describe extracellular vesicles (EVs) isolation in in vitro cultured medium from adult Schistosoma...

Isolation and Characterization of Extracellular Vesicles from Adult Schistosoma japonicum

Ultracentrifuge-Based Isolation of Extracellular Vesicles from Human ADSCs

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flow cytometric analysis of extracellular vesicles from cell-conditioned media

Flow Cytometric Analysis of Extracellular Vesicles from Cell-conditioned Media

The protocol describes a reproducible method designed for use with cell culture supernatants to detect surface epitopes on small extracellular vesicles (EV). It utilizes specific EV immunoprecipitation using beads coupled with antibodies that recognize surface antigen CD9, CD63, and CD81. The method is optimized for downstream flow cytometry...

setting a successful sorting for extracellular vesicle isolation

Author Spotlight: Advancing Fluorescence-Based Sorting Techniques for Characterizing Extracellular Vesicles

This protocol provides a detailed description of sorting extracellular vesicles (EVs) released by mesenchymal stromal cells. In particular, it focuses on the instrument setting and the optimization of the sorting conditions. The goal is to sort extracellular vesicles while preserving their...

Fluorescence-Based Sorting of Adipose-Derived Extracellular Vesicles

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a rapid, scalable method for the isolation, functional study, and analysis of cell-derived extracellular matrix

A Rapid, Scalable Method for the Isolation, Functional Study, and Analysis of Cell-derived Extracellular Matrix

The extracellular matrix plays a major role in defining the microenvironment of cells and in modulating cell behavior and phenotype. We describe a rapid method for the isolation of cell-derived extracellular matrix, which can be adapted to different scales for microscopic, biochemical, proteomic, or functional studies.

paper-based devices for isolation and characterization of extracellular vesicles

Paper-based Devices for Isolation and Characterization of Extracellular Vesicles

This protocol details a method to isolate extracellular vesicles (EVs), small membranous particles released from cells, from as little as 10 &#956;l serum samples. This approach circumvents the need for ultracentrifugation, requires only a few minutes of assay time, and enables the isolation of EVs from samples of limited...

enrichment of astrocyte-derived extracellular vesicles from human plasma

Enrichment of Astrocyte-Derived Extracellular Vesicles from Human Plasma

This protocol describes the enrichment of astrocyte-derived extracellular vesicles (ADEVs) from human plasma. It is based on the separation of EVs by polymer precipitation, followed by ACSA-1 based immunocapture of ADEVs. Analysis of ADEVs may offer clues to study changes in inflammatory pathways of living patients, non-invasively by liquid...

characterization of immune cells and proinflammatory mediators in the pulmonary environment

Characterization of Immune Cells and Proinflammatory Mediators in the Pulmonary Environment

This protocol describes the use of flow cytometry to identify the changes in immune cell composition, cytokine profile, and chemokine profile in the pulmonary environment following transient middle cerebral artery occlusion, a murine model of ischemic...

isolation and characterization of extracellular vesicles produced by iron-limited mycobacteria

Isolation and Characterization of Extracellular Vesicles Produced by Iron-limited Mycobacteria

Mycobacterium tuberculosis shows increased production and release of extracellular vesicles in response to low iron conditions. This work details a protocol for generating low iron conditions and methods for the purification and characterization of mycobacterial extracellular vesicles released in response to iron...

Modeling Neural Immune Signaling of Episodic and Chronic Migraine Using Spreading Depression In Vitro

Migraine and its transformation to chronic migraine are healthcare burdens in need of improved treatment options. We seek to define how neural immune signaling modulates the susceptibility to migraine, modeled in vitro using spreading depression (SD), as a means to develop novel therapeutic targets for episodic and chronic migraine. SD is the likely cause of migraine aura and migraine pain. It is a paroxysmal loss of neuronal function triggered by initially increased neuronal activity, which slowly propagates within susceptible brain regions. Normal brain function is exquisitely sensitive to, and relies on, coincident low-level immune signaling. Thus, neural immune signaling likely affects electrical activity of SD, and therefore migraine. Pain perception studies of SD in whole animals are fraught with difficulties, but whole animals are well suited to examine systems biology aspects of migraine since SD activates trigeminal nociceptive pathways. However, whole animal studies alone cannot be used to decipher the cellular and neural circuit mechanisms of SD. Instead, in vitro preparations where environmental conditions can be controlled are necessary. Here, it is important to recognize limitations of acute slices and distinct advantages of hippocampal slice cultures. Acute brain slices cannot reveal subtle changes in immune signaling since preparing the slices alone triggers: pro-inflammatory changes that last days, epileptiform behavior due to high levels of oxygen tension needed to vitalize the slices, and irreversible cell injury at anoxic slice centers. 
In contrast, we examine immune signaling in mature hippocampal slice cultures since the cultures closely parallel their in vivo counterpart with mature trisynaptic function; show quiescent astrocytes, microglia, and cytokine levels; and SD is easily induced in an unanesthetized preparation. Furthermore, the slices are long-lived and SD can be induced on consecutive days without injury, making this preparation the sole means to-date capable of modeling the neuroimmune consequences of chronic SD, and thus perhaps chronic migraine. We use electrophysiological techniques and non-invasive imaging to measure neuronal cell and circuit functions coincident with SD. Neural immune gene expression variables are measured with qPCR screening, qPCR arrays, and, importantly, use of cDNA preamplification for detection of ultra-low level targets such as interferon-gamma using whole, regional, or specific cell enhanced (via laser dissection microscopy) sampling. Cytokine cascade signaling is further assessed with multiplexed phosphoprotein related targets with gene expression and phosphoprotein changes confirmed via cell-specific immunostaining. Pharmacological and siRNA strategies are used to mimic and modulate SD immune signaling.

Modeling Neural Immune Signaling of Episodic and Chronic Migraine Using Spreading Depression In Vitro

Migraine and its transformation to chronic migraine are immense healthcare burdens in need of improved treatment options. We seek to define how neural immune signaling modulates the susceptibility to migraine, modeled in vitro using spreading depression in hippocampal slice cultures, as a means to develop novel therapeutic targets.

Migraine and its transformation to chronic migraine are healthcare burdens in need of improved treatment options.  We seek to define how neural immune ...

Functional Evaluation of Biological Neurotoxins in Networked Cultures of Stem Cell-derived Central Nervous System Neurons

Therapeutic and mechanistic studies of the presynaptically targeted clostridial neurotoxins (CNTs) have been limited by the need for a scalable, cell-based model that produces functioning synapses and undergoes physiological responses to intoxication. Here we describe a simple and robust method to efficiently differentiate murine embryonic stem cells (ESCs) into defined lineages of synaptically active, networked neurons. Following an 8 day differentiation protocol, mouse embryonic stem cell-derived neurons (ESNs) rapidly express and compartmentalize neurotypic proteins, form neuronal morphologies and develop intrinsic electrical responses. By 18 days after differentiation (DIV 18), ESNs exhibit active glutamatergic and &#947;-aminobutyric acid (GABA)ergic synapses and emergent network behaviors characterized by an excitatory:inhibitory balance. To determine whether intoxication with CNTs functionally antagonizes synaptic neurotransmission, thereby replicating the in vivo pathophysiology that is responsible for clinical manifestations of botulism or tetanus, whole-cell patch clamp electrophysiology was used to quantify spontaneous miniature excitatory post-synaptic currents (mEPSCs) in ESNs exposed to tetanus neurotoxin (TeNT) or botulinum neurotoxin (BoNT) serotypes /A-/G. In all cases, ESNs exhibited near-complete loss of synaptic activity within 20 hr. Intoxicated neurons remained viable, as demonstrated by unchanged resting membrane potentials and intrinsic electrical responses. To further characterize the sensitivity of this approach, dose-dependent effects of intoxication on synaptic activity were measured 20 hr after addition of BoNT/A. Intoxication with 0.005 pM BoNT/A resulted in a significant decrement in mEPSCs, with a median inhibitory concentration (IC50) of 0.013 pM. Comparisons of median doses indicate that functional measurements of synaptic inhibition are faster, more specific and more sensitive than SNARE cleavage assays or the mouse lethality assay. These data validate the use of synaptically coupled, stem cell-derived neurons for the highly specific and sensitive detection of CNTs.

A custom protocol is described to differentiate mouse ES cells into defined populations of highly pure neurons exhibiting functioning synapses and emergent network behavior. Electrophysiological analysis demonstrates the loss of synaptic transmission following exposure to botulinum neurotoxin serotypes /A-/G and tetanus neurotoxin.

Therapeutic and mechanistic studies of the presynaptically targeted clostridial neurotoxins (CNTs) have been limited by the need for a scalable, ...

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

Modelling Zika Virus Infection of the Developing Human Brain In Vitro Using Stem Cell Derived Cerebral Organoids

The recent emergence of Zika virus (ZIKV) in susceptible populations has led to an abrupt increase in microcephaly and other neurodevelopmental conditions in newborn infants. While mosquitos are the main route of viral transmission, it has also been shown to spread via sexual contact and vertical mother-to-fetus transmission. In this latter case of transmission, due to the unique viral tropism of ZIKV, the virus is believed to predominantly target the neural progenitor cells (NPCs) of the developing brain.
Here a method for modeling ZIKV infection, and the resulting microcephaly, that occur when human cerebral organoids are exposed to live ZIKV is described. The organoids display high levels of virus within their neural progenitor population, and exhibit severe cell death and microcephaly over time. This three-dimensional cerebral organoid model allows researchers to conduct species-matched experiments to observe and potentially intervene with ZIKV infection of the developing human brain. The model provides improved relevance over standard two-dimensional methods, and contains human-specific cellular architecture and protein expression that are not possible in animal models.

Modelling Zika Virus Infection of the Developing Human Brain In Vitro Using Stem Cell Derived Cerebral Organoids

This protocol describes a technique used to model Zika virus infection of the developing human brain. Using wildtype or engineered stem cell lines, researchers may use this technique to uncover the various mechanisms or treatments that may affect early brain infection and resulting microcephaly in Zika virus-infected embryos.

The recent emergence of Zika virus (ZIKV) in susceptible populations has led to an abrupt increase in microcephaly and other neurodevelopmental conditions ...

Monitoring the Effect of Osmotic Stress on Secretory Vesicles and Exocytosis

Amperometry recording of cells subjected to osmotic shock show that secretory cells respond to this physical stress by reducing the exocytosis activity and the amount of neurotransmitter released from vesicles in single exocytosis events. It has been suggested that the reduction in neurotransmitters expelled is due to alterations in membrane biophysical properties when cells shrink in response to osmotic stress and with assumptions made that secretory vesicles in the cell cytoplasm are not affected by extracellular osmotic stress. Amperometry recording of exocytosis monitors what is released from cells the moment a vesicle fuses with the plasma membrane, but does not provide information on the vesicle content before the vesicle fusion is triggered. Therefore, by combining amperometry recording with other complementary analytical methods that are capable of characterizing the secretory vesicles before exocytosis at cells is triggered offers a broader overview for examining how secretory vesicles and the exocytosis process are affected by osmotic shock. We here describe how complementing amperometry recording with intracellular electrochemical cytometry and transmission electron microscopy (TEM) imaging can be used to characterize alterations in secretory vesicles size and neurotransmitter content at chromaffin cells in relation to exocytosis activity before and after exposure to osmotic stress. By linking the quantitative information gained from experiments using all three analytical methods, conclusions were previously made that secretory vesicles respond to extracellular osmotic stress by shrinking in size and reducing the vesicle quantal size to maintain a constant vesicle neurotransmitter concentration. Hence, this gives some clarification regarding why vesicles, in response to osmotic stress, reduce the amount neurotransmitters released during exocytosis release. The amperometric recordings here indicate this is a reversible process and that vesicle after osmotic shock are refilled with neurotransmitters when placed cells are reverted into an isotonic environment.

Osmotic stress affects exocytosis and the amount of neurotransmitter released during this process. We demonstrate how combining electrochemical methods together with transmission electron microscopy can be used to study the effect of extracellular osmotic pressure on exocytosis activity, vesicle quantal size, and the amount of neurotransmitter released during exocytosis.

Amperometry recording of cells subjected to osmotic shock show that secretory cells respond to this physical stress by reducing the exocytosis activity ...

In Vivo Calcium Imaging of Lateral-line Hair Cells in Larval Zebrafish

Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory stimuli that mechanically deflect apical protrusions called hair bundles. Deflection opens mechanotransduction (MET) channels in hair bundles, leading to an influx of cations, including calcium. This cation influx depolarizes the cell and opens voltage-gated calcium channels located basally at the hair-cell presynapse. In mammals, hair cells are encased in bone, and it is challenging to functionally assess these activities in vivo. In contrast, larval zebrafish are transparent and possess an externally located lateral-line organ that contains hair cells. These hair cells are functionally and structurally similar to mammalian hair cells and can be functionally assessed in vivo. This article outlines a technique that utilizes a genetically encoded calcium indicator (GECI), GCaMP6s, to measure stimulus-evoked calcium signals in zebrafish lateral-line hair cells. GCaMP6s can be used, along with confocal imaging, to measure in vivo calcium signals at the apex and base of lateral-line hair cells. These signals provide a real-time, quantifiable readout of both mechanosensation- and presynapse-dependent calcium activities within these hair cells. These calcium signals also provide important functional information regarding how hair cells detect and transmit sensory stimuli. Overall, this technique generates useful data about relative changes in calcium activity in vivo. It is less well-suited for quantification of the absolute magnitude of calcium changes. This in vivo technique is sensitive to motion artifacts. A reasonable amount of practice and skill are required for proper positioning, immobilization, and stimulation of larvae. Ultimately, when properly executed, the protocol outlined in this article provides a powerful way to collect valuable information about the activity of hair-cells in their natural, fully integrated states within a live animal.

The zebrafish is a model system that has many valuable features including optical clarity, rapid external development, and, of particular importance to the field of hearing and balance, externally located sensory hair cells. This article outlines how transgenic zebrafish can be used to assay both hair-cell mechanosensation and presynaptic function in toto.

Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory ...

Compartmentalization of Human Stem Cell-Derived Neurons within Pre-Assembled Plastic Microfluidic Chips

Use of microfluidic devices to compartmentalize cultured neurons has become a standard method in neuroscience. This protocol shows how to use a pre-assembled multi-compartment chip made in a cyclic olefin copolymer (COC) to compartmentalize neurons differentiated from human stem cells. The footprint of these COC chips are the same as a standard microscope slide and are equally compatible with high resolution microscopy. Neurons are differentiated from human neural stem cells (NSCs) into glutamatergic neurons within the chip and maintained for 5 weeks, allowing sufficient time for these neurons to develop synapses and dendritic spines. Further, we demonstrate multiple common experimental procedures using these multi-compartment chips, including viral labeling, establishing microenvironments, axotomy, and immunocytochemistry.

This protocol demonstrates the use of compartmentalized microfluidic chips, injection molded in a cyclic olefin copolymer to cultured neurons differentiated from human stem cells. These chips are preassembled and easier-to-use than traditional compartmentalized poly(dimethylsiloxane) devices. Multiple common experimental paradigms are described here, including viral labeling, fluidic isolation, axotomy, and immunostaining.

Use of microfluidic devices to compartmentalize cultured neurons has become a standard method in neuroscience. This protocol shows how to use a ...

Migration, Chemo-Attraction, and Co-Culture Assays for Human Stem Cell-Derived Endothelial Cells and GABAergic Neurons

Role of brain vasculature in nervous system development and etiology of brain disorders is increasingly gaining attention. Our recent studies have identified a special population of vascular cells, the periventricular endothelial cells, that play a critical role in the migration and distribution of forebrain GABAergic interneurons during embryonic development. This, coupled with their cell-autonomous functions, alludes to novel roles of periventricular endothelial cells in the pathology of neuropsychiatric disorders like schizophrenia, epilepsy, and autism. Here, we have described three different in vitro assays that collectively evaluate the functions of periventricular endothelial cells and their interaction with GABAergic interneurons. Use of these assays, particularly in a human context, will allow us to identify the link between periventricular endothelial cells and brain disorders. These assays are simple, low cost, and reproducible, and can be easily adapted to any adherent cell type.

We present three simple in vitro assays-the long-distance migration assay, the co-culture migration assay, and chemo-attraction assay-that collectively evaluate the functions of human stem cell derived periventricular endothelial cells and their interaction with GABAergic interneurons.

Role of brain vasculature in nervous system development and etiology of brain disorders is increasingly gaining attention. Our recent studies have ...

Subretinal Transplantation of Human Embryonic Stem Cell-Derived Retinal Tissue in a Feline Large Animal Model

Retinal degenerative (RD) conditions associated with photoreceptor loss such as age-related macular degeneration (AMD), retinitis pigmentosa (RP) and Leber Congenital Amaurosis (LCA) cause progressive and debilitating vision loss. There is an unmet need for therapies that can restore vision once photoreceptors have been lost. Transplantation of human pluripotent stem cell (hPSC)-derived retinal tissue (organoids) into the subretinal space of an eye with advanced RD brings retinal tissue sheets with thousands of healthy mutation-free photoreceptors and has a potential to treat most/all blinding diseases associated with photoreceptor degeneration with one approved protocol. Transplantation of fetal retinal tissue into the subretinal space of animal models and people with advanced RD has been developed successfully but cannot be used as a routine therapy due to ethical concerns and limited tissue supply. Large eye inherited retinal degeneration (IRD) animal models are valuable for developing vision restoration therapies utilizing advanced surgical approaches to transplant retinal cells/tissue into the subretinal space. The similarities in globe size, and photoreceptor distribution (e.g., presence of macula-like region area centralis) and availability of IRD models closely recapitulating human IRD would facilitate rapid translation of a promising therapy to the clinic. Presented here is a surgical technique of transplanting hPSC-derived retinal tissue into the subretinal space of a large animal model allowing assessment of this promising approach in animal models.

Presented here is a surgical technique for transplanting human pluripotent stem cell (hPSC)-derived retinal tissue into the subretinal space of a large animal model.

Retinal degenerative (RD) conditions associated with photoreceptor loss such as age-related macular degeneration (AMD), retinitis pigmentosa (RP) and ...

High-Content Screening Differentiation and Maturation Analysis of Fetal and Adult Neural Stem Cell-Derived Oligodendrocyte Precursor Cell Cultures

The main hurdle in developing drug screening techniques for assessing the efficacy of therapeutic strategies in complex diseases is striking a balance between in vitro simplification and recreating the complex in vivo environment, along with the main aim, shared by all screening strategies, of obtaining robust and reliable data, highly predictive for in vivo translation.
In the field of demyelinating diseases, the majority of drug screening strategies are based on immortalized cell lines or pure cultures of isolated primary oligodendrocyte precursor cells (OPCs) from newborn animals, leading to strong biases due to the lack of age-related differences and of any real pathological condition or complexity.
Here we show the setup of an in vitro system aimed at modeling the physiological differentiation/maturation of neural stem cell (NSC)-derived OPCs, easily manipulated to mimic pathological conditions typical of demyelinating diseases. Moreover, the method includes isolation from fetal and adult brains, giving a system which dynamically differentiates from OPCs to mature oligodendrocytes (OLs) in a spontaneous co-culture which also includes astrocytes. This model physiologically resembles the thyroid hormone-mediated myelination and myelin repair process, allowing the addition of pathological interferents which model disease mechanisms. We show how to mimic the two main components of demyelinating diseases (i.e., hypoxia/ischemia and inflammation), recreating their effect on developmental myelination and adult myelin repair and taking all the cell components of the system into account throughout, while focusing on differentiating OPCs.
This spontaneous mixed model, coupled with cell-based high-content screening technologies, allows the development of a robust and reliable drug screening system for therapeutic strategies aimed at combating the pathological processes involved in demyelination and at inducing remyelination.

We describe the production of mixed cultures of astrocytes and oligodendrocyte precursor cells derived from fetal or adult neural stem cells differentiating into mature oligodendrocytes, and in vitro modeling of noxious stimuli. The coupling with a cell-based high-content screening technique builds a reliable and robust drug screening system.

The main hurdle in developing drug screening techniques for assessing the efficacy of therapeutic strategies in complex diseases is striking a balance ...