Name: migration, chemo-attraction, and co-culture assays for human stem cell-derived endothelial cells and gabaergic neurons
Uploaded: 2020-01-23T12:00:00
Description: Watch this Scientific Journal Video about Migration, Chemo-Attraction, and Co-Culture Assays for Human Stem Cell-Derived Endothelial Cells and GABAergic Neurons at JoVE.com

This work was supported by awards from the National Institute of Mental Health (R01MH110438) and National Institute of Neurological Disorders and Stroke (R01NS100808) to AV.

1. Culture and Storage of Human Periventricular Endothelial Cells
<ol>
	<li>Maintain human periventricular endothelial cells on basement membrane matrix-coated (see Table of Materials) 6-well plates in periventricular endothelial cell medium (E6 medium containing 50 ng/mL VEGF-A, 100 ng/mL FGF2 and 5 &#181;M GABA) at 37 &#176;C and 5% CO2. Change medium every alternate day.</li>
	<li>Thaw basement membrane matrix in 4 &#176;C, and make a 1:100 solution by diluting it in cold DMEM/F12 medium....

<ol>
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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+induced+pluripotent+stem+cells+for+modelling+neurodevelopmental+disorders.">Human induced pluripotent stem cells for modelling neurodevelopmental disorders.</a> Nature Reviews Neurology. 13 (5), 265-278 (2017).</li><li>Stubbs, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurovascular+congruence+during+cerebral+cortical+development.">Neurovascular congruence during cerebral cortical development.</a> Cerebral Cortex. 19 (1), 32-41 (2009).</li><li>Vissapragada, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bidirectional+crosstalk+between+periventricular+endothelial+cells+and+neural+progenitor+cells+promotes+the+formation+of+a+neurovascular+unit.">Bidirectional crosstalk between periventricular endothelial cells and neural progenitor cells promotes the formation of a neurovascular unit.</a> Brain Research. 1565, 8-17 (2014).</li><li>JoVE Science Education Database. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+Biology.+The+Transwell+Migration+Assay.">Cell Biology. 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Here, we described three in vitro assays that together provide quantitative assessment of human periventricular endothelial cell-specific properties. These assays will be valuable in gaining mechanistic insights into the interaction of human periventricular endothelial cells with human interneurons. Experiments using ligands, inhibitors, or cells with gene-specific knockdown or overexpression will identify or validate molecular players that mediate endothelial cell-guided interneuron migration or long-distance migratory ...

Endothelial cells form the lining of blood vessels and mediate important functions that include maintenance of vessel wall permeability, regulation of blood flow, platelet aggregation, and formation of new blood vessels. In the brain, endothelial cells form part of a critical blood-brain-barrier that tightly controls exchange of materials between the brain and the bloodstream1. Our studies in the past decade have identified novel neurogenic roles of brain endothelial cells that have significant implications for brain development and behavior2,3,4,5. We have shown that the mouse embryonic forebrain is vascularized by two distinct subtypes of vessels, the pial vessels and the periventricular vessels, that differ in anatomy, origin, and developmental profile2. Endothelial cells lining these two vessel subtypes show distinct differences in their gene expression profiles. While pial endothelial cells mostly express genes related to inflammation and immune response, periventricular endothelial cells are uniquely enriched in expression of genes commonly associated with neurogenesis, neuronal migration, chemotaxis, and axon guidance3. Periventricular endothelial cells also house a novel GABA signaling pathway that is distinct from the traditional neuronal GABA signaling pathway5. Concomitant with its gene expression, periventricular endothelial cells were found to regulate migration and distribution of GABAergic interneurons in the developing neocortex. During embryonic development, periventricular endothelial cells undergo long-distance migration along a ventral-dorsal gradient to establish the periventricular vascular network2,3. This migratory route is mirrored a day later by interneurons. Migrating interneurons physically interact with the pre-formed periventricular vascular network and use it as a guiderail to reach their final destination in the neocortex. In addition to acting as a physical substrate, periventricular endothelial cells serve as the source of navigational cues for migrating neurons. Periventricular endothelial cell-secreted GABA guides interneuron migration and regulates their final distribution patterns4. Defects in interneuron migration and distribution are associated with neuropsychiatric disorders such as autism, epilepsy, schizophrenia and depression6,7,8,9,10. Therefore, study of periventricular endothelial cell functions and their influence on interneuron migration in human context becomes critical for addressing the pathogenesis of these disorders.
We have generated human periventricular-like endothelial cells from human embryonic stem cells in our laboratory11, using induced pluripotent stem cell (iPSC) technology12,13. To validate whether human periventricular endothelial cells faithfully mimic mouse periventricular endothelial cells, and to quantitatively assess their influence on interneuron migration, we developed three in vitro assays: a long-distance migration assay, a co-culture migration assay, and a chemo-attraction assay. Here we describe protocols for these assays in detail. All three assays are based on the usage of silicone culture inserts to create a small rectangular patch of cells (of fixed dimensions) surrounded by cell-free space. Migration distance is evaluated by measuring the distance between the final positions of cells from the border of the rectangular patch that has been outlined on day 0. In the long-distance migration assay, human periventricular endothelial cells are seeded as a patch in the center of a 35 mm dish, and the distances traveled by the cells over a long range of time are calculated. In the co-culture migration assay, human periventricular endothelial cells are co-seeded with human interneurons as one patch in a 35 mm dish. This setup allows examination of the effect of direct physical interactions of these two cell types on the rate of migration of interneurons. The chemo-attraction assay measures the migration of interneurons in response to chemo-attractive cues secreted by human periventricular endothelial cells. Interneurons are seeded as a rectangular patch, with human periventricular endothelial cells and control non-periventricular endothelial cells seeded as similar sized patches on either side. Each of the cell patches are separated by a cell-free gap of 500 &#181;m. Response of interneurons is assessed by quantifying the number of cells that have migrated towards periventricular endothelial cells compared to control non-periventricular endothelial cells.
These assays provide robust assessment of human periventricular endothelial cell functions and their influence on interneuron migration. The novel setup of long-distance assay and co-culture migration assay provides cell-free space in the range of centimeters (~1-1.5 cm) to allow detection of long-distance migration. A summary of the features of our assays compared to other popular assays is presented in Table 1. Collectively, the assays described here will serve as a platform for assessing &#34;diseased&#34; periventricular endothelial cells and interneurons generated from iPSCs of brain disorders like schizophrenia, autism or epilepsy. These assays can also be used to determine how different conditions (e.g. inhibitors, ligands, RNAi) affect cell migration. Finally, these assays can be optimized for other cell types to measure long-distance migration, chemo-attraction or cell-cell mediated migration.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Accutase dissociation solution</td>
			<td>Millipore Sigma</td>
			<td>SCR005</td>
			<td>Cell dissociation solution (for periventricular endothelial cells, step 1.4)</td>
		</tr>
		<tr>
			<td>Anti-human &#946;-Tubulin antibody</td>
			<td>Biolegend</td>
			<td>802001</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-human CD31 antibody</td>
			<td>Millipore Sigma</td>
			<td>CBL468</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti- MAP2 antibody</td>
			<td>Neuromics</td>
			<td>CH22103</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-active Caspase 3 antibody</td>
			<td>Millipore Sigma</td>
			<td>AB3623</td>
			<td></td>
		</tr>
		<tr>
			<td>Control human endothelial cells</td>
			<td>Cellular Dynamics</td>
			<td>R1022</td>
			<td></td>
		</tr>
		<tr>
			<td>Control endothelial Cells Medium Supplement</td>
			<td>Cellular Dynamics</td>
			<td>M1019</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryogenic vials</td>
			<td>Fisher Scientific</td>
			<td>03-337-7Y</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEMF/12 medium</td>
			<td>Thermofisher Scientific</td>
			<td>11320033</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma-Aldrich</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr>
			<td>E6 medium</td>
			<td>Thermofisher Scientific</td>
			<td>A1516401</td>
			<td></td>
		</tr>
		<tr>
			<td>FGF2</td>
			<td>Thermofisher Scientific</td>
			<td>PHG0261</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibronectin</td>
			<td>Thermofisher Scientific</td>
			<td>33016-015</td>
			<td></td>
		</tr>
		<tr>
			<td>Freezing Container</td>
			<td>Thermofisher Scientific</td>
			<td>5100</td>
			<td></td>
		</tr>
		<tr>
			<td>GABA</td>
			<td>Sigma-Aldrich</td>
			<td>A2129</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemacytometer</td>
			<td>Sigma-Aldrich</td>
			<td>Z359629</td>
			<td></td>
		</tr>
		<tr>
			<td>Human GABAergic neurons</td>
			<td>Cellular Dynamics</td>
			<td>R1013</td>
			<td></td>
		</tr>
		<tr>
			<td>Human GABAergic neurons base medium</td>
			<td>Cellular Dynamics</td>
			<td>M1010</td>
			<td></td>
		</tr>
		<tr>
			<td>Human GABAergic neuron Neural supplement</td>
			<td>Cellular Dynamics</td>
			<td>M1032</td>
			<td></td>
		</tr>
		<tr>
			<td>Laminin</td>
			<td>Sigma</td>
			<td>L2020</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>Corning</td>
			<td>356230</td>
			<td>Basement membrane matrix</td>
		</tr>
		<tr>
			<td>Mounting Medium</td>
			<td>Vector laboratories</td>
			<td>H-1200</td>
			<td></td>
		</tr>
		<tr>
			<td>poly-L-ornithin</td>
			<td>Sigma</td>
			<td>p4957</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Thermofisher Scientific</td>
			<td>14190</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan blue</td>
			<td>Thermofisher Scientific</td>
			<td>15250061</td>
			<td></td>
		</tr>
		<tr>
			<td>TrypLE</td>
			<td>Thermofisher Scientific</td>
			<td>12563011</td>
			<td>Cell dissociation solution (for GABAergic interneurons and endothelial cells, sections 3 and 4)</td>
		</tr>
		<tr>
			<td>VEGF-A</td>
			<td>Peprotech</td>
			<td>100-20</td>
			<td></td>
		</tr>
		<tr>
			<td>VascuLife VEGF Medium Complete Kit</td>
			<td>Lifeline Cell Technologies</td>
			<td>LL-0003</td>
			<td>Component of control human endothelial cell medium</td>
		</tr>
		<tr>
			<td>2-well silicone culture-Insert</td>
			<td>ibidi</td>
			<td>80209</td>
			<td></td>
		</tr>
		<tr>
			<td>3-well silicone culture-Insert</td>
			<td>ibidi</td>
			<td>80369</td>
			<td></td>
		</tr>
		<tr>
			<td>35 mm dish</td>
			<td>Corning</td>
			<td>430165</td>
			<td></td>
		</tr>
		<tr>
			<td>15-ml conical tube</td>
			<td>Fisher Scientific</td>
			<td>07-200-886</td>
			<td></td>
		</tr>
		<tr>
			<td>4% PFA solution</td>
			<td>Fisher Scientific</td>
			<td>AAJ19943K2</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well tissue culture plate</td>
			<td>Fisher Scientific</td>
			<td>14-832-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted phase contrast microscope</td>
			<td>Zeiss</td>
			<td>Zeiss Axiovert 40C</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Olympus</td>
			<td>FSX-100</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

The steps to set up a one-well culture insert inside a 35 mm dish are shown in Figure 1. Long-distance migration assay and co-culture migration assay used a one-well insert to seed the desired number of cells in the center of a poly-L-ornithine/laminin coated 35 mm dish. On day 0, cells were present as a rectangular patch (Figure 2A,C). In day 0 images, the day 0 line could be easily identified by the sharp edge ...

Watch this Scientific Journal Video about Migration, Chemo-Attraction, and Co-Culture Assays for Human Stem Cell-Derived Endothelial Cells and GABAergic Neurons at JoVE.com

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

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 ...

This protocol describes three in vitro assays that collectively assess the functions of human periventricular endothelial cells and their interaction with human GABAergic interneurons. Results from these assays will provide critical insight into the link between periventricular endothelial cells and brain disorders. These assays are simple, low-cost and allow measurement of cell migration in the range of centimeters, which is not achieved by other existing assays.Defects in migration and distribution of GABAergic interneurons are associated with psychiatric disorders, such as autism, epilepsy, schizophrenia and depression. Therefore, it is critical to study the interaction of periventricular endothelial cells with GABAergic interneurons in human context to address the pathogenesis of these disorders. Begin by preparing human cells for the assay.Allow human periventricular endothelial cells to reach 70 to 80%confluency then dissociate them according to the manuscript's directions and count them using the trypan blue exclusion method. To prepare human GABAergic interneurons, warm cell dissociation solution and an aliquot of neuronal medium at 37 degrees celsius for 10 minutes. Then aspirate the medium from each well containing cells and wash them with one millimeter of PBS per well.Detach the cells by adding 0.5 milliliters of prewarmed dissociation solution per well and incubating them at 37 degrees celsius for five minutes. After the incubation, add one milliliter of neuronal medium per well and transfer the cell solution into a 15 milliliter conical tube, gently triturating to dissociate cell clumps. Centrifuge the cells at 380 times G for five minutes at room temperature, aspirate the supernatant and resuspend the cell pellet in one milliliter of neuronal medium.Then count the live cells using trypan blue exclusion. Prepare control human endothelial cells by warming the cell dissociation solution and an aliquot of endothelial medium at 37 degrees celsius, 10 minutes prior to use. Aspirate medium from each well and wash them with one milliliter of PBS per well.Detach the cells by adding 0.5 milliliters of the prewarmed dissociation solution to each well and incubating the plate at room temperature for five minutes. Then, add one milliliter of endothelial cell medium per well to neutralize the dissociation solution, and transfer the cells to a 15 milliliter conical tube. Centrifuge the cells at 200 times G for five minutes, aspirate the supernatant and resuspend the cells in one milliliter of endothelial cell medium.Then use the trypan exclusion method to count the cells. Prepare one well culture insert by cutting three sides of one well of a two well silicone culture insert with a sterile blade. Remove the insert with sterile tweezers and place it in the center of a poly-L-ornithine and laminin-coated dish, then press along the edge of the insert to fix it to the surface.Carefully turn the dish upside down to verify that the insert is firmly adhered, and mark the boundary of the insert compartment using a permanent black market with an ultra fine tip. Suspend human GABAergic interneurons in neuronal medium and human periventricular endothelial cells and endothelial cell medium at a concentration of 30, 000 per 70 microliters, then seed 70 microliters of the cell solution inside each one well culture insert. Add one milliliter of neuronal medium to the neuron dish to fill the area around the insert and prevent the coating from drying.Similarly, add one milliliter of endothelial cell medium to the periventricular endothelial cell dish. Check the cells under a microscope to verify that they are not leaking from the insert compartment, then incubate them at 37 degrees celsius and 5%carbon dioxide for 24 hours. After the incubation, check the cells again under the microscope to verify that they have properly attached.48 hours after seeding, gently remove the insert with sterile tweezers and check the cells under the microscope to verify that the cell layer remains undisturbed. Remove the medium from both the neuron and the periventricular endothelial cell dishes, and add one milliliter of fresh medium to each dish. Incubate the cells at 37 degrees celsius and 5%carbon dioxide for five days.Then, remove the medium, fix the cells with 4%PFA for 10 minutes and wash them three times with PBS. To perform the co-culture assay, suspend 30, 000 GABAergic interneurons and 30, 000 human periventricular endothelial cells in 70 microliters of co-culture medium, then seed this cell solution inside a one well insert compartment. After 48 hours, remove the insert.Incubate the co-culture at 37 degrees celsius and 5%carbon dioxide for five days. After the incubation, remove the medium, fix the cells with 4%PFA and wash them three times with PBS. To perform the chemo-attraction assay, place a three well culture insert in the center of a poly-L-ornithine and laminin-coated 35 millimeter dish, turn the dish upside down, and mark the boundary around the middle compartment of the insert using a permanent marker with an ultra fine tip.Seed 30, 000 GABAergic interneurons in 70 microliters of neuronal medium in the middle compartment, then seed 10, 000 periventricular endothelial cells and 10, 000 control endothelial cells and 70 microliters of their respective medium in the two outer compartments. Add one milliliter of co-culture medium along the side of the dish to prevent the coating on the dish from drying. After 48 hours, remove the insert and incubate the cells at 37 degrees celsius and 5%carbon dioxide for 36 hours.After the incubation, remove the medium, fix the cells and wash them three times with PBS. Long distance and co-culture migration assays were used to investigate the interactions between periventricular endothelial cells and GABAergic neurons. In the long distance migration assay, cells started out as a rectangular patch on day zero, but by 48 hours, they had migrated out into the cell-free space.Immunocytochemical staining with Anti-Active Caspase-3 antibody, a marker of apoptosis, showed no apoptotic signal in the seeded neurons. In the co-culture migration assay, when interneurons were co-seeded with human periventricular endothelial cells, neurons traveled farther distances compared to when interneurons were seeded alone or when co-seeded with control endothelial cells. In the chemo-attraction assay, a significantly higher number of interneurons migrated towards periventricular endothelial cells compared to control endothelial cells, confirming that GABAergic interneurons respond selectively to chemo-attractive cues secreted by periventricular endothelial cells.These assays can be modified using ligands, inhibitors or assay arenes to get mechanistic insights into interactions of human periventricular endothelial cells with human interneurons. They can also be used to study the interaction of human periventricular endothelial cells with other neural cells as reported by our group and others. When attempting this procedure, it is important to fix the insert firmly on the dish and keep it undisturbed throughout the assay, otherwise it may lead to cell leakage, cell detachment or misalignment of the insert with the drawn boundary.Our work has indicated cell autonomous role of human periventricular endothelial cells in pathogenesis of psychiatric disorders like schizophrenia, epilepsy and autism. These assays will therefore allow assessment of diseased periventricular endothelial cells derived from patients with these disorders using the IPSC technology.

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Research

JoVE Journal

Neuroscience

Bilaminar Co-culture of Primary Rat Cortical Neurons and Glia

This video will guide you through the process of culturing rat cortical neurons in the presence of a glial feeder layer, a system known as a bilaminar or co-culture model. This system is suitable for a variety of experimental needs requiring either a glass or plastic growth substrate and can also be used for culture of other types of neurons.
Rat cortical neurons obtained from the late embryonic stage (E17) are plated on glass coverslips or tissue culture dishes facing a feeder layer of glia grown on dishes or plastic coverslips (known as Thermanox), respectively. The choice between the two configurations depends on the specific experimental technique used, which may require, or not, that neurons are grown on glass (e.g. calcium imaging versus Western blot). The glial feeder layer, an astroglia-enriched secondary culture of mixed glia, is separately prepared from the cortices of newborn rat pups (P2-4) prior to the neuronal dissection.
A major advantage of this culture system as compared to a culture of neurons only is the support of neuronal growth, survival, and differentiation provided by trophic factors secreted from the glial feeder layer, which more accurately resembles the brain environment in vivo. Furthermore, the co-culture can be used to study neuronal-glial interactions1.
At the same time, glia contamination in the neuronal layer is prevented by different means (low density culture, addition of mitotic inhibitors, lack of serum and use of optimized culture medium) leading to a virtually pure neuronal layer, comparable to other established methods1-3. Neurons can be easily separated from the glial layer at any time during culture and used for different experimental applications ranging from electrophysiology4, cellular and molecular biology5-8, biochemistry5, imaging and microscopy4,6,7,9,10. The primary neurons extend axons and dendrites to form functional synapses11, a process which is not observed in neuronal cell lines, although some cell lines do extend processes.
A detailed protocol of culturing rat hippocampal neurons using this co-culture system has been described previously4,12,13. Here we detail a modified protocol suited for cortical neurons. As approximately 20x106 cells are recovered from each rat embryo, this method is particularly useful for experiments requiring large numbers of neurons (but not concerned about a highly homogenous neuronal population). The preparation of neurons and glia needs to be planned in a time-specific manner. We will provide the step-by-step protocol for culturing rat cortical neurons as well as culturing glial cells to support the neurons.

Here we provide a protocol for culturing rat cortical neurons in the presence of a glial feeder layer. The cultured neurons establish polarity and create synapses, and can be separated from the glia for use in various applications, such as electrophysiology, calcium imaging, cell survival assays, immunocytochemistry, and RNA/DNA/protein isolation.

This video will guide you through the process of culturing rat cortical neurons in the presence of a glial feeder layer, a system known as a bilaminar or ...

Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors

Inhibitory neurons act in the central nervous system to regulate the dynamics and spatio-temporal co-ordination of neuronal networks. GABA (&#947;-aminobutyric acid) is the predominant inhibitory neurotransmitter in the brain. It is released from the presynaptic terminals of inhibitory neurons within highly specialized intercellular junctions known as synapses, where it binds to GABAA receptors (GABAARs) present at the plasma membrane of the synapse-receiving, postsynaptic neurons. Activation of these GABA-gated ion channels leads to influx of chloride resulting in postsynaptic potential changes that decrease the probability that these neurons will generate action potentials. 
During development, diverse types of inhibitory neurons with distinct morphological, electrophysiological and neurochemical characteristics have the ability to recognize their target neurons and form synapses which incorporate specific GABAARs subtypes. This principle of selective innervation of neuronal targets raises the question as to how the appropriate synaptic partners identify each other. 
To elucidate the underlying molecular mechanisms, a novel in vitro co-culture model system was established, in which medium spiny GABAergic neurons, a highly homogenous population of neurons isolated from the embryonic striatum, were cultured with stably transfected HEK293 cell lines that express different GABAAR subtypes. Synapses form rapidly, efficiently and selectively in this system, and are easily accessible for quantification. Our results indicate that various GABAAR subtypes differ in their ability to promote synapse formation, suggesting that this reduced in vitro model system can be used to reproduce, at least in part, the in vivo conditions required for the recognition of the appropriate synaptic partners and formation of specific synapses. Here the protocols for culturing the medium spiny neurons and generating HEK293 cells lines expressing GABAARs are first described, followed by detailed instructions on how to combine these two cell types in co-culture and analyze the formation of synaptic contacts.

Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors

The molecular mechanisms that co-ordinate the formation of inhibitory GABAergic synapses during ontogeny are largely unknown. To study these processes,we have developed a co-culture model system which incorporates embryonic medium spiny GABAergic neurons cultured together with stably transfected human embryonic kidney 293 (HEK293) cells expressing functional GABAA receptors.

Inhibitory neurons act in the central nervous system to regulate the dynamics and spatio-temporal co-ordination of neuronal networks. GABA ...

Dorsal Root Ganglia Neurons and Differentiated Adipose-derived Stem Cells: An In Vitro Co-culture Model to Study Peripheral Nerve Regeneration

Dorsal root ganglia (DRG) neurons, located in the intervertebral foramina of the spinal column, can be used to create an in vitro system facilitating the study of nerve regeneration and myelination. The glial cells of the peripheral nervous system, Schwann cells (SC), are key facilitators of these processes; it is therefore crucial that the interactions of these cellular components are studied together. Direct contact between DRG neurons and glial cells provides additional stimuli sensed by specific membrane receptors, further improving the neuronal response. SC release growth factors and proteins in the culture medium, which enhance neuron survival and stimulate neurite sprouting and extension. However, SC require long proliferation time to be used for tissue engineering applications and the sacrifice of an healthy nerve for their sourcing. Adipose-derived stem cells (ASC) differentiated into SC phenotype are a valid alternative to SC for the set-up of a co-culture model with DRG neurons to study nerve regeneration. The present work presents a detailed and reproducible step-by-step protocol to harvest both DRG neurons and ASC from adult rats; to differentiate ASC towards a SC phenotype; and combines the two cell types in a direct co-culture system to investigate the interplay between neurons and SC in the peripheral nervous system. This tool has great potential in the optimization of tissue-engineered constructs for peripheral nerve repair.

Dorsal Root Ganglia Neurons and Differentiated Adipose-derived Stem Cells: An In Vitro Co-culture Model to Study Peripheral Nerve Regeneration

Dorsal root ganglia (DRG) are structures containing the sensory neurons of the peripheral nervous system. When dissociated, they can be co-cultured with SC-like adipose-derived stem cells (ASC), providing a valuable model to study in vitro nerve regeneration and myelination, mimicking the in vivo environment at the injury site.

Dorsal root ganglia (DRG) neurons, located in the intervertebral foramina of the spinal column, can be used to create an in vitro system facilitating the ...

Enumeration of Neural Stem Cells Using Clonal Assays

Neural stem cells (NSCs) have the ability to self-renew and generate the three major neural lineages &#8212; astrocytes, neurons and oligodendrocytes. NSCs and neural progenitors (NPs) are commonly cultured in vitro as neurospheres. This protocol describes in detail how to determine the NSC frequency in a given cell population under clonal conditions. The protocol begins with the seeding of the cells at a density that allows for the generation of clonal neurospheres. The neurospheres are then transferred to chambered coverslips and differentiated under clonal conditions in conditioned medium, which maximizes the differentiation potential of the neurospheres. Finally, the NSC frequency is calculated based on neurosphere formation and multipotency capabilities. Utilities of this protocol include the evaluation of candidate NSC markers, purification of NSCs, and the ability to distinguish NSCs from NPs. This method takes 13 days to perform, which is much shorter than current methods to enumerate NSC frequency.

Neural stem cells (NSCs) refer to cells&#160;which can self-renew and differentiate into the three neural lineages. Here, we describe a protocol to determine NSC frequency in a given cell population using neurosphere formation and differentiation under clonal conditions.

Neural stem cells (NSCs) have the ability to self-renew and generate the three major neural lineages &#8212; astrocytes, neurons and oligodendrocytes. ...

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 ...

Method for High Speed Stretch Injury of Human Induced Pluripotent Stem Cell-derived Neurons in a 96-well Format

Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven therapies for TBI have been developed. This paper presents a novel method for pre-clinical neurotrauma research intended to complement existing pre-clinical models. It introduces human pathophysiology through the use of human induced pluripotent stem cell-derived neurons (hiPSCNs). It achieves loading pulse duration similar to the loading durations of clinical closed head impact injury. It employs a 96-well format that facilitates high throughput experiments and makes efficient use of expensive cells and culture reagents. Silicone membranes are first treated to remove neurotoxic uncured polymer and then bonded to commercial 96-well plate bodies to create stretchable 96-well plates. A custom-built device is used to indent some or all of the well bottoms from beneath, inducing equibiaxial mechanical strain that mechanically injures cells in culture in the wells. The relationship between indentation depth and mechanical strain is determined empirically using high speed videography of well bottoms during indentation. Cells, including hiPSCNs, can be cultured on these silicone membranes using modified versions of conventional cell culture protocols. Fluorescent microscopic images of cell cultures are acquired and analyzed after injury in a semi-automated fashion to quantify the level of injury in each well. The model presented is optimized for hiPSCNs but could in theory be applied to other cell types.

Here we present a method for a human in vitro model of stretch injury in a 96-well format on a timescale relevant to impact trauma. This includes methods for fabricating stretchable plates, quantifying the mechanical insult, culturing and injuring cells, imaging, and high content analysis to quantify injury.

Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven ...

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 ...

Post-differentiation Replating of Human Pluripotent Stem Cell-derived Neurons for High-content Screening of Neuritogenesis and Synapse Maturation

Neurons differentiated in two-dimensional culture from human pluripotent stem-cell-derived neural progenitor cells (NPCs) represent a powerful model system to explore disease mechanisms and carry out high content screening (HCS) to interrogate compound libraries or identify gene mutation phenotypes. However, with human cells the transition from NPC to functional, mature neuron requires several weeks. Synapses typically start to form after 3 weeks of differentiation in monolayer culture, and several neuron-specific proteins, for example the later expressing pan-neuronal marker NeuN, or the layer 5/6 cerebral cortical neuron marker CTIP2, begin to express around 4-5 weeks post-differentiation. This lengthy differentiation time can be incompatible with optimal culture conditions used for small volume, multi-well HCS platforms. Among the many challenges are the need for well-adhered, uniformly distributed cells with minimal cell clustering, and culture procedures that foster long-term viability and functional synapse maturation. One approach is to differentiate neurons in a large volume format, then replate them at a later time point in HCS-compatible multi-wells. Some main challenges when using this replating approach concern reproducibility and cell viability, due to the stressful disruption of the dendritic and axonal network. Here we demonstrate a detailed and reliable procedure for enzymatically resuspending human induced pluripotent stem cell (hiPSC)-derived neurons after their differentiation for 4-8 weeks in a large-volume format, transferring them to 384-well microtiter plates, and culturing them for a further 1-3 weeks with excellent cell survival. This replating of human neurons not only allows the study of synapse assembly and maturation within two weeks from replating, but also enables studies of neurite regeneration and growth cone characteristics. We provide examples of scalable assays for neuritogenesis and synaptogenesis using a 384-well platform.

This protocol describes a detailed procedure for resuspending and culturing human stem cell derived neurons that were previously differentiated from neural progenitors in vitro for multiple weeks. The procedure facilitates imaging-based assays of neurites, synapses, and late-expressing neuronal markers in a format compatible with light microscopy and high-content screening.

Neurons differentiated in two-dimensional culture from human pluripotent stem-cell-derived neural progenitor cells (NPCs) represent a powerful model ...

Analyzing Mitochondrial Transport and Morphology in Human Induced Pluripotent Stem Cell-Derived Neurons in Hereditary Spastic Paraplegia

Neurons have intense demands for high energy in order to support their functions. Impaired mitochondrial transport along axons has been observed in human neurons, which may contribute to neurodegeneration in various disease states. Although it is challenging to examine mitochondrial dynamics in live human nerves, such paradigms are critical for studying the role of mitochondria in neurodegeneration. Described here is a protocol for analyzing mitochondrial transport and mitochondrial morphology in forebrain neuron axons derived from human induced pluripotent stem cells (iPSCs). The iPSCs are differentiated into telencephalic glutamatergic neurons using well-established methods. Mitochondria of the neurons are stained with MitoTracker CMXRos, and mitochondrial movement within the axons are captured using a live-cell imaging microscope equipped with an incubator for cell culture. Time-lapse images are analyzed using software with &#34;MultiKymograph&#34;, &#34;Bioformat importer&#34;, and &#34;Macros&#34; plugins. Kymographs of mitochondrial transport are generated, and average mitochondrial velocity in the anterograde and retrograde directions is read from the kymograph. Regarding mitochondrial morphology analysis, mitochondrial length, area, and aspect ratio are obtained using the ImageJ. In summary, this protocol allows characterization of mitochondrial trafficking along axons and analysis of their morphology to facilitate studies of neurodegenerative diseases.

Impaired mitochondrial transport and morphology are involved in various neurodegenerative diseases. The presented protocol uses induced pluripotent stem cell-derived forebrain neurons to assess mitochondrial transport and morphology in hereditary spastic paraplegia. This protocol allows characterization of mitochondrial trafficking along axons and analysis of their morphology, which will facilitate the study of neurodegenerative disease.

Neurons have intense demands for high energy in order to support their functions. Impaired mitochondrial transport along axons has been observed in human ...

Derivation, Expansion, Cryopreservation and Characterization of Brain Microvascular Endothelial Cells from Human Induced Pluripotent Stem Cells

Brain microvascular endothelial cells (BMECs) can be differentiated from human induced pluripotent stem cells (iPSCs) to develop ex vivo cellular models for studying blood-brain barrier (BBB) function. This modified protocol provides detailed steps to derive, expand, and cryopreserve BMECs from human iPSCs using a different donor and reagents than those reported in previous protocols. iPSCs are treated with essential 6 medium for 4 days, followed by 2 days of human endothelial serum-free culture medium supplemented with basic fibroblast growth factor, retinoic acid, and B27 supplement. At day 6, cells are sub-cultured onto a collagen/fibronectin matrix for 2 days. Immunocytochemistry is performed at day 8 for BMEC marker analysis using CLDN5, OCLN, TJP1, PECAM1, and SLC2A1. Western blotting is performed to confirm BMEC marker expression, and absence of SOX17, an endodermal marker. Angiogenic potential is demonstrated with a sprouting assay. Trans-endothelial electrical resistance (TEER) is measured using chopstick electrodes and voltohmmeter starting at day 7. Efflux transporter activity for ATP binding cassette subfamily B member 1 and ATP binding cassette subfamily C member 1 is measured using a multi-plate reader at day 8. Successful derivation of BMECs is confirmed by the presence of relevant cell markers, low levels of SOX17, angiogenic potential, transporter activity, and TEER values ~2000 &#937; x cm2. BMECs are expanded until day 10 before passaging onto freshly coated collagen/fibronectin plates or cryopreserved. This protocol demonstrates that iPSC-derived BMECs can be expanded and passaged at least once. However, lower TEER values and poorer localization of BMEC markers was observed after cryopreservation. BMECs can be utilized in co-culture experiments with other cell types (neurons, glia, pericytes), in three-dimensional brain models (organ-chip and hydrogel), for vascularization of brain organoids, and for studying BBB dysfunction in neuropsychiatric disorders.

This protocol details an adapted method to derive, expand, and cryopreserve brain microvascular endothelial cells obtained by differentiating human induced pluripotent stem cells, and to study blood brain barrier properties in an ex vivo model.

Brain microvascular endothelial cells (BMECs) can be differentiated from human induced pluripotent stem cells (iPSCs) to develop ex vivo cellular models ...