Name: derivation, expansion, cryopreservation and characterization of brain microvascular endothelial cells from human induced pluripotent stem cells
Uploaded: 2020-11-19T14:00:00
Description: Watch this Scientific Journal Video about Derivation, Expansion, Cryopreservation and Characterization of Brain Microvascular Endothelial Cells from Human Induced Pluripotent Stem Cells at JoVE.com

This work was supported by a National Institute of Mental Health Biobehavioral Research Awards for Innovative New Scientists (BRAINS) Award R01MH113858 (to R.K.), a National Institutes of Health Award KL2 TR002542 (PL). a National Institute of Mental Health Clinical Scientist Development Award K08MH086846 (to R.K.), a Sydney R Baer Jr Foundation Grant (to P.L.) the Doris Duke Charitable Foundation Clinical Scientist Development Award (to R.K.), the Ryan Licht Sang Bipolar Foundation (to R.K.), the Phyllis &#38; Jerome Lyle Rappaport Foundation (to R.K.), the Harvard Stem Cell Institute (to R.K.) and by Steve Willis and Elissa Freud (to R.K.). We thank Dr. Annie Kathuria for her critical reading and feedback on the manuscript.

Human iPSCs were reprogrammed from the fibroblasts of healthy donors using a protocol approved by the Institutional Review Boards of Massachusetts General Hospital and McLean Hospital, and characterized as described in previous studies44,45,46.
NOTE: Briefly, fibroblasts were reprogrammed to iPSC via mRNA-based genetic reprogramming47. The iPSCs were maintained in stem cell med...

Modifications and Troubleshooting
In this protocol, we made some modifications in using a commonly used extracellular matrix and cell culture media during iPSC culturing for derivation of BMECs (Figure 1). These changes did not impact the ability to derive BMECS from human iPSCs as described in the Lippmann protocol1. An iPSC line from a different healthy donor was used to demonstrate that this modified protocol shows resul...

Blood-Brain Barrier Function 
The blood-brain barrier (BBB) forms a boundary that limits movement of substances from the blood to the brain. The BBB is comprised of brain microvascular endothelial cells (BMECs) that form a monolayer lining the vasculature. BMECs, together with astrocytes, neurons, pericytes, microglia, and extracellular matrix, form the neurovascular unit. BMECs have a tightly regulated paracellular structure that allows the BBB to maintain high trans-endothelial electrical resistance (TEER), which limits passive diffusion and serves as an indicator of barrier integrity1,2. BMECs also have proteins that assist with transcellular movement such as endocytosis, transcytosis, and transmigration, as well as extravasation of leukocytes during an immune response3. BMECs rely on influx and efflux transporters for nourishment and removal of waste products, in order to maintain a homeostatic balance in the brain3. For example, solute carrier family 2 member 1 (SLC2A1) is an influx transporter responsible for the movement of glucose across the BBB4, while efflux transporters such as the ATP binding cassette subfamily B member 1 (ABCB1) and the ATP binding cassette subfamily C member 1 (ABCC1) are responsible for returning substrates back into the blood stream3,5,6,7. ABCB1 substrates include morphine, verapamil4, and antipsychotics such as olanzapine and risperidone8, while the ABCC1 transporter has a variety of substrates including sulfate conjugates, vincristine, and glucuronide conjugates4.
Application of BBB Models in Psychiatric Disorders 
BBB dysfunction has been implicated in a number of neurological and psychiatric disorders, including schizophrenia and bipolar disorder9,10. Recently, iPSC-derived ex vivo cellular models are being utilized to interrogate the cellular and molecular underpinnings of psychiatric disorders, but these models currently do not take into account the potential role played by the neurovasculature11,12,13. It is hypothesized that peripheral inflammatory cytokines circulating in the blood can adversely impact the BBB14,15,16,17, but there is also evidence for paracellular18,19,20,21,22, transcellular23,24,25,26,27,28,29,&#160;and extracellular matrix20,29,30,31,32&#160;abnormalities contributing to BBB dysfunction. Disruption of the BBB can result in the contents of the blood entering the brain parenchyma and activating astrocytes and/or microglia to release proinflammatory cytokines, which in turn initiate an inflammatory response33&#160;that can have detrimental effects on the brain34. BMECs are the primary component of the BBB and examining the structure and function of these cells can enhance the understanding of BBB dysfunction in neurological and psychiatric disorders.
Alternative BMEC Models 
Prior to the development of efficient protocols for deriving BMECs from iPSCs1,6,35,36, researchers had employed immortalized BMECs37&#160;to study BBB function. However, many of these models failed to attain desirable BBB phenotypes, such a&#160;physiological range of TEER values38,39. Utilizing iPSCs has the advantage of retaining the genetic background of the individual from which the cells are derived. Scientists are actively working on establishing iPSC-derived ex vivo microenvironment models that recapitulate the structure and function of the human brain. Researchers have developed methods to derive BMECs that are structurally and physiologically similar to BMECs found in vivo. Methods for obtaining purified populations of iPSC-derived BMECs require a number of different steps with protocols being optimized in the last few years1,6,35,36. Generally, iPSC-derived BMECs are cultured in Essential 6 (E6) medium for 4 days, followed by 2 days in human endothelial serum-free medium (hESFM) supplemented with basic fibroblast growth factor (bFGF), retinoic acid (RA), and B27 supplement. The cells are then cultured on a collagen IV (COL4) and fibronectin (FN) matrix to obtain &#62;90% homogeneous BMECs1.
The identity of BMECs are confirmed by immunofluorescence showing the co-expression of BMEC proteins including platelet-endothelial cell adhesion molecule-1 (PECAM1), SLC2A1, and tight junction proteins such as tight junction protein 1 (TJP1), occludin (OCLN), and claudin-5 (CLDN5)6. Sprouting assays have been used to confirm the angiogenic potential of iPSC-derived BMECs.6 The BBB integrity of BMECs is evaluated by the presence of physiologic in vitro TEER values (~2000&#937; x cm2)37&#160;and measurable activity for efflux transporters such as ABCB1 and ABCC11,6,36. Recent methodological advances by the Lippmann group have led to iPSC-derived BMEC protocols with reduced experimental variability and enhanced reproducibility1. However, it&#160;is not known whether they can be expanded and passaged beyond the sub-culturing stage. Our modified protocol aims to address this issue by passaging iPSC-derived BMECs beyond day 8 and assessing whether they can be further expanded to retain BBB properties after cryopreservation. While no studies have described passaging of iPSC-derived BMECs, a protocol exists for BMEC cryopreservation that retains physiologic BBB properties after undergoing a freeze-thaw cycle40. However, it&#160;is not known post-cryopreservation BMECs can be passaged and retain BBB properties.
BMECs derived from iPSCs using the Lippmann protocol have been utilized to model BBB disruption in neurological disorders such as Huntington&#8217;s disease7. Such iPSC-derived BMECs have also been used to investigate the effects of bacterial infection such as Neisseria meningitidis or Group B Streptococcus on disruption of blood-CSF barrier and BBB respectively41,42. Also, using iPSC-derived BMECs from 22q deletion syndrome patients with schizophrenia, researchers observed an increase in intercellular adhesion molecule-1 (ICAM-1), a major adhesion molecule in BMECs that assist with recruitment and extravasation of leukocytes into the brain43. Taken together, these studies demonstrate the utility of iPSC-derived BMECs for studying BBB disruption in complex neuropsychiatric disorders.

<table>
	<tbody>
		<tr>
			<td>2&#8242;,7&#8242;-dichlorodihydrofluorescein diacetate</td>
			<td>Sigma Aldrich</td>
			<td>D6883-50MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Accutase</td>
			<td>Sigma Aldrich</td>
			<td>A6964-100mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 488 Donkey anti-Mouse IgG</td>
			<td>Life Technologies</td>
			<td>A-21202</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 555 Donkey anti-Rabbit IgG</td>
			<td>Life Technologies</td>
			<td>A-31572</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 Supplement</td>
			<td>Thermo Fisher Scientific</td>
			<td>17504044</td>
			<td></td>
		</tr>
		<tr>
			<td>CD31 (PECAM-1) (89C2) Mouse mAb</td>
			<td>Cell Signaling</td>
			<td>3528S</td>
			<td></td>
		</tr>
		<tr>
			<td>CLDN5 (Claudin-5)</td>
			<td>Thermo Fisher Scientific</td>
			<td>35-2500</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagen IV from human placenta</td>
			<td>Sigma Aldrich</td>
			<td>C5533-5mg</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning 2 mL Internal Threaded Polypropylene Cryogenic Vial&#160;</td>
			<td>Corning</td>
			<td>&#160;8670</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning&#160;Costar Flat Bottom Cell Culture Plates (6-wells)</td>
			<td>Corning</td>
			<td>353046</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning&#160;Falcon Flat Bottom Cell Culture Plates (24-wells)</td>
			<td>Corning</td>
			<td>353047</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning Transwell Multiple Well Plate with Permeable Polyester Membrane Inserts (12-wells)</td>
			<td>Corning</td>
			<td>3460</td>
			<td></td>
		</tr>
		<tr>
			<td>Countess slides</td>
			<td>Thermo Fisher Scientific</td>
			<td>C10228</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12 (without phenol red)</td>
			<td>Thermo Fisher Scientific</td>
			<td>&#160;A1413202</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma Aldrich</td>
			<td>D2438-50mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey serum</td>
			<td>Sigma Aldrich</td>
			<td>D9663-10ML</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS (+/+)</td>
			<td>Gibco/Thermo Fisher Scientific</td>
			<td>14040-117</td>
			<td></td>
		</tr>
		<tr>
			<td>Epithelial Volt/Ohm (TEER) Meter (EVOM2) STX2</td>
			<td>World Precision Instruments</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Essential 6 Medium (Thermo Fisher)</td>
			<td>Thermo Fisher Scientific</td>
			<td>A1516401</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Sigma Aldrich</td>
			<td>F2442</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibronectin</td>
			<td>Sigma Aldrich</td>
			<td>F2006-2mg</td>
			<td></td>
		</tr>
		<tr>
			<td>Geltrex LDEV-Free Reduced Growth Factor Basement Membrane Matrix</td>
			<td>Thermo Fisher Scientific</td>
			<td>A1413202</td>
			<td></td>
		</tr>
		<tr>
			<td>Hanks&#39; Balance Salt Solution with calcium and magnesium&#160;</td>
			<td>Thermo Fisher Scientific</td>
			<td>24020-117</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst 33342, Trihydrochloride, Trihydrate</td>
			<td>Thermo Fisher Scientific</td>
			<td>H3570</td>
			<td></td>
		</tr>
		<tr>
			<td>Human endothelial serum-free medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>11111044</td>
			<td></td>
		</tr>
		<tr>
			<td>InCell Analyzer 6000</td>
			<td>General Electric</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Invitrogen&#160;Countess Automated Cell Counter</td>
			<td>Thermo Fisher Scientific</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>MK-571</td>
			<td>Sigma Aldrich</td>
			<td>M7571-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>NutriStem</td>
			<td>Stemgent</td>
			<td>01-0005</td>
			<td></td>
		</tr>
		<tr>
			<td>Occludin</td>
			<td>Thermo Fisher Scientific</td>
			<td>33-1500</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde 16%</td>
			<td>Electron Microscopy Services</td>
			<td>15710</td>
			<td></td>
		</tr>
		<tr>
			<td>Perkin Elmer Envision 2103 multi-plate Reader</td>
			<td>Perkin Elmer</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Human VEGF 165</td>
			<td>Peprotech</td>
			<td>100-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Human FGF-basic (154 a.a.)</td>
			<td>Peprotech</td>
			<td>100-18B</td>
			<td></td>
		</tr>
		<tr>
			<td>Retinoic acid</td>
			<td>Sigma Aldrich</td>
			<td>R2625-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Rhodamine 123</td>
			<td>Sigma Aldrich</td>
			<td>83702-10MG</td>
			<td></td>
		</tr>
		<tr>
			<td>SLC2A1 (GLUT-1)</td>
			<td>ThermoFisher</td>
			<td>PA1-21041</td>
			<td></td>
		</tr>
		<tr>
			<td>SOX17</td>
			<td>Cell Signaling</td>
			<td>81778S</td>
			<td></td>
		</tr>
		<tr>
			<td>TJP-1 (ZO-1)</td>
			<td>ThermoFisher</td>
			<td>PA5-28869</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma Aldrich</td>
			<td>T8787-50ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue Stain (0.4%) for use with the Countess Automated Cell Counter</td>
			<td>Thermo Fisher Scientific</td>
			<td>T10282</td>
			<td></td>
		</tr>
		<tr>
			<td>Valspodar (Sigma) (cyclosporin A)</td>
			<td>Sigma Aldrich</td>
			<td>SML0572-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Versene solution</td>
			<td>Thermo Fisher Scientific</td>
			<td>15040066</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-27632 dihydrochloride (ROCK inhibitor)</td>
			<td>Tocris/Thermo Fisher Scientific</td>
			<td>1254</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

BMEC Differentiation 
A few critical steps in this protocol should be&#160;followed precisely (Figure 1). E6 medium use on day 1 is important, since it is often used for deriving neuroectoderm lineage from iPSCs within a relatively short period of time yielding reproducible&#160;results across multiple cell lines36. Another important step is on day 4 of differentiation, where E6 medium should be switched to hESFM with diluted (1:200) B27, 20 ng/m...

Watch this Scientific Journal Video about Derivation, Expansion, Cryopreservation and Characterization of Brain Microvascular Endothelial Cells from Human Induced Pluripotent Stem Cells at JoVE.com

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

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 ...

BMECs generated from iPSC provide new experimental models for studying blood brain barrier function and dysfunction. We have used this protocol to examine whether BMECs retain their barrier properties after expansion and cryopreservation. This technique enables the generation of disease-specific BMECs from patients with disorders in which blood-brain barrier disruption plays a role in the pathophysiology of disease.To induce BMEC differentiation from human iPSCs, wash the confluent iPSC culture with DPBS one time before incubating the cells with the appropriate volume of enzymatic EDTA for approximately five minutes at 37 degrees Celsius. When a single cell suspension has been obtained collect the cells by centrifugation and resuspend the pellet in an appropriate volume of stem cell medium supplemented with 10 micromolar ROCK inhibitor for counting. Dilute the cells to 1.56 times 10 to the fourth cells per cubic centimeter concentration and seed two milliliters of cells into individual wells of a six-well flat bottom.After 24 hours in the cell culture incubator replace the supernatant in each well with E6 medium and return the plate to the incubator for four more days. To purify the iPSC-derived BMECs, coat the subculturing plates with the appropriate volume of a freshly prepared collagen IV and fibronectin solution per well and incubate the plates for a minimum of two hours at 37 degrees Celsius. On day six of differentiation collect the cells by centrifugation and resuspend the pellets in the appropriate volume of fresh human endothelial serum-free medium supplemented with B27, basic fibroblasts growth factor, and retinoic acid.For TEER analysis, plate the differentiated cells into each well of a collagen and fibronectin coated 12-transwell filtered plate. For efflux transporter activity analysis, plate the cells into each well of a collagen and fibronectin coated 24-well flat bottom plate. After 24 hours of subculture, replace the supernatant in each well with fresh human endothelial serum-free medium supplemented only with B27 supplement.To measure the blood brain barrier properties of the BMECs using TEER, charge the TEER instrument overnight and lightly wipe the instrument and chopstick electrodes with 70%ethanol before placing them into the safety hood. Switch on the power and calibrate the ohm meter according to the manufacturer's specifications. Plug in the electrodes and rinse them one time with 70%ethanol and one time with DPBS.Place the shorter end of the electrode into the atypical chamber of the insert and the longer end into the basolateral chamber of a blank well. After measuring the negative control response, quickly rinse the electrodes as demonstrated and measure the first experimental well. After all of the measurements have been recorded rinse chopstick electrodes again, gently wipe the electrodes and let them air dry in the safety hood.To assess the efflux transporter activity of the cells, on day eight of culturing treat the appropriate number of wells with a 10 micromolar efflux transporter inhibitor solution and place in an incubator for one hour at 37 degrees Celsius. At the end of the incubation, treat the cells with a 10 micromolar efflux transporter substrate solution for one hour in the incubator. At the end of the incubation, wash each well twice with 500 microliters of DPBS per well before lysing the cells with 500 microliters DPBS supplemented with 5%Triton-X per well.After five minutes, use a microplate reader to measure the fluorescence of the lysed cells at a 485 nanometer excitation and a 530 nanometer emission. For wells not used in the transporter assay, wash the cells twice with DPBS before fixing with 4%paraformaldehyde per cell nuclei quantification. After one day of culture in E6 medium, the cell morphology is similar to that of iPSCs.By day four, the cells are visibly distinct from iPSCs and cover most of the well. Two days of culture in human endothelial serum-free medium induces an elongated and cobblestone appearance in the cells. At day eight, individual cells form a mostly large cobblestone pattern.A sprouting assay can be performed to demonstrate the angiogenic potential of iPSC-derived BMECs. This leads to the development of tube-like structures after three days of growth factor treatment. The iPSC-derived BMECs generated using this protocol co-expressed tight junction proteins expressed in endothelial cells in the brain, lung, liver, and kidney, as well as vascular endothelial markers expressed at the blood brain barrier.As observed, 48 hours after subculture and medium change iPSC-derived BMECs demonstrate TEER values within the range described for iPSC-derived BMECs that were co-cultured with rat primary astrocytes. Efflux transporter activity was also observed at this stage. After cryopreservation, TEER measurements are lower compared to freshly derived BMECs.Western blot analysis reveals reduced levels of tight junction markers, such as occludin, while immunocytochemistry shows freckled and or frayed patterns of tight junction proteins. A too high or too low iPSC density will affect the differentiation efficiency and impact the development of appropriate blood brain barrier properties. This method enables the investigation of barrier properties cellular signaling and transporter activity using individualized BMECs to model the physiology and pathophysiology of the blood-brain barrier function.

derivation-expansion-cryopreservation-characterization-brain

Research

JoVE Journal

Neuroscience

Efficient Derivation of Human Neuronal Progenitors and Neurons from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

There is a large unfulfilled need for a clinically-suitable human neuronal cell source for repair or regeneration of the damaged central nervous system (CNS) structure and circuitry in today's healthcare industry. Cell-based therapies hold great promise to restore the lost nerve tissue and function for CNS disorders. However, cell therapies based on CNS-derived neural stem cells have encountered supply restriction and difficulty to use in the clinical setting due to their limited expansion ability in culture and failing plasticity after extensive passaging1-3. Despite some beneficial outcomes, the CNS-derived human neural stem cells (hNSCs) appear to exert their therapeutic effects primarily by their non-neuronal progenies through producing trophic and neuroprotective molecules to rescue the endogenous cells1-3. Alternatively, pluripotent human embryonic stem cells (hESCs) proffer cures for a wide range of neurological disorders by supplying the diversity of human neuronal cell types in the developing CNS for regeneration1,4-7. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity7-10. In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic11-13. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules14 (please see a schematic in Fig. 1). Retinoic acid (RA) does not induce neuronal differentiation of undifferentiated hESCs maintained on feeders1, 14. And unlike mouse ESCs, treating hESC-differentiated embryoid bodies (EBs) only slightly increases the low yield of neurons1, 14, 15. However, after screening a variety of small molecules and growth factors, we found that such defined conditions rendered retinoic acid (RA) sufficient to induce the specification of neuroectoderm direct from pluripotent hESCs that further progressed to neuroblasts that generated human neuronal progenitors and neurons in the developing CNS with high efficiency (Fig. 2). We defined conditions for induction of neuroblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human neuronal cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of neuroblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human neuronal progenitors and neuronal cell types in the developing CNS for neural repair.

There is a large unfulfilled need for a clinically-suitable human neuronal cell source for repair or regeneration of the damaged central nervous system ...

The Specification of Telencephalic Glutamatergic Neurons from Human Pluripotent Stem Cells

Here, a stepwise procedure for efficiently generating telencephalic glutamatergic neurons from human pluripotent stem cells (PSCs) has been described. The differentiation process is initiated by breaking the human PSCs into clumps which round up to form aggregates when the cells are placed in a suspension culture. The aggregates are then grown in hESC medium from days 1-4 to allow for spontaneous differentiation. During this time, the cells have the capacity to become any of the three germ layers. From days 5-8, the cells are placed in a neural induction medium to push them into the neural lineage. Around day 8, the cells are allowed to attach onto 6 well plates and differentiate during which time the neuroepithelial cells form. These neuroepithelial cells can be isolated at day 17. The cells can then be kept as neurospheres until they are ready to be plated onto coverslips. Using a basic medium without any caudalizing factors, neuroepithelial cells are specified into telencephalic precursors, which can then be further differentiated into dorsal telencephalic progenitors and glutamatergic neurons efficiently. Overall, our system provides a tool to generate human glutamatergic neurons for researchers to study the development of these neurons and the diseases which affect them.

This procedure yields telencephalic neurons by going through checkpoints which are similar to those observed during human development. The cells are allowed to spontaneously differentiate, are exposed to factors which push them towards the neural lineage, are isolated, and are plated onto coverslips to allow for terminal differentiation and maturation.

Here, a stepwise procedure for efficiently generating telencephalic glutamatergic neurons from human pluripotent stem cells (PSCs) has been described. The ...

Isolation and Culture of Endothelial Cells from the Embryonic Forebrain

Embryonic brain endothelial cells can serve as an important tool in the study of angiogenesis and neurovascular development and interactions. The two vascular networks of the embryonic forebrain, pial and periventricular, are spatially distinctive and have different origins and growth patterns. Endothelial cells from the pial and periventricular vascular networks have unique gene expression profiles and functions. Here we present a step-by-step protocol for isolation, culture, and verification of pure populations of endothelial cells from the periventricular vascular network (PVECs) of the embryonic forebrain (telencephalon). In this approach, telencephalon devoid of pial membrane obtained from embryonic day 15 mice is minced, digested with collagenase/dispase, and dispersed mechanically into a single cell suspension. PVECs are purified from cell suspension using positive selection with anti-CD-31/PECAM-1 antibody conjugated to MicroBeads using a strong magnetic separation method. Purified cells are cultured on collagen 1&#160;coated culture dishes in endothelial cell culture medium until they become confluent and further subcultured. PVECs obtained with this protocol exhibit cobblestone and spindle shaped phenotypes, as visualized by phase-contrast light microscopy and fluorescence microscopy. Purity of PVEC cultures was established with endothelial cell markers. In our hands, this method reliably and consistently yields pure populations of PVECs. This protocol will benefit studies aimed at gaining mechanistic insights into forebrain angiogenesis, understanding PVEC interactions, and cross-talks with neuronal cell types and holds tremendous potential for therapeutic angiogenesis.

This video demonstrates an easy and reliable strategy for preparation of pure cultures of endothelial cells from the embryonic forebrain within 10-12 days and will be useful for research focused on many aspects of cerebral angiogenesis.

Embryonic brain endothelial cells can serve as an important tool in the study of angiogenesis and neurovascular development and interactions. The two ...

A cGMP-applicable Expansion Method for Aggregates of Human Neural Stem and Progenitor Cells Derived From Pluripotent Stem Cells or Fetal Brain Tissue

A cell expansion technique to amass large numbers of cells from a single specimen for research experiments and clinical trials would greatly benefit the stem cell community. Many current expansion methods are laborious and costly, and those involving complete dissociation may cause several stem and progenitor cell types to undergo differentiation or early senescence. To overcome these problems, we have developed an automated mechanical passaging method referred to as &#8220;chopping&#8221; that is simple and inexpensive. This technique avoids chemical or enzymatic dissociation into single cells and instead allows for the large-scale expansion of suspended, spheroid cultures that maintain constant cell/cell contact. The chopping method has primarily been used for fetal brain-derived neural progenitor cells or neurospheres, and has recently been published for use with neural stem cells derived from embryonic and induced pluripotent stem cells. The procedure involves seeding neurospheres onto a tissue culture Petri dish and subsequently passing a sharp, sterile blade through the cells effectively automating the tedious process of manually mechanically dissociating each sphere. Suspending cells in culture provides a favorable surface area-to-volume ratio; as over 500,000 cells can be grown within a single neurosphere of less than 0.5 mm in diameter. In one T175 flask, over 50 million cells can grow in suspension cultures compared to only 15 million in adherent cultures. Importantly, the chopping procedure has been used under current good manufacturing practice (cGMP), permitting mass quantity production of clinical-grade cell products.

This protocol describes a novel mechanical chopping method that allows the expansion of spherical neural stem and progenitor cell aggregates without dissociation to a single cell suspension.&#160; Maintaining cell/cell contact allows rapid and stable growth for over 40 passages.

A cell expansion technique to amass large numbers of cells from a single specimen for research experiments and clinical trials would greatly benefit the ...

Feeder-free Derivation of Neural Crest Progenitor Cells from Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) have great potential for studying human embryonic development, for modeling human diseases in the dish and as a source of transplantable cells for regenerative applications after disease or accidents. Neural crest (NC) cells are the precursors for a large variety of adult somatic cells, such as cells from the peripheral nervous system and glia, melanocytes and mesenchymal cells. They are a valuable source of cells to study aspects of human embryonic development, including cell fate specification and migration. Further differentiation of NC progenitor cells into terminally differentiated cell types offers the possibility to model human diseases in vitro, investigate disease mechanisms and generate cells for regenerative medicine. This article presents the adaptation of a currently available in vitro differentiation protocol for the derivation of NC cells from hPSCs. This new protocol requires 18 days of differentiation, is feeder-free, easily scalable and highly reproducible among human embryonic stem cell (hESC) lines as well as human induced pluripotent stem cell (hiPSC) lines. Both old and new protocols yield NC cells of equal identity.

Neural crest (NC) cells derived from human pluripotent stem cells (hPSC) have great potential for modeling human development and disease and for cell replacement therapies. Here, a feeder-free adaptation of the currently widely used in vitro differentiation protocol for the derivation of NC cells from hPSCs is presented.

Human pluripotent stem cells (hPSCs) have great potential for studying human embryonic development, for modeling human diseases in the dish and as a ...

Directed Dopaminergic Neuron Differentiation from Human Pluripotent Stem Cells

Dopaminergic (DA) neurons in the substantia nigra pars compacta (also known as A9 DA neurons) are the specific cell type that is lost in Parkinson&#8217;s disease (PD). There is great interest in deriving A9 DA neurons from human pluripotent stem cells (hPSCs) for regenerative cell replacement therapy for PD. During neural development, A9 DA neurons originate from the floor plate (FP) precursors located at the ventral midline of the central nervous system. Here, we optimized the culture conditions for the stepwise differentiation of hPSCs to A9 DA neurons, which mimics embryonic DA neuron development. In our protocol, we first describe the efficient generation of FP precursor cells from hPSCs using a small molecule method, and then convert the FP cells to A9 DA neurons, which could be maintained in vitro for several months. This efficient, repeatable and controllable protocol works well in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) from normal persons and PD patients, in which one could derive A9 DA neurons to perform in vitro disease modeling and drug screening and in vivo cell transplantation therapy for PD.

We, based on knowledge from developmental biology and published research, developed an optimized protocol to efficiently generate A9 midbrain dopaminergic neurons from both human embryonic stem cells and human induced pluripotent stem cells, which would be useful for disease modeling and cell replacement therapy for Parkinson&#8217;s disease.

Dopaminergic (DA) neurons in the substantia nigra pars compacta  (also known as A9 DA neurons) are the specific cell type that is lost in ...

Isolation of Primary Murine Brain Microvascular Endothelial Cells

The blood-brain-barrier is ultrastructurally assembled by a monolayer of brain microvascular endothelial cells (BMEC) interconnected by a junctional complex of tight and adherens junctions. Together with other cell-types such as astrocytes or pericytes, they form the neurovascular unit (NVU), which specifically regulates the interchange of fluids, molecules and cells between the peripheral blood and the CNS. Through this complex and dynamic system BMECs are involved in various processes maintaining the homeostasis of the CNS. A dysfunction of the BBB is observed as an essential step in the pathogenesis of many severe CNS diseases. However, specific and targeted therapies are very limited, as the underlying mechanisms are still far from being understood. 
Animal and in vitro models have been extensively used to gain in-depth understanding of complex physiological and pathophysiological processes. By reduction and simplification it is possible to focus the investigation on the subject of interest and to exclude a variety of confounding factors. However, comparability and transferability are also reduced in model systems, which have to be taken into account for evaluation. The most common animal models are based on mice, among other reasons, mainly due to the constantly increasing possibilities of methodology. In vitro studies of isolated murine BMECs might enable an in-depth analysis of their properties and of the blood-brain-barrier under physiological and pathophysiological conditions. Further insights into the complex mechanisms at the BBB potentially provide the basis for new therapeutic strategies.
This protocol describes a method to isolate primary murine microvascular endothelial cells by a sequence of physical and chemical purification steps. Special considerations for purity and cultivation of MBMECs as well as quality control, potential applications and limitations are discussed.

Brain microvascular endothelial cells (BMEC) are interconnected by specific junctional proteins forming a highly regulated barrier separating blood and the central nervous system (CNS), the so-called blood-brain-barrier (BBB). The isolation of primary murine brain microvascular endothelial cells, as discussed in this protocol, enables detailed in vitro studies of the BBB.

The blood-brain-barrier is ultrastructurally assembled by a monolayer of brain microvascular endothelial cells (BMEC) interconnected by a junctional ...

Isolation of Primary Murine Skeletal Muscle Microvascular Endothelial Cells

The endothelial cells of skeletal muscle capillaries (muscle microvascular endothelial cells, MMEC) build up the barrier between blood stream and skeletal muscles regulating the exchange of fluids and nutrients as well as the immune response against infectious agents by controlling immune cell migration. For these functions, MMEC form a functional &#34;myovascular unit&#34; (MVU), with further cell types, such as fibroblasts, pericytes and skeletal muscle cells. Consequently, a dysfunction of MMEC and therefore the MVU contributes to a vast variety of myopathies. However, regulatory mechanisms of MMEC in health and disease remain insufficiently understood and their elucidation precedes more specific treatments for myopathies. The isolation and in-depth investigation of primary MMEC functions in the context of the MVU might facilitate a better understanding of these processes.
This article provides a protocol to isolate primary murine MMEC of the skeletal muscle by mechanical and enzymatic dissociation including purification and culture maintenance steps.

Microvascular endothelial cells of skeletal muscles (MMEC) shape the inner wall of muscle capillaries and regulate both, exchange of fluids/molecules and migration of (immune) cells between muscle tissue and blood. Isolation of primary murine MMEC, as described here, enables comprehensive in vitro investigations of the &#34;myovascular unit&#34;.

The endothelial cells of skeletal muscle capillaries (muscle microvascular endothelial cells, MMEC) build up the barrier between blood stream and skeletal ...

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 ...

Generation of Human Neurons and Oligodendrocytes from Pluripotent Stem Cells for Modeling Neuron-Oligodendrocyte Interactions

In Alzheimer&#8217;s disease (AD) and other neurodegenerative disorders, oligodendroglial failure is a common early pathological feature, but how it contributes to disease development and progression, particularly in the gray matter of the brain, remains largely unknown. The dysfunction of oligodendrocyte lineage cells is hallmarked by deficiencies in myelination and impaired self-renewal of oligodendrocyte precursor cells (OPCs). These two defects are caused at least in part by the disruption of interactions between neuron and oligodendrocytes along the buildup of pathology. OPCs give rise to myelinating oligodendrocytes during CNS development. In the mature brain cortex, OPCs are the major proliferative cells (comprising ~5% of total brain cells) and control new myelin formation in a neural activity-dependent manner. Such neuron-to-oligodendrocyte communications are significantly understudied, especially in the context of neurodegenerative conditions such as AD, due to the lack of appropriate tools. In recent years, our group and others have made significant progress to improve currently available protocols to generate functional neurons and oligodendrocytes individually from human pluripotent stem cells. In this manuscript, we describe our optimized procedures, including the establishment of a co-culture system to model the neuron-oligodendrocyte connections. Our illustrative results suggest an unexpected contribution from OPCs/oligodendrocytes to the brain amyloidosis and synapse integrity and highlight the utility of this methodology for AD research. This reductionist approach is a powerful tool to dissect the specific hetero-cellular interactions out of the inherent complexity inside the brain. The protocols we describe here are expected to facilitate future studies on oligodendroglial defects in the pathogenesis of neurodegeneration.

The neuron-glial interactions in neurodegeneration are not well understood due to inadequate tools and methods. Here, we describe optimized protocols to obtain induced neurons, oligodendrocyte precursor cells, and oligodendrocytes from human pluripotent stem cells and provide examples of the values of these methods in understanding cell-type-specific contributions in Alzheimer&#8217;s disease.

In Alzheimer&#8217;s disease (AD) and other neurodegenerative disorders, oligodendroglial failure is a common early pathological feature, but how it ...