This work is supported by NHMRC Program Grant # 568969 (PSS) and Faculty of Medicine, University of New South Wales, Stem Cell Initiative (KSS).

All of the procedures below are carried out using aseptic techniques inside a Class II Biosafety Cabinet. Reagents and equipments used are listed in the tables below.
1. Preparation of 1.1% Alginate (w/v)
<ol>
	<li>Add 0.275 g of purified sodium alginate (high glucuronic acid content &ge;60%, viscosity &gt;200 mPa s, and endotoxin &le;100 EU/g) in a sterile 50 ml tube and add 25 ml sterile 0.1% gelatin solution prepared earlier (0.5g gelatin/500 ml milli-Q H2O and dissolved by autoclaving).</li>
	<li>Vortex the tube for approximately 30 seconds to partially dissolve the alginate powder then place the tube on an orbital mixer at 10 x g for overnight (room temperature).</li>
	<li>Add 2.778 ml of 9% sterile NaCl (4.5 g of NaCl/50 ml milli-Q H2O) to 25 ml of alginate solution. Vortex the tube for approximately 30 seconds followed by centrifugation at 95 x g for 5 min.</li>
	<li>Store the alginate solution at 4 &deg;C for short-term storage (1-2 months) or at -20 &deg;C for long-term storage (about a year).</li>
</ol>
2. Preparation of CaCl2 Precipitation Bath
<ol>
	<li>Dissolve 14.7 g of CaCl2.2H2O and 2.38 g of HEPES in 1 litre of milli-Q H2O.</li>
	<li>Adjust the pH level to 7.4.</li>
	<li>Sterilize the solution using a 0.22 &mu;m filter.</li>
	<li>Precipitation bath can be stored at room temperature (6-12 months).</li>
</ol>
3. Preparation of Decapsulating Solution
<ol>
	<li>In 500 ml of Dulbecco's Phosphate Buffered Saline (D-PBS), add 50 ml of 0.5M EDTA and 5 ml of 1M HEPES.</li>
	<li>Sterilize using a 0.22 &mu;m filter or autoclave at 121 &deg;C for 20 min.</li>
	<li>Store the decapsulating solution at room temperature (6-12 months).</li>
</ol>
4. Preparation of Serum Replacement (SR) Medium
<ol>
	<li>Prior to encapsulation, prepare SR medium in advance as described in Table of specific reagents and equipment.</li>
</ol>
5. Preparation of ROCK Inhibitor (Y-27632)
<ol>
	<li>Dilute Y-27632 powder in 0.1% human serum albumin (HSA) in D-PBS to make a 5 mM solution.</li>
</ol>
6. Preparation of hESC for Encapsulation
<ol>
	<li>Pre-treat the cells with culturing media supplemented with 10 &mu;M of ROCK inhibitor (RI) for two hours at 37 &deg;C (protect from light).</li>
	<li>After the RI treatment, wash cells with D-PBS twice and dislodge the cells from culture plates enzymatically with accutase for 10 min at 37 &deg;C.</li>
	<li>Gently scrape the cells with the pipette or cell scraper and collect in a 15 ml tube. Neutralize the accutase with SR medium in 1:1 ratio.</li>
	<li>To prepare a single cell suspension, filter the neutralized cells using a 40 &mu;m filter and collect in a fresh 50 ml centrifuge tube.</li>
	<li>Calculate the total number of cells in the solution using a hemacytometer.</li>
	<li>Centrifuge the cell suspension 95 x g for 5 min and carefully discard the supernatant afterwards. Wash the cells with pre-warmed 0.9% NaCl. Centrifuge 95 x g for 5 min and discard the supernatant.</li>
</ol>
7. Encapsulation of Cells
<ol>
	<li>Prepare a 1 ml syringe attached to a soft plastic tubing of 14G x 2" I.V. catheter. This is used to aspirate the cell suspension to be loaded on to the syringe pump as shown in Figure 1.</li>
	<li>Resuspend the cells with pre-warmed alginate solution at a density of 1.25 million cells/ml alginate. Gently mix with the syringe and avoid creating bubbles.</li>
	<li>Set up the bead generator, syringe pump and the air flow meter as shown in Figure 1. More details of these devices are listed in Table of specific reagents and equipment.</li>
	<li>With the cells aspirated into the syringe, discard the plastic tubing of I.V. catheter and attach the syringe to the encapsulation machine. Ensure that there is a 10 cm gap between the end of the encapsulation machine and the collection point as shown in Figure 1.</li>
	<li>Encapsulate the cells by setting the syringe pump at 20 ml/hr, air flow rate at 8 L/min and a pressure of 100 kPa (the size of capsules can be changed by altering the air flow rate).</li>
	<li>Collect the encapsulated cells into a petri dish (100 x 15 mm) filled with 20 ml of pre-warmed precipitation bath for 7 min to stabilize the capsules.</li>
	<li>Transfer the encapsulated cells by gentle aspiration into 50 ml centrifuge tubes filled with 20 ml of 0.9% NaCl.</li>
	<li>Allow the capsules to settle into the bottom of the tube then gently discard the supernatant. Repeat the washing process with 0.9% NaCl.</li>
	<li>Resuspend the encapsulated cells in pre-warmed culturing medium supplemented with RI (10 &mu;M), transfer into a culture flask and incubated at 37 &deg;C/5% CO2.</li>
</ol>
8. Differentiation of Encapsulated hESC to DA Neurons
The encapsulated hESC are treated with RI for 3 days prior to differentiation.
<ol>
	<li>Seed the mouse stromal cell line, PA6 cells at a density of 1.0 x 104 per cm2 in 0.1% gelatin-coated T75 flask and condition the PA6 cells in DA neural differentiation medium (Materials Table) 24 hours before the differentiation.</li>
	<li>Transfer the capsules to a 50 ml centrifuge tube and allow them to settle into the bottom of the tube.</li>
	<li>Discard the supernatant and resuspend the capsules in PA6 cell-conditioned DA neural differentiation medium.</li>
	<li>Culture the encapsulated hESC with the PA6 cell monolayer ( 9 x 106 hESCs per 7.5 x 105 PA6 cells ) for 28 days with a media change on day 4 and every other day thereafter (change only half of the medium each time).</li>
	<li>After 3 weeks in culture with PA6 cells, supplement the DA neural differentiation medium with 100 ng/ml SHH and 100 ng/ml FGF8a for the remaining week.</li>
</ol>
9. Decapsulation of Encapsulated hESC
<ol>
	<li>Aspirate the capsules into a 15 ml centrifuge tube and allow them to settle at the bottom of the tube. Then discard the supernatant carefully.</li>
	<li>Wash the capsules with D-PBS twice. Let the capsules settle at the bottom of the tube then remove the supernatant.</li>
	<li>Add 5 ml decapsulating solution to the capsules. Mix the suspension thoroughly via aspiration prior to incubation at room temperature for 4-5 min.</li>
	<li>Centrifuge the decapsulated cells at 95 x g for 3 min and discard the supernatant.</li>
	<li>Wash the cell pellet with D-PBS followed by centrifugation at 95 x g for 3 min. Repeat.</li>
	<li>The decapsulated cells can be further cultured as a monolayer or used for downstream analysis.</li>
</ol>
10. Representative Results
The diameter of alginate microcapsules is 400-500 &mu;m. The number of cells within the capsule was estimated by calculating the total number of cells divided by total number of capsules per run. Therefore, approximately 5.0 x 104 cells per capsule was estimated. From this, we presume that the maximum number of cells the capsule can contain is approximately 1.0 x 105. The viability of encapsulated hESC is &gt;80% (Figure 2) as determined by using using carboxyfluorescein diacetate succinimidly ester (CFDA)/propidium iodide (PI) assay. We have optimized the conditions of hESC encapsulation by decreasing the alginate concentration from 2.2% down to 1.1% and by changing the precipitation bath from barium chloride to calcium chloride. From these conditions, we showed that only the cells which were encapsulated with 1.1% calcium alginate could survive, proliferate and form EBs in vitro1. To further optimize the condition, the effects of culturing media and RI, Y-27632 were investigated. The data as presented in Figure 2 and 3 demonstrate that RI prevented dissociation-induced apoptosis and maintained cell viability and promoted cluster formation1,6. Furthermore, the viability of encapsulated hESC cultured in hFF-CM + RI was significantly higher than other groups without RI supplementation; however this was not significantly different to encapsulated hESC cultured in SR + RI. Similarly, cell proliferation using BrdU assay increased from 25% to 75% as single cells developed into clusters (Figure 3). Apoptosis assay by TUNEL revealed that the single cells in microcapsules cultured in SR medium were apoptotic (data not shown) whereas the retrieved clusters from the hFF-CM were mostly negative for TUNEL. To a certain extent, hFF-CM supplemented with bFGF also promoted the survival and proliferation of encapsulated hESCs in the absence of Y-27632. However, treatment with Y-27632 before (2 hours) and after encapsulation (for an additional 4 days) markedly enhanced viability, proliferation and cluster formation of encapsulated hESC in 1.1% calcium alginate microcapsules.
Previously we demonstrated that encapsulated hESC can be successfully differentiated to definitive endoderm1. Here, we examined the application of cell encapsulation as a 3D platform to differentiate encapsulated hESC into DA neurons. hESC, that formed embryoid bodies (EB) in capsules were direct differentiated and on decapsulation under the conditions described showed a progressive neuronal morphology (Figure 4) after 2-3 days of culture with more than 90% viability. Gene expression analysis showed a down-regulation of pluripotent marker, OCT4 while neuroprogenitor marker, PAX6 and DA neuronal marker, TH were up-regulated after 7 days of differentiation (Figure 5A). Immunofluorescent staining revealed that differentiated hESC were PAX6-positive (&gt;80%) but OCT4-negative at day 7. Further differentiated hESC showed TH-positive (&gt;90%) neurons after 21 days (Figure 5B). Western blot analysis also showed an up-regulation of TH expression from day 14 (Figure 5C) while PAX6 expression was down-regulated after day 21. In comparison, the cells cultured under two-dimensional (2D) environment under similar conditions (e.g. RI pre-treatment for 2 hours and RI post-treatment for 3 days prior to differentiation) maintained a high percentage of PAX6-positive cells (&gt;80%) throughout the differentiation period and were not as efficient in differentiating to TH-positive cells (&lt;60%) as in 3D environment provided by encapsulation (Figure 5A and C).

<ol>
	<li>Chayosumrit, M., Tuch, B., Sidhu, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alginate+microcapsule+for+propagation+and+directed+differentiation+of+hESCs+to+definitive+endoderm.">Alginate microcapsule for propagation and directed differentiation of hESCs to definitive endoderm.</a> Biomaterials. 31, 505-514 (2010).</li><li>Dean, S. K., Yulyana, Y., Williams, G., Sidhu, K. S., Tuch, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+of+encapsulated+embryonic+stem+cells+after+transplantation.">Differentiation of encapsulated embryonic stem cells after transplantation.</a> Transplantation. 82, 1175-1184 (2006).</li><li>Siti-Ismail, N., Bishop, A. E., Polak, J. M., Mantalaris, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+benefit+of+human+embryonic+stem+cell+encapsulation+for+prolonged+feeder-free+maintenance.">The benefit of human embryonic stem cell encapsulation for prolonged feeder-free maintenance.</a> Biomaterials. 29, 3946-3952 (2008).</li><li>Dawson, E., Mapili, G., Erickson, K., Taqvi, S., Roy, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomaterials+for+stem+cell+differentiation.">Biomaterials for stem cell differentiation.</a> Adv. Drug Deliv. Rev. 60, 215-228 (2008).</li><li>Orive, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+encapsulation:+promise+and+progress.">Cell encapsulation: promise and progress.</a> Nat. Med. 9, 104-107 (2003).</li><li>Watanabe, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+ROCK+inhibitor+permits+survival+of+dissociated+human+embryonic+stem+cells.">A ROCK inhibitor permits survival of dissociated human embryonic stem cells.</a> Nat. Biotechnol. 25, 681-686 (2007).</li><li>Dang, S. M., Gerecht-Nir, S., Chen, J., Itskovitz-Eldor, J., Zandstra, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled,+scalable+embryonic+stem+cell+differentiation+culture.">Controlled, scalable embryonic stem cell differentiation culture.</a> Stem Cells. 22, 275-282 (2004).</li><li>Drukker, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+expression+of+MHC+proteins+in+human+embryonic+stem+cells.">Characterization of the expression of MHC proteins in human embryonic stem cells.</a> Proc. Natl. Acad. Sci. U S A. 99, 9864-9869 (2002).</li><li>Calafiore, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standard+Technical+Procedures+for+Microencapsulation+of+Human+Islets+for+Graft+into+Nonimmunosuppressed+Patients+With+Type+1+Diabetes+Mellitus.">Standard Technical Procedures for Microencapsulation of Human Islets for Graft into Nonimmunosuppressed Patients With Type 1 Diabetes Mellitus.</a> Transplantation Proceedings. 38, 1156-1157 (2006).</li><li>Cho, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+efficient+and+large-scale+generation+of+functional+dopamine+neurons+from+human+embryonic+stem+cells.">Highly efficient and large-scale generation of functional dopamine neurons from human embryonic stem cells.</a> Proc. Natl. Acad. Sci. U.S.A. 105, 3392-3397 (2008).</li><li>Vazin, T., Chen, J., Lee, C. T., Amable, R., Freed, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+stromal-derived+inducing+activity+in+the+generation+of+dopaminergic+neurons+from+human+embryonic+stem+cells.">Assessment of stromal-derived inducing activity in the generation of dopaminergic neurons from human embryonic stem cells.</a> Stem Cells. 26, 1517-1525 (2008).</li></ol>

We have nothing to disclose.

Several studies using mouse embryonic stem cells and hESC have demonstrated the benefits of 3D culture system in biomaterials and tissue engineering2,3. We used calcium alginate microcapsules as a suitable 3D platform to study hESC propagation and differentiation in comparison to barium alginate since hESC showed significant higher viability when encapsulated in calcium alginate than barium alginate. This culture system also allows a high-density cell culture and exchange of nutrients and oxygen across the mem...

<table border="1">
<tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Notes</td>
 </tr>
 <tr>
 <td>Alginate (Pronova UP MVG) </td>
 <td>NovoMatrix</td>
 <td>4200101</td>
 <td>high glucuronic acid content &ge;60%, viscosity &gt;200 mPa s, and endotoxin &lt;100 EU/g</td>
 </tr>
 <tr>
 <td>Gelatin</td>
 <td>Sigma-Aldrich</td>
 <td>G1890-100G </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>0.9% NaCl</td>
 <td>Baxter healthcare</td>
 <td>AHF7123</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Type J1 bead generator </td>
 <td>Nisco engineering Inc</td>
 <td>SPA-0447</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Multi-Phaser syringe pump</td>
 <td>New Era Pump Systems Inc</td>
 <td>Model NE-1000 </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Ezi-Flow Medical Flowmeter</td>
 <td>Gascon Systems</td>
 <td>G0149</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Y-27632</td>
 <td>Merck</td>
 <td>688000 </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Human Serum Albumin</td>
 <td>Sigma-Aldrich</td>
 <td>A4327-1G </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Accutase</td>
 <td>Millipore</td>
 <td>SCR005 </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>14G x 2&rdquo; I.V. catheter</td>
 <td>Terumo</td>
 <td>SR-OX1451C</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Knockout-DMEM</td>
 <td>Invitrogen</td>
 <td>10829-018</td>
 <td>For SR medium (basal)</td>
 </tr>
 <tr>
 <td>GlutaMAX -I </td>
 <td>Invitrogen</td>
 <td>35050-061</td>
 <td>For SR medium (2 mM)</td>
 </tr>
 <tr>
 <td>Knockout Serum Replacement </td>
 <td>Invitrogen</td>
 <td>10828-028</td>
 <td>For SR medium (20%)</td>
 </tr>
 <tr>
 <td>Penicillin-Streptomycin</td>
 <td>Invitrogen</td>
 <td>15070063</td>
 <td>For SR medium (2.5 U/ml)</td>
 </tr>
 <tr>
 <td>Insulin-Transferrin-Selenium (ITS)</td>
 <td>Invitrogen</td>
 <td>41400045</td>
 <td>For SR medium (1x)</td>
 </tr>
 <tr>
 <td>&beta;-Mercaptoethanol</td>
 <td>Invitrogen</td>
 <td>21985-023</td>
 <td>For SR medium (0.1 mM)</td>
 </tr>
 <tr>
 <td>MEM NEAA Solution</td>
 <td>Invitrogen</td>
 <td>11140-050</td>
 <td>For SR medium (5 mM)</td>
 </tr>
 <tr>
 <td>Glasgow Minimum Essential Medium</td>
 <td>Invitrogen</td>
 <td>11710035 </td>
 <td>For DA neural differentiation medium (basal)</td>
 </tr>
 <tr>
 <td>Knockout Serum Replacement </td>
 <td>Invitrogen</td>
 <td>10828-028</td>
 <td>For DA neural differentiation medium (10%)</td>
 </tr>
 <tr>
 <td>Sodium pyruvate</td>
 <td>Invitrogen</td>
 <td>11360070</td>
 <td>For DA neural differentiation medium (1 mM)</td>
 </tr>
 <tr>
 <td>MEM NEAA Solution</td>
 <td>Invitrogen</td>
 <td>11140-050</td>
 <td>For DA neural differentiation medium (0.1 mM)</td>
 </tr>
 <tr>
 <td>&beta;-Mercaptoethanol</td>
 <td>Invitrogen</td>
 <td>21985-023</td>
 <td>For DA neural differentiation medium (0.1 mM)</td>
 </tr>
 <tr>
 <td>Sonic hedgehog (SHH)</td>
 <td>R &amp; D Systems</td>
 <td>1314-SH-025/CF</td>
 <td>For DA neural differentiation
 (100 ng/ml)</td>
 </tr>
 <tr>
 <td>Fibroblast growth factor 8a (FGF8a) </td>
 <td>R &amp; D Systems</td>
 <td>4745-F8-050</td>
 <td>For DA neural differentiation
 (100 ng/ml)</td>
 </tr>
 </tbody>
</table>

alginate microcapsule as a 3d platform for propagation and differentiation of human embryonic stem cells (hesc) to different lineages

Human embryonic stem cells (hESC) are emerging as an attractive alternative source for cell replacement therapy since they can be expanded in culture indefinitely and differentiated to any cell types in the body. Various types of biomaterials have also been used in stem cell cultures to provide a microenvironment mimicking the stem cell niche1-3. The latter is important for promoting cell-to-cell interaction, cell proliferation, and differentiation into specific lineages as well as tissue organization by providing a three-dimensional (3D) environment4 such as encapsulation. The principle of cell encapsulation involves entrapment of living cells within the confines of semi-permeable membranes in 3D cultures2. These membranes allow for the exchange of nutrients, oxygen and stimuli across the membranes, whereas antibodies and immune cells from the host that are larger than the capsule pore size are excluded5. Here, we present an approach to culture and differentiate hESC DA neurons in a 3D microenvironment using alginate microcapsules. We have modified the culture conditions2 to enhance the viability of encapsulated hESC. We have previously shown that the addition of p160-Rho-associated coiled-coil kinase (ROCK) inhibitor, Y-27632 and human fetal fibroblast-conditioned serum replacement medium (hFF-CM) to the 3D platform significantly enhanced the viability of encapsulated hESC in which the cells expressed definitive endoderm marker genes1. We have now used this 3D platform for the propagation of hESC and efficient differentiation to DA neurons. Protein and gene expression analyses after the final stage of DA neuronal differentiation showed an increased expression of tyrosine hydroxylase (TH), a marker for DA neurons, &gt;100 folds after 2 weeks. We hypothesized that our 3D platform using alginate microcapsules may be useful to study the proliferation and directed differentiation of hESC to various lineages. This 3D system also allows the separation of feeder cells from hESC during the process of differentiation and also has potential for immune-isolation during transplantation in the future.

Watch this Scientific Journal Video about Alginate Microcapsule as a 3D Platform for Propagation and Differentiation of Human Embryonic Stem Cells hESC to Different Lineages at JoVE.com

Alginate Microcapsule as a 3D Platform for Propagation and Differentiation of Human Embryonic Stem Cells hESC to Different Lineages

We have optimized a microencapsulation technique as an effective 3D platform for propagation and differentiation of embryonic stem cells to endoderm and dopaminergic (DA) neurons. It also provides an opportunity for immune-isolation of cells from the host during transplantation. This platform can be adapted for other cell types.

Alginate Microcapsule as a 3D Platform for Propagation and Differentiation of Human Embryonic Stem Cells (hESC) to Different Lineages

Human embryonic stem cells (hESC) are emerging as an attractive alternative source for cell replacement therapy since they can be expanded in culture ...

alginate-microcapsule-as-3d-platform-for-propagation-differentiation

Research

JoVE Journal

Bioengineering

16.2K Views.  The University of New South Wales. We have optimized a microencapsulation technique as an effective 3D platform for propagation and differentiation of embryonic stem cells to endoderm and dopaminergic (DA) neurons. It also provides an opportunity for immune-isolation of cells from the host during transplantation. This platform can be adapted for other cell types.

Video: Alginate Microcapsule as a 3D Platform for Propagation and Differentiation of Human Embryonic Stem Cells hESC to Different Lineages

Rotating Cell Culture Systems for Human Cell Culture: Human Trophoblast Cells as a Model

The field of human trophoblast research aids in understanding the complex environment established during placentation. Due to the nature of these studies, human in vivo experimentation is impossible. A combination of primary cultures, explant cultures and trophoblast cell lines1 support our understanding of invasion of the uterine wall2 and remodeling of uterine spiral arteries3,4 by extravillous trophoblast cells (EVTs), which is required for successful establishment of pregnancy. Despite the wealth of knowledge gleaned from such models, it is accepted that in vitro cell culture models using EVT-like cell lines display altered cellular properties when compared to their in vivo counterparts5,6. Cells cultured in the rotating cell culture system (RCCS) display morphological, phenotypic, and functional properties of EVT-like cell lines that more closely mimic differentiating in utero EVTs, with increased expression of genes mediating invasion (e.g. matrix metalloproteinases (MMPs)) and trophoblast differentiation7,8,9. The Saint Georges Hospital Placental cell Line-4 (SGHPL-4) (kindly donated by Dr. Guy Whitley and Dr. Judith Cartwright) is an EVT-like cell line that was used for testing in the RCCS.
The design of the RCCS culture vessel is based on the principle that organs and tissues function in a three-dimensional (3-D) environment. Due to the dynamic culture conditions in the vessel, including conditions of physiologically relevant shear, cells grown in three dimensions form aggregates based on natural cellular affinities and differentiate into organotypic tissue-like assemblies10,11,12 . The maintenance of a fluid orbit provides a low-shear, low-turbulence environment similar to conditions found in vivo. Sedimentation of the cultured cells is countered by adjusting the rotation speed of the RCCS to ensure a constant free-fall of cells. Gas exchange occurs through a permeable hydrophobic membrane located on the back of the bioreactor. Like their parental tissue in vivo, RCCS-grown cells are able to respond to chemical and molecular gradients in three dimensions (i.e. at their apical, basal, and lateral surfaces) because they are cultured on the surface of porous microcarrier beads. When grown as two-dimensional monolayers on impermeable surfaces like plastic, cells are deprived of this important communication at their basal surface. Consequently, the spatial constraints imposed by the environment profoundly affect how cells sense and decode signals from the surrounding microenvironment, thus implying an important role for the 3-D milieu13.
We have used the RCCS to engineer biologically meaningful 3-D models of various human epithelial tissues7,14,15,16. Indeed, many previous reports have demonstrated that cells cultured in the RCCS can assume physiologically relevant phenotypes that have not been possible with other models10,17-21. In summary, culture in the RCCS represents an easy, reproducible, high-throughput platform that provides large numbers of differentiated cells that are amenable to a variety of experimental manipulations. 
In the following protocol, using EVTs as an example, we clearly describe the steps required to three-dimensionally culture adherent cells in the RCCS.

Traditional, two dimensional cell culture techniques often result in altered characteristics with respect to differentiation markers, cytokines and growth factors. Three-dimensional cell culture in the rotating cell culture system (RCCS) reestablishes expression of many of these factors as shown here with an extravillous trophoblast cell line.

The field of human trophoblast research aids in  understanding the complex environment established during placentation. Due to the  nature of these ...

Development, Expansion, and In vivo Monitoring of Human NK Cells from Human Embryonic Stem Cells (hESCs) and Induced Pluripotent Stem Cells (iPSCs)

We present a method for deriving natural killer (NK) cells from undifferentiated hESCs and iPSCs using a feeder-free approach. This method gives rise to high levels of NK cells after 4 weeks culture and can undergo further 2-log expansion with artificial antigen presenting cells. hESC- and iPSC-derived NK cells developed in this system have a mature phenotype and function. The production of large numbers of genetically modifiable NK cells is applicable for both basic mechanistic as well as anti-tumor studies. Expression of firefly luciferase in hESC-derived NK cells allows a non-invasive approach to follow NK cell engraftment, distribution, and function. We also describe a dual-imaging scheme that allows separate monitoring of two different cell populations to more distinctly characterize their interactions in vivo. This method of derivation, expansion, and dual in vivo imaging provides a reliable approach for producing NK cells and their evaluation which is necessary to improve current NK cell adoptive therapies.

Development, Expansion, and In vivo Monitoring of Human NK Cells from Human Embryonic Stem Cells hESCs and Induced Pluripotent Stem Cells iPSCs

This protocol describes the development, expansion, and in vivo imaging of NK cells derived from hESCs and iPSCs.

We present a method for deriving natural killer (NK) cells from undifferentiated hESCs and iPSCs using a feeder-free approach. This method gives rise to ...

Ordering Single Cells and Single Embryos in 3D Confinement: A New Device for High Content Screening

Biological cells are usually observed on flat (2D) surfaces. This condition is not physiological, and phenotypes and shapes are highly variable. Screening based on cells in such environments have therefore serious limitations: cell organelles show extreme phenotypes, cell morphologies and sizes are heterogeneous and/or specific cell organelles cannot be properly visualized. In addition, cells in vivo are located in a 3D environment; in this situation, cells show different phenotypes mainly because of their interaction with the surrounding extracellular matrix of the tissue. In order to standardize and generate order of single cells in a physiologically-relevant 3D environment for cell-based assays, we report here the microfabrication and applications of a device for in vitro 3D cell culture. This device consists of a 2D array of microcavities (typically 105 cavities/cm2), each filled with single cells or embryos. Cell position, shape, polarity and internal cell organization become then normalized showing a 3D architecture. We used replica molding to pattern an array of microcavities, &#8216;eggcups&#8217;, onto a thin polydimethylsiloxane (PDMS) layer adhered on a coverslip. Cavities were covered with fibronectin to facilitate adhesion. Cells were inserted by centrifugation. Filling percentage was optimized for each system allowing up to 80%. Cells and embryos viability was confirmed. We applied this methodology for the visualization of cellular organelles, such as nucleus and Golgi apparatus, and to study active processes, such as the closure of the cytokinetic ring during cell mitosis. This device allowed the identification of new features, such as periodic accumulations and inhomogeneities of myosin and actin during the cytokinetic ring closure and compacted phenotypes for Golgi and nucleus alignment. We characterized the method for mammalian cells, fission yeast, budding yeast, C. elegans with specific adaptation in each case. Finally, the characteristics of this device make it particularly interesting for drug screening assays and personalized medicine.

We report a device and a new method to study cells and embryos. Single cells are precisely ordered in microcavity arrays. Their 3D confinement is a step towards 3D environments encountered in physiological conditions and allows organelle orientation. By controlling cell shape, this setup minimizes variability reported in standard assays.

Biological cells are usually observed on flat (2D) surfaces. This condition is not physiological, and phenotypes and shapes are highly variable. Screening ...

Layered Alginate Constructs: A Platform for Co-culture of Heterogeneous Cell Populations

Many load bearing tissues possess structurally and functionally distinct regions, typically accompanied by different cell phenotypes with differential mechanosensing characteristics. Engineering and analysis of these tissue types remain a challenge. Layered hydrogel constructs provide an opportunity for investigating the interactions among multiple cell populations within single constructs. Alginate hydrogels are both biocompatible and allow for easy isolation of cells after experimentation. Here, we describe a method for the development of small sized dual layered alginate hydrogel discs. This process maintains high cell viability of human mesenchymal stem cells during the formation process and these layered discs can withstand unconfined cyclic compression, commonly used for stimulation of hMSCs undergoing chondrogenesis. These layered constructs can potentially be scaled up to include additional levels, and also be used to segregate cell populations initially after layering. This dual layer alginate hydrogel culture platform can be used for many different applications including engineering and analysis of cells of load bearing tissues and co-cultures of other cell types.

Engineering and analysis of load bearing tissues with heterogeneous cell populations are still a challenge. Here, we describe a method for creating bi-layered alginate hydrogel discs as a platform for co-culture of diverse cell populations within one construct.

Many load bearing tissues possess structurally and functionally distinct regions, typically accompanied by different cell phenotypes with differential ...

Micropatterning and Assembly of 3D Microvessels

In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass based substrates, and hydrogel-based tube formation assays. These assays, while informative, do not recapitulate lumen geometry, proper extracellular matrix, and multi-cellular proximity, which play key roles in modulating vascular function. This manuscript describes an injection molding method to generate engineered vessels with diameters on the order of 100 &#181;m. Microvessels are fabricated by seeding endothelial cells in a microfluidic channel embedded within a native type I collagen hydrogel. By incorporating parenchymal cells within the collagen matrix prior to channel formation, specific tissue microenvironments can be modeled and studied. Additional modulations of hydrodynamic properties and media composition allow for control of complex vascular function within the desired microenvironment. This platform allows for the study of perivascular cell recruitment, blood-endothelium interactions, flow response, and tissue-microvascular interactions. Engineered microvessels offer the ability to isolate the influence from individual components of a vascular niche and precisely control its chemical, mechanical, and biological properties to study vascular biology in both health and disease.

This manuscript presents an injection molding method to engineer microvessels that recapitulate physiological properties of endothelium. The microfluidic-based process creates patent 3D vascular networks with tailorable conditions, such as flow, cellular composition, geometry, and biochemical gradients. The fabrication process and examples of potential applications are described.

In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass ...

Single-Cell Optical Action Potential Measurement in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Conventional intracellular microelectrode techniques to quantify cardiomyocyte electrophysiology are extremely complex, labor intensive, and typically carried out in low throughput. Rapid and ongoing expansion of induced pluripotent stem cell (iPSC) technology presents a new standard in cardiovascular research and alternate methods are now necessary to increase throughput of electrophysiological data at a single cell level. VF2.1Cl is a recently derived voltage sensitive dye which provides a rapid single channel, high magnitude response to fluctuations in membrane potential. It possesses kinetics superior to those of other existing voltage indicators and makes available functional data equivalent to that of traditional microelectrode techniques. Here, we demonstrate simplified, non-invasive action potential characterization in externally paced human iPSC derived cardiomyocytes using a modular and highly affordable photometry system.

Here we describe optical acquisition and characterization of action potentials from induced pluripotent stem cell derived cardiomyocytes using a high-speed modular photometry system.

Conventional intracellular microelectrode techniques to quantify cardiomyocyte electrophysiology are extremely complex, labor intensive, and typically ...

A Culture Method to Maintain Quiescent Human Hematopoietic Stem Cells

Human hematopoietic stem cells (HSCs), like other mammalian HSCs, maintain lifelong hematopoiesis in the bone marrow. HSCs remain quiescent in vivo, unlike more differentiated progenitors, and enter the cell cycle rapidly after chemotherapy or irradiation to treat bone marrow injury or in vitro culture. By mimicking the bone marrow microenvironment in the presence of abundant fatty acids, cholesterol, low concentration of cytokines, and hypoxia, human HSCs maintain quiescence in vitro. Here, a detailed protocol for maintaining functional HSCs in the quiescent state in vitro is described. This method will enable studies of the behavior of human HSCs under physiological conditions.

This protocol enables the maintenance of quiescent human hematopoietic stem cells in vitro by mimicking the bone marrow microenvironment using abundant fatty acids, cholesterol, lower concentrations of cytokines, and hypoxia.

Human hematopoietic stem cells (HSCs), like other mammalian HSCs, maintain lifelong hematopoiesis in the bone marrow. HSCs remain quiescent in vivo, ...

Real-Time Intravital Multiphoton Microscopy to Visualize Focused Ultrasound and Microbubble Treatments to Increase Blood-Brain Barrier Permeability

The blood-brain barrier (BBB) is a key challenge for the successful delivery of drugs to the brain. Ultrasound exposure in the presence of microbubbles has emerged as an effective method to transiently and locally increase the permeability of the BBB, facilitating para- and transcellular transport of drugs across the BBB. Imaging the vasculature during ultrasound-microbubble treatment will provide valuable and novel insights on the mechanisms and dynamics of ultrasound-microbubble treatments in the brain.
Here, we present an experimental procedure for intravital multiphoton microscopy using a cranial window aligned with a ring transducer and a 20x objective lens. This set-up enables high spatial and temporal resolution imaging of the brain during ultrasound-microbubble treatments. Optical access to the brain is obtained via an open-skull cranial window. Briefly, a 3-4 mm diameter piece of the skull is removed, and the exposed area of the brain is sealed with a glass coverslip. A 0.82 MHz ring transducer, which is attached to a second glass coverslip, is mounted on top. Agarose (1% w/v) is used between the coverslip of the transducer and the coverslip covering the cranial window to prevent air bubbles, which impede ultrasound propagation. When sterile surgery procedures and anti-inflammatory measures are taken, ultrasound-microbubble treatments and imaging sessions can be performed repeatedly over several weeks. Fluorescent dextran conjugates are injected intravenously to visualize the vasculature and quantify ultrasound-microbubble induced effects (e.g., leakage kinetics, vascular changes). This paper describes the cranial window placement, ring transducer placement, imaging procedure, common troubleshooting steps, as well as advantages and limitations of the method.

This protocol describes the surgical and technical procedures that enable real-time in vivo multiphoton fluorescence imaging of the rodent brain during focused ultrasound and microbubble treatments to increase blood-brain barrier permeability.

The blood-brain barrier (BBB) is a key challenge for the successful delivery of drugs to the brain. Ultrasound exposure in the presence of microbubbles ...

In vitro Induction of Human Dental Pulp Stem Cells Toward Pancreatic Lineages

As of 2000, the success of pancreatic islet transplantation using the Edmonton protocol to treat type I diabetes mellitus still faced some obstacles. These include the limited number of cadaveric pancreas donors and the long-term use of immunosuppressants. Mesenchymal stem cells (MSCs) have been considered to be a potential candidate as an alternative source of islet-like cell generation. Our previous reports have successfully illustrated the establishment of induction protocols for differentiating human dental pulp stem cells (hDPSCs) to insulin-producing cells (IPCs). However, the induction efficiency varied greatly. In this paper, we demonstrate the comparison of hDPSCs pancreatic induction efficiency via integrative (microenvironmental and genetic manipulation) and non-integrative (microenvironmental manipulation) induction protocols for delivering hDPSC-derived IPCs (hDPSC-IPCs). The results suggest distinct induction efficiency for both the induction approaches in terms of 3-dimensional colony structure, yield, pancreatic mRNA markers, and functional property upon multi-dosage glucose challenge. These findings will support the future establishment of a clinically applicable IPCs and pancreatic lineage production platform.

In vitro Induction of Human Dental Pulp Stem Cells Toward Pancreatic Lineages

This protocol presents a comparison between two different induction protocols for differentiating human dental pulp stem cells (hDPSCs) toward pancreatic lineages in vitro: the integrative protocol and the non-integrative protocol. The integrative protocol generates more insulin producing cells (IPCs).

As of 2000, the success of pancreatic islet transplantation using the Edmonton protocol to treat type I diabetes mellitus still faced some obstacles. ...

Developing 3D Organized Human Cardiac Tissue within a Microfluidic Platform

The leading cause of death worldwide persists as cardiovascular disease (CVD). However, modeling the physiological and biological complexity of the heart muscle, the myocardium, is notoriously difficult to accomplish in vitro. Mainly, obstacles lie in the need for human cardiomyocytes (CMs) that are either adult or exhibit adult-like phenotypes and can successfully replicate the myocardium&#39;s cellular complexity and intricate 3D architecture. Unfortunately, due to ethical concerns and lack of available primary patient-derived human cardiac tissue, combined with the minimal proliferation of CMs, the sourcing of viable human CMs has been a limiting step for cardiac tissue engineering. To this end, most research has transitioned toward cardiac differentiation of human induced pluripotent stem cells (hiPSCs) as the primary source of human CMs, resulting in the wide incorporation of hiPSC-CMs within in vitro assays for cardiac tissue modeling.
Here in this work, we demonstrate a protocol for developing a 3D mature stem cell-derived human cardiac tissue within a microfluidic device. We specifically explain and visually demonstrate the production of a 3D in vitro anisotropic cardiac tissue-on-a-chip model from hiPSC-derived CMs. We primarily describe a purification protocol to select for CMs, the co-culture of cells with a defined ratio via mixing CMs with human CFs (hCFs), and suspension of this co-culture within the collagen-based hydrogel. We further demonstrate the injection of the cell-laden hydrogel within our well-defined microfluidic device, embedded with staggered elliptical microposts that serve as surface topography to induce a high degree of alignment of the surrounding cells and the hydrogel matrix, mimicking the architecture of the native myocardium. We envision that the proposed 3D anisotropic cardiac tissue-on-chip model is suitable for fundamental biology studies, disease modeling, and, through its use as a screening tool, pharmaceutical testing.

The goal of this protocol is to explain and demonstrate the development of a three-dimensional (3D) microfluidic model of highly aligned human cardiac tissue, composed of stem cell-derived cardiomyocytes co-cultured with cardiac fibroblasts (CFs) within a biomimetic, collagen-based hydrogel, for applications in cardiac tissue engineering, drug screening, and disease modeling.

The leading cause of death worldwide persists as cardiovascular disease (CVD). However, modeling the physiological and biological complexity of the heart ...