This work was supported by the National Institutes of Health through Grant Award Numbers R37-CA260223, R21CA246414. We thank the NCSU flow cytometry core for training and guidance on flow cytometry analysis. Schematics were created with Biorender.com

All the procedures involving human primacy cells and retroviral vectors were performed in compliance with North Carolina State University&#39;s Biological Safety guidelines and approved by the Environmental Health and Safety Office. Human peripheral blood mononuclear cells were purchased as buffy coats from commercial sources. Primary human cells must be isolated from human buffy coat fractions and require Biosafety Level 2 clearance and detailed standard operating procedures and approval from the institution where the work is to take place. Viral vectors, including the retroviral vector supernatants used for the transduction prepared as previously described19, can be classified either as Biosafety Level 1 or Biosafety Level 2 depending on the encoded protein and require approval from the relevant institutional biosafety committee.
1. Making the macroporous alginate scaffolds
<ol>
	<li>Prepare a stock solution of 0.4% (weight per volume) calcium D gluconate by adding sterile-filtered deionized water to calcium D gluconate in a beaker. Stir on medium speed until the calcium gluconate has dissolved (~1.5 h), sterile-filter, and store at room temperature. 
	NOTE: It is not necessary to check the pH of the solution.</li>
	<li>Prepare a solution of 2% (weight per volume) alginate in a screw cap vial or beaker. Carefully add the ultrapure alginate to the vessel and add sterile-filtered deionized water to the alginate. Choose the largest stir bar possible that will not impede mixing and add it to the vessel. 
	NOTE: Information on the type of ultrapure alginate used for this protocol can be found in the Table of Materials and on the Novamatrix website20. Different alginates were not explored for these scaffolds, as they can lead to undesired changes in porosity and biocompatibility of the scaffolds9,10,11.</li>
	<li>Stir the solution on high speed until the alginate dissolves (~1 h). If there are large clumps on the sides of the vessel, tilt the vessel to dislodge them. Small amounts of alginate on the sides will dissolve while stirring and are not cause for concern. 
	NOTE: It is not necessary to check the pH of the solution.</li>
	<li>When the alginate dissolves, reduce the stirring speed, slowly add an equal volume of 0.4% calcium D gluconate to the alginate solution to prevent crosslinking clumps from forming, and stir vigorously for 15 min.</li>
	<li>Tilt the beaker or vial sideways to remove any clumps that may have formed. 
	NOTE: It is recommended to use a homogenizer. The final solution should be optically clear.</li>
	<li>Pipette the desired volume of the solution into each well of a 48-well plate or 24-well plate. Use 300 &#181;L/well for a 48-well plate and 1 mL/well for a 24-well plate. Cast slowly and change tips frequently, as the solution will be viscous and will stick to the tip.</li>
	<li>Cover the plates with lids and freeze overnight at -20 &#730;C.</li>
	<li>Prepare the plate for the lyophilizer by removing the lid and securing the top with wipes and rubber bands. Place the plates in 750 mL to 2,000 mL lyophilizer flasks, and place on the lyophilizer for 72 h.</li>
	<li>After 72 h, remove the plate from the lyophilizer and replace the lid. Seal the plate and store at 4 &#730;C. For long term storage, vacuum-seal the plate before storing at 4 &#730;C. Keep dry until needed. 
	&#8203;NOTE: Make extra calcium-alginate solution due to volume error (some sticks to the walls of the vial, pipette tips). For example, to make four scaffolds in a 24-well plate, 4 mL of combined solution (2 mL alginate + 2 mL calcium D gluconate) is required, but it is recommended to prepare 2.5 mL of 2% alginate solution and 2.5 mL of 0.4% calcium D gluconate solution.</li>
</ol>
2. Transduction
<ol>
	<li>Concentration of viral supernatant using 100 kDa filters
	<ol>
		<li>Hydrate the centrifugal filter for 2 min with 1 mL of 1x phosphate-buffered saline (PBS). Discard the PBS.</li>
		<li>Concentrate the viral suspension by adding 2 mL of viral suspension (1 &#215; 106 TU/mL) and centrifuging it through the centrifugal filter at 1,500 &#215; g for 10 min in a swinging bucket rotor. 
		NOTE: One to two hundred microliters of concentrated virus is needed per scaffold.</li>
		<li>Spin for a few additional minutes if the concentrated virus suspension volume is greater than 200 &#181;L.</li>
		<li>Repeat steps 2.1.1-2.1.3 for each scaffold. 
		NOTE: It is also acceptable to concentrate a large stock of virus and take 100-200 &#181;L aliquots from the concentrated stock.</li>
	</ol>
	</li>
	<li>Seed activated cells and virus together.
	<ol>
		<li>For each scaffold, prepare an aliquot by suspending 1 &#215; 106 activated peripheral blood mononuclear cells (PBMCs) in 50 &#181;L of complete cell culture media (250 mL Click&#39;s media + 250 mL RPMI 1640 media + 50 mL fetal bovine serum + 5 mL glutamine substitute + 5 mL penicillin/streptomycin). 
		NOTE: See Supplemental File 1 for a protocol on how to activate PBMCs.</li>
		<li>Add the concentrated viral supernatant (~2 &#215; 106 TU, MOI 2) to the cell suspension. The total volume of the cell-virus suspension should not exceed 200 &#181;L for a 48-well scaffold or 350 &#181;L for a 24-well scaffold.</li>
		<li>Add the cell-virus mixture dropwise to the top of the dry scaffold. For negative control experiments, use complete cell culture media in place of the concentrated virus. Add the cell suspension to the top of the dry scaffold.</li>
		<li>Repeat steps 2.2.1-2.2.3 for each scaffold.</li>
		<li>Incubate the scaffolds in a cell culture incubator at 37 &#730;C for 45-60 min. Remove the scaffolds from the incubator; the scaffolds will fully absorb the solution during this time.</li>
		<li>To induce proliferation, add complete cell culture media supplemented with IL-15 (5 ng/mL) and IL-7 (10 ng/mL) to each well; IL-2 can also be used. Add 500 &#181;L to each 48-well scaffold or 1 mL to each 24-well scaffold.</li>
		<li>Incubate the scaffolds at 37 &#730;C for 72 h. As the cells proliferate, the media will turn orange.</li>
	</ol>
	</li>
	<li>Isolate cells from the scaffolds for analysis.
	<ol>
		<li>Dilute 0.5 M EDTA to 0.25 M EDTA in 1x PBS.</li>
		<li>Remove excess medium from each well and collect into separate 15 mL centrifuge tubes.</li>
		<li>To isolate cells from the scaffold, add 0.25 M EDTA to each scaffold. Add 300 &#181;L to 48-well scaffolds or 1 mL to 24-well scaffolds. Let the plate sit or gently agitate for 3-4 min.</li>
		<li>Once the scaffold is mostly dissolved, pipette in and out gently inside the well. A few in-and-out pipetting steps might be necessary to fully dissolve the scaffold. If it does not dissolve in 10 min, add another 200 &#181;L of 0.25 M EDTA.</li>
		<li>Once the scaffold dissolves completely, transfer the solution to a 15 mL centrifuge tube.</li>
		<li>Repeat steps 2.3.4 and 2.3.5 for each scaffold.</li>
		<li>Wash the cells twice by adding 12 mL PBS to each centrifuge tube and centrifuging at 400 &#215; g for 5 min. A cell pellet will form at the bottom of each tube. Aspirate the supernatant and repeat the wash. Be careful to fully aspirate the supernatant with every wash as it is crucial to remove all the EDTA.</li>
		<li>After the second wash with PBS, the cell pellet is now ready for analysis. Follow the appropriate protocol required for the analysis.</li>
	</ol>
	</li>
</ol>

<ol>
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P.A. and Y.B. are inventors on patents related to the use of biomaterials for generation of CAR-T cell therapeutics. Y.B. receives an industry-sponsored research grant related to CAR-T cell therapeutic technology (unrelated to this work).&#160;All other authors declare that they have no competing interests.

CAR-T cell therapy continues to gain interest for both research and commercial applications. Despite the success CAR-T cell therapy has had in treating blood cancers, the high cost of the procedure limits its use. The protocol presented here introduces a new method for viral gene transfer of T cells without the need for spinoculation of retronectin-coated plates. Producing dry macroporous alginate scaffolds to mediate transduction is relatively simple and is a suitable low-cost replacement for the conventional method.</p...

Immunotherapy has emerged as a revolutionary cancer treatment paradigm due to its ability to specifically target tumors, limit off-target cytotoxicity, and prevent relapse. Particularly, chimeric antigen receptor T (CAR-T) cell therapy has gained popularity due to its success in treating lymphomas and leukemias. The FDA approved the first CAR-T cell therapy in 2017, and, since then, has approved four more CAR-T cell therapies1,2,3,4,5. CARs have an antigen recognition domain usually consisting of a single chain variable fragment of a monoclonal antibody that is specific for a tumor associated antigen3,4. When a CAR interacts with its tumor-associated antigen, the CAR-T cells become activated, leading to an antitumor response involving cytokine release, cytolytic degranulation, transcription factor expression, and T cell proliferation. To produce CAR-T cells, blood is collected from the patient to obtain their T cells. CARs are genetically added to the patient&#39;s T cells using a virus. The CAR-T cells are grown in vitro and infused back into the patient2,3,4,6. Successful generation of CAR-T cells is determined by the transduction efficiency, which describes the number of T cells that are genetically modified into CAR-T cells.
Currently, the gold standard for CAR-T cell generation is spinoculation of activated T cells and virus on retronectin-coated plates7,8. Transduction begins when viral particles engage with the surface of the T cells. Retronectin promotes colocalization of virus and cells by increasing the binding efficiency between the viral particles and the cells, enhancing transduction7,8. Retronectin does not work well on its own and needs to be accompanied by spinoculation, which enhances gene transfer by concentrating the viral particles and increasing the surface permeability of the T cell, allowing for easier viral infection8. Despite the success of spinoculation on retronectin-coated plates, it is a complex process that requires multiple spin cycles and expensive reagents. Therefore, alternate methods for viral gene transfer that are quicker and cheaper are highly desirable.
Alginate is a natural anionic polysaccharide extensively used in the biomedical industry due to its low cost, good safety profile, and ability to form hydrogels upon mixing with divalent cations9,10,11,12. Alginate is a GMP-compliant polymer and is generally recognized as safe (GRAS) by the FDA13. Cross-linking alginate with cations creates stable hydrogels often used in wound healing, delivery of small chemical drugs and proteins, and cell transportation9,10,11,12,14,15,16. Due to its excellent gelling properties, alginate is the preferred material to create porous scaffolds by freeze-drying10,17. These characteristics of alginate make it an attractive candidate for producing a scaffold that can mediate viral gene transfer of activated cells.
Described here is a protocol for making dry macroporous alginate scaffolds, known as Drydux scaffolds, that statically transduce T cells by viral gene transfer17,18. The process for making these scaffolds is shown in Figure 1. These scaffolds eliminate the need for spinoculation of retronectin-coated plates. The macroporous alginate scaffolds encourage the interaction of viral particles and T cells to enable efficient gene transfer in a single step without affecting functionality and viability of the engineered T cells17. When followed correctly, these macroporous alginate scaffolds have a transduction efficiency of at least 80%, simplifying and shortening the viral transduction process.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64036/64036fig01v2.jpg" /> 
Figure 1: Schematic and timeline of the protocol. (A) Timeline for making the dry macroporous alginate scaffolds. Alginate is cross-linked with calcium-D-gluconate and frozen overnight. The frozen scaffolds are lyophilized for 72 h to create the Drydux scaffolds. (B) Timeline for viral transduction of activated cells. Activated cells and virus (MOI 2) are seeded on top of the scaffold and incubated in complete media supplemented with IL-7 and IL-15. The scaffolds absorb the mixture and promote viral gene transfer. EDTA is used to dissolve the scaffolds and isolate the transduced cells. After washing twice with PBS, the cell pellet can be used for analysis. Abbreviations: PBS = phosphate-buffered saline; PBMCs = peripheral blood mononuclear cells. <a href="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/64036/64036fig01largev2.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.5 M EDTA</td>
			<td>Invitrogen</td>
			<td>15575-038</td>
			<td>UltraPure, pH 8.0</td>
		</tr>
		<tr>
			<td>1x DPBS</td>
			<td>Gibco</td>
			<td>14190-144</td>
			<td>No calcium chloride or magnesium chloride</td>
		</tr>
		<tr>
			<td>3% Acetic Acid with Methylene Blue</td>
			<td>Stemcell Technologies Inc</td>
			<td>07060</td>
			<td></td>
		</tr>
		<tr>
			<td>Activated Periphreal Blood Mononuclear Cells</td>
			<td>-</td>
			<td>-</td>
			<td>Fresh or frozen</td>
		</tr>
		<tr>
			<td>Calcium-D-Gluconate</td>
			<td>Alfa Aesar</td>
			<td>A11649</td>
			<td></td>
		</tr>
		<tr>
			<td>CD28.2 Antibody</td>
			<td>BD</td>
			<td>555725</td>
			<td>1 mg/mL</td>
		</tr>
		<tr>
			<td>CD3 Antibody</td>
			<td>Miltenyi</td>
			<td>130-093-387</td>
			<td>100 &#956;g/mL</td>
		</tr>
		<tr>
			<td>Click&#39;s Media</td>
			<td>FUJIFILM IRVINE SCIENTIFIC MS</td>
			<td>9195</td>
			<td></td>
		</tr>
		<tr>
			<td>DI Water</td>
			<td>-</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamax</td>
			<td>Gibco</td>
			<td>35-050-061</td>
			<td></td>
		</tr>
		<tr>
			<td>HyClone FBS</td>
			<td>Cytvia</td>
			<td>SH3039603</td>
			<td></td>
		</tr>
		<tr>
			<td>HyClone RPMI 1640 Media</td>
			<td>Cytvia</td>
			<td>SH3009601</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin (P/S)</td>
			<td>Gibco</td>
			<td>15-140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Peripheral Blood Mononuclear Cells</td>
			<td>-</td>
			<td>-</td>
			<td>Fresh or frozen</td>
		</tr>
		<tr>
			<td>PRONOVA UP MVG</td>
			<td>NovaMatrix</td>
			<td>4200101</td>
			<td>Sodium alginate</td>
		</tr>
		<tr>
			<td>Recombinant Human IL-15</td>
			<td>Peprotech</td>
			<td>200-15</td>
			<td>5 ng/mL</td>
		</tr>
		<tr>
			<td>Recombinant Human IL-7</td>
			<td>Peprotech</td>
			<td>200-07</td>
			<td>10 ng/mL</td>
		</tr>
		<tr>
			<td>Retrovirus</td>
			<td>-</td>
			<td>-</td>
			<td>1 x 106 TU/mL</td>
		</tr>
	</tbody>
</table>

fabrication and use of dry macroporous alginate scaffolds for viral transduction of t cells

Genetic engineering of T cells for CAR-T cell therapy has come to the forefront of cancer treatment over the last few years. CAR-T cells are produced by viral gene transfer into T cells. The current gold standard of viral gene transfer involves spinoculation of retronectin-coated plates, which is expensive and time-consuming. There is a significant need for efficient and cost-effective methods to generate CAR-T cells. Described here is a method for fabricating inexpensive, dry macroporous alginate scaffolds, known as Drydux scaffolds, that efficiently promote viral transduction of activated T cells. The scaffolds are designed to be used in place of gold standard spinoculation of retronectin-coated plates seeded with virus and simplify the process for transducing cells. Alginate is cross-linked with calcium-D-gluconate and frozen overnight to create the scaffolds. The frozen scaffolds are freeze-dried in a lyophilizer for 72 h to complete the formation of the dry macroporous scaffolds. The scaffolds mediate viral gene transfer when virus and activated T cells are seeded together on top of the scaffold to produce genetically modified cells. The scaffolds produce &gt;85% primary T cell transduction, which is comparable to the transduction efficiency of spinoculation on retronectin-coated plates. These results demonstrate that dry macroporous alginate scaffolds serve as a cheaper and more convenient alternative to the conventional transduction method.

These macroporous alginate scaffolds are easy to make and should come out of the lyophilizer as porous, fluffy, and white discs. Although not studied in this experiment, calcium-alginate solution can be cast into different molds to create scaffolds of varying shapes, depending on the needs of the user9,10. The scaffolds are electrostatic and may stick to the lid of the well-plate or to a gloved finger. Figure 2 demonstrates what the ...

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Fabrication and Use of Dry Macroporous Alginate Scaffolds for Viral Transduction of T Cells

Herein is a protocol for creating dry macroporous alginate scaffolds that mediate efficient viral gene transfer for use in genetic engineering of T cells, including T cells for CAR-T cell therapy. The scaffolds were shown to transduce activated primary T cells with &gt;85% transduction.

Genetic engineering of T cells for CAR-T cell therapy has come to the forefront of cancer treatment over the last few years. CAR-T cells are produced by ...

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Research

JoVE Journal

Bioengineering

2.7K Views.  University of North Carolina at Chapel Hill and North Carolina State University. Herein is a protocol for creating dry macroporous alginate scaffolds that mediate efficient viral gene transfer for use in genetic engineering of T cells, including T cells for CAR-T cell therapy. The scaffolds were shown to transduce activated primary T cells with >85% transduction.

Video: Fabrication and Use of Dry Macroporous Alginate Scaffolds for Viral Transduction of T Cells

Fabrication of Micro-tissues using Modules of Collagen Gel Containing Cells

This protocol describes the fabrication of a type of micro-tissues called modules.  The module approach generates uniform, scalable and vascularized tissues.  The modules can be made of collagen as well as other gelable or crosslinkable materials.  They are approximately 2 mm in length and 0.7 mm in diameter upon fabrication but shrink in size with embedded cells or when the modules are coated with endothelial cells.  The modules individually are small enough that the embedded cells are within the diffusion limit of oxygen and other nutrients but modules can be packed together to form larger tissues that are perfusable.  These tissues are modular in construction because different cell types can be embedded in or coated on the modules before they are packed together to form complex tissues.  There are three main steps to making the modules: (1) neutralizing the collagen and embedding cells in it, (2) gelling the collagen in the tube and cutting the modules and (3) coating the modules with endothelial cells.

Creation of micro-tissues using cylindrical collagen gels, called modules, that contain embedded cells and which surface is coated with endothelial cells.

This protocol describes the fabrication of a type of micro-tissues called modules.  The module approach generates uniform, scalable and vascularized ...

Alginate Hydrogels for Three-Dimensional Organ Culture of Ovaries and Oviducts

Ovarian cancer is the fifth leading cause of cancer deaths in women and has a 63% mortality rate in the United States1. The cell type of origin for ovarian cancers is still in question and might be either the ovarian surface epithelium (OSE) or the distal epithelium of the fallopian tube fimbriae2,3. Culturing the normal cells as a primary culture in vitro will enable scientists to model specific changes that might lead to ovarian cancer in the distinct epithelium, thereby definitively determining the cell type of origin. This will allow development of more accurate biomarkers, animal models with tissue-specific gene changes, and better prevention strategies targeted to this disease.
Maintaining normal cells in alginate hydrogels promotes short term in vitro culture of cells in their three-dimensional context and permits introduction of plasmid DNA, siRNA, and small molecules. By culturing organs in pieces that are derived from strategic cuts using a scalpel, several cultures from a single organ can be generated, increasing the number of experiments from a single animal. These cuts model aspects of ovulation leading to proliferation of the OSE, which is associated with ovarian cancer formation. Cell types such as the OSE that do not grow well on plastic surfaces can be cultured using this method and facilitate investigation into normal cellular processes or the earliest events in cancer formation4.
Alginate hydrogels can be used to support the growth of many types of tissues5. Alginate is a linear polysaccharide composed of repeating units of &beta;-D-mannuronic acid and &alpha;-L-guluronic acid that can be crosslinked with calcium ions, resulting in a gentle gelling action that does not damage tissues6,7. Like other three-dimensional cell culture matrices such as Matrigel, alginate provides mechanical support for tissues; however, proteins are not reactive with the alginate matrix, and therefore alginate functions as a synthetic extracellular matrix that does not initiate cell signaling5. The alginate hydrogel floats in standard cell culture medium and supports the architecture of the tissue growth in vitro.
A method is presented for the preparation, separation, and embedding of ovarian and oviductal organ pieces into alginate hydrogels, which can be maintained in culture for up to two weeks. The enzymatic release of cells for analysis of proteins and RNA samples from the organ culture is also described. Finally, the growth of primary cell types is possible without genetic immortalization from mice and permits investigators to use knockout and transgenic mice.

Culture of normal cells in their three-dimensional context represents an alternative method to study early events required for cellular transformation and tumorigenesis. This method is used to grow normal ovarian and oviductal cells to study early events in ovarian cancer formation.

Ovarian cancer is the fifth leading cause of cancer deaths in women and has a 63% mortality rate in the United States1. The cell type of origin for ...

Use of Human Perivascular Stem Cells for Bone Regeneration

Human perivascular stem cells (PSCs) can be isolated in sufficient numbers from multiple tissues for purposes of skeletal tissue engineering1-3. PSCs are a FACS-sorted population of 'pericytes' (CD146+CD34-CD45-) and 'adventitial cells' (CD146-CD34+CD45-), each of which we have previously reported to have properties of mesenchymal stem cells. PSCs, like MSCs, are able to undergo osteogenic differentiation, as well as secrete pro-osteogenic cytokines1,2. In the present protocol, we demonstrate the osteogenicity of PSCs in several animal models including a muscle pouch implantation in SCID (severe combined immunodeficient) mice, a SCID mouse calvarial defect and a femoral segmental defect (FSD) in athymic rats. The thigh muscle pouch model is used to assess ectopic bone formation. Calvarial defects are centered on the parietal bone and are standardly 4 mm in diameter (critically sized)8. FSDs are bicortical and are stabilized with a polyethylene bar and K-wires4. The FSD described is also a critical size defect, which does not significantly heal on its own4. In contrast, if stem cells or growth factors are added to the defect site, significant bone regeneration can be appreciated. The overall goal of PSC xenografting is to demonstrate the osteogenic capability of this cell type in both ectopic and orthotopic bone regeneration models.

Human perivascular stem cells (PSCs) are a novel stem cell class for skeletal tissue regeneration similar to mesenchymal stem cells (MSCs). PSCs can be isolated by FACS (fluorescence activated cell sorting) from adipose tissue procured during standard liposuction procedures, then combined with an osteoinductive scaffold to achieve bone formation in vivo.

Human perivascular stem cells (PSCs) can be isolated in sufficient numbers from multiple tissues for purposes of skeletal tissue engineering1-3. PSCs are ...

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.

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.

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

Fabrication of Mechanically Tunable and Bioactive Metal Scaffolds for Biomedical Applications

Biometal systems have been widely used for biomedical applications, in particular, as load-bearing materials. However, major challenges are high stiffness and low bioactivity of metals. In this study, we have developed a new method towards fabricating a new type of bioactive and mechanically reliable porous metal scaffolds-densified porous Ti scaffolds. The method consists of two fabrication processes, 1) the fabrication of porous Ti scaffolds by dynamic freeze casting, and 2) coating and densification of the porous scaffolds. The dynamic freeze casting method to fabricate porous Ti scaffolds allowed the densification of porous scaffolds by minimizing the chemical contamination and structural defects. The densification process is distinctive for three reasons. First, the densification process is simple, because it requires a control of only one parameter (degree of densification). Second, it is effective, as it achieves mechanical enhancement and sustainable release of biomolecules from porous scaffolds. Third, it has broad applications, as it is also applicable to the fabrication of functionally graded porous scaffolds by spatially varied strain during densification.

Bioactive and mechanically reliable metal scaffolds have been fabricated through a method which consists of two processes, dynamic freeze casting for the fabrication of porous Ti, and coating and densification of the Ti scaffolds. The densification process is simple, effective and applicable to the fabrication of functionally graded scaffolds.

Biometal systems have been widely used for biomedical applications, in particular, as load-bearing materials. However, major challenges are high stiffness ...

Generation of ESC-derived Mouse Airway Epithelial Cells Using Decellularized Lung Scaffolds

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and cell-matrix interactions. Due to this complexity, recapitulation of lung development in vitro to promote differentiation of stem cells to lung epithelial cells has been challenging. In this protocol, decellularized lung scaffolds are used to mimic the 3-dimensional environment of the lung and generate stem cell-derived airway epithelial cells. Mouse embryonic stem cell are first differentiated to the endoderm lineage using an embryoid body (EB) culture method with activin A. Endoderm cells are then seeded onto decellularized scaffolds and cultured at air-liquid interface for up to 21 days. This technique promotes differentiation of seeded cells to functional airway epithelial cells (ciliated cells, club cells, and basal cells) without additional growth factor supplementation. This culture setup is defined, serum-free, inexpensive, and reproducible. Although there is limited contamination from non-lung endoderm lineages in culture, this protocol only generates airway epithelial populations and does not give rise to alveolar epithelial cells. Airway epithelia generated with this protocol can be used to study cell-matrix interactions during lung organogenesis and for disease modeling or drug-discovery platforms of airway-related pathologies such as cystic fibrosis.

This protocol efficiently directs mouse embryonic stem cell-derived definitive endoderm to mature airway epithelial cells. This differentiation technique uses 3-dimensional decellularized lung scaffolds to direct lung lineage specification, in a defined, serum-free culture setting.

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and ...

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An easy-to-use and low-cost sensor platform is highly desired to measure various types of analytes (e.g., biomarkers, hormones, and drugs) quantitatively and specifically. For this reason, dry film photoresist technology - enabling cheap, facile, and high-throughput fabrication - was used to manufacture the microfluidic biosensor presented here. Depending on the bioassay used afterwards, the versatile platform is capable of detecting various types of biomolecules. For the fabrication of the device, platinum electrodes are structured on a flexible polyimide (PI) foil in the only clean-room process step. The PI foil serves as a substrate for the electrodes, which are insulated with an epoxy-based photoresist. The microfluidic channel is subsequently generated by the development and lamination of dry film photoresist (DFR) foils onto the PI wafer. By using a hydrophobic stopping barrier in the channel, the channel is separated into two specific areas: an immobilization section for the enzyme-linked assay and an electrochemical measurement cell for the amperometric signal readout.
The on-chip bioassay immobilization is performed by the adsorption of the biomolecules to the channel surface. The glucose oxidase enzyme is used as a transducer for electrochemical signal generation. In the presence of the substrate, glucose, hydrogen peroxide is produced, which is detected at the platinum working electrode. The stop-flow technique is applied to obtain signal amplification along with rapid detection. Different biomolecules can quantitatively be measured by means of the introduced microfluidic system, giving an indication of different types of diseases, or, in regard to therapeutic drug monitoring, facilitating a personalized therapy.

A microfluidic biosensor platform was designed and fabricated using low-cost dry film photoresist technology for the rapid and sensitive quantification of various analytes. This single-use system allows for the electrochemical readout of on-chip-immobilized enzyme-linked assays by means of the stop-flow technique.

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Fabrication and Characterization of Griffithsin-modified Fiber Scaffolds for Prevention of Sexually Transmitted Infections

Electrospun fibers (EFs) have been widely used in a variety of therapeutic applications; however, they have only recently been applied as a technology to prevent and treat sexually transmitted infections (STIs). Moreover, many EF technologies focus on encapsulating the active agent, relative to utilizing the surface to impart biofunctionality. Here we describe a method to fabricate and surface-modify poly(lactic-co-glycolic) acid (PLGA) electrospun fibers, with the potent antiviral lectin Griffithsin (GRFT). PLGA is an FDA-approved polymer that has been widely used in drug delivery due to its outstanding chemical and biocompatible properties. GRFT is a natural, potent, and safe lectin that possesses broad activity against numerous viruses including human immunodeficiency virus type 1 (HIV-1). When combined, GRFT-modified fibers have demonstrated potent inactivation of HIV-1 in vitro. This manuscript describes the methods to fabricate and characterize GRFT-modified EFs. First, PLGA is electrospun to create a fiber scaffold. Fibers are subsequently surface-modified with GRFT using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS)chemistry. Scanning electron microscopy (SEM) was used to assess the size and morphology of surface-modified formulations. Additionally, a gp120 or hemagglutinin (HA)-based ELISA may be used to quantify the amount of GRFT conjugated to, as well as GRFT desorption from the fiber surface. This protocol can be more widely applied to fabricate fibers that are surface-modified with a variety of different proteins.

This manuscript describes the procedure to fabricate and characterize Griffithsin-modified poly(lactic-co-glycolic acid) electrospun fibers that demonstrate potent adhesive and antiviral activity against human immunodeficiency virus type 1 infection in vitro. Methods used to synthesize, surface-modify, and characterize the resulting morphology, conjugation, and desorption of Griffithsin from surface-modified fibers are described.

Electrospun fibers (EFs) have been widely used in a variety of therapeutic applications; however, they have only recently been applied as a technology to ...

Use of High-Throughput Automated Microbioreactor System for Production of Model IgG1 in CHO Cells

Automated microscale bioreactors (15 mL) can be a useful tool for cell culture engineers. They facilitate the simultaneous execution of a wide variety of experimental conditions while minimizing potential process variability. Applications of this approach include: clone screening, temperature and pH shifts,&#160;media and supplement optimization. Furthermore, the small reactor volumes are conducive to large Design of Experiments that investigate a wide range of conditions. This allows upstream processes to be significantly optimized before scale-up where experimentation is more limited in scope due to time and economic constraints. Automated microscale bioreactor systems offer various advantages over traditional small scale cell culture units, such as shake flasks or spinner flasks. However, during pilot scale process development&#160;significant care must be taken to ensure that these advantages are realized. When run with care, the system can enable high level automation, can be programmed to run DOE&#39;s with a higher number of variables&#160;and can reduce sampling time when integrated with a nutrient analyzer or cell counter. Integration of the expert-derived heuristics presented here, with current automated microscale bioreactor experiments can minimize common pitfalls that hinder meaningful results. In the extreme, failure to adhere to the principles laid out here can lead to equipment damage that requires expensive repairs. Furthermore, the microbioreactor systems have small culture volumes&#160;making characterization of cell culture conditions difficult. The number and amount of samples taken in-process in batch mode culture is limited as operating volumes cannot fall below 10 mL. This method will discuss the benefits and drawbacks of microscale bioreactor systems.

A detailed protocol for the concurrent operation of 48 parallel cell cultures under varied conditions in a microbioreactor system is presented. Cell culture process, harvest and subsequent antibody titer analysis are described.

Automated microscale bioreactors (15 mL) can be a useful tool for cell culture engineers. They facilitate the simultaneous execution of a wide variety of ...