Name: fabrication and use of dry macroporous alginate scaffolds for viral transduction of t cells
Uploaded: 2022-09-09T13:00:00
Description: Watch this Scientific Journal Video about Fabrication and Use of Dry Macroporous Alginate Scaffolds for Viral Transduction of T Cells at JoVE.com

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 w...

<ol>
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A., Rahbarizadeh, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinoculation+and+retronectin+highly+enhance+the+gene+transduction+efficiency+of+Mucin-1-specific+chimeric+antigen+receptor+(CAR)+in+human+primary+T+cells.">Spinoculation and retronectin highly enhance the gene transduction efficiency of Mucin-1-specific chimeric antigen receptor (CAR) in human primary T cells.</a> BMC Molecular and Cell Biology. 22 (1), 57 (2021).</li><li>Sun, J., Tan, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alginate-based+biomaterials+for+regenerative+medicine+applications.">Alginate-based biomaterials for regenerative medicine applications.</a> Materials. 6 (4), 1285-1309 (2013).</li><li>Nayak, A. K., Mohanta, B. C., Hasnain, M. S., Hoda, M. N., Tripathi, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+14+-+Alginate-based+scaffolds+for+drug+delivery+in+tissue+engineering.">Chapter 14 - Alginate-based scaffolds for drug delivery in tissue engineering.</a> Alginates in Drug Delivery. , 359-386 (2020).</li><li>Lee, K. Y., Mooney, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alginate:+properties+and+biomedical+applications.">Alginate: properties and biomedical applications.</a> Progress in Polymer Science. 37 (1), 106-126 (2012).</li><li>Kuo, C. K., Ma, P. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ionically+crosslinked+alginate+hydrogels+as+scaffolds+for+tissue+engineering:+part+1.+Structure,+gelation+rate+and+mechanical+properties.">Ionically crosslinked alginate hydrogels as scaffolds for tissue engineering: part 1. Structure, gelation rate and mechanical properties.</a> Biomaterials. 22 (6), 511-521 (2001).</li><li>Soccol, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probiotic+nondairy+beverages.">Probiotic nondairy beverages.</a> Handbook of Plant-Based Fermented Food and Beverage Technology, Second Edition. , 707-728 (2012).</li><li>Moody, C. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Restoring+carboxylates+on+highly+modified+alginates+improves+gelation,+tissue+retention+and+systemic+capture.">Restoring carboxylates on highly modified alginates improves gelation, tissue retention and systemic capture.</a> Acta Biomaterialia. 138, 208-217 (2022).</li><li>Brudno, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Replenishable+drug+depot+to+combat+post-resection+cancer+recurrence.">Replenishable drug depot to combat post-resection cancer recurrence.</a> Biomaterials. 178, 373-382 (2018).</li><li>Moody, C. T., Palvai, S., Brudno, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Click+cross-linking+improves+retention+and+targeting+of+refillable+alginate+depots.">Click cross-linking improves retention and targeting of refillable alginate depots.</a> Acta Biomaterialia. 112, 112-121 (2020).</li><li>Agarwalla, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scaffold-mediated+static+transduction+of+T+Cells+for+CAR-T+Cell+therapy.">Scaffold-mediated static transduction of T Cells for CAR-T Cell therapy.</a> Advanced Healthcare Materials. 9 (14), 2000275 (2020).</li><li>Agarwalla, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioinstructive+implantable+scaffolds+for+rapid+in+vivo+manufacture+and+release+of+CAR-T+cells.">Bioinstructive implantable scaffolds for rapid in vivo manufacture and release of CAR-T cells.</a> Nature Biotechnology. 40 (8), 1250-1258 (2022).</li><li>Vera, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T+lymphocytes+redirected+against+the+kappa+light+chain+of+human+immunoglobulin+efficiently+kill+mature+B+lymphocyte-derived+malignant+cells.">T lymphocytes redirected against the kappa light chain of human immunoglobulin efficiently kill mature B lymphocyte-derived malignant cells.</a> Blood. 108 (12), 3890-3897 (2006).</li><li>. PRONOVA UP MVG. IFF Nutrition Norge AS Available from: <a target="_blank" href="https://novamatrix.biz/store/pronova-up-mvg/">https://novamatrix.biz/store/pronova-up-mvg/</a> (2022)</li><li>Zappasodi, R., Budhu, S., Abu-Akeel, M., Merghoub, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+assays+for+effector+T+cell+functions+and+activity+of+immunomodulatory+antibodies.">In vitro assays for effector T cell functions and activity of immunomodulatory antibodies.</a> Methods in Enzymology. 631, 43-59 (2020).</li><li>Kong, B. S., Lee, C., Cho, Y. 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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://www.jove.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 ...

Watch this Scientific Journal Video about Fabrication and Use of Dry Macroporous Alginate Scaffolds for Viral Transduction of T Cells at JoVE.com

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 ...

Described in this video is a protocol for creating and using dry macroporous alginate scaffolds known as Drydux that efficiently promote transduction of activated T-cells. Drydux is designed to be used in place of gold standard spinoculation of RetroNectin-coated plates seeded with virus and simplifies the process for transducing cells. Drydux has a transduction efficiency comparable to spinoculation on RetroNectin-coated plates, and serves as a cheaper and more convenient alternative to the conventional transduction method.First, prepare a 0.4%solution of calcium-D-gluconate. Add sterile filtered DI water to calcium-D-gluconate in a beaker. Stir on medium speed until the calcium-D-gluconate has dissolved, which takes approximately 1 1/2 hours.Once dissolved, sterile filter the calcium-D-gluconate solution. This solution can be stored at room temperature. Next, prepare a 2%alginate solution.This can be accomplished using a screw cap vial, or a beaker. Both will be shown here. Carefully add the ultrapure alginate to the vessel.Add the appropriate amount of DI water to the alginate. Choose the largest stir bar possible that will not impede mixing and add it to the vessel. Stir the solution on high until the alginate dissolves, which takes approximately one hour.If there are any large alginate clumps on the side of the vessel, tilt the vessel sideways to dislodge them. Small clumps will dissolve over the hour, and are not cause for concern. Once the 2%alginate solution dissolves, reduce the stirring speed.Slowly add an equal volume of the calcium-D-gluconate solution to the alginate solution. Adding it slowly will help prevent cross-linking clumps from forming. When the calcium-gluconate solution has been added, increase the stirring speed, and stir vigorously for 15 minutes.Tilt the vessel sideways to remove any clumps that may have formed. After stirring vigorously for 15 minutes, ensure there are no clumps in the solution. Pipette the solution into a 48, or 24-well plate.For a 48-well plate, pipette 300 microliters into each well. Ensure to cast slowly and change tips often, as the solution will be viscous, and may stick to the tip. For a 24-well plate, pipette one milliliter into each well.Again, cast slowly, and change pipette tips often. Cover the well plates with a lid, and freeze at negative 20 degrees Celsius overnight. Prepare the plates for the lyophilizer by removing the lids and securing the top with wipes and rubber bands.Place the plates in the lyophilizer tube, and put on the lyophilizer for 72 hours. After 72 hours, remove the plate from the lyophilizer. The scaffolds are now ready to be used for transduction.If not using the scaffolds immediately, seal the plate with Parafilm and store at four degrees Celsius until needed. For long-term storage, it is recommended to vacuum seal the plate in addition to sealing with Parafilm. Concentrate viral supernatant by centrifuging two milliliters of viral solution through a centrifugal filter at 1, 500 g for 10 minutes.100 to 200 microliters of concentrated virus is needed per scaffold. Spin for a few additional minutes if the concentrated virus solution volume is greater than 200 microliters. For each scaffold, make an aliquot of 1 million activated T-cells suspended in 50 microliters of complete cell culture media.Add the concentrated virus to the cell suspension. The total volume of the cell virus suspension should not exceed 200 microliters for a 48-well scaffold, or 350 microliters for a 24-well scaffolded. Add the cell virus mixture drop-wise to the top of the dry scaffold.For negative control experiments, use complete cell culture media in place of concentrated virus. Add this cell suspension to the top of the dry scaffold. Incubate the scaffolds in the cell culture incubator at 37 degrees Celsius for 45 to 60 minutes.Remove the scaffolds from the incubator. The scaffolds should fully absorb the solution during this time. To induce proliferation, add complete cell culture media supplemented with IL-7 and IL-15 to each well.IL-2 can also be used. For a 24-well scaffold, add one milliliter. For a 48-well scaffold, add 500 microliters.Incubate at 37 degrees Celsius for 72 hours. The cells will proliferate over the 72 hours, which may turn the media orange. Remove excess media from each well.To isolate cells from the scaffold, add 0.25 molar EDTA solution to each scaffold. Add one milliliter for 24-well scaffolds, or 300 microliters for 48-well scaffolds. Let the plate sit, or gently agitate for three to four minutes.Once 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. Transfer the solution to a 15-milliliter centrifuge tube.Wash the cells twice with PBS. Add 12 milliliters of PBS to each centrifuge tube. Centrifuge at 400 g for five minutes.A cell pellet will form at the bottom of the tube. Aspirate the supernatant solution, and repeat the wash. Be careful to fully remove supernatant with every wash as it is crucial to get rid of all EDTA.After washing with PBS a second time, the cell pellet is ready for analysis. Flow cytometry was used to determine the transduction efficiency of each group. Non-transduced cells were used as a negative control, and showed no transduction.Cells seeded on scaffolds without GFP retrovirus also showed no transduction. The Drydux group, which had activated cells seeded onto the dry macroporous alginate scaffolds, showed 85%transduction, just lower than the RetroNectin group. These results demonstrate that Drydux scaffolds effectively transduced cells by retroviral gene transfer without the need for spinoculation of RetroNectin-coated plates.Drydux scaffolds exhibit high transduction efficiency comparable to RetroNectin, providing an alternative method for transducing T-cells. Due to the low cost of manufacturing the Drydux scaffolds, this process has the potential to significantly lower the cost of CAR T-cell therapies.

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Bioengineering

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 ...

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 ...

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 ...

Fabrication of Decellularized Cartilage-derived Matrix Scaffolds

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage research has focused on the development of regenerative scaffolds. This article describes the development of scaffolds that are completely derived from natural cartilage extracellular matrix, coming from an equine donor. Potential applications of the scaffolds include producing allografts for cartilage repair, serving as a scaffold for osteochondral tissue engineering, and providing in vitro models to study tissue formation. By decellularizing the tissue, the donor cells are removed, but many of the natural bioactive cues are thought to be retained. The main advantage of using such a natural scaffold in comparison to a synthetically produced scaffold is that no further functionalization of polymers is required to drive osteochondral tissue regeneration. The cartilage-derived matrix scaffolds can be used for bone and cartilage tissue regeneration in both in vivo and in vitro settings.

Decellularized cartilage-derived scaffolds can be used as a scaffold to guide cartilage repair and as a means to regenerate osteochondral tissue. This paper describes the decellularization process in detail and provides suggestions to use these scaffolds in in vitro settings.

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage ...

Transduction and Expansion of Primary T Cells in Nine Days with Maintenance of Central Memory Phenotype

Emerging immunotherapies to treat infectious diseases and cancers often involve transduction of cellular populations with genes encoding disease-targeting proteins. For example, chimeric antigen receptor (CAR)-T cells to treat cancers and viral infections involve the transduction of T cells with synthetic genes encoding CAR molecules. The CAR molecules make the T cells specifically recognize and kill cancer or virally infected cells. Cells can also be co-transduced with other genes of interest. For example, cells can be co-transduced with genes encoding proteins that target cells to specific locations. Here, we present a protocol to transduce primary peripheral blood mononuclear cells (PBMCs) with genes encoding a virus-specific CAR and the B cell follicle homing molecule chemokine receptor type 5 (CXCR5). This procedure takes nine days and results in transduced T cell populations that maintain a central memory phenotype. Maintenance of a central memory or less differentiated phenotype has been shown to associate with persistence of cells post-infusion. Furthermore, cells produced with this method show high levels of viability, high levels of co-expression of the two transduced genes, and large enough quantities of cells for immunotherapeutic infusion. This nine-day protocol may be broadly used for CAR-T cell and other T cell immunotherapy approaches. The methods described here are based on studies presented in our previous publications.

We outline a 9-day protocol for the transduction and expansion of rhesus macaque peripheral blood mononuclear cells which yields cells with excellent co-expression of the genes of interest in sufficient number for infusion studies of cell efficacy.

Emerging immunotherapies to treat infectious diseases and cancers often involve transduction of cellular populations with genes encoding disease-targeting ...

Interlinked Macroporous 3D Scaffolds from Microgel Rods

A two-component system of functionalized microgels from microfluidics allows for fast interlinking into 3D macroporous constructs in aqueous solutions without further additives. Continuous photoinitiated on-chip gelation enables variation of the microgel aspect ratio, which determines the building block properties for the obtained constructs. Glycidyl methacrylate (GMA) or 2-aminoethyl methacrylate (AMA) monomers are copolymerized into the microgel network based on polyethylene glycol (PEG) star-polymers to achieve either epoxy or amine functionality. A focusing oil flow is introduced into the microfluidic outlet structure to ensure continuous collection of the functionalized microgel rods. Based on a recent publication, microgel rod-based constructs result in larger pores of several hundred micrometers and, at the same time, lead to overall higher scaffold stability in comparison to a spherical-based model. In this way, it is possible to produce higher-volume constructs with more free volume while reducing the amount of material required. The interlinked macroporous scaffolds can be picked up and transported without damage or disintegration. Amine and epoxy groups not involved in interlinking remain active and can be used independently for post-modification. This protocol describes an optimized method for the fabrication of microgel rods to form macroporous interlinked scaffolds that can be utilized for subsequent cell experiments.

Microgel rods with complementary reactive groups are produced via microfluidics with the ability to interlink in aqueous solution. The anisometric microgels jam and interlink into stable constructs with larger pores compared to spherical-based systems. Microgels modified with GRGDS-PC form macroporous 3D constructs that can be used for cell culture.

A two-component system of functionalized microgels from microfluidics allows for fast interlinking into 3D macroporous constructs in aqueous solutions ...

Gelatin Methacryloyl Granular Hydrogel Scaffolds: High-throughput Microgel Fabrication, Lyophilization, Chemical Assembly, and 3D Bioprinting

The emergence of granular hydrogel scaffolds (GHS), fabricated via assembling hydrogel microparticles (HMPs), has enabled microporous scaffold formation in situ. Unlike conventional bulk hydrogels, interconnected microscale pores in GHS facilitate degradation-independent cell infiltration as well as oxygen, nutrient, and cellular byproduct transfer. Methacryloyl-modified gelatin (GelMA), a (photo)chemically crosslinkable, protein-based biopolymer containing cell adhesive and biodegradable moieties, has widely been used as a cell-responsive/instructive biomaterial. Converting bulk GelMA to GHS&#160;may open a plethora of opportunities for tissue engineering and regeneration. In this article, we demonstrate the procedures of high-throughput GelMA microgel fabrication, conversion to resuspendable dry microgels (micro-aerogels), GHS formation via the chemical assembly of microgels, and granular bioink fabrication for extrusion bioprinting. We show how a sequential physicochemical treatment via cooling and photocrosslinking enables the formation of mechanically robust GHS.&#160;When light is inaccessible (e.g., during deep tissue injection), individually crosslinked GelMA HMPs may be bioorthogonally assembled via enzymatic crosslinking using transglutaminases. Finally, three-dimensional (3D) bioprinting of microporous GHS&#160;at low HMP packing density is demonstrated via the interfacial self-assembly of heterogeneously charged nanoparticles.

This article describes protocols for high-throughput gelatin methacryloyl microgel fabrication using microfluidic devices, converting microgels to resuspendable powder (micro-aerogels), the chemical assembly of microgels to form granular hydrogel scaffolds, and developing granular hydrogel bioinks with preserved microporosity for 3D bioprinting.

The emergence of granular hydrogel scaffolds (GHS), fabricated via assembling hydrogel microparticles (HMPs), has enabled microporous scaffold formation ...