Name: bioprintable alginate/gelatin hydrogel 3d in vitro model systems induce cell spheroid formation
Uploaded: 2018-07-02T14:30:00
Description: Watch this Scientific Journal Video about Bioprintable Alginate/Gelatin Hydrogel 3D In Vitro Model Systems Induce Cell Spheroid Formation at JoVE.com

Tao Jiang thanks the China Scholarship Council (201403170354) and McGill Engineering Doctoral Award (90025) for their scholarship funding. Jose G. Munguia-Lopez thanks CONACYT (250279, 290936 and 291168) and FRQNT (258421) for their scholarship funding. Salvador Flores-Torres thanks CONACYT for their scholarship funding (751540). Joseph M. Kinsella thanks the National Science and Engineering Research Council, the Canadian Foundation for Innovation, the Townshend-Lamarre Family Foundation, and McGill University for their funding. We would like to thank Allen Ehrlicher for allowing us to use his rheometer, Dan Nicolau for allowing us to use his confocal microscope, and Morag Park for granting us access to fluorescently labeled cell lines.

1. Preparation of the Materials, Hydrogel, and Cell Culture Materials
<ol>
	<li>Material and solution preparation
	<ol>
		<li>Wash and dry 250 mL and 100 mL glass beakers, magnetic stirrers, spatulas, 10 mL cartridges, 25 G cylindrical nozzles (with a length of 0.5 in and an inner diameter of 250 &#181;m). Sterilize the materials by autoclaving them at 121 &#176;C/15 min/1 atm. Keep the materials under sterile conditions until use. 
		Note: Refer to the Table of Materials for vend...

<ol>
	<li>Cui, X., Hartanto, Y., Zhang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+multicellular+spheroids+formation.">Advances in multicellular spheroids formation.</a> Journal of the Royal Society Interface. 14 (127), (2017).</li><li>Yip, D., Cho, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multicellular+3D+heterospheroid+model+of+liver+tumor+and+stromal+cells+in+collagen+gel+for+anti-cancer+drug+testing.">A multicellular 3D heterospheroid model of liver tumor and stromal cells in collagen gel for anti-cancer drug testing.</a> Biochemical and Biophysical Research Communications. 433 (3), 327-332 (2013).</li><li>Breslin, S., O'Driscoll, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relevance+of+using+3D+cell+cultures,+in+addition+to+2D+monolayer+cultures,+when+evaluating+breast+cancer+drug+sensitivity+and+resistance.">The relevance of using 3D cell cultures, in addition to 2D monolayer cultures, when evaluating breast cancer drug sensitivity and resistance.</a> Oncotarget. 7 (29), 45745-45756 (2016).</li><li>Yue, X., Lukowski, J. K., Weaver, E. M., Skube, S. B., Hummon, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+proteomic+and+phosphoproteomic+comparison+of+2D+and+3D+colon+cancer+cell+culture+models.">Quantitative proteomic and phosphoproteomic comparison of 2D and 3D colon cancer cell culture models.</a> Journal of Proteome Research. 15 (12), 4265-4276 (2016).</li><li>Priwitaningrum, D. L., 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=Tumor+stroma-containing+3D+spheroid+arrays:+a+tool+to+study+nanoparticle+penetration.">Tumor stroma-containing 3D spheroid arrays: a tool to study nanoparticle penetration.</a> Journal of Controlled Release. 244 (Pt B), 257-268 (2016).</li><li>Hong, S., 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=Cellular+behavior+in+micropatterned+hydrogels+by+bioprinting+system+depended+on+the+cell+types+and+cellular+interaction.">Cellular behavior in micropatterned hydrogels by bioprinting system depended on the cell types and cellular interaction.</a> Journal of Bioscience and Bioengineering. 116 (2), 224-230 (2013).</li><li>Dolati, F., 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=In+vitro+evaluation+of+carbon-nanotube-reinforced+bioprintable+vascular+conduits.">In vitro evaluation of carbon-nanotube-reinforced bioprintable vascular conduits.</a> Nanotechnology. 25 (14), 145101 (2014).</li><li>Murphy, S. V., Atala, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+bioprinting+of+tissues+and+organs.">3D bioprinting of tissues and organs.</a> Nature Biotechnology. 32 (8), 773-785 (2014).</li><li>Kang, H. W., 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=A+3D+bioprinting+system+to+produce+human-scale+tissue+constructs+with+structural+integrity.">A 3D bioprinting system to produce human-scale tissue constructs with structural integrity.</a> Nature Biotechnology. 34 (3), 312-319 (2016).</li><li>Miller, J. S., 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=Rapid+casting+of+patterned+vascular+networks+for+perfusable+engineered+three-dimensional+tissues.">Rapid casting of patterned vascular networks for perfusable engineered three-dimensional tissues.</a> Nature Materials. 11 (9), 768-774 (2012).</li><li>Jia, W., 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=Direct+3D+bioprinting+of+perfusable+vascular+constructs+using+a+blend+bioink.">Direct 3D bioprinting of perfusable vascular constructs using a blend bioink.</a> Biomaterials. 106, 58-68 (2016).</li><li>Kolesky, D. B., Homan, K. A., Skylar-Scott, M. A., Lewis, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+bioprinting+of+thick+vascularized+tissues.">Three-dimensional bioprinting of thick vascularized tissues.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (12), 3179-3184 (2016).</li><li>Lee, V., 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=Design+and+fabrication+of+human+skin+by+three-dimensional+bioprinting.">Design and fabrication of human skin by three-dimensional bioprinting.</a> Tissue Engineering Part C: Methods. 20 (6), 473-484 (2014).</li><li>Jiang, 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=Directing+the+self-assembly+of+tumour+spheroids+by+bioprinting+cellular+heterogeneous+models+within+alginate/gelatin+hydrogels.">Directing the self-assembly of tumour spheroids by bioprinting cellular heterogeneous models within alginate/gelatin hydrogels.</a> Scientific Reports. 7 (1), 4575 (2017).</li><li>Knowlton, S., Onal, S., Yu, C. H., Zhao, J. J., Tasoglu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioprinting+for+cancer+research.">Bioprinting for cancer research.</a> Trends in Biotechnology. 33 (9), 504-513 (2015).</li><li>Derby, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Printing+and+prototyping+of+tissues+and+scaffolds.">Printing and prototyping of tissues and scaffolds.</a> Science. 338 (6109), 921-926 (2012).</li><li>Nair, K., 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=Characterization+of+cell+viability+during+bioprinting+processes.">Characterization of cell viability during bioprinting processes.</a> Biotechnology Journal. 4 (8), 1168-1177 (2009).</li><li>Costa, E. 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=3D+tumor+spheroids:+an+overview+on+the+tools+and+techniques+used+for+their+analysis.">3D tumor spheroids: an overview on the tools and techniques used for their analysis.</a> Biotechnology Advances. 34 (8), 1427-1441 (2016).</li><li>Zhao, 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=Three-dimensional+printing+of+Hela+cells+for+cervical+tumor+model+in+vitro.">Three-dimensional printing of Hela cells for cervical tumor model in vitro.</a> Biofabrication. 6 (3), 035001 (2014).</li><li>Ling, K., 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=Bioprinting-based+high-throughput+fabrication+of+three-dimensional+MCF-7+human+breast+cancer+cellular+spheroids.">Bioprinting-based high-throughput fabrication of three-dimensional MCF-7 human breast cancer cellular spheroids.</a> Engineering. 1 (2), 269-274 (2015).</li><li>Liang, 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=A+cell-instructive+hydrogel+to+regulate+malignancy+of+3D+tumor+spheroids+with+matrix+rigidity.">A cell-instructive hydrogel to regulate malignancy of 3D tumor spheroids with matrix rigidity.</a> Biomaterials. 32 (35), 9308-9315 (2011).</li><li>Szot, C. S., Buchanan, C. F., Freeman, J. W., Rylander, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+in+vitro+bioengineered+tumors+based+on+collagen+I+hydrogels.">3D in vitro bioengineered tumors based on collagen I hydrogels.</a> Biomaterials. 32 (31), 7905-7912 (2011).</li><li>Carey, S. P., Kraning-Rush, C. M., Williams, R. M., Reinhart-King, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biophysical+control+of+invasive+tumor+cell+behavior+by+extracellular+matrix+microarchitecture.">Biophysical control of invasive tumor cell behavior by extracellular matrix microarchitecture.</a> Biomaterials. 33 (16), 4157-4165 (2012).</li><li>Hospodiuk, M., Dey, M., Sosnoski, D., Ozbolat, I. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+bioink:+a+comprehensive+review+on+bioprintable+materials.">The bioink: a comprehensive review on bioprintable materials.</a> Biotechnology Advances. 35 (2), 217-239 (2017).</li><li>Caliari, S. R., Burdick, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+practical+guide+to+hydrogels+for+cell+culture.">A practical guide to hydrogels for cell culture.</a> Nature Methods. 13 (5), 405-414 (2016).</li><li>Bhutani, U., Laha, A., Mitra, K., Majumdar, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sodium+alginate+and+gelatin+hydrogels:+viscosity+effect+on+hydrophobic+drug+release.">Sodium alginate and gelatin hydrogels: viscosity effect on hydrophobic drug release.</a> Materials Letters. 164, 76-79 (2016).</li><li>Biswal, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+mechanical+and+electrical+behavior+of+gelatin+hydrogels+on+drug+release+and+cell+proliferation.">Effect of mechanical and electrical behavior of gelatin hydrogels on drug release and cell proliferation.</a> Journal of the Mechanical Behavior of Biomedical Materials. 53, 174-186 (2016).</li><li>Rowley, J. A., Madlambayan, G., 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+hydrogels+as+synthetic+extracellular+matrix+materials.">Alginate hydrogels as synthetic extracellular matrix materials.</a> Biomaterials. 20 (1), 45-53 (1999).</li><li>Djabourov, M., Leblond, J., Papon, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gelation+of+aqueous+gelatin+solutions.+I.+Structural+investigation.">Gelation of aqueous gelatin solutions. I. Structural investigation.</a> Journal de Physique (France). 49 (2), 319-332 (1988).</li><li>Djabourov, M., Leblond, J., Papon, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gelation+of+aqueous+gelatin+solutions.+II.+Rheology+of+the+sol-gel+transition.">Gelation of aqueous gelatin solutions. II. Rheology of the sol-gel transition.</a> Journal de Physique (France). 49 (2), 333-343 (1988).</li><li>Coussot, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Rheometry of Pastes, Suspensions, and Granular Materials: Applications in Industry and Environment. , (2005).</li><li>Ouyang, L., Yao, R., Zhao, Y., Sun, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+bioink+properties+on+printability+and+cell+viability+for+3D+bioplotting+of+embryonic+stem+cells.">Effect of bioink properties on printability and cell viability for 3D bioplotting of embryonic stem cells.</a> Biofabrication. 8 (3), 035020 (2016).</li><li>Michon, C., Cuvelier, G., Launay, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concentration+dependence+of+the+critical+viscoelastic+properties+of+gelatin+at+the+gel+point.">Concentration dependence of the critical viscoelastic properties of gelatin at the gel point.</a> Rheologica Acta Rheologica Acta: An International Journal of Rheology. 32 (1), 94-103 (1993).</li><li>Mouser, V. H., 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=Yield+stress+determines+bioprintability+of+hydrogels+based+on+gelatin-methacryloyl+and+gellan+gum+for+cartilage+bioprinting.">Yield stress determines bioprintability of hydrogels based on gelatin-methacryloyl and gellan gum for cartilage bioprinting.</a> Biofabrication. 8 (3), 035003 (2016).</li><li>Benbow, J. J., Oxley, E. W., Bridgwater, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+extrusion+mechanics+of+pastes-the+influence+of+paste+formulation+on+extrusion+parameters.">The extrusion mechanics of pastes-the influence of paste formulation on extrusion parameters.</a> Chemical Engineering Science. 42 (9), 2151-2162 (1987).</li><li>Bingham, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fluidity and plasticity. , (1922).</li><li>Horrobin, D. J., Nedderman, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Die+entry+pressure+drops+in+paste+extrusion.">Die entry pressure drops in paste extrusion.</a> Chemical Engineering Science. 53 (18), 3215-3225 (1998).</li><li>Soman, 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=Cancer+cell+migration+within+3D+layer-by-layer+microfabricated+photocrosslinked+PEG+scaffolds+with+tunable+stiffness.">Cancer cell migration within 3D layer-by-layer microfabricated photocrosslinked PEG scaffolds with tunable stiffness.</a> Biomaterials. 33 (29), 7064-7070 (2012).</li><li>Asghar, W., 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=Engineering+cancer+microenvironments+for+in+vitro+3-D+tumor+models.">Engineering cancer microenvironments for in vitro 3-D tumor models.</a> Materials Today. 18 (10), 539-553 (2015).</li><li>Lin, R. Z., Chang, H. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+three-dimensional+multicellular+spheroid+culture+for+biomedical+research.">Recent advances in three-dimensional multicellular spheroid culture for biomedical research.</a> Biotechnology Journal. 3 (9-10), 1172-1184 (2008).</li><li>Akasov, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+multicellular+tumor+spheroids+induced+by+cyclic+RGD-peptides+and+use+for+anticancer+drug+testing+in+vitro.">Formation of multicellular tumor spheroids induced by cyclic RGD-peptides and use for anticancer drug testing in vitro.</a> International Journal of Pharmaceutics. 506 (1-2), 148-157 (2016).</li></ol>

Cell-laden structures can be compromised if contamination (biological or chemical) occurs at any point in the process. Usually, biological contamination is seen after two or three days of culture as a color change in the culture media or the bioprinted structure. Therefore, the sterilization (physical and chemical disinfection) is a key step for all the cell-related processes. Noteworthy, autoclaving gelatin changes its gelling properties, which made it gel slower in the trials we conducted. Therefore, we sterilized the ...

Although 2D cell culture is widely used in cancer research, limitations exist as the cells are grown in a monolayer format with a uniform concentration of nutrients and oxygen. These cultures lack important cell-cell and cell-matrix interactions present in the native tumor microenvironment (TME). Consequently, these models poorly recapitulate physiological conditions, resulting in aberrant cell behaviors, including unnatural morphologies, irregular receptor organization, membrane polarization, and abnormal gene expression, among other conditions1,2,3,4. On the other hand, 3D cell culture, where cells are expanded in a volumetric space as aggregates, spheroids, or organoids, offers an alternative technique to create more accurate in vitro environments to study fundamental cell biology and physiology. 3D cell culture models can also encourage cell-ECM interactions that are critical physiological characteristics of the native TME in vitro1,4,5. The emerging 3D bioprinting technology provides possibilities to build models that mimic the heterogeneous TME.
3D bioprinting is derived from rapid prototyping and enables the fabrication of 3D microstructures that are capable of mimicking some of the complexities of living tissue samples6,7. The current bioprinting methods include inkjet, extrusion, and laser-assisted printing8. Among them, the extrusion method allows the heterogeneity to be controlled within the printed matrices by precisely positioning distinct types of materials at different initial locations. Therefore, it is the best approach to fabricate heterogeneous in vitro models involving multiple types of cells or matrices. Extrusion bioprinting has been successfully used to build auricular shaped scaffolds9, vascular structures10,11,12, and skin tissues13, resulting in high printing fidelity and cell viability. The technology also features versatile material selections, the ability to deposit materials with cells embedded with a known density, and high reproducibility14,15,16,17. Natural and synthetic hydrogels are frequently used as bioinks for 3D bioprinting due to their biocompatibility, bioactivity, and their hydrophilic networks that can be engineered to structurally resemble the ECM7,18,19,20,21,22,23.Hydrogels are also advantageous since they can include adhesive sites for cells, structural elements, permeability for nutrients and gases, and the appropriate mechanical properties to encourage cell development24. For instance, collagen hydrogels offer integrin anchorage sites that cells can use to attach to the matrix. Gelatin, denatured collagen, retains similar cell adhesion sites. In contrast, alginate is bioinert but provides mechanical integrity by forming crosslinks with divalent ions25,26,27,28.
In this work, we developed a composite hydrogel as a bioink, comprised of alginate and gelatin, with similarities to the microscopic architecture of a native tumor stroma. Breast cancer cells and fibroblasts were embedded in the hydrogels and printed via an extrusion-based bioprinter to create a 3D model that mimics the in vivo microenvironment. The engineered 3D environment allows cancer cells to form multicellular tumor spheroids (MCTS) with a high viability for long periods of cell culture (&#62; 30 days). This protocol demonstrates the methodologies of synthesizing composite hydrogels, characterizing the materials&#39; microstructure and printability, bioprinting cellular heterogeneous models, and observing the formation of MCTS. These methodologies can be applied to other bioinks in extrusion bioprinting as well as to different designs of heterogeneous tissue models with potential applications in drug screening, cell migration assays, and studies that focus on fundamental cell physiological functions.

<table border="0" cellpadding="0" cellspacing="0" width="925">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Sodium alginate</td>
			<td style="width:213px;">FMC BioPolymer</td>
			<td style="width:173px;">CAS-No: 9005-38-3</td>
			<td style="width:167px;">Protanal LF 10/60 FT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Gelatin</td>
			<td style="width:213px;">Sigma-Aldrich</td>
			<td style="width:173px;">G9391</td>
			<td>Type B gelatin from bovine skin</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Dubelcco&#39;s phosphate buffered saline (DPBS 1X)</td>
			<td style="width:213px;">Gibco</td>
			<td style="width:173px;">LS14190136</td>
			<td>1&#215;, w/o calcium, w/o magnesium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Magnetic hotplate</td>
			<td style="width:213px;">Corning&#160;</td>
			<td style="width:173px;">N/A</td>
			<td>Stirrer/hot plate model PC-420</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">50 mL centrifuge tubes</td>
			<td style="width:213px;">Corning</td>
			<td style="width:173px;">352098</td>
			<td>Falcon&#174; 50mL High Clarity PP Centrifuge Tube, Conical Bottom, Sterile</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Centrifuge</td>
			<td style="width:213px;">GMI</td>
			<td style="width:173px;">N/A</td>
			<td>Sorvall RT6000D, GMI, USA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calcium chloride anhydrous</td>
			<td style="width:213px;">Sigma-Aldrich</td>
			<td>C1016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">MilliQ water</td>
			<td style="width:213px;">Millipore</td>
			<td style="width:173px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Millipore 0.22 &#181;m filters</td>
			<td style="width:213px;">Millipore</td>
			<td style="width:173px;">SLGS033SB</td>
			<td>Millex-GS Syringe Filter Unit, 0.22&#160;&#181;m, mixed cellulose esters, 33&#160;mm, ethylene oxide sterilized</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Oscillation rheometer MCR 302</td>
			<td style="width:213px;">Anton Paar</td>
			<td style="width:173px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Rheometer measuring tool CP25</td>
			<td style="width:213px;">Anton Paar</td>
			<td style="width:173px;">79038</td>
			<td>Conical plate geometry for rheometer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">RheoCompass</td>
			<td style="width:213px;">Anton Paar</td>
			<td style="width:173px;">N/A</td>
			<td>Software controlling rheometer MCR 302</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Scanning electron microscope</td>
			<td style="width:213px;">Hitachi</td>
			<td style="width:173px;">N/A</td>
			<td>SEM, Hitachi SU-3500 Variable Pressure</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Paraformaldehyde, 96%, extra pure</td>
			<td style="width:213px;">Acros Organics</td>
			<td style="width:173px;">416785000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Dulbecco modified eagle medium (DMEM)</td>
			<td style="width:213px;">Gibco</td>
			<td>11965092</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antibiotic/Antimycotic solution (100X) stabilized</td>
			<td style="width:213px;">Sigma</td>
			<td>A5955</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal bovine serum</td>
			<td>Wisent Bioproducts</td>
			<td style="width:173px;">080-150</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:372px;">Cell culture T-75 flasks</td>
			<td style="width:213px;">Sigma-Aldrich</td>
			<td style="width:173px;">CLS430641</td>
			<td>75 cm2 TC-Treated surface treatment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3D bioprinter BioScaffolder 3.1</td>
			<td style="width:213px;">GeSiM</td>
			<td style="width:173px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GeSim software</td>
			<td style="width:213px;">GeSiM</td>
			<td style="width:173px;">N/A</td>
			<td>Software controlling BioScaffolder 3.1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10cc cartridge UV resist</td>
			<td>EFD Nordson</td>
			<td>7012126</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">End cap</td>
			<td>EFD Nordson</td>
			<td>7014472</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tip cap</td>
			<td>EFD Nordson</td>
			<td>7014469</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Piston&#160;</td>
			<td>EFD Nordson</td>
			<td>7012182</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stainless nozzle G25</td>
			<td>EFD Nordson</td>
			<td>7018345</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Water bath</td>
			<td style="width:213px;">VWR</td>
			<td style="width:173px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Agarose</td>
			<td style="width:213px;">Sigma-Aldrich</td>
			<td style="width:173px;">A9539</td>
			<td>Bioreagent, for molecular biology</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Costar 6-well plates&#160;</td>
			<td style="width:213px;">Corning</td>
			<td style="width:173px;">3516</td>
			<td>TC-Treated Multiple Well Plates, Individually Wrapped, Sterile&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Confocal spinning disk inverted microscope</td>
			<td style="width:213px;">Olympus Life Science</td>
			<td style="width:173px;">N/A</td>
			<td>Olympus IX83</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">MTS assay kit</td>
			<td style="width:213px;">Promega</td>
			<td style="width:173px;">G3582</td>
			<td>CellTiter 96&#174; AQueous&#160;One Solution Cell Proliferation Assay&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Live/Dead viability cytotoxicity kit</td>
			<td>Molecular Probes,ThermoFisher Scientific</td>
			<td>L3224</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin 0.25/EDTA 1X</td>
			<td>Gibco</td>
			<td>25200-072</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Corning 96-well plate</td>
			<td style="width:213px;">Corning</td>
			<td style="width:173px;">3595</td>
			<td>Clear Flat Bottom Polystyrene TC-Treated Microplate, Individually Wrapped, with Low Evaporation Lid, Sterile</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Autoclave Tuttnauer</td>
			<td style="width:213px;">Heidolph Brinkmann</td>
			<td style="width:173px;">N/A</td>
			<td>Heidolph Tuttnauer 2540E Autoclave Sterilizer Electronic Model with 4 Stainless Steel Trays, 23L Capacity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Trypan blue</td>
			<td style="width:213px;">Invitrogen&#160;</td>
			<td style="width:173px;">T10282</td>
			<td>0.4% solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Ethanol</td>
			<td style="width:213px;">Commercial Alcohols</td>
			<td style="width:173px;">P016EA95</td>
			<td>Greenfield Speciality Alcohols</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:372px;">CO2 Incubator</td>
			<td style="width:213px;">Panasonic</td>
			<td style="width:173px;">N/A</td>
			<td>MCO 19AIC-PA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">Lyophilizer&#160;</td>
			<td style="width:213px;">SP Scientific</td>
			<td style="width:173px;">N/A</td>
			<td>Virtis Sentry 2.0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">SolidWorks</td>
			<td style="width:213px;">Dassault Systems</td>
			<td style="width:173px;">N/A</td>
			<td>A CAD software used to build demostrative propeller-like model</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:372px;">MATLAB</td>
			<td style="width:213px;">The MathWorks</td>
			<td style="width:173px;">N/A</td>
			<td>A programming software used to generate G-code for BioScaffolder 3.1</td>
		</tr>
	</tbody>
</table>

bioprintable alginate/gelatin hydrogel 3d in vitro model systems induce cell spheroid formation

The cellular, biochemical, and biophysical heterogeneity of the native tumor microenvironment is not recapitulated by growing immortalized cancer cell lines using conventional two-dimensional (2D) cell culture. These challenges can be overcome by using bioprinting techniques to build heterogeneous three-dimensional (3D) tumor models whereby different types of cells are embedded. Alginate and gelatin are two of the most common biomaterials employed in bioprinting due to their biocompatibility, biomimicry, and mechanical properties. By combining the two polymers, we achieved a bioprintable composite hydrogel with similarities to the microscopic architecture of a native tumor stroma. We studied the printability of the composite hydrogel via rheology and obtained the optimal printing window. Breast cancer cells and fibroblasts were embedded in the hydrogels and printed to form a 3D model mimicking the in vivo microenvironment. The bioprinted heterogeneous model achieves a high viability for long-term cell culture (&#62; 30 days) and promotes the self-assembly of breast cancer cells into multicellular tumor spheroids (MCTS). We observed the migration and interaction of the cancer-associated fibroblast cells (CAFs) with the MCTS in this model. By using bioprinted cell culture platforms as co-culture systems, it offers a unique tool to study the dependence of tumorigenesis on the stroma composition. This technique features a high-throughput, low cost, and high reproducibility, and it can also provide an alternative model to conventional cell monolayer cultures and animal tumor models to study cancer biology.

The temperature sweep shows a distinct difference of the A3G7 precursor at 25 &#176;C and 37 &#176;C. The precursor is liquid at 37 &#176;C and has a complex viscosity of 1938.1 &#177; 84.0 mPa x s, which is validated by a greater G&#34; over G&#39;. As the temperature decreases, the precursor undergoes physical gelation due to the spontaneous physical entanglement of the gelatin molecules into a tri-helix formation29,30. Both the...

Watch this Scientific Journal Video about Bioprintable Alginate/Gelatin Hydrogel 3D In Vitro Model Systems Induce Cell Spheroid Formation at JoVE.com

Bioprintable Alginate/Gelatin Hydrogel 3D In Vitro Model Systems Induce Cell Spheroid Formation

We developed a heterogeneous breast cancer model consisting of immortalized tumor and fibroblast cells embedded in a bioprintable alginate/gelatin bioink. The model recapitulates the in vivo tumor microenvironment and facilitates the formation of multicellular tumor spheroids, yielding insight into the mechanisms driving tumorigenesis.

Bioprintable Alginate/Gelatin Hydrogel 3D In Vitro Model Systems Induce Cell Spheroid Formation

The cellular, biochemical, and biophysical heterogeneity of the native tumor microenvironment is not recapitulated by growing immortalized cancer cell ...

This method can help answer key questions in the cancer biology field, such as tumor formation, cell migration tracking, and cancer and healthy cell signaling. The main advantage of this technique is that it allows us to study tumorigenesis in a 3D environment along with stromal cells, such as fibroblasts, with low cost and high reproducibility. It is important to make sure the materials are both bioprintable and biofunctional, which requires quantitative study of its rheological properties and cell compatibility.Visual demonstration of this method is critical as the hydrogel preparation and cell hydrogel mixing steps are difficult to learn because bubble formation interferes with the fidelity of the printed model. In a biosafety cabinet, mix three grams of alginate and seven grams of gelatin powder in a 250-milliliter beaker. Add a magnetic stirrer and 100 milliliters of DPBS.Seal the beaker with sterile paraffin film and aluminum foil to avoid contamination. Then show the participant the unique and specific polar plots which correspond to their electromyography, or EMG, patterns. After this, continue the agitation at room temperature for two hours.Heat the solution at 37 degrees Celsius until the gel undergoes a phase transition to the liquid state. Then transfer the solution into sterile 50-milliliter conical centrifuge tubes, and seal them. Centrifuge the tubes at 834 times g for five minutes to eliminate any gas bubbles.Next, aspirate the hydrogel precursor into 10-milliliter syringes. Seal the syringes with caps and paraffin film. Store at four degrees Celsius until ready to use.When ready to begin testing, place a syringe of prepared hydrogel precursor in a 37 degree Celsius water bath for one hour. While the syringe is warming, turn on and initialize the rheometer. After an hour, remove the syringe from the water bath.Extrude approximately 0.5 milliliters of the precursor onto the rheometer platform. On the control panel, click the downward triangle button. Wait for the measuring tool to move down to the trimming position.Using a spatula, trim any excess precursor that escaped the edge of the measuring tool, and discard the superfluous material. Then pipette mineral oil onto the edge of the measuring tool. Wait for the oil to fully seal the boundary.On the control panel, click Continue. Then click the Start button. After the testing is complete, release the measuring tool, and click the upward triangle button.Remove the measuring tool. Clean both the measuring tool and the platform with 70%ethanol. First, complete amplitude and temperature sweeps as outlined in the text protocol.To begin an isothermal time sweep, click My Apps, and click the template for Isothermal time-temperature test. Click the Measurement step in the workflow. Then click the variable oscillation strain, and pull up the setup window.Set the oscillation strain to 0.1%and set the oscillation frequency to one hertz. In the pull-up window, set the number of data points to 120. Set the data collection frequency to one point per minute.Click Add button to add the temperature variable. Click the variable temperature, and set it to 25 degrees Celsius. Right-click the step Device, Move to measuring point in the workflow.Click Delete. Then click the step Device, Set value. Uncheck the box Wait until value is reached, and set value to 25 degrees Celsius.Click Picture, Title, Buttons at the bottom screen. Uncheck the box Continue. Then click the step Start, name the project, and save it.Now load the sample onto the rheometer platform, and start the test following the previously described general testing protocol. After this, observe the G prime and G double prime versus the time. Find the crossover point of G prime and G double prime, and determine the time at the crossover point.Then click Table, copy all of the data, and paste it into a text file. To measure the yield strength at various gelling times, click My Apps. Click the template for Yield and flow stress, Gel-like.Name this project. Next, click on the Start step in the workflow. In the top menu, click Insert.Then, in the drop-down menu, select Wait. Pull up the setup window, and set the waiting time to 50 minutes. Click Start, then click Insert again.Select Device from the drop-down menu. Pull up the setup window, select Temperature, and set it 25 degrees Celsius. Uncheck the box Wait until value is reached.In the workflow, select the Measurement step. Select the variable Shear Stress, and pull up the setup window. Set the initial and final shear stress to zero and 10, 000 pascal, respectively.Then click Calculator, set the Point density to 0.2 point per pascal. In the Data points tab on the left, set one point per second. At the bottom of the pull-up window, select the Event Control tab, set the criterion Stop the measurement if the shear rate is greater than 100 per second.Load the sample onto the rheometer platform, and begin the test following the previously described general testing protocol. After the test is complete, click Diagram to observe the strain-stress curve. Repeat this test for waiting times of 30, 40, and 50 minutes.The following steps must be performed in sterile conditions. To begin, sterilize the bioprinter by spraying it thoroughly with 70%ethanol and then exposing it to UV light overnight. Remove a syringe of hydrogel precursor from storage, and warm it in a 37 degree Celsius water bath for one hour.Transfer a T-flask of previously cultured cells from a CO2 incubator to the biosafety cabinet. Discard the culture medium, and then rinse the cells twice with DPBS. Add a warmed trypsin-EDTA solution to the cells.Incubate at 37 degrees Celsius for six minutes. After this, inactivate the trypsin by adding the same volume of FBS. Remove the syringe of hydrogel precursor from the water bath, and clean it.Sterilize the syringe with 70%ethanol before transferring it into the biosafety cabinet. Extrude approximately three milliliters of hydrogel precursor into a 10-milliliter printing cartridge. Mix precursor with MDA-MB-231-GFP cells at a concentration of one million cells per milliliter by slowly pipetting it to avoid producing bubbles.Cover the cartridge with the end and top caps, and seal it with paraffin film. Then centrifuge it at 834 times g for one minute to eliminate any gas bubbles. Repeat this entire process for the other precursors.After this, sterilize all three cartridges with 70%ethanol. Load the sterilized cartridges into the chambers of the bioprinter. In the printer's control software, click manual.Then expand the Tool head tab in the printer's control software. Click on one cartridge at the graphic interface at the left side, set the cartridge temperature to 25 degrees Celsius, and wait 35 minutes to allow the precursor to reach printable conditions. Repeat this for the other two cartridges.In the printer's control software, expand the Tool head tab. Click on one cartridge in the graphic interface, then click the measure short button to measure the position of the nozzle tip. Repeat this for the other two cartridges.Next, position a clear polystyrene microplate on the printer stage. Open the G-code file, and change the pressure to 200 kilopascals for all cartridges. Return to the control software, and click the Scaffolder Generator tab.Select a point to start printing, and then click the Run button. Repeat this process to obtain three replicates. After this, add a 100-millimolar calcium chloride solution for one minute to cross-link the models.Rinse twice with DPBS. Then use a spatula to carefully transfer the models onto an agarose-coated, six-well plate. Add five milliliters of DMEM to each well, and incubate at 37 degrees Celsius and 5%carbon dioxide, replacing the cell culture medium every three days.In this study, three-dimensional hydrogel systems are fabricated to recapitulates in vivo tumor microenvironments and facilitate the formation of multicellular tumor spheroids. A temperature sweep of the A3G7 precursor shows G double prime to be greater than G prime at 37 degrees Celsius, which validates the known properties of the precursor. As the temperature decreases, the precursor undergoes physical gelation due to the spontaneous physical entanglement of the gelatin molecules into a tri-helix formation.Both the G prime and G double prime increases the temperature decreases and converge at 30.6 degrees Celsius, indicating a sol-gel transition. Confocal microscopy of the printed propeller model shows that the MDA-MB-231-GFP cells begin to develop spheroids 15 days into the culture period, and the spheroids continue to increase in size and numbers until day 30. Some of the IMR-90-mCherry cells are also seen to form agglomerations.After 30 days of culture, IMR-90-mCherry cells could be observed in the region initially occupied by the MDA-MB-231-GFP cells, while MDA-MB-231-GFP cells could be seen in the IMR-90-mCherry-dominated region. This implies possible migration events in the model. Confocal microscopy of the disk model reveals that MDA-MB-231-GFP cells behave similarly to how they did in the propeller model, resulting in a spheroid-laden hydrogel after 21 days of culture.Once mastered, this technique to print models can be done in two hours, if it is performed properly. While attempting this procedure, it's important to remember to keep hydrogel and cells fresh as possible, do not mix old hydrogel batches with new ones, and to work under a sterile condition to avoid misleading results. Following this procedure, other methods like scanning electron and time-lapse microscopy can be performed in order to answer additional questions, like material porosity, cell migration rate, and matrix remodeling.The implication of this technique extend toward cancer therapy because this in vitro model allows systematically controlled studies of tumor formation and behavior in co-culture systems. Besides breast cancer cells, the model can also be readily applied to systems using other types of cells at various initial locations. After watching this video, you should have a good understanding of how to create 3D heterogeneous disease models by properly preparing hydrogels, embedding cells into and printing the material within the optimal printing window.Don't forget that working with biological samples can be extremely hazardous and precautions such as wearing personal protective equipment, such as gloves, lab coat, and safety goggles while performing this procedure.

bioprintable-alginategelatin-hydrogel-3d-vitro-model-systems-induce

Research

JoVE Journal

Bioengineering

Eye Irritation Test (EIT) for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial (RhCE) Tissue Model

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and accurate assessment of ocular toxicity in man are needed. To address this need, we have developed an eye irritation test (EIT) which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model that is based on normal human cells. The EIT is able to separate ocular&#160;irritants and corrosives (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category). The test utilizes two separate protocols, one designed for liquid chemicals and a second, similar protocol for solid test articles. The EIT prediction model uses a single exposure period (30 min for liquids, 6 hr for solids) and a single tissue viability cut-off (60.0% as determined by the MTT assay). Based on the results for 83 chemicals (44 liquids and 39 solids) EIT achieved 95.5/68.2/ and 81.8% sensitivity/specificity and accuracy (SS&#38;A) for liquids, 100.0/68.4/ and 84.6% SS&#38;A for solids, and 97.6/68.3/ and 83.1% for overall SS&#38;A. The EIT will contribute significantly to classifying the ocular irritation potential of a wide range of liquid and solid chemicals without the use of animals to meet regulatory testing requirements. The EpiOcular EIT method was implemented in 2015 into the OECD Test Guidelines as TG 492.

Eye Irritation Test EIT for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial RhCE Tissue Model

We have developed an eye irritation test which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model. The test is able to discriminate between ocular irritant and corrosive materials (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category).

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and ...

Modeling Ovarian Cancer Multicellular Spheroid Behavior in a Dynamic 3D Peritoneal Microdevice

Ovarian cancer is characterized by extensive peritoneal metastasis, with tumor spheres commonly found in the malignant ascites. This is associated with poor clinical outcomes and currently lacks effective treatment. Both the three-dimensional (3D) environment and the dynamic mechanical forces are very important factors in this metastatic cascade. However, traditional cell cultures fail to recapitulate this natural tumor microenvironment. Thus, in vivo-like models that can emulate the intraperitoneal environment are of obvious importance. In this study, a new microfluidic platform of the peritoneum was set up to mimic the situation of ovarian cancer spheroids in the peritoneal cavity during metastasis. Ovarian cancer spheroids generated under a non-adherent condition were cultured in microfluidic channels coated with peritoneal mesothelial cells subjected to physiologically relevant shear stress. In summary, this dynamic 3D ovarian cancer-mesothelium microfluidic platform can provide new knowledge on basic cancer biology and serve as a platform for potential drug screening and development.

To study ovarian tumor progression in a physiologically relevant model, multicellular spheroids were cultured in a microdevice under simulated fluid flow. This dynamic 3D model emulates the intraperitoneal environment with the cellular and mechanical components where ovarian cancer metastasis occurs.

Ovarian cancer is characterized by extensive peritoneal metastasis, with tumor spheres commonly found in the malignant ascites. This is associated with ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Improved 3D Hydrogel Cultures of Primary Glial Cells for In Vitro Modelling of Neuroinflammation

In the central nervous system, numerous acute injuries and neurodegenerative disorders, as well as implanted devices or biomaterials engineered to enhance function result in the same outcome: excess inflammation leads to gliosis, cytotoxicity, and/or formation of a glial scar that collectively exacerbate injury or prevent healthy recovery. With the intent of creating a system to model glial scar formation and study inflammatory processes, we have generated a 3D cell scaffold capable of housing primary cultured glial cells: microglia that regulate the foreign body response and initiate the inflammatory event, astrocytes that respond to form a fibrous scar, and oligodendrocytes that are typically vulnerable to inflammatory injury. The present work provides a detailed step-by-step method for the fabrication, culture, and microscopic characterization of a hyaluronic acid-based 3D hydrogel scaffold with encapsulated rat brain-derived glial cells. Further, protocols for characterization of cell encapsulation and the hydrogel scaffold by confocal immunofluorescence and scanning electron microscopy are demonstrated, as well as the capacity to modify the scaffold with bioactive substrates, with incorporation of a commercial basal lamina mixture to improved cell integration.

Improved 3D Hydrogel Cultures of Primary Glial Cells for In Vitro Modelling of Neuroinflammation

Herein, we present a protocol for the 3D culture of rat brain-derived glia cells, including astrocytes, microglia, and oligodendrocytes. We demonstrate primary cell culture, methacrylated hyaluronic acid (HAMA) hydrogel synthesis, HAMAphoto-polymerization and cell encapsulation, and sample processing for confocal and scanning electron microscopic imaging.

In the central nervous system, numerous acute injuries and neurodegenerative disorders, as well as implanted devices or biomaterials engineered to enhance ...

3D Printed Porous Cellulose Nanocomposite Hydrogel Scaffolds

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with controlled pore structure and mechanical properties. Cellulose nanocrystals (CNCs, 69.62 wt%) based hydrogel ink with matrix (sodium alginate and gelatin) was developed and 3D printed into scaffolds with uniform and gradient pore structure (110-1,100 &#181;m). The scaffolds showed compression modulus in the range of 0.20-0.45 MPa when tested in simulated in vivo conditions (in distilled water at 37 &#176;C). The pore sizes and the compression modulus of the 3D scaffolds matched with the requirements needed for cartilage regeneration applications. This work demonstrates that the consistency of the ink can be controlled by the concentration of the precursors and porosity can be controlled by the 3D printing process and both of these factors in return defines the mechanical properties of the 3D printed porous hydrogel scaffold. This process method can therefore be used to fabricate structurally and compositionally customized scaffolds according to the specific needs of patients.&#160;

The three critical steps of this protocol are i) developing the right composition and consistency of the cellulose hydrogel ink, ii) 3D printing of scaffolds into various pore structures with good shape fidelity and dimensions and iii) demonstration of the mechanical properties in simulated body conditions for cartilage regeneration.

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with ...

A Human 3D Extracellular Matrix-Adipocyte Culture Model for Studying Matrix-Cell Metabolic Crosstalk

The extracellular matrix (ECM) plays a central role in regulating tissue homeostasis, engaging in crosstalk with cells and regulating multiple aspects of cellular function. The ECM plays a particularly important role in adipose tissue function in obesity, and alterations in adipose tissue ECM deposition and composition are associated with metabolic disease in mice and humans. Tractable in vitro models that permit dissection of the roles of the ECM and cells in contributing to global tissue phenotype are sparse. We describe a novel 3D in vitro model of human ECM-adipocyte culture that permits study of the specific roles of the ECM and adipocytes in regulating adipose tissue metabolic phenotype. Human adipose tissue is decellularized to isolate ECM, which is subsequently repopulated with preadipocytes that are then differentiated within the ECM into mature adipocytes. This method creates ECM-adipocyte constructs that are metabolically active and retain characteristics of the tissues and patients from which they are derived. We have used this system to demonstrate disease-specific ECM-adipocyte crosstalk in human adipose tissue. This culture model provides a tool for dissecting the roles of the ECM and adipocytes in contributing to global adipose tissue metabolic phenotype and permits study of the role of the ECM in regulating adipose tissue homeostasis.

We describe a 3D human extracellular matrix-adipocyte in vitro culture system that permits dissection of the roles of the matrix and adipocytes in contributing to adipose tissue metabolic phenotype.

The extracellular matrix (ECM) plays a central role in regulating tissue homeostasis, engaging in crosstalk with cells and regulating multiple aspects of ...

Protocols of 3D Bioprinting of Gelatin Methacryloyl Hydrogel Based Bioinks

Gelatin methacryloyl (GelMA) has become a popular biomaterial in the field of bioprinting. The derivation of this material is gelatin, which is hydrolyzed from mammal collagen. Thus, the arginine-glycine-aspartic acid (RGD) sequences and target motifs of matrix metalloproteinase (MMP) remain on the molecular chains, which help achieve cell attachment and degradation. Furthermore, formation properties of GelMA are versatile. The methacrylamide groups allow a material to become rapidly crosslinked under light irradiation in the presence of a photoinitiator. Therefore, it makes great sense to establish suitable methods for synthesizing three-dimensional (3D) structures with this promising material. However, its low viscosity restricts GelMA's printability. Presented here are methods to carry out 3D bioprinting of GelMA hydrogels, namely the fabrication of GelMA microspheres, GelMA fibers, GelMA complex structures, and GelMA-based microfluidic chips. The resulting structures and biocompatibility of the materials as well as the printing methods are discussed. It is believed that this protocol may serve as a bridge between previously applied biomaterials and GelMA as well as contribute to the establishment of GelMA-based 3D architectures for biomedical applications.

Presented here is a method for the 3D bioprinting of gelatin methacryloyl.

Gelatin methacryloyl (GelMA) has become a popular biomaterial in the field of bioprinting. The derivation of this material is gelatin, which is hydrolyzed ...

Using Multilayered Hydrogel Bioink in Three-Dimensional Bioprinting for Homogeneous Cell Distribution

During the extrusion-based three-dimensional bioprinting process, liquid-like bioinks with low viscosity can protect cells from membrane damage induced by shear stress and improve the survival of the encapsulated cells. However, rapid gravity-driven cell sedimentation in the reservoir could lead to an inhomogeneous cell distribution in bioprinted structures and therefore hinder the application of liquid-like bioinks. Here, we developed a novel multilayered modified strategy for liquid-like bioinks (e.g., gelatin methacryloyl with low viscosity) to prevent the sedimentation of encapsulated cells. Multiple liquid interfaces were manipulated in the multilayered bioink to provide interfacial retention. Consequently, the cell sedimentation action going across adjacent layers in the multilayered system was retarded in the bioink reservoir. It was found that the interfacial retention was much higher than the sedimental pull of cells, demonstrating a critical role of the interfacial retention in preventing cell sedimentation and promoting a more homogeneous dispersion of cells in the multilayered bioink.

Here, we developed a novel multilayered modified strategy for liquid-like bioinks (gelatin methacryloyl with low viscosity) to prevent the sedimentation of encapsulated cells.

During the extrusion-based three-dimensional bioprinting process, liquid-like bioinks with low viscosity can protect cells from membrane damage induced by ...

Advanced 3D Liver Models for In vitro Genotoxicity Testing Following Long-Term Nanomaterial Exposure

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of robust, predictive in vitro test systems is essential. Hepatic toxicology is key when considering ENM exposure, as the liver serves a vital role in metabolic homeostasis and detoxification as well as being a major site of ENM accumulation post exposure. Based upon this and the accepted understanding that 2D hepatocyte models do not accurately mimic the complexities of intricate multi-cellular interactions and metabolic activity observed in vivo, there is a greater focus on the development of physiologically relevant 3D liver models tailored for ENM hazard assessment purposes in vitro. In line with the principles of the 3Rs to replace, reduce and refine animal experimentation, a 3D HepG2 cell-line based liver model has been developed, which is a user friendly, cost effective system that can support both extended and repeated ENM exposure regimes (&#8804;14 days). These spheroid models (&#8805;500 &#181;m in diameter) retain their proliferative capacity (i.e., dividing cell models) allowing them to be coupled with the &#8216;gold standard&#8217; micronucleus assay to effectively assess genotoxicity in vitro. Their ability to report on a range of toxicological endpoints (e.g., liver function, (pro-)inflammatory response, cytotoxicity and genotoxicity) has been characterized using several ENMs across both acute (24 h) and long-term (120 h) exposure regimes. This 3D in vitro hepatic model has the capacity to be utilized for evaluating more realistic ENM exposures, thereby providing a future in vitro approach to better support ENM hazard assessment in a routine and easily accessible manner.

This procedure was established to be used for developing advanced 3D hepatic cultures in vitro, which can provide a more physiologically relevant assessment of the genotoxic hazards associated with nanomaterial exposures over both an acute or long-term, repeated dose regimes.

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of ...

3D Printing of In Vitro Hydrogel Microcarriers by Alternating Viscous-Inertial Force Jetting

Microcarriers are beads with a diameter of 60-250 &#181;m and a large specific surface area, which are commonly used as carriers for large-scale cell cultures. Microcarrier culture technology has become one of the main techniques in cytological research and is commonly used in the field of large-scale cell expansion. Microcarriers have also been shown to play an increasingly important role in in vitro tissue engineering construction and clinical drug screening. Current methods for preparing microcarriers include microfluidic chips and inkjet printing, which often rely on complex flow channel design, an incompatible two-phase interface, and a fixed nozzle shape. These methods face the challenges of complex nozzle processing, inconvenient nozzle changes, and excessive extrusion forces when applied to multiple bioink. In this study, a 3D printing technique, called alternating viscous-inertial force jetting, was applied to enable the construction of hydrogel microcarriers with a diameter of 100-300 &#181;m. Cells were subsequently seeded on microcarriers to form tissue engineering modules. Compared to existing methods, this method offers a free nozzle tip diameter, flexible nozzle switching, free control of printing parameters, and mild printing conditions for a wide range of bioactive materials.

3D Printing of In Vitro Hydrogel Microcarriers by Alternating Viscous-Inertial Force Jetting

Presented here is a mild 3D printing technique driven by alternating viscous-inertial forces to enable the construction of hydrogel microcarriers. Homemade nozzles offer flexibility, allowing easy replacement for different materials and diameters. Cell binding microcarriers with a diameter of 50-500 &#181;m can be obtained and collected for further culturing.

Microcarriers are beads with a diameter of 60-250 &#181;m and a large specific surface area, which are commonly used as carriers for large-scale cell ...