The authors acknowledge the following funding sources: Magic That Matters Fund for Cardiovascular Research and the Maryland Stem Cell Research Fund (2016-MSCRFI-2735).

1. Preparation of Cardiomyocytes
<ol>
	<li>Generate and culture human induced pluripotent stem cells (hiPSCs) on 6-well plates coated with basement membrane matrix as described10.</li>
	<li>Differentiate hiPSCs into hiPSC-derived cardiomyocytes (hiPSC-CMs) using previously described methods11,12.</li>
	<li>On Day 19 after differentiation, isolate the cardiomyocytes using 2 mL of Trypsin/EDTA 0.05% in each well for 5 min at room temperatu...

<ol>
	<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> Nat Biotech. 32, 773-785 (2014).</li><li>Bajaj, P., Schweller, R. M., Khademhosseini, A., West, J. L., Bashir, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+biofabrication+strategies+for+tissue+engineering+and+regenerative+medicine.">3D biofabrication strategies for tissue engineering and regenerative medicine.</a> Ann Rev Biomed Eng. 16, 247-276 (2014).</li><li>Patra, S., Young, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Review+of+3D+Printing+Techniques+and+the+Future+in+Biofabrication+of+Bioprinted+Tissue.">A Review of 3D Printing Techniques and the Future in Biofabrication of Bioprinted Tissue.</a> Cell Biochem Biophy. 74, 93-98 (2016).</li><li>Moldovan, N. I., Hibino, N., Nakayama, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Principles+of+the+Kenzan+Method+for+Robotic+Cell+Spheroid-Based+Three-Dimensional+Bioprinting.">Principles of the Kenzan Method for Robotic Cell Spheroid-Based Three-Dimensional Bioprinting.</a> Tissue Eng Part B Rev. , (2017).</li><li>Cui, X., Boland, T., D'Lima, D. D., Lotz, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+inkjet+printing+in+tissue+engineering+and+regenerative+medicine.">Thermal inkjet printing in tissue engineering and regenerative medicine.</a> Recent Pat Drug Deliv Formul. 6, 149-155 (2012).</li><li>Murphy, C. M., Haugh, M. G., O'Brien, F. 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+effect+of+mean+pore+size+on+cell+attachment,+proliferation+and+migration+in+collagen-glycosaminoglycan+scaffolds+for+bone+tissue+engineering.">The effect of mean pore size on cell attachment, proliferation and migration in collagen-glycosaminoglycan scaffolds for bone tissue engineering.</a> Biomater. 31, 461-466 (2010).</li><li>Noguchi, 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=Development+of+a+three-dimensional+pre-vascularized+scaffold-free+contractile+cardiac+patch+for+treating+heart+disease.">Development of a three-dimensional pre-vascularized scaffold-free contractile cardiac patch for treating heart disease.</a> J Heart Lung Transpl. 35, 137-145 (2016).</li><li>Mironov, 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=Organ+printing:+tissue+spheroids+as+building+blocks.">Organ printing: tissue spheroids as building blocks.</a> Biomater. 30, 2164-2174 (2009).</li><li>Itoh, M., 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-Free+Tubular+Tissues+Created+by+a+Bio-3D+Printer+Undergo+Remodeling+and+Endothelialization+when+Implanted+in+Rat+Aortae.">Scaffold-Free Tubular Tissues Created by a Bio-3D Printer Undergo Remodeling and Endothelialization when Implanted in Rat Aortae.</a> PloS One. 10, e0136681 (2015).</li><li>Lieu, P. T., Fontes, A., Vemuri, M. C., Macarthur, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+induced+pluripotent+stem+cells+with+CytoTune,+a+non-integrating+Sendai+virus.">Generation of induced pluripotent stem cells with CytoTune, a non-integrating Sendai virus.</a> Methods Mol Biol. 997, 45-56 (2013).</li><li>Li, S., Cheng, H., Tomaselli, G. F., Li, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+basis+of+excitation-contraction+coupling+in+human+pluripotent+stem+cell-derived+ventricular+cardiomyocytes+revealed+by+Ca2++spark+characteristics:+direct+evidence+of+functional+Ca2+-induced+Ca2++release.">Mechanistic basis of excitation-contraction coupling in human pluripotent stem cell-derived ventricular cardiomyocytes revealed by Ca2+ spark characteristics: direct evidence of functional Ca2+-induced Ca2+ release.</a> Heart Rhythm. 11, 133-140 (2014).</li><li>Boheler, K. 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=A+Human+Pluripotent+Stem+Cell+Surface+N-Glycoproteome+Resource+Reveals+Markers,+Extracellular+Epitopes,+and+Drug+Targets.">A Human Pluripotent Stem Cell Surface N-Glycoproteome Resource Reveals Markers, Extracellular Epitopes, and Drug Targets.</a> Stem Cell Rep. 3, 185-203 (2014).</li><li>ScienCell Research Laboratories. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Human Cardiac Fibroblasts (adult ventricular) Product Sheet. , (2017).</li><li>Lonza Walkersville, Inc. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Endothelial Cell Systems - Technical Information &amp; Instructions.,. , (2015).</li><li>Thermo Fisher Scientific, Inc. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Immunofluorescence Method for IHC Detection. , (2017).</li><li>Murata, 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=A+preliminary+study+of+osteochondral+regeneration+using+a+scaffold-free+three-dimensional+construct+of+porcine+adipose+tissue-derived+mesenchymal+stem+cells.">A preliminary study of osteochondral regeneration using a scaffold-free three-dimensional construct of porcine adipose tissue-derived mesenchymal stem cells.</a> J Orthop Surg Res. 10, (2015).</li><li>Mosadegh, B., Xiong, G., Dunham, S., Min, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+progress+in+3D+printing+for+cardiovascular+tissue+engineering.">Current progress in 3D printing for cardiovascular tissue engineering.</a> Biomed Mater. 10, 034002 (2015).</li><li>Chang, C. C., Boland, E. D., Williams, S. K., Hoying, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct-write+Bioprinting+Three-Dimensional+Biohybrid+Systems+for+Future+Regenerative+Therapies.">Direct-write Bioprinting Three-Dimensional Biohybrid Systems for Future Regenerative Therapies.</a> J Biomed Mater Res. Part B, Appl Biomater. 98, 160-170 (2011).</li><li>Lee, J. M., Sing, S. L., Tan, E. Y. S., Yeong, W. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioprinting+in+cardiovascular+tissue+engineering:+a+review.">Bioprinting in cardiovascular tissue engineering: a review.</a> International J Bioprinting. 2 (2016), (2016).</li></ol>

The authors have nothing to disclose.

It is important to use beating, functional spheroids for 3D bioprinting. If spheroids are not beating, continuing to use them will invariably result in a non-functional 3D bioprinted patch.
One benefit of this approach is the ability to manipulate the cell content of the patch by varying the total number of cells and the percentage of cardiomyocytes, endothelial cells, and fibroblasts in the spheroids. This allows for many different types of cardiac patches to be printed, with varying histolog...

There are many different methods of 3D bioprinting1,2,3. 3D bioprinting is frequently classified by printing technology1, with examples such as inkjet bioprinting, microextrusion bioprinting, laser assisted bioprinting, a combination of methods, or newer approaches. 3D bioprinting can also be classified into scaffold-free or scaffold-dependent methods4. Most methods of 3D bioprinting are scaffold-dependent, where there is a need for biomaterials, e.g. bioinks5 or scaffolds6. However, scaffold-dependent 3D bioprinting face many issues and limitations4,7, such as immunogenicity of scaffolding material, cost of proprietary bioinks, slow speed and toxicity of degradation products.
Scaffold-free cardiac tissue engineering using spheroids has been attempted8, with the potential to overcome these disadvantages of scaffold-dependent tissue engineering. However, as acknowledged by the authors in that paper, it had been difficult to robustly handle and position spheroids in fixed locations, in the process of biofabrication. The concomitant use of 3D bioprinting and spheroid-based tissue engineering has the potential to overcome these difficulties. In this protocol, we describe 3D bioprinting of cardiac tissue without other biomaterials, using only cells in the form of spheroids.
Scaffold-free spheroid-based 3D bioprinters9 have the ability to pick up individual spheroids using vacuum suction and position them on a needle array. The concept of positioning spheroids on a needle array in 3D bioprinting, is inspired from the use of needle arrays (known as &#34;kenzan&#34;) in the ancient Japanese art of flower arrangement, ikebana. This system allows spheroids to be precisely positioned in any configuration and results in the individual spheroids fusing together over a short period to create a 3D bioprinted tissue. This method thus allows spheroids to be manipulated with ease, with potential implications for the future of scaffold-free organ biofabrication.

<table border="0" cellpadding="0" cellspacing="0" width="587">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:176px;">Geltrex</td>
			<td style="width:157px;">Invitrogen&#160;</td>
			<td style="width:88px;">A1413202</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:176px;">Trypsin/EDTA 0.05%</td>
			<td style="width:157px;">Thermo Fisher</td>
			<td style="width:88px;">15400054</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:176px;">Defined Trypsin inhibitor 0.0125%</td>
			<td style="width:157px;">Thermo Fisher</td>
			<td style="width:88px;">R007100</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="65">
			<td height="65" style="height:65px;width:176px;">RPMI Cell Media</td>
			<td style="width:157px;">Invitrogen</td>
			<td style="width:88px;">11875-093</td>
			<td style="width:167px;">RPMI supplemented with B27 constitutes HIPSC-CM culture media</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:176px;">B-27 Supplement</td>
			<td style="width:157px;">Thermo Fisher</td>
			<td style="width:88px;">17504044</td>
			<td style="width:167px;">RPMI supplemented with B27 constitutes HIPSC-CM culture media</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:176px;">Countess Automated Cell Counter</td>
			<td style="width:157px;">Invitrogen</td>
			<td style="width:88px;">C10227</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:176px;">Human cardiac fibroblasts (adult ventricular type)</td>
			<td style="width:157px;">Sciencell</td>
			<td style="width:88px;">6310</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:176px;">Human umbilical vein endothelial cells</td>
			<td style="width:157px;">Lonza</td>
			<td style="width:88px;">CC-2935</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:176px;">PrimeSurface ultra-low attachment 96-well U-bottom plates&#160;</td>
			<td style="width:157px;">Akita Sumitomo Bakelite Co.</td>
			<td style="width:88px;">MS-9096UZ</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:176px;">Regenova Bio 3D Printer</td>
			<td style="width:157px;">Cyfuse Biomedical K.K.</td>
			<td style="width:88px;">N/A</td>
			<td>www.cyfusebio.com/en/</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypan Blue Solution, 0.4%</td>
			<td style="width:157px;">Thermo Fisher</td>
			<td style="width:88px;">15250061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:176px;">Troponin T Antibody</td>
			<td style="width:157px;">Thermo Fisher</td>
			<td style="width:88px;">701620</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:176px;">Connexin 43 (Cx43) Antibody</td>
			<td style="width:157px;">Chemicon</td>
			<td>MAB3068</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:176px;">ProLong Gold Antifade Mountant with DAPI</td>
			<td style="width:157px;">Thermo Fisher</td>
			<td style="width:88px;">P36935</td>
			<td></td>
		</tr>
	</tbody>
</table>

creation of cardiac tissue exhibiting mechanical integration of spheroids using 3d bioprinting

This protocol describes 3D bioprinting of cardiac tissue without the use of biomaterials, using only cells. Cardiomyocytes, endothelial cells and fibroblasts are first isolated, counted and mixed at desired cell ratios. They are co-cultured in individual wells in ultra-low attachment 96-well plates. Within 3 days, beating spheroids form. These spheroids are then picked up by a nozzle using vacuum suction and assembled on a needle array using a 3D bioprinter. The spheroids are then allowed to fuse on the needle array. Three days after 3D bioprinting, the spheroids are removed as an intact patch, which is already spontaneously beating. 3D bioprinted cardiac patches exhibit mechanical integration of component spheroids and are highly promising in cardiac tissue regeneration and as 3D models of heart disease.

At the end of step 4.4 (co-culture), the cells in each well should aggregate at the bottom of the ultra-low attachment 96-well U-bottom plates to form spheroids by gravity. These spheroids contain hiPSC-CM, HCFs, and HUVECs, and can be visually inspected under light microscopy, where they should appear circular by two-dimensional projection (Figure 1). At the end of step 6.3, the 3D bioprinted cardiac patch should contain tissue voids, due to needle holes cre...

Watch this Scientific Journal Video about Creation of Cardiac Tissue Exhibiting Mechanical Integration of Spheroids Using 3D Bioprinting at JoVE.com

Creation of Cardiac Tissue Exhibiting Mechanical Integration of Spheroids Using 3D Bioprinting

This protocol describes 3D bioprinting of cardiac tissue without the use of biomaterials. 3D bioprinted cardiac patches exhibit mechanical integration of component spheroids and are highly promising in cardiac tissue regeneration and as 3D models of heart disease.

This protocol describes 3D bioprinting of cardiac tissue without the use of biomaterials, using only cells. Cardiomyocytes, endothelial cells and ...

The purpose of this video is to demonstrate 3D bioprinting of cardiac tissue without the use of biomaterials, using only cells. Firstly, cardiomyocytes, endothelial cells and fibroblasts are isolated, counted and mixed at desired cell ratios. They're then distributed using a multi-channel pipette and to individual wells in ultra low attachment 96 well plates.The cells in the 96 well plates are incubated for three days, after three days, they form spheroids that beat spontaneously. Confocal microscopy reveals the expression of connects in 43, which is fluorescently labeled green in Troponin T positive cardiomyocytes, which are fluorescently labeled far red within the spheroids. The 96 well plates containing the spheroids are then loaded into the 3D bio-printer.The 3D bio-printer starts by transferring the 96 well plate to a location just beside the needle array using a moving platform. The 3D bio-printer then inspects all the spheroids in the 96 well plate to obtain relevant data regarding each spheroid such as its diameter and its shape. This is a close up view of the 3D bioprinting process.The spheroid is picked up from the 96 well plate on the left by a nozzle using vacuum suction and placed a specific location in a needle array on the right. This process is repeated until the 3D bioprinting process is complete. Until all the spheroids and 96 well plate have been bioprinted, then the 3D bioprinter will store the exising 96 well plate and load a new plate, using the moving platform.This is a timelapse video showing an aerial view of the 3D bioprinting of a nine by nine patch at 100 times speed, the needles in the needle array are arranged in a group formation and spheroids are loaded onto each needle from above. After three days under sterile conditions, the 3D bioprinter cardiac patch is very carefully removed from the needle array by gently sliding the piece of hard plastic in the needle array under the patch upwards. Lubrication with phosphate buffered saline or PBS, maybe applied to the needles during this step as needed, for smoother and easier removal.The 3D bioprinted cardiac patch is very fragile, immediately after removal from the needle array, so due care must be taken in order not to damage it. The 3D bioprinted cardiac patch is then transferred into a 35 millimeter tissue culture dish containing appropriate cell media. Immediately after removal from the needle array, it is noted that the patch is already beating, with the needle holes changing in size with each beat.The 3D bioprinted cardiac patch is allowed to mature, during which time, the tissue voids caused by the needle array are filled up by surrounding tissue. The 3D bioprinting cardiac patch continues to beat spontaneously. In conclusion, it is feasible to 3D bioprint cardiac tissue without the use of biomaterials.3D bioprinted cardiac patches exhibit mechanical integration of component spheroids. 3D bioprinting of cardiac tissue has promising clinical applications and cardiac tissue regeneration and has 3D models of heart tissue, replication in predictive pharmacology and toxicology and development of cell and genome directed therapies.

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JoVE Journal

Bioengineering

9.9K Görüntüleme.  Johns Hopkins Hospital. The purpose of this video is to demonstrate 3D bioprinting of cardiac tissue without the use of biomaterials, using only cells. Firstly, cardiomyocytes, endothelial cells and fibroblasts are isolated, counted and mixed at desired cell ratios. They're then distributed using a multi-channel pipette and to individual wells in ultra low attachment 96 well plates.The cells in the 96 well plates are incubated for three days, after three days, they form spheroids that beat spontaneously. Conf...