Name: a net mold-based method of scaffold-free three-dimensional cardiac tissue creation
Uploaded: 2018-08-05T13:00:00
Description: Watch this Scientific Journal Video about A Net Mold-based Method of Scaffold-free Three-Dimensional Cardiac Tissue Creation at JoVE.com

The authors acknowledge the following funding source: the Magic That Matters Fund for Cardiovascular Research.

1. Preparation of Cardiomyocytes
<ol>
	<li>Coat 6-well plates with basement membrane matrix and culture human-induced pluripotent stem cells (hiPSCs) as previously described17.</li>
	<li>Differentiate hiPSCs into hiPSC-CMs using previously described methods18.</li>
	<li>At 16 - 18 d post-differentiation, suspend the cardiomyocytes by rinsing each well with 2 mL of 1x phosphate-buffered saline (PBS) without calcium or magnesium, followed by incubation with 1 mL/well of try...

<ol>
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K., Shinoka, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-engineered+cardiac+patch+seeded+with+human+induced+pluripotent+stem+cell+derived+cardiomyocytes+promoted+the+regeneration+of+host+cardiomyocytes+in+a+rat+model.">Tissue-engineered cardiac patch seeded with human induced pluripotent stem cell derived cardiomyocytes promoted the regeneration of host cardiomyocytes in a rat model.</a> Journal of Cardiothoracic Surgery. 11 (1), 163 (2016).</li><li>Caspi, O., 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=Tissue+engineering+of+vascularized+cardiac+muscle+from+human+embryonic+stem+cells.">Tissue engineering of vascularized cardiac muscle from human embryonic stem cells.</a> Circulation Research. 100 (2), 263-272 (2007).</li><li>Ong, C. 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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=A+novel+concept+for+scaffold-free+vessel+tissue+engineering:+self-assembly+of+microtissue+building+blocks.">A novel concept for scaffold-free vessel tissue engineering: self-assembly of microtissue building blocks.</a> Journal of Biotechnology. 148 (1), 46-55 (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> The Journal of Heart and Lung Transplantation. 35 (1), 137-145 (2016).</li><li>Zuppinger, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+culture+for+cardiac+cells.">3D culture for cardiac cells.</a> Biochimica et Biophysica Acta. 1863 (7 Pt B), 1873-1881 (2016).</li><li>Langenbach, 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=Generation+and+differentiation+of+microtissues+from+multipotent+precursor+cells+for+use+in+tissue+engineering.">Generation and differentiation of microtissues from multipotent precursor cells for use in tissue engineering.</a> Nature Protocols. 6 (11), 1726-1735 (2011).</li><li>Fennema, E., Rivron, N., Rouwkema, J., van Blitterswijk, C., de Boer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spheroid+culture+as+a+tool+for+creating+3D+complex+tissues.">Spheroid culture as a tool for creating 3D complex tissues.</a> Trends in Biotechnology. 31 (2), 108-115 (2013).</li><li>Agocha, A., Sigel, A. V., Eghbali-Webb, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+adult+human+heart+fibroblasts+in+culture:+a+comparative+study+of+growth,+proliferation+and+collagen+production+in+human+and+rabbit+cardiac+fibroblasts+and+their+response+to+transforming+growth+factor-beta1.">Characterization of adult human heart fibroblasts in culture: a comparative study of growth, proliferation and collagen production in human and rabbit cardiac fibroblasts and their response to transforming growth factor-beta1.</a> Cell Tissue Research. 288 (1), 87-93 (1997).</li><li>Baudin, B., Bruneel, A., Bosselut, N., Vaubourdolle, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+protocol+for+isolation+and+culture+of+human+umbilical+vein+endothelial+cells.">A protocol for isolation and culture of human umbilical vein endothelial cells.</a> Nature Protocols. 2 (3), 481-485 (2007).</li><li>Pimentel, C. 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=Three-dimensional+fabrication+of+thick+and+densely+populated+soft+constructs+with+complex+and+actively+perfused+channel+network.">Three-dimensional fabrication of thick and densely populated soft constructs with complex and actively perfused channel network.</a> Acta Biomaterialia. 65, 174-184 (2018).</li><li>Shimizu, 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=Polysurgery+of+cell+sheet+grafts+overcomes+diffusion+limits+to+produce+thick,+vascularized+myocardial+tissues.">Polysurgery of cell sheet grafts overcomes diffusion limits to produce thick, vascularized myocardial tissues.</a> The FASEB Journal. 20 (6), 708-710 (2006).</li><li>Sakaguchi, K., Shimizu, T., Okano, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+of+three-dimensional+vascularized+cardiac+tissue+with+cell+sheet+engineering.">Construction of three-dimensional vascularized cardiac tissue with cell sheet engineering.</a> Journal of Controlled Release. 205, 83-88 (2015).</li><li>Ong, C. 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=Creation+of+Cardiac+Tissue+Exhibiting+Mechanical+Integration+of+Spheroids+Using+3D+Bioprinting.">Creation of Cardiac Tissue Exhibiting Mechanical Integration of Spheroids Using 3D Bioprinting.</a> Journal of Visualized Experiments. 125 (e55438), (2017).</li><li>Tan, 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=Cell+number+per+spheroid+and+electrical+conductivity+of+nanowires+influence+the+function+of+silicon+nanowired+human+cardiac+spheroids.">Cell number per spheroid and electrical conductivity of nanowires influence the function of silicon nanowired human cardiac spheroids.</a> Acta Biomaterialia. 51, 495-504 (2017).</li><li>Karra, R., Poss, K. 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The significance of this method lies in its reproducibility and the effectiveness of the resultant multilayered cardiac tissue. In the field of cardiac tissue engineering, one of the current goals is to identify a method to construct beating, multilayered, and functional 3-D cardiac patches. We report an efficient and reproducible method of creating multilayered cardiac tissues by direct manual seeding of spheroids composed of cardiomyocytes, endothelial cells, and fibroblasts into a novel net mold. The net mold used in ...

The goal of current cardiac tissue engineering is to develop a therapy to replace or repair the structure and function of injured myocardial tissue1. Methods to create 3-D cardiac tissue models exhibiting the important contractile and electrophysiological properties of native cardiac tissue have been rapidly expanding2,3. A variety of strategies have been explored and used in studies4,5. These methods range from the use of specific synthetic and natural bioactive hydrogels, such as gelatin, collagen, fibrin, and peptides6, to bio-ink deposition technologies2 and bioprinting technologies7. 
It has been shown that scaffold-free methods can produce comparable tissues as biomaterial-based methods, without the drawbacks of incorporating foreign scaffolding material8. Oren Caspi et al. demonstrated that the incorporation of various types of cells enables the generation of highly vascularized human engineered cardiac tissue9. Chin et al. developed a 3-D printing method for cardiac patch creation from spheroids. Resulting patches are composed of cardiomyocytes, fibroblasts, and endothelial cells in a 70:15:15 ratio10. Spheroids have been shown to be effective "building blocks" of scaffold-free cardiac tissue creation, as they are resistant against hypoxia and possess sufficient mechanical integrity for implantation11,12. Previous studies have demonstrated several fabrication methods for spheroid creation, including the use of the hanging drop method, spinner flasks13, microfluidic systems14, and non-adherent culture surfaces uncoated or coated with agarose micro-molds15. In this protocol, we use the hanging drop device, which contains micropores for condensing hundreds of spheroids at one time.
This study presents a novel and efficient scaffold-free method for cardiac tissue creation, which includes manually seeding the spheroids into a square mold cavity and incubating the tissue on a shaker for maturation. Under usual static culture conditions, oxygen diffusion is limited to the outer aspects of the tissue construct, resulting in central necrosis. However, with the net mold, all the spheroids seeded into the mold are immersed in media with a constant fluidic motion, allowing for the increased diffusion of nutrients and oxygen. Additionally, this mold-based method allows for the simultaneous creation of different-sized tissue patches with minimal manual effort and the resultant tissue can be easily removed from the mold. This novel method allows for the efficient and reproducible creation of scaffold-free, multilayered cardiac patches.

<table border="0" cellpadding="0" cellspacing="0" style="width:708px;" width="708">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Human Cardiac fibroblasts (HCF)</td>
			<td style="width:139px;">Sciencell</td>
			<td style="width:119px;">6310</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">FM-2 Consists of Basal Medium</td>
			<td style="width:139px;">Sciencell</td>
			<td style="width:119px;">2331</td>
			<td style="width:220px;">HCF culture medium</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:231px;">Human umbilical vein endothelial cells (HUVEC)</td>
			<td style="width:139px;">Lonza</td>
			<td style="width:119px;">CC-2935</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">EGM+Bullet Kit&#160;</td>
			<td style="width:139px;">Lonza</td>
			<td style="width:119px;">CC5035</td>
			<td>HUVEC culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">E8 media&#160;</td>
			<td style="width:139px;">Invitrogen</td>
			<td style="width:119px;">A1517001</td>
			<td>HiPSC culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Geltrex&#160;</td>
			<td style="width:139px;">Invitrogen</td>
			<td style="width:119px;">A1413202</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">TrypLE Express Enzyme (1X)</td>
			<td style="width:139px;">Thermo Fisher</td>
			<td style="width:119px;">12604013</td>
			<td>Trypsin and Cell dissociation reagent</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:231px;">RPMI media</td>
			<td style="width:139px;">Invitrogen</td>
			<td style="width:119px;">11875093</td>
			<td style="width:220px;">RPMI media with B-27 supplement is hiPSC-CM culture medium</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:231px;">B-27 supplement (50x)</td>
			<td style="width:139px;">Thermo Fisher</td>
			<td style="width:119px;">17504044</td>
			<td style="width:220px;">RPMI media with B-27 supplement is hiPSC-CM culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Trypan Blue Solution, 0.4%</td>
			<td style="width:139px;">Thermo Fisher</td>
			<td style="width:119px;">15250061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Novel net mold&#160;</td>
			<td style="width:139px;">TissueByNet Co.,Ltd</td>
			<td style="width:119px;">NM25-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Hanging drop plate</td>
			<td style="width:139px;">Kuraray Co.,Ltd</td>
			<td style="width:119px;">MPc350</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">6 well plates&#160;</td>
			<td style="width:139px;">Sigma-Aldrich</td>
			<td style="width:119px;">CLS-3516</td>
			<td></td>
		</tr>
	</tbody>
</table>

a net mold-based method of scaffold-free three-dimensional cardiac tissue creation

This protocol describes a novel and easy net mold-based method to create three-dimensional (3-D) cardiac tissues without additional scaffold material. Human-induced pluripotent stem-cell-derived cardiomyocytes (iPSC-CMs), human cardiac fibroblasts (HCFs), and human umbilical vein endothelial cells (HUVECs) are isolated and used to generate a cell suspension with 70% iPSC-CMs, 15% HCFs, and 15% HUVECs. They are co-cultured in an ultra-low attachment "hanging drop" system, which contains micropores for condensing hundreds of spheroids at one time. The cells aggregate and spontaneously form beating spheroids after 3 days of co-culture. The spheroids are harvested, seeded into a novel mold cavity, and cultured on a shaker in the incubator. The spheroids become a mature functional tissue approximately 7 days after seeding. The resultant multilayered tissues consist of fused spheroids with satisfactory structural integrity and synchronous beating behavior. This new method has promising potential as a reproducible and cost-effective method to create engineered tissues for the treatment of heart failure in the future.

In our experiments, we utilized a cell suspension of 70% iPSC-CMs, 15% HCFs, and 15% HUVECs in RPMI/B-27 cell media at a concentration of 2,475,000 cells per mL. After creating the cell suspension, we dispensed 4 mL of the cell suspension to each well of an ultra-low attachment hanging drop system, as described in step 4.3 of the protocol. The use of the hanging drop system resulted in the spontaneous formation of hundreds of beating spheroids after 3 days of culture at 37 &#176;C, 5% CO<...

Watch this Scientific Journal Video about A Net Mold-based Method of Scaffold-free Three-Dimensional Cardiac Tissue Creation at JoVE.com

A Net Mold-based Method of Scaffold-free Three-Dimensional Cardiac Tissue Creation

This protocol describes a net mold-based method to create three-dimensional scaffold-free cardiac tissues with satisfactory structural integrity and synchronous beating behavior.

This protocol describes a novel and easy net mold-based method to create three-dimensional (3-D) cardiac tissues without additional scaffold material. ...

This protocol describes a novel and easy mold based method for three dimensional cardiac tissue creation, which uses spheroids as a tool for scaffold free cardiac tissue creation. In our experiments three types of cells, human induced pluripotent stem cell-derived cardiomyocytes, human cardiac fibroblasts, and human umbilical vein endothelial cells were isolated and used to generate a cell suspension. With 70%cardiomyocytes, 15%fibroblasts, and 15%endothelial cells, in a 50ML conical tube.We then dispense the cell suspension into each well of an ultra low attachment hanging drop system, which will result in the spontaneous formation of hundreds of beating spheroids after three days. The spheroids are then harvested and seated into a novel mold cavity. The tissue is then maintained in a sterile container with medium, on a shaker in the incubator for several days.The mold is subsequently removed, resulting in a scaffold free tissue patch with mechanical integrity. The hanging drop device is a reusable, ultra low attachment well with 850 micro pores, each with a diameter of 350 microns. The hanging drop is compatible with standard six well plates.After making the cell suspension we dispense four milliliters of cell suspension containing 10 million cells, to each well of the hanging drop system. The devices are cultured at 37 degrees celsius, 5%carbon dioxide and 95%humidity. After 72 hours spontaneous formation of beating spheroids, with an average diameter of 350 microns is observed.The spheroids are harvested by placing the hanging drop device into another dish with medium, and swirling gently to release the spheroids and allow them to drift through the pores at the bottom of the hanging drop system. This is a schematic of the novel mold for three dimensional, scaffold free, cardiac tissue creation. It includes the handling mat, filling base and novel mold.The novel mold is comprised of a base, a bottom square plate, a bottom net, 10 layers of side nets made with fine stainless steel prongs. A top net, a top square plate, the holding tubes, and stopper pins. The Novel Mold system can create different sizes of tissues, including two by two millimeters, four by four millimeters, and six by six millimeters.The base bottom square plate and bottom net are stacked and aligned using the corner posts. 10 layers of side nets are then stacked in alternating directions to create a net of fine stainless steel prongs, with the aid of a pair of sterile forceps. The filling base is then flushed with 1X phosphate buffer solution, or PBS, to reduce the surface tension prior to seating the spheroids into the novel mold.After wetting the novel mold cavity in the same methane the spheroids are seated into the presupposed cavity of desired size. Upon seating the excess medium drains through the net mold, allowing the spheroids to fill and assume the shape of the predefined cavity. The top net and top square plate are then assembled onto the corner posts and the stopper pins and the holding tubes are fixed, to prevent washout of the spheroids.The filled novel mold system is transferred to a six well plate, with six millimeters of B-27 supplemented medium, and then maintained in the incubator on a swinging shaker for seven to ten days, at 30 to 40 RPM. The duration of incubation can be altered, depending on the size of the cardiac patch. After incubation the system is taken out and the holding tube, stoppers, the top square plate and the top net are removed.The layered side nets are then carefully slid out one by one, taking care not to disrupt the tissue. After removal of all side nets, an intact cardiac patch is obtained on top of the bottom net. Functional synchronous beating is observed within 24 hours.This novel mold based method is an efficient and easy method of creating three dimensional scaffold free cardiac tissues, with minimal manual effort. The resulting multi-layered tissues consist of fused spheroids with satisfactory structural integrity and synchronous beating behavior. This novel mold based method presents a cost effective and scalable alternative to current bio-fabrication methods of engineered tissues.

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Research

JoVE Journal

Bioengineering

Planar and Three-Dimensional Printing of Conductive Inks

Printed electronics rely on low-cost, large-area fabrication routes to create flexible or multidimensional electronic, optoelectronic, and biomedical devices1-3. In this paper, we focus on one- (1D), two- (2D), and three-dimensional (3D) printing of conductive metallic inks in the form of flexible, stretchable, and spanning microelectrodes.
Direct-write assembly4,5 is a 1-to-3D printing technique that enables the fabrication of features ranging from simple lines to complex structures by the deposition of concentrated inks through fine nozzles (~0.1 - 250 &mu;m). This printing method consists of a computer-controlled 3-axis translation stage, an ink reservoir and nozzle, and 10x telescopic lens for visualization. Unlike inkjet printing, a droplet-based process, direct-write assembly involves the extrusion of ink filaments either in- or out-of-plane. The printed filaments typically conform to the nozzle size. Hence, microscale features (&lt; 1 &mu;m) can be patterned and assembled into larger arrays and multidimensional architectures.
In this paper, we first synthesize a highly concentrated silver nanoparticle ink for planar and 3D printing via direct-write assembly. Next, a standard protocol for printing microelectrodes in multidimensional motifs is demonstrated. Finally, applications of printed microelectrodes for electrically small antennas, solar cells, and light-emitting diodes are highlighted.

Planar and three-dimensional printing of conductive metallic inks is described. Our approach provides new avenues for fabricating printed electronic, optoelectronic, and biomedical devices in unusual layouts at the microscale.

Printed electronics rely on low-cost, large-area fabrication routes to create flexible or multidimensional electronic, optoelectronic, and biomedical ...

Human Cartilage Tissue Fabrication Using Three-dimensional Inkjet Printing Technology

Bioprinting, which is based on thermal inkjet printing, is one of the most attractive enabling technologies in the field of tissue engineering and regenerative medicine. With digital control&#160;cells, scaffolds, and growth factors can be precisely deposited to the desired two-dimensional (2D) and three-dimensional (3D) locations rapidly. Therefore, this technology is an ideal approach to fabricate tissues mimicking their native anatomic structures. In order to engineer cartilage with native zonal organization, extracellular matrix composition (ECM), and mechanical properties, we developed a bioprinting platform using a commercial inkjet printer with simultaneous photopolymerization capable for 3D cartilage tissue engineering. Human chondrocytes suspended in poly(ethylene glycol) diacrylate (PEGDA) were printed for 3D neocartilage construction via layer-by-layer assembly. The printed cells were fixed at their original deposited positions, supported by the surrounding scaffold in simultaneous photopolymerization. The mechanical properties of the printed tissue were similar to the native cartilage. Compared to conventional tissue fabrication, which requires longer UV exposure, the viability of the printed cells with simultaneous photopolymerization was significantly higher. Printed neocartilage demonstrated excellent glycosaminoglycan (GAG) and collagen type II production, which was consistent with gene expression. Therefore, this platform is ideal for accurate cell distribution and arrangement for anatomic tissue engineering.

The methods described in this paper show how to convert a commercial inkjet printer into a bioprinter with simultaneous UV polymerization. The printer is capable of constructing 3D tissue structure with cells and biomaterials. The study demonstrated here constructed a 3D neocartilage.

Bioprinting, which is based on thermal inkjet printing, is one of the most attractive enabling technologies in the field of tissue engineering and ...

Analysis of Cell Migration within a Three-dimensional Collagen Matrix

The ability to migrate is a hallmark of various cell types and plays a crucial role in several physiological processes, including&#160;embryonic development, wound healing, and immune responses. However, cell migration is also a key mechanism in cancer enabling these cancer cells to detach from the primary tumor to start metastatic spreading. Within the past years various cell migration assays have been developed to analyze the migratory behavior of different cell types. Because the locomotory behavior of cells markedly differs between a two-dimensional (2D) and three-dimensional (3D) environment it can be assumed that the analysis of the migration of cells that are embedded within a 3D environment would yield in more significant cell migration data. The advantage of the described 3D collagen matrix migration assay is that cells are embedded within a physiological 3D network of collagen fibers representing the major component of the extracellular matrix. Due to time-lapse video microscopy real cell migration is measured allowing the determination of several migration parameters as well as their alterations in response to pro-migratory factors or inhibitors. Various cell types could be analyzed using this technique, including lymphocytes/leukocytes, stem cells, and tumor cells. Likewise, also cell clusters or spheroids could be embedded within the collagen matrix concomitant with analysis of the emigration of single cells from the cell cluster/ spheroid into the collagen lattice. We conclude that the 3D collagen matrix migration assay is a versatile method to analyze the migration of cells within a physiological-like 3D environment.

Cell migration is a biological phenomenon that is involved in a plethora of physiological, such as wound healing and immune responses, and pathophysiological processes, like cancer. The 3D-collagen matrix migration assay is a versatile tool to analyze the migratory properties of different cell types within in a 3D physiological-like environment.

The ability to migrate is a hallmark of various cell types and plays a crucial role in several physiological processes, including&#160;embryonic ...

Generation of a Three-dimensional Full Thickness Skin Equivalent and Automated Wounding

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models reflect the human wound situation better than animal models. Although two-dimensional models are widely used to investigate processes such as cellular migration and proliferation, models that are more complex are required to gain a deeper knowledge about wound healing. Besides a suitable model system, the generation of precise and reproducible wounds is crucial to ensure comparable results between different test runs. In this study, the generation of a three-dimensional full thickness skin equivalent to study wound healing is shown. The dermal part of the models is comprised of human dermal fibroblast embedded in a rat-tail collagen type I hydrogel. Following the inoculation with human epidermal keratinocytes and consequent culture at the air-liquid interface, a multilayered epidermis is formed on top of the models. To study the wound healing process, we additionally developed an automated wounding device, which generates standardized wounds in a sterile atmosphere.

The goal of this protocol is to build up a three-dimensional full thickness skin equivalent, which resembles natural skin. With a specifically constructed automated wounding device, precise and reproducible wounds can be generated under maintenance of sterility.

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models ...

Fabrication of Inverted Colloidal Crystal Poly(ethylene glycol) Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing drugs targeted at the liver, requires a platform in which cells receive proper biochemical and mechanical cues. Recent liver tissue engineering systems have employed three-dimensional (3D) scaffolds composed of synthetic or natural hydrogels, given their high water retention and their ability to provide the mechanical stimuli needed by the cells. There has been growing interest in the inverted colloidal crystal (ICC) scaffold, a recent development, which allows high spatial organization, homotypic and heterotypic cell interaction, as well as cell-extracellular matrix (ECM) interaction. Herein, we describe a protocol to fabricate the ICC scaffold using poly (ethylene glycol) diacrylate (PEGDA) and the particle leaching method. Briefly, a lattice is made from microsphere particles, after which a pre-polymer solution is added, properly polymerized, and the particles are then removed, or leached, using an organic solvent (e.g., tetrahydrofuran). The dissolution of the lattice results in a highly porous scaffold with controlled pore sizes and interconnectivities that allow media to reach cells more easily. This unique structure allows high surface area for the cells to adhere to as well as easy communication between pores, and the ability to coat the PEGDA ICC scaffold with proteins also shows a marked effect on cell performance. We analyze the morphology of the scaffold as well as the hepatocarcinoma cell (Huh-7.5) behavior in terms of viability and function to explore the effect of ICC structure and ECM coatings. Overall, this paper provides a detailed protocol of an emerging scaffold that has wide applications in tissue engineering, especially liver tissue engineering.

Fabrication of Inverted Colloidal Crystal Polyethylene glycol Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

This manuscript presents a detailed protocol for the fabrication of an emerging three-dimensional hepatocyte culture platform, the inverted colloidal crystal scaffold, and the concomitant techniques to assess hepatocyte behavior. The size-controllable pores, interconnectivity and ability to conjugate extracellular matrix proteins to the poly(ethylene glycol) (PEG) scaffold enhance Huh-7.5 cell performance.

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing ...

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.

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 ...

Three-dimensional Tissue Engineered Aligned Astrocyte Networks to Recapitulate Developmental Mechanisms and Facilitate Nervous System Regeneration

Neurotrauma and neurodegenerative disease often result in lasting neurological deficits due to the limited capacity of the central nervous system (CNS) to replace lost neurons and regenerate axonal pathways. However, during nervous system development, neuronal migration and axonal extension often occur along pathways formed by other cells, referred to as &#34;living scaffolds&#34;. Seeking to emulate these mechanisms and to design a strategy that circumvents the inhibitory environment of the CNS, this manuscript presents a protocol to fabricate tissue engineered astrocyte-based &#34;living scaffolds&#34;. To create these constructs, we employed a novel biomaterial encasement scheme to induce astrocytes to self-assemble into dense three-dimensional bundles of bipolar longitudinally-aligned somata and processes. First, hollow hydrogel micro-columns were assembled, and the inner lumen was coated with collagen extracellular-matrix. Dissociated cerebral cortical astrocytes were then delivered into the lumen of the cylindrical micro-column and, at a critical inner diameter of &#60;350 &#181;m, spontaneously self-aligned and contracted to produce long fiber-like cables consisting of dense bundles of astrocyte processes and collagen fibrils measuring &#60;150 &#181;m in diameter yet extending several cm in length. These engineered living scaffolds exhibited &#62;97% cell viability and were virtually exclusively comprised of astrocytes expressing a combination of the intermediate filament proteins glial-fibrillary acidic protein (GFAP), vimentin, and nestin. These aligned astrocyte networks were found to provide a permissive substrate for neuronal attachment and aligned neurite extension. Moreover, these constructs maintain integrity and alignment when extracted from the hydrogel encasement, making them suitable for CNS implantation. These preformed constructs structurally emulate key cytoarchitectural elements of naturally occurring glial-based &#34;living scaffolds&#34; in vivo. As such, these engineered living scaffolds may serve as test-beds to study neurodevelopmental mechanisms in vitro or facilitate neuroregeneration by directing neuronal migration and/or axonal pathfinding following CNS degeneration in vivo.

We showcase the development of self-assembled, three-dimensional bundles of longitudinally aligned astrocytic somata and processes within a novel biomaterial encasement. These engineered &#34;living scaffolds&#34;, exhibiting micron-scale diameter yet extending centimeters in length, may serve as test-beds to study neurodevelopmental mechanisms or facilitate neuroregeneration by directing neuronal migration and/or axonal pathfinding.

Neurotrauma and neurodegenerative disease often result in lasting neurological deficits due to the limited capacity of the central nervous system (CNS) to ...

Culturing Mammalian Cells in Three-dimensional Peptide Scaffolds

A useful technique for culturing cells in a self-assembling nanofiber three-dimensional (3D) scaffold is described. This culture system recreates an environment that closely mimics the structural features of non-polarized tissue. Furthermore, the particular intrinsic nanofiber structure of the scaffold makes it transparent to visual light, which allows for easy visualization of the sample under microscopy. This advantage was largely used to study cell migration, organization, proliferation, and differentiation and thus any development of their particular cellular function by staining with specific dyes or probes. Furthermore, in this work, we describe the good performance of this system to easily study the redifferentiation of expanded human articular chondrocytes into cartilaginous tissue. Cells were encapsulated into self-assembling peptide scaffolds and cultured under specific conditions to promote chondrogenesis. Three-dimensional cultures showed good viability during the 4 weeks of the experiment. As expected, samples cultured with chondrogenic inducers (compared to non-induced controls) stained strongly positive for toluidine blue (which stains glycosaminoglycans (GAGs) that are highly present in cartilage extracellular matrix) and expressed specific molecular markers, including collagen type I, II and X, according to Western Blot analysis. This protocol is easy to perform and can be used at research laboratories, industries and for educational purposes in laboratory courses.

Here, we present a protocol to obtain 3D-culture systems in self-assembling peptide scaffolds to promote the differentiation of dedifferentiated human articular chondrocytes into cartilage-like tissue.

A useful technique for culturing cells in a self-assembling nanofiber three-dimensional (3D) scaffold is described. This culture system recreates an ...

Microdissection of Primary Renal Tissue Segments and Incorporation with Novel Scaffold-free Construct Technology

Kidney transplantation is now a mainstream therapy for end-stage renal disease. However, with approximately 96,000 people on the waiting list and only one-fourth of these patients achieving transplantation, there is a dire need for alternatives for those with failing organs. In order to decrease the harmful consequences of dialysis along with the overall healthcare costs it incurs, active investigation is ongoing in search of alternative solutions to organ transplantation. Implantable tissue-engineered renal cellular constructs are one such feasible approach to replacing lost renal functionality. Here, described for the first time, is the microdissection of murine kidneys for isolation of living corticomedullary renal segments. These segments are capable of rapid incorporation within scaffold-free endothelial-fibroblast constructs which may enable rapid connection with host vasculature once implanted. Adult mouse kidneys were procured from living donors, followed by stereoscope microdissection to obtain renal segments 200 - 300 &#181;m in diameter. Multiple renal constructs were fabricated using primary renal segments harvested from only one kidney. This method demonstrates a procedure which could salvage functional renal tissue from organs that would otherwise be discarded.

Tissue-engineered renal constructs provide a solution for the organ shortage and deleterious effects of dialysis. Here, we describe a protocol to micro dissect murine kidneys for isolation of cortico-medullary segments. These segments are implanted into scaffold-free cellular constructs, forming renal organoids.

Kidney transplantation is now a mainstream therapy for end-stage renal disease. However, with approximately 96,000 people on the waiting list and only ...

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 ...