The authors are grateful to Alessandra Moretti and Dennis Schade for their kind contribution of material. We acknowledge the great support of the iPS and EHT working group at the Department of Experimental Pharmacology and Toxicology of the UKE. The work of the authors is supported by grants from the DZHK (German Centre for Cardiovascular Research) and the German Ministry of Education and Research (BMBF), the German Research Foundation (DFG Es 88/12-1, HA 3423/5-1), British National Centre for the Replacement Refinement &amp; Reduction of Animals in Research (NC3Rs CRACK-IT grant 35911-259146), the British Heart Foundation RM/13/30157, the European Research Council (Advanced Grant IndivuHeart), the German Heart Foundation and the Freie und Hansestadt Hamburg.

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I.M., T.E. and A.H. are co-founders of EHT Technologies GmbH, Germany.

Engineered heart tissue offers a valuable option to the tool box of cardiovascular research. EHTs in the 24-well format have proven valuable for disease modeling8,14, drug safety screening7,8,10,11,15, or basic cardiovascular research16,17....

Cardiac side effects such as the drug-induced long QT syndrome have led to market withdrawals over the past years. Statistics indicate that about 45% of all withdrawals are due to unwanted effects on the cardiovascular system1. This drug failure after the expensive developmental process and approval is the worst-case scenario for pharmaceutical companies. Research and development departments therefore focus on detection of such unwanted cardiovascular effects early on. For economic and ethical concerns, efforts to reduce animal experiments and replace them with new in vitro screening assays are ongoing.
A set of established assays are included in the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines for preclinical evaluation of proarrhythmic drug effects2. The technology of reprogramming somatic cells followed by differentiation of human induced pluripotent stem cells (hiPSC) boosted this research field3. It now offers the possibility to screen new drug candidates on human cardiomyocytes in vitro and avoids issues with inter-species differences. Recent cardiac differentiation protocols4,5 provide unlimited supply of cardiomyocytes without ethical concern. However, the measurement of contractile force, the most important and best characterized in vivo parameter of cardiomyocytes, is not well established. This is related to the relative immaturity6 of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) as compared to the adult cardiomyocyte. A possible advancement is to engineer 3-dimensional heart tissue from single cells7 (engineered heart tissue, EHT). The EHT protocol is based on embedding single murine or human cardiomyocytes8,9,10 in fibrin hydrogel between two flexible polydimethylsiloxane (PDMS) posts11 in 24-well format. Within a few days the cardiomyocytes start to contract spontaneously as single cells and start to form cellular networks. After 7-10 days, macroscopic contractions of the entire tissue are visible. During this process the extracellular matrix is remodeled, which leads to a decrease of diameter and length. The shortening of the EHT results in bending of the PDMS post even during rest, subjecting cardiomyocytes in the developing EHT to continuous load. EHTs continue to perform auxotonic muscle contractions over several weeks. Human EHTs show responses to physiological and pharmacological stimulation indicating their suitability for drug screening and disease modeling7.
In this manuscript we present a robust and easy protocol for the generation of human EHT, and the automated contractility analysis of concentration dependent changes of the contraction pattern in the presence of hERG channel inhibitors.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>EHT analysis intrument</td>
			<td>EHT Technologies GmbH</td>
			<td>A0001</td>
			<td>Software is included</td>
		</tr>
		<tr>
			<td>EHT PDMS rack</td>
			<td>EHT Technologies GmbH</td>
			<td>C0001</td>
			<td></td>
		</tr>
		<tr>
			<td>EHT PTFE spacer</td>
			<td>EHT Technologies GmbH</td>
			<td>C0002</td>
			<td></td>
		</tr>
		<tr>
			<td>EHT electrode</td>
			<td>EHT Technologies GmbH</td>
			<td>P0001</td>
			<td></td>
		</tr>
		<tr>
			<td>EHT pacing adapter/cable</td>
			<td>EHT Technologies GmbH</td>
			<td>P0002</td>
			<td></td>
		</tr>
		<tr>
			<td>24-well-plate</td>
			<td>Nunc</td>
			<td>144530</td>
			<td></td>
		</tr>
		<tr>
			<td>6 well-cell culture plate</td>
			<td>Nunc</td>
			<td>140675</td>
			<td></td>
		</tr>
		<tr>
			<td>15 ml falcon tube, graduated&#160;</td>
			<td>Sarstedt</td>
			<td>62,554,502</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell scraper</td>
			<td>Sarstedt</td>
			<td>831,830</td>
			<td></td>
		</tr>
		<tr>
			<td>Spinner flask</td>
			<td>Integra</td>
			<td>182 101</td>
			<td></td>
		</tr>
		<tr>
			<td>Stirrer Variomag/ Cimarec Biosystem Direct&#160;</td>
			<td>Thermo scientific</td>
			<td>70101</td>
			<td>Adjust rotor speed to 40 rpm</td>
		</tr>
		<tr>
			<td>T175 cell culture flask&#160;</td>
			<td>Sarstedt&#160;</td>
			<td>831,812,002</td>
			<td></td>
		</tr>
		<tr>
			<td>V-shaped sedimentation rack&#160;</td>
			<td>Custom made at UKE Hamburg</td>
			<td>na</td>
			<td></td>
		</tr>
		<tr>
			<td>10&#215; DMEM</td>
			<td>Gibco</td>
			<td>52100</td>
			<td></td>
		</tr>
		<tr>
			<td>1-Thioglycerol&#160;</td>
			<td>Sigma Aldrich</td>
			<td>M6145</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Phospho-L-ascorbic acid trisodium salt</td>
			<td>Sigma Aldrich</td>
			<td>49752</td>
			<td></td>
		</tr>
		<tr>
			<td>Activin-A&#160;</td>
			<td>R&#38;D systems</td>
			<td>338-AC</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose&#160;</td>
			<td>Invitrogen</td>
			<td>15510-019</td>
			<td></td>
		</tr>
		<tr>
			<td>Aprotinin</td>
			<td>Sigma Aldrich</td>
			<td>A1153</td>
			<td></td>
		</tr>
		<tr>
			<td>Aqua ad injectabilia</td>
			<td>Baxter GmbH</td>
			<td>1428</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 PLUS insulin&#160;</td>
			<td>Gibco</td>
			<td>17504-044</td>
			<td></td>
		</tr>
		<tr>
			<td>BMP-4</td>
			<td>R&#38;D systems</td>
			<td>314-BP</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase II&#160;</td>
			<td>Worthington</td>
			<td>LS004176</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Biochrom</td>
			<td>F0415</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO&#160;</td>
			<td>Sigma Aldrich</td>
			<td>D4540</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase II, type V (from bovine spleen)</td>
			<td>Sigma&#160;</td>
			<td>D8764</td>
			<td></td>
		</tr>
		<tr>
			<td>Dorsomorphin&#160;</td>
			<td>abcam</td>
			<td>ab120843</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA&#160;</td>
			<td>Roth</td>
			<td>8043.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal calf serum</td>
			<td>Gibco</td>
			<td>10437028</td>
			<td></td>
		</tr>
		<tr>
			<td>FGF2</td>
			<td>Miltenyi Biotec</td>
			<td>130-104-921</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibrinogen (bovine)</td>
			<td>Sigma Aldrich</td>
			<td>F8630</td>
			<td></td>
		</tr>
		<tr>
			<td>Geltrex&#160;</td>
			<td>Gibco</td>
			<td>A1413302</td>
			<td>For coating: 1:200 dilution</td>
		</tr>
		<tr>
			<td>HBSS w/o Ca2+/Mg2+&#160;</td>
			<td>Gibco</td>
			<td>14175-053</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES&#160;</td>
			<td>Roth</td>
			<td>9105.4</td>
			<td></td>
		</tr>
		<tr>
			<td>Horse serum</td>
			<td>Life technologies</td>
			<td>26050088</td>
			<td></td>
		</tr>
		<tr>
			<td>Human serum albumin&#160;</td>
			<td>Biological Industries</td>
			<td>05-720-1B</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin, human</td>
			<td>Sigma Aldrich</td>
			<td>I9278</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamin</td>
			<td>Gibco</td>
			<td>25030-024</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipidmix&#160;</td>
			<td>Sigma Aldrich</td>
			<td>L5146</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>BD Biosciences</td>
			<td>354234</td>
			<td>For EHT reconsitutionmix.</td>
		</tr>
		<tr>
			<td>N-Benzyl-p-Toluenesulfonamide</td>
			<td>TCI</td>
			<td>B3082-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS w/o MgCl2/CaCl2</td>
			<td>Biochrom</td>
			<td>14190</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Gibco</td>
			<td>15140</td>
			<td></td>
		</tr>
		<tr>
			<td>Pluronic F-127&#160;</td>
			<td>Sigma Aldrich</td>
			<td>P2443</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyvinyl alcohol&#160;</td>
			<td>Sigma Aldrich</td>
			<td>P8136</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI 1640&#160;</td>
			<td>Gibco</td>
			<td>21875</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium selenite</td>
			<td>Sigma Aldrich</td>
			<td>S5261</td>
			<td></td>
		</tr>
		<tr>
			<td>TGF&#223;1</td>
			<td>Peprotech</td>
			<td>100-21</td>
			<td></td>
		</tr>
		<tr>
			<td>Thrombin</td>
			<td>Sigma Aldrich</td>
			<td>T7513</td>
			<td></td>
		</tr>
		<tr>
			<td>Transferrin&#160;</td>
			<td>Sigma Aldrich</td>
			<td>T8158</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-27632</td>
			<td>Biorbyt</td>
			<td>orb6014</td>
			<td></td>
		</tr>
		<tr>
			<td>hiPSC</td>
			<td>Custom made at UKE hamburg</td>
			<td>na</td>
			<td></td>
		</tr>
		<tr>
			<td>iCell cardiomyocytes kit</td>
			<td>Cellular Dynamics International</td>
			<td>CMC-100-010-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Pluricyte cardiomyocyte kit</td>
			<td>Pluriomics</td>
			<td>PCK-1.5</td>
			<td></td>
		</tr>
		<tr>
			<td>Cor.4U - HiPSC cardiomyocytes kit</td>
			<td>Axiogenesis AG</td>
			<td>Ax-C-HC02-FR3</td>
			<td></td>
		</tr>
		<tr>
			<td>Cellartis cardiomyocytes</td>
			<td>Takara Bio USA, Inc.</td>
			<td>Y10075</td>
			<td></td>
		</tr>
	</tbody>
</table>

automated contraction analysis of human engineered heart tissue for cardiac drug safety screening

Cardiac tissue engineering describes techniques to constitute three dimensional force-generating engineered tissues. For the implementation of these procedures in basic research and preclinical drug development, it is important to develop protocols for automated generation and analysis under standardized conditions. Here, we present a technique to generate engineered heart tissue (EHT) from cardiomyocytes of different species (rat, mouse, human). The technique relies on the assembly of a fibrin-gel containing dissociated cardiomyocytes between elastic polydimethylsiloxane (PDMS) posts in a 24-well format. Three-dimensional, force-generating EHTs constitute within two weeks after casting. This procedure allows for the generation of several hundred EHTs per week and is technically limited only by the availability of cardiomyocytes (0.4-1.0 x 106/EHT). Evaluation of auxotonic muscle contractions is performed in a modified incubation chamber with a mechanical interlock for 24-well plates and a camera placed on top of this chamber. A software controls a camera moved on an XYZ axis system to each EHT. EHT contractions are detected by an automated figure recognition algorithm, and force is calculated based on shortening of the EHT and the elastic propensity and geometry of the PDMS posts. This procedure allows for automated analysis of high numbers of EHT under standardized and sterile conditions. The reliable detection of drug effects on cardiomyocyte contraction is crucial for cardiac drug development and safety pharmacology. We demonstrate, with the example of the hERG channel inhibitor E-4031, that the human EHT system replicates drug responses on contraction kinetics of the human heart, indicating it to be a promising tool for cardiac drug safety screening.

Cardiac Differentiation and Preparation of EHT
HiPSC were expanded on reduced growth factor basement membrane matrix, dissociated with EDTA and embryoid bodies (EBs) formed in spinner flasks overnight. After mesodermal induction for three days, cardiac differentiation was initiated with the Wnt inhibitor. After ~17 days of differentiation protocol, beating EBs were dissociated into single cells with collagenase type II (Fig...

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Automated Contraction Analysis of Human Engineered Heart Tissue for Cardiac Drug Safety Screening

Here, we show the generation of human engineered heart tissue from induced pluripotent stem cells (hiPSC)-derived cardiomyocytes. We present a method to analyze contraction force and exemplary alteration of contraction pattern by the hERG channel inhibitor E-4031. This method shows high level of robustness and suitability for cardiac drug screening.

Cardiac tissue engineering describes techniques to constitute three dimensional force-generating engineered tissues. For the implementation of these ...

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Cardiovascular Drugs: Antiarrhythmic and Heart Failure Drugs

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12.5K Views.  University Medical Center Hamburg-Eppendorf and DZHK (German Center for Cardiovascular Research). Here, we show the generation of human engineered heart tissue from induced pluripotent stem cells (hiPSC)-derived cardiomyocytes. We present a method to analyze contraction force and exemplary alteration of contraction pattern by the hERG channel inhibitor E-4031. This method shows high level of robustness and suitability for cardiac drug screening. 

Video: Automated Contraction Analysis of Human Engineered Heart Tissue for Cardiac Drug Safety Screening

Bioluminescence Imaging for Assessment of Immune Responses Following Implantation of Engineered Heart Tissue (EHT)

Various techniques of cardiac tissue engineering have been pursued in the past decades including scaffolding strategies using either native or bioartificial scaffold materials, entrapment of cardiac myocytes in hydrogels such as fibrin or collagen and stacking of myocyte monolayers 1. These concepts aim at restoration of compromised cardiac function (e.g. after myocardial infarction) or as experimental models (e.g. predictive toxicology and substance screening or disease modelling). Precise monitoring of cell survival after implantation of engineered heart tissue (EHT) has now become possible using in-vivo bioluminescence imaging (BLI) techniques 2. Here we describe the generation of fibrin-based EHT from a transgenic rat strain with ubiquitous expression of firefly luciferase (ROSA/luciferase-LEW Tg; 3). Implantation is performed into the greater omentum of different rat strains to assess immune responses of the recipient organism following EHT implantation. Comparison of results generated by BLI and the Enzyme Linked Immuno Spot Technique (ELISPOT) confirm the usability of BLI for the assessment of immune responses.

Bioluminescence Imaging for Assessment of Immune Responses Following Implantation of Engineered Heart Tissue EHT

This video demonstrates the use of in vivo bioluminescence imaging to study immune responses after implantation of Engineered Heart Tissue (EHT) in rats.

Various techniques of cardiac tissue engineering have been pursued in the past decades including scaffolding strategies using either native or ...

Self-reporting Scaffolds for 3-Dimensional Cell Culture

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting 3D cellular construct can often be more relevant to studying the molecular events and cell-cell interactions than similar experiments studied in 2D. To create effective 3D cultures with high cell viability throughout the scaffold the culture conditions such as oxygen and pH need to be carefully controlled as gradients in analyte concentration can exist throughout the 3D construct. Here we describe the methods of preparing biocompatible pH responsive sol-gel nanosensors and their incorporation into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds along with their subsequent preparation for the culture of mammalian cells. The pH responsive scaffolds can be used as tools to determine microenvironmental pH within a 3D cellular construct. Furthermore, we detail the delivery of pH responsive nanosensors to the intracellular environment of mammalian cells whose growth was supported by electrospun PLGA scaffolds. The cytoplasmic location of the pH responsive nanosensors can be utilized to monitor intracellular pH (pHi) during ongoing experimentation.

Biocompatible pH responsive sol-gel nanosensors can be incorporated into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds. The produced self-reporting scaffolds can be used for in&#160;situ monitoring of microenvironmental conditions whilst culturing cells upon the scaffold. This is beneficial as the 3D cellular construct can be monitored in real-time without disturbing the experiment.

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting ...

Analysis of Tubular Membrane Networks in Cardiac Myocytes from Atria and Ventricles

In cardiac myocytes a complex network of membrane tubules - the transverse-axial tubule system (TATS) - controls deep intracellular signaling functions. While the outer surface membrane and associated TATS membrane components appear to be continuous, there are substantial differences in lipid and protein content. In ventricular myocytes (VMs), certain TATS components are highly abundant contributing to rectilinear tubule networks and regular branching 3D architectures. It is thought that peripheral TATS components propagate action potentials from the cell surface to thousands of remote intracellular sarcoendoplasmic reticulum (SER) membrane contact domains, thereby activating intracellular Ca2+ release units (CRUs). In contrast to VMs, the organization and functional role of TATS membranes in atrial myocytes (AMs) is significantly different and much less understood. Taken together, quantitative structural characterization of TATS membrane networks in healthy and diseased myocytes is an essential prerequisite towards better understanding of functional plasticity and pathophysiological reorganization. Here, we present a strategic combination of protocols for direct quantitative analysis of TATS membrane networks in living VMs and AMs. For this, we accompany primary cell isolations of mouse VMs and/or AMs with critical quality control steps and direct membrane staining protocols for fluorescence imaging of TATS membranes. Using an optimized workflow for confocal or superresolution TATS image processing, binarized and skeletonized data are generated for quantitative analysis of the TATS network and its components. Unlike previously published indirect regional aggregate image analysis strategies, our protocols enable direct characterization of specific components and derive complex physiological properties of TATS membrane networks in living myocytes with high throughput and open access software tools. In summary, the combined protocol strategy can be readily applied for quantitative TATS network studies during physiological myocyte adaptation or disease changes, comparison of different cardiac or skeletal muscle cell types, phenotyping of transgenic models, and pharmacological or therapeutic interventions.

In cardiac myocytes, tubular membrane structures form intracellular networks. We describe optimized protocols for i) isolation of myocytes from mouse heart including quality control, ii) live cell staining for state-of-the-art fluorescence microscopy, and iii) direct image analysis to quantify the component complexity and the plasticity of intracellular membrane networks.

In cardiac myocytes a complex network of membrane tubules - the transverse-axial tubule system (TATS) - controls deep intracellular signaling functions. ...

Production, Characterization and Potential Uses of a 3D Tissue-engineered Human Esophageal Mucosal Model

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore esophageal adenocarcinoma generally has a poor prognosis, with little improvement in survival rates in recent years. These are difficult conditions to study and there has been a lack of suitable experimental platforms to investigate disorders of the esophageal mucosa.
A model of the human esophageal mucosa has been developed in the MacNeil laboratory which, unlike conventional 2D cell culture systems, recapitulates the cell-cell and cell-matrix interactions present in vivo and produces a mature, stratified epithelium similar to that of the normal human esophagus. Briefly, the model utilizes non-transformed normal primary human esophageal fibroblasts and epithelial cells grown within a porcine-derived acellular esophageal scaffold. Immunohistochemical characterization of this model by CK4, CK14, Ki67 and involucrin staining demonstrates appropriate recapitulation of the histology of the normal human esophageal mucosa.
This model provides a robust, biologically relevant experimental model of the human esophageal mucosa. It can easily be manipulated to investigate a number of research questions including the effectiveness of pharmacological agents and the impact of exposure to environmental factors such as alcohol, toxins, high temperature or gastro-esophageal refluxate components. The model also facilitates extended culture periods not achievable with conventional 2D cell culture, enabling, inter alia, the study of the impact of repeated exposure of a mature epithelium to the agent of interest for up to 20 days. Furthermore, a variety of cell lines, such as those derived from esophageal tumors or Barrett&#8217;s Metaplasia, can be incorporated into the model to investigate processes such as tumor invasion and drug responsiveness in a more biologically relevant environment.

This manuscript describes the production, characterization and potential uses of a tissue engineered 3D esophageal construct prepared from normal primary human esophageal fibroblast and squamous epithelial cells seeded within a de-cellularized porcine scaffold. The results demonstrate the formation of a mature stratified epithelium similar to the normal human esophagus.

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore ...

Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture

Tissue culture has been used for over 100 years to study cells and responses ex vivo. The convention of this technique is the growth of anchorage dependent cells on the 2-dimensional surface of tissue culture plastic. More recently, there is a growing body of data demonstrating more in vivo-like behaviors of cells grown in 3-dimensional culture systems. This manuscript describes in detail the set-up and operation of a hollow fiber bioreactor system for the in vivo-like culture of mammalian cells. The hollow fiber bioreactor system delivers media to the cells in a manner akin to the delivery of blood through the capillary networks in vivo. The system is designed to fit onto the shelf of a standard CO2 incubator and is simple enough to be set-up by any competent cell biologist with a good understanding of aseptic technique. The systems utility is demonstrated by culturing the hepatocarcinoma cell line HepG2/C3A for 7 days. Further to this and in line with other published reports on the functionality of cells grown in 3-dimensional culture systems the cells are shown to possess increased albumin production (an important hepatic function) when compared to standard 2-dimensional tissue culture.

Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture

The functional behavior of cells in culture can be improved by culturing in more in vivo-like 3-dimensional culture environments16-21. This manuscript describes the set-up and operation of a hollow fiber bioreactor system for in vivo-like mammalian tissue culture.

Tissue culture has been used for over 100 years to study cells and responses ex vivo. The convention of this technique is the growth of anchorage ...

Construction of Defined Human Engineered Cardiac Tissues to Study Mechanisms of Cardiac Cell Therapy

Human cardiac tissue engineering can fundamentally impact therapeutic discovery through the development of new species-specific screening systems that replicate the biofidelity of three-dimensional native human myocardium, while also enabling a controlled level of biological complexity, and allowing non-destructive longitudinal monitoring of tissue contractile function. Initially, human engineered cardiac tissues (hECT) were created using the entire cell population obtained from directed differentiation of human pluripotent stem cells, which typically yielded less than 50% cardiomyocytes. However, to create reliable predictive models of human myocardium, and to elucidate mechanisms of heterocellular interaction, it is essential to accurately control the biological composition in engineered tissues. 
To address this limitation, we utilize live cell sorting for the cardiac surface marker SIRP&#945; and the fibroblast marker CD90 to create tissues containing a 3:1 ratio of these cell types, respectively, that are then mixed together and added to a collagen-based matrix solution. Resulting hECTs are, thus, completely defined in both their cellular and extracellular matrix composition.
Here we describe the construction of defined hECTs as a model system to understand mechanisms of cell-cell interactions in cell therapies, using an example of human bone marrow-derived mesenchymal stem cells (hMSC) that are currently being used in human clinical trials. The defined tissue composition is imperative to understand how the hMSCs may be interacting with the endogenous cardiac cell types to enhance tissue function. A bioreactor system is also described that simultaneously cultures six hECTs in parallel, permitting more efficient use of the cells after sorting.

This manuscript describes the creation of defined engineered cardiac tissues using surface marker expression and cell sorting. The defined tissues can then be used in a multi-tissue bioreactor to investigate mechanisms of cardiac cell therapy in order to provide a functional, yet controlled, model system of the human heart.

Human cardiac tissue engineering can fundamentally impact therapeutic discovery through the development of new species-specific screening systems that ...

A Combined 3D Tissue Engineered In Vitro/In Silico Lung Tumor Model for Predicting Drug Effectiveness in Specific Mutational Backgrounds

In the present study, we combined an in vitro 3D lung tumor model with an in silico model to optimize predictions of drug response based on a specific mutational background. The model is generated on a decellularized porcine scaffold that reproduces tissue-specific characteristics regarding extracellular matrix composition and architecture including the basement membrane. We standardized a protocol that allows artificial tumor tissue generation within 14 days including three days of drug treatment. Our article provides several detailed descriptions of 3D read-out screening techniques like the determination of the proliferation index Ki67 staining&#39;s, apoptosis from supernatants by M30-ELISA and assessment of epithelial to mesenchymal transition (EMT), which are helpful tools for evaluating the effectiveness of therapeutic compounds. We could show compared to 2D culture a reduction of proliferation in our 3D tumor model that is related to the clinical situation. Despite of this lower proliferation, the model predicted EGFR-targeted drug responses correctly according to the biomarker status as shown by comparison of the lung carcinoma cell lines HCC827 (EGFR -mutated, KRAS wild-type) and A549 (EGFR wild-type, KRAS-mutated) treated with the tyrosine-kinase inhibitor (TKI) gefitinib. To investigate drug responses of more advanced tumor cells, we induced EMT by long-term treatment with TGF-beta-1 as assessed by vimentin/pan-cytokeratin immunofluorescence staining. A flow-bioreactor was employed to adjust culture to physiological conditions, which improved tissue generation. Furthermore, we show the integration of drug responses upon gefitinib treatment or TGF-beta-1 stimulation - apoptosis, proliferation index and EMT - into a Boolean in silico model. Additionally, we explain how drug responses of tumor cells with a specific mutational background and counterstrategies against resistance can be predicted. We are confident that our 3D in vitro approach especially with its in silico expansion provides an additional value for preclinical drug testing in more realistic conditions than in 2D cell culture.

A Combined 3D Tissue Engineered In Vitro/In Silico Lung Tumor Model for Predicting Drug Effectiveness in Specific Mutational Backgrounds

We present a three-dimensional (3D) lung cancer model based on a biological collagen scaffold to study sensitivity towards non-small-cell-lung-cancer-(NSCLC)-targeted therapies. We demonstrate different read-out techniques to determine the proliferation index, apoptosis and epithelial-mesenchymal transition (EMT) status. Collected data are integrated into an in silico model for prediction of drug sensitivity.

In the present study, we combined an in vitro 3D lung tumor model with an in silico model to optimize predictions of drug response based on a specific ...

Neonatal Cardiac Scaffolds: Novel Matrices for Regenerative Studies

The only definitive therapy for end stage heart failure is orthotopic heart transplantation. Each year, it is estimated that more than 100,000 donor hearts are needed for cardiac transplantation procedures in the United States1-2. Due to the limited numbers of donors, only approximately 2,400 transplants are performed each year in the U.S.2. Numerous approaches, from cell therapy studies to implantation of mechanical assist devices, have been undertaken, either alone or in combination, in an attempt to coax the heart to repair itself or to rest the failing heart3. In spite of these efforts, ventricular assist devices are still largely used for the purpose of bridging to transplantation and the utility of cell therapies, while they hold some curative promise, is still limited to clinical trials. Additionally, direct xenotransplantation has been attempted but success has been limited due to immune rejection. Clearly, another strategy is required to produce additional organs for transplantation and, ideally, these organs would be autologous so as to avoid the complications associated with rejection and lifetime immunosuppression. Decellularization is a process of removing resident cells from tissues to expose the native extracellular matrix (ECM) or scaffold. Perfusion decellularization offers complete preservation of the three dimensional structure of the tissue, while leaving the bulk of the mechanical properties of the tissue intact4. These scaffolds can be utilized for repopulation with healthy cells to generate research models and, possibly, much needed organs for transplantation. We have exposed the scaffolds from neonatal mice (P3), known to retain remarkable cardiac regenerative capabilities,5-8 to detergent mediated decellularization and we repopulated these scaffolds with murine cardiac cells. These studies support the feasibility of engineering a neonatal heart construct. They further allow for the investigation as to whether the ECM of early postnatal hearts may harbor cues that will result in improved recellularization strategies.

In these studies, we provide methodology for novel, neonatal, murine cardiac scaffolds for use in regenerative studies.

The only definitive therapy for end stage heart failure is orthotopic heart transplantation.  Each year, it is estimated that more than 100,000 donor ...

Preparation of Mesh-Shaped Engineered Cardiac Tissues Derived from Human iPS Cells for In Vivo Myocardial Repair

The current protocol describes methods to generate scalable, mesh-shaped engineered cardiac tissues (ECTs) composed of cardiovascular cells derived from human induced pluripotent stem cells (hiPSCs), which are developed towards the goal of clinical use. HiPSC-derived cardiomyocytes, endothelial cells, and vascular mural cells are mixed with gel matrix and then poured into a polydimethylsiloxane (PDMS) tissue mold with rectangular internal staggered posts. By culture day 14 ECTs mature into a 1.5 cm x 1.5 cm mesh structure with 0.5 mm diameter myofiber bundles. Cardiomyocytes align to the long-axis of each bundle and spontaneously beat synchronously. This approach can be scaled up to a larger (3.0 cm x 3.0 cm) mesh ECT while preserving construct maturation and function. Thus, mesh-shaped ECTs generated from hiPSC-derived cardiac cells may be feasible for cardiac regeneration paradigms.

The present protocol generates mesh-shaped engineered cardiac tissues containing cardiovascular cells derived from human induced pluripotent stem cells to allow the investigation of cell implantation therapy for heart diseases.

The current protocol describes methods to generate scalable, mesh-shaped engineered cardiac tissues (ECTs) composed of cardiovascular cells derived from ...

Cardiac Spheroids as in vitro Bioengineered Heart Tissues to Study Human Heart Pathophysiology

Despite several advances in cardiac tissue engineering, one of the major challenges to overcome remains the generation of a fully functional vascular network comprising several levels of complexity to provide oxygen and nutrients within bioengineered heart tissues. Our laboratory has developed a three-dimensional in vitro model of the human heart, known as the "cardiac spheroid" or "CS". This presents biochemical, physiological, and pharmacological features typical of the human heart and is generated by co-culturing its three major cell types, such as cardiac myocytes, endothelial cells, and fibroblasts. Human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs or iCMs) are co-cultured at ratios approximating the ones found in vivo with human cardiac fibroblasts (HCFs) and human coronary artery endothelial cells (HCAECs) in hanging drop culture plates for three to four days. The confocal analysis of CSs stained with antibodies against cardiac Troponin T, CD31 and vimentin (markers for cardiac myocytes, endothelial cells and fibroblasts, respectively) shows that CSs present a complex endothelial cell network, resembling the native one found in the human heart. This is confirmed by the 3D rendering analysis of these confocal images. CSs also present extracellular matrix (ECM) proteins typical of the human heart, such as collagen type IV, laminin and fibronectin. Finally, CSs present a contractile activity measured as syncytial contractility closer to the one typical of the human heart compared to CSs that contain iCMs only. When treated with a cardiotoxic anti-cancer agent, such as doxorubicin (DOX, used to treat leukemia, lymphoma and breast cancer), the viability of DOX-treated CSs is significantly reduced at 10 &#181;M genetic and chemical inhibition of endothelial nitric oxide synthase, a downstream target of DOX in HCFs and HCAECs, reduced its toxicity in CSs. Given these unique features, CSs are currently used as in vitro models to study heart biochemistry, pathophysiology, and pharmacology.

This protocol aims to fabricate 3D cardiac spheroids (CSs) by co-culturing cells in hanging drops.&#160;Collagen-embedded CSs are treated with doxorubicin (DOX, a cardiotoxic agent) at physiological concentrations to model heart failure. In vitro testing using DOX-treated CSs may be used to identify novel therapies for heart failure patients.

Despite several advances in cardiac tissue engineering, one of the major challenges to overcome remains the generation of a fully functional vascular ...