Human engineered heart tissue as a model system for drug testing

The Role of Human-Induced Pluripotent Stem Cells in Studying Cardiac Channelopathies

Cardiac channelopathies are inherited diseases that increase the risk of sudden cardiac death. While different genes have been associated with inherited channelopathies, there are still subtypes, e.g., catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome, where the genetic cause remains unknown. Various models, including animal models, heterologous expression systems, and the human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSCs-CMs) model, have been used to study the pathophysiological mechanisms of channelopathies. Recently, researchers have focused on using hiPSCs-CMs to understand the genotype-phenotype correlation and screen drugs. By combining innovative techniques such as Clustered Regularly Interspaced Short Palindromic Repeats/Clustered Regularly Interspaced Short Palindromic Repeats associated protein 9 (CRISPR/Cas9)-mediated genome editing, and three-dimensional (3D) engineered heart tissues, we can gain new insights into the pathophysiological mechanisms of channelopathies. This approach holds promise for improving personalized drug treatment. This review highlights the role of hiPSCs-CMs in understanding the pathomechanism of Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia and how these models can be utilized for drug screening.

Evaluation of cell survival in different 3D-printed geometric shapes of human iPSC-derived engineered heart tissue

OBJECTIVES

Engineered Heart Tissue (EHT) is a promising tool to repair heart muscle defects and can additionally be used for drug testing. Due to the absence of an in vitro vascularization, EHT geometry crucially impacts nutrient and oxygen supply by diffusion capacity. We analyzed cardiomyocyte survival in different EHT geometries.

METHODS

Different geometries with varying surface-area-to-volume-ratios were calculated (structure A (Ring) AS/V = 58.47 mm2/440 μL3, structure B (Infinity) 25.86 mm2/440 μL3). EHTs were generated from hiPSC-derived cardiomyocytes (4 × 106) and a fibrin/thrombin hydrogel. Cell viability was evaluated by RT-PCR, cytometric studies, and Bioluminescence imaging.

RESULTS

Using 3D-printed casting molds, spontaneously beating EHTs can be generated in various geometric forms. At day 7, the RT-PCR analyses showed a significantly higher Troponin-T value in ring EHTs, compared to infinity EHTs. In cytometric studies, we evaluated 15% more Troponin-T positive cells in ring (73% ± 12%), compared to infinity EHTs (58% ± 11%, p = 0.04). BLI visualized significantly higher cell survival in ring EHTs (ROI = A: 1.14 × 106 p/s and B: 8.47 × 105 p/s, p < 0.001) compared to infinity EHTs during longitudinal cultivation process.

CONCLUSION

Use of 3D-printing allows the creation of EHTs in all desired geometric shapes. The geometry with an optimized surface-area-to-volume-ratio (ring EHT) demonstrated a significantly higher cell survival measured by RT-PCR, Bioluminescence imaging, and cytometric studies using FACS analysis.

Promising tools for future drug discovery and development in antiarrhythmic therapy

Arrhythmia refers to irregularities in the rate and rhythm of the heart, with symptoms spanning from mild palpitations to life-threatening arrhythmias and sudden cardiac death (SCD). The complex molecular nature of arrhythmias complicates the selection of appropriate treatment. Current therapies involve the use of antiarrhythmic drugs (class I-IV) with limited efficacy and dangerous side effects and implantable pacemakers and cardioverter-defibrillators with hardware-related complications and inappropriate shocks. The number of novel antiarrhythmic drug in the development pipeline has decreased substantially during the last decade and underscores uncertainties regarding future developments in this field. Consequently, arrhythmia treatment poses significant challenges, prompting the need for alternative approaches. Remarkably, innovative drug discovery and development technologies show promise in helping advance antiarrhythmic therapies. Here, we review unique characteristics and the transformative potential of emerging technologies that offer unprecedented opportunities for transitioning from traditional antiarrhythmics to next-generation therapies. We assess stem cell technology, emphasizing the utility of innovative cell profiling using multi-omics, high-throughput screening, and advanced computational modeling in developing treatments tailored precisely to individual genetic and physiological profiles. We offer insights into gene therapy, peptide and peptibody approaches for drug delivery. We finally discuss potential strengths and weaknesses of such techniques in reducing adverse effects and enhancing overall treatment outcomes, leading to more effective, specific, and safer therapies. Altogether, this comprehensive overview introduces innovative avenues for personalized rhythm therapy, with particular emphasis on drug discovery, aiming to advance the arrhythmia treatment landscape and the prevention of SCD. Significance Statement Arrhythmias and sudden cardiac death account for 15-20% of deaths worldwide. However, current antiarrhythmic therapies are ineffective and with dangerous side effects. Here, we review the field of arrhythmia treatment underscoring the slow progress in advancing the cardiac rhythm therapy pipeline and the uncertainties regarding evolution of this field. We provide information on how emerging technological and experimental tools can help accelerate progress and address the limitations of antiarrhythmic drug discovery.

Gellan gum-gelatin based cardiac models support formation of cellular networks and functional cardiomyocytes

Cardiovascular diseases remain as the most common cause of death worldwide. To reveal the underlying mechanisms in varying cardiovascular diseases, in vitro models with cells and supportive biomaterial can be designed to recapitulate the essential components of human heart. In this study, we analyzed whether 3D co-culture of cardiomyocytes (CM) with vascular network and with adipose tissue-derived mesenchymal stem/stromal cells (ASC) can support CM functionality. CM were cultured with either endothelial cells (EC) and ASC or with only ASC in hydrazide-modified gelatin and oxidized gellan gum hybrid hydrogel to form cardiovascular multiculture and myocardial co-culture, respectively. We studied functional characteristics of CM in two different cellular set-ups and analyzed vascular network formation, cellular morphology and orientation. The results showed that gellan gum-gelatin hydrogel supports formation of two different cellular networks and functional CM. We detected formation of a modest vascular network in cardiovascular multiculture and extensive ASC-derived alpha smooth muscle actin -positive cellular network in multi- and co-culture. iPSC-CM showed elongated morphology, partly aligned orientation with the formed networks and presented normal calcium transients, beating rates, and contraction and relaxation behavior in both setups. These 3D cardiac models provide promising platforms to study (patho) physiological mechanisms of cardiovascular diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00630-5.

Endothelial dysfunction and cardiovascular diseases: The role of human induced pluripotent stem cells and tissue engineering

Cardiovascular disease (CVD) remains to be the leading cause of death globally today and therefore the need for the development of novel therapies has become increasingly important in the cardiovascular field. The mechanism(s) behind the pathophysiology of CVD have been laboriously investigated in both stem cell and bioengineering laboratories. Scientific breakthroughs have paved the way to better mimic cell types of interest in recent years, with the ability to generate any cell type from reprogrammed human pluripotent stem cells. Mimicking the native extracellular matrix using both organic and inorganic biomaterials has allowed full organs to be recapitulated in vitro. In this paper, we will review techniques from both stem cell biology and bioengineering which have been fruitfully combined and have fueled advances in the cardiovascular disease field. We will provide a brief introduction to CVD, reviewing some of the recent studies as related to the role of endothelial cells and endothelial cell dysfunction. Recent advances and the techniques widely used in both bioengineering and stem cell biology will be discussed, providing a broad overview of the collaboration between these two fields and their overall impact on tissue engineering in the cardiovascular devices and implications for treatment of cardiovascular disease.

Non-Coding RNA-Targeted Therapy: A State-of-the-Art Review

The use of non-coding RNAs (ncRNAs) as drug targets is being researched due to their discovery and their role in disease. Targeting ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), is an attractive approach for treating various diseases, such as cardiovascular disease and cancer. This seminar discusses the current status of ncRNAs as therapeutic targets in different pathological conditions. Regarding miRNA-based drugs, this approach has made significant progress in preclinical and clinical testing for cardiovascular diseases, where the limitations of conventional pharmacotherapy are evident. The challenges of miRNA-based drugs, including specificity, delivery, and tolerability, will be discussed. New approaches to improve their success will be explored. Furthermore, it extensively discusses the potential development of targeted therapies for cardiovascular disease. Finally, this document reports on the recent advances in identifying and characterizing microRNAs, manipulating them, and translating them into clinical applications. It also addresses the challenges and perspectives towards clinical application.

The new era of cardiovascular research: revolutionizing cardiovascular research with 3D models in a dish

Cardiovascular research has heavily relied on studies using patient samples and animal models. However, patient studies often miss the data from the crucial early stage of cardiovascular diseases, as obtaining primary tissues at this stage is impracticable. Transgenic animal models can offer some insights into disease mechanisms, although they usually do not fully recapitulate the phenotype of cardiovascular diseases and their progression. In recent years, a promising breakthrough has emerged in the form of in vitro three-dimensional (3D) cardiovascular models utilizing human pluripotent stem cells. These innovative models recreate the intricate 3D structure of the human heart and vessels within a controlled environment. This advancement is pivotal as it addresses the existing gaps in cardiovascular research, allowing scientists to study different stages of cardiovascular diseases and specific drug responses using human-origin models. In this review, we first outline various approaches employed to generate these models. We then comprehensively discuss their applications in studying cardiovascular diseases by providing insights into molecular and cellular changes associated with cardiovascular conditions. Moreover, we highlight the potential of these 3D models serving as a platform for drug testing to assess drug efficacy and safety. Despite their immense potential, challenges persist, particularly in maintaining the complex structure of 3D heart and vessel models and ensuring their function is comparable to real organs. However, overcoming these challenges could revolutionize cardiovascular research. It has the potential to offer comprehensive mechanistic insights into human-specific disease processes, ultimately expediting the development of personalized therapies.

Deciphering the Tumor Microenvironment of Colorectal Cancer and Guiding Clinical Treatment With Patient-Derived Organoid Technology: Progress and Challenges

Colorectal cancer (CRC) is one of the most prevalent malignant tumors of the digestive tract worldwide. Despite notable advancements in CRC treatment, there is an urgent requirement for preclinical model systems capable of accurately predicting drug efficacy in CRC patients, to identify more effective therapeutic options. In recent years, substantial strides have been made in the field of organoid technology, patient-derived organoid models can phenotypically replicate the original intra-tumor and inter-tumor heterogeneity of CRC, reflecting cellular interactions of the tumor microenvironment. Patient-derived organoid models have become an indispensable tool for investigating the pathogenesis of CRC and facilitating translational research. This review focuses on the application of organoid technology in CRC modeling, tumor microenvironment, and guiding clinical treatment, particularly in drug screening and personalized medicine. It also examines the existing challenges encountered in clinical organoid research and provides a prospective outlook on the future development directions of clinical organoid research, encompassing the standardization of organoid culture technology and the application of tissue engineering technology.

FRESH™ 3D bioprinted cardiac tissue, a bioengineered platform for in vitro pharmacology

There is critical need for a predictive model of human cardiac physiology in drug development to assess compound effects on human tissues. In vitro two-dimensional monolayer cultures of cardiomyocytes provide biochemical and cellular readouts, and in vivo animal models provide information on systemic cardiovascular response. However, there remains a significant gap in these models due to their incomplete recapitulation of adult human cardiovascular physiology. Recent efforts in developing in vitro models from engineered heart tissues have demonstrated potential for bridging this gap using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in three-dimensional tissue structure. Here, we advance this paradigm by implementing FRESH™ 3D bioprinting to build human cardiac tissues in a medium throughput, well-plate format with controlled tissue architecture, tailored cellular composition, and native-like physiological function, specifically in its drug response. We combined hiPSC-CMs, endothelial cells, and fibroblasts in a cellular bioink and FRESH™ 3D bioprinted this mixture in the format of a thin tissue strip stabilized on a tissue fixture. We show that cardiac tissues could be fabricated directly in a 24-well plate format were composed of dense and highly aligned hiPSC-CMs at >600 million cells/mL and, within 14 days, demonstrated reproducible calcium transients and a fast conduction velocity of ∼16 cm/s. Interrogation of these cardiac tissues with the β-adrenergic receptor agonist isoproterenol showed responses consistent with positive chronotropy and inotropy. Treatment with calcium channel blocker verapamil demonstrated responses expected of hiPSC-CM derived cardiac tissues. These results confirm that FRESH™ 3D bioprinted cardiac tissues represent an in vitro platform that provides data on human physiological response.

Miniaturized engineered heart tissues from hiPSC-derived triple cell type co-cultures to study human cardiac function

Human heart tissues grown as three-dimensional spheroids and consisting of different cardiac cell types derived from pluripotent stem cells (hiPSCs) recapitulate aspects of human physiology better than standard two-dimensional models in vitro. They typically consist of less than 5000 cells and are used to measure contraction kinetics although not contraction force. By contrast, engineered heart tissues (EHTs) formed around two flexible pillars, can measure contraction force but conventional EHTs often require between 0.5 and 2 million cells. This makes large-scale screening of many EHTs costly. Our goals here were (i) to create a physiologically relevant model that required fewer cells than standard EHTs making them less expensive, and (ii) to ensure that this miniaturized model retained correct functionality. We demonstrated that fully functional EHTs could be generated from physiologically relevant combinations of hiPSC-derived cardiomyocytes (70%), cardiac fibroblasts (15%) and cardiac endothelial cells (15%), using as few as 1.6 × 104 cells. Our results showed that these EHTs were viable and functional up to 14 days after formation. The EHTs could be electrically paced in the frequency range between 0.6 and 3 Hz, with the optimum between 0.6 and 2 Hz. This was consistent across three downscaled EHT sizes tested. These findings suggest that miniaturized EHTs could represent a cost-effective microphysiological system for disease modelling and examining drug responses particularly in secondary screens for drug discovery.

A highly versatile biopolymer-based platform for the maturation of human pluripotent stem cell-derived cardiomyocytes enables functional analysis in vitro and 3D printing of heart patches

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) represent a valuable tool for in vitro modeling of the cardiac niche and possess great potential in tissue engineering applications. However, conventional polystyrene-based cell culture substrates have adverse effects on cardiomyocytes in vitro due to the stress applied by a stiff substrate on contractile cells. Ultra-high viscosity alginates offer a unique versatility as tunable substrates for cardiac cell cultures due to their biocompatibility, flexible biofunctionalization, and stability. In this work, we analyzed the effect of alginate substrates on hPSC-CM maturity and functionality. Alginate substrates in high-throughput compatible culture formats fostered a more mature gene expression and enabled the simultaneous assessment of chronotropic and inotropic effects upon beta-adrenergic stimulation. Furthermore, we produced 3D-printed alginate scaffolds with differing mechanical properties and plated hPSC-CMs on the surface of these to create Heart Patches for tissue engineering applications. These exhibited synchronous macro-contractions in concert with more mature gene expression patterns and extensive intracellular alignment of sarcomeric structures. In conclusion, the combination of biofunctionalized alginates and human cardiomyocytes represents a valuable tool for both in vitro modeling and regenerative medicine, due to its beneficial effects on cardiomyocyte physiology, the possibility to analyze cardiac contractility, and its applicability as Heart Patches.

In Vitro Models for Improved Therapeutic Interventions in Atrial Fibrillation

Atrial fibrillation is the most common type of cardiac arrhythmias in humans, mostly caused by hyper excitation of specific areas in the atrium resulting in dyssynchronous atrial contractions, leading to severe consequences such as heart failure and stroke. Current therapeutics aim to target this condition through both pharmacological and non-pharmacological approaches. To test and validate any of these treatments, an appropriate preclinical model must be carefully chosen to refine and optimise the therapy features to correctly reverse this condition. A broad range of preclinical models have been developed over the years, with specific features and advantages to closely mimic the pathophysiology of atrial fibrillation. In this review, currently available models are described, from traditional animal models and in vitro cell cultures to state-of-the-art organoids and organs-on-a-chip. The advantages, applications and limitations of each model are discussed, providing the information to select the appropriate model for each research application.

Heart-derived collagen promotes maturation of engineered heart tissue

Although the extracellular matrix (ECM) plays essential roles in heart tissue engineering, the optimal ECM components for heart tissue organization have not previously been elucidated. Here, we focused on the main ECM component, fibrillar collagen, and analyzed the effects of collagens on heart tissue engineering, by comparing the use of porcine heart-derived collagen and other organ-derived collagens in generating engineered heart tissue (EHT). We demonstrate that heart-derived collagen induces better contraction and relaxation of human induced pluripotent stem cell-derived EHT (hiPSC-EHT) and that hiPSC-EHT with heart-derived collagen exhibit more mature profiles than those with collagens from other organs. Further, we found that collagen fibril formation and gel stiffness influence the contraction, relaxation, and maturation of hiPSC-EHT, suggesting the importance of collagen types III and type V, which are relatively abundant in the heart. Thus, we demonstrate the effectiveness of organ-specific collagens in tissue engineering and drug discovery.

Quantification of Cardiomyocyte Contraction In Vitro and Drug Screening by MyocytoBeats

Cardiomyocyte contractility is the crucial feature of heart function. Quantifying cardiomyocyte contraction in vitro is essential for disease phenotype characterization, mechanism illumination, and drug screening. Although many experimental methods have been employed to determine contraction dynamics in vitro, a time-saving and easy-to-use software is still needed to be developed. We presented a reliable tool, named MyocytoBeats, to measure cardiomyocyte contraction by processing recorded videos. Analysis results by MyocytoBeats of various experimental models have shown a significant linear relationship with another validated software. We also performed pharmacology screen in the platform, and astragaloside IV was identified to stabilize the frequency and amplitude of cardiomyocyte in the arrhythmia model. MyocytoBeats is a high-performance tool for generating cardiomyocyte contraction data of vitro study and shows a great potential in cardiac pharmacology study.

Heart in a dish - choosing the right in vitro model

The heart is the first functional organ established during embryogenesis. Investigating heart development and disease is a fascinating and crucial field of research because cardiovascular diseases remain the leading cause of morbidity and mortality worldwide. Therefore, there is great interest in establishing in vitro models for recapitulating both physiological and pathological aspects of human heart development, tissue function and malfunction. Derived from pluripotent stem cells, a large variety of three-dimensional cardiac in vitro models have been introduced in recent years. In this At a Glance article, we discuss the available methods to generate such models, grouped according to the following classification: cardiac organoids, cardiac microtissues and engineered cardiac tissues. For these models, we provide a systematic overview of their applications for disease modeling and therapeutic development, as well as their advantages and limitations to assist scientists in choosing the most suitable model for their research purpose.

Automated assessment of human engineered heart tissues using deep learning and template matching for segmentation and tracking

The high rate of drug withdrawal from the market due to cardiovascular toxicity or lack of efficacy, the economic burden, and extremely long time before a compound reaches the market, have increased the relevance of human in vitro models like human (patient-derived) pluripotent stem cell (hPSC)-derived engineered heart tissues (EHTs) for the evaluation of the efficacy and toxicity of compounds at the early phase in the drug development pipeline. Consequently, the EHT contractile properties are highly relevant parameters for the analysis of cardiotoxicity, disease phenotype, and longitudinal measurements of cardiac function over time. In this study, we developed and validated the software HAARTA (Highly Accurate, Automatic and Robust Tracking Algorithm), which automatically analyzes contractile properties of EHTs by segmenting and tracking brightfield videos, using deep learning and template matching with sub-pixel precision. We demonstrate the robustness, accuracy, and computational efficiency of the software by comparing it to the state-of-the-art method (MUSCLEMOTION), and by testing it with a data set of EHTs from three different hPSC lines. HAARTA will facilitate standardized analysis of contractile properties of EHTs, which will be beneficial for in vitro drug screening and longitudinal measurements of cardiac function.

Proliferation and Maturation: Janus and the Art of Cardiac Tissue Engineering

During cardiac development and morphogenesis, cardiac progenitor cells differentiate into cardiomyocytes that expand in number and size to generate the fully formed heart. Much is known about the factors that regulate initial differentiation of cardiomyocytes, and there is ongoing research to identify how these fetal and immature cardiomyocytes develop into fully functioning, mature cells. Accumulating evidence indicates that maturation limits proliferation and conversely proliferation occurs rarely in cardiomyocytes of the adult myocardium. We term this oppositional interplay the proliferation-maturation dichotomy. Here we review the factors that are involved in this interplay and discuss how a better understanding of the proliferation-maturation dichotomy could advance the utility of human induced pluripotent stem cell-derived cardiomyocytes for modeling in 3-dimensional engineered cardiac tissues to obtain truly adult-level function.

An efficient human stem cells derived cardiotoxicity testing platform for testing oncotherapeutic analogues of quercetin and cinnamic acid

Oncotherapeutics research is progressing at a rapid pace, however, not many drugs complete the successful clinical trial because of severe off-target toxicity to cardiomyocytes which ultimately leads to cardiac dysfunction. It is thus important to emphasize the need for early testing for possible cardiotoxicity of emerging oncotherapeutics. In this study, we assessed a novel stem cell-derived cardiac model for testing for cardiotoxicity of novel oncotherapeutics. We evaluated the cardiotoxic effect of synthesized derivatives of oncotherapeutics, quercetin (QMJ-2, -5, and -6) and cinnamic acid (NMJ-1, -2, and -3) using human Wharton's jelly mesenchymal stem cells-derived cardiomyocytes (WJCM) against known cardiotoxic oncologic drugs, doxorubicin, 5-fluorouracil, cisplatin. QMJ-6, NMJ-2, and NMJ-3 were not cardiotoxic and had minimum cardiac side effects. They did not show any effect on cardiomyocyte viability, caused low LDH release, and intracellular ROS production kept the calcium flux minimal and protected the active mitochondrial status in cardiomyocytes. They persevered cardiac-specific gene expression as well. However, compounds QMJ-2, QMJ-5, and NMJ-1 were cardiotoxic and the concentration needs to be reduced to prevent toxic effects on cardiomyocytes. Significantly, we were able to demonstrate that WJCM is an efficient cardiac testing model to analyze the cardiotoxicity of drugs in a human context.

Engineering approaches for cardiac organoid formation and their characterization

Cardiac organoids are 3-dimensional (3D) structures composed of tissue or niche-specific cells, obtained from diverse sources, encapsulated in either a naturally derived or synthetic, extracellular matrix scaffold, and include exogenous biochemical signals such as essential growth factors. The overarching goal of developing cardiac organoid models is to establish a functional integration of cardiomyocytes with physiologically relevant cells, tissues, and structures like capillary-like networks composed of endothelial cells. These organoids used to model human heart anatomy, physiology, and disease pathologies in vitro have the potential to solve many issues related to cardiovascular drug discovery and fundamental research. The advent of patient-specific human-induced pluripotent stem cell-derived cardiovascular cells provide a unique, single-source approach to study the complex process of cardiovascular disease progression through organoid formation and incorporation into relevant, controlled microenvironments such as microfluidic devices. Strategies that aim to accomplish such a feat include microfluidic technology-based approaches, microphysiological systems, microwells, microarray-based platforms, 3D bioprinted models, and electrospun fiber mat-based scaffolds. This article discusses the engineering or technology-driven practices for making cardiac organoid models in comparison with self-assembled or scaffold-free methods to generate organoids. We further discuss emerging strategies for characterization of the bio-assembled cardiac organoids including electrophysiology and machine-learning and conclude with prospective points of interest for engineering cardiac tissues in vitro.

A Bionic Testbed for Cardiac Ablation Tools

Bionic-engineered tissues have been proposed for testing the performance of cardiovascular medical devices and predicting clinical outcomes ex vivo. Progress has been made in the development of compliant electronics that are capable of monitoring treatment parameters and being coupled to engineered tissues; however, the scale of most engineered tissues is too small to accommodate the size of clinical-grade medical devices. Here, we show substantial progress toward bionic tissues for evaluating cardiac ablation tools by generating a centimeter-scale human cardiac disk and coupling it to a hydrogel-based soft-pressure sensor. The cardiac tissue with contiguous electromechanical function was made possible by our recently established method to 3D bioprint human pluripotent stem cells in an extracellular matrix-based bioink that allows for in situ cell expansion prior to cardiac differentiation. The pressure sensor described here utilized electrical impedance tomography to enable the real-time spatiotemporal mapping of pressure distribution. A cryoablation tip catheter was applied to the composite bionic tissues with varied pressure. We found a close correlation between the cell response to ablation and the applied pressure. Under some conditions, cardiomyocytes could survive in the ablated region with more rounded morphology compared to the unablated controls, and connectivity was disrupted. This is the first known functional characterization of living human cardiomyocytes following an ablation procedure that suggests several mechanisms by which arrhythmia might redevelop following an ablation. Thus, bionic-engineered testbeds of this type can be indicators of tissue health and function and provide unique insight into human cell responses to ablative interventions.

Functional microvascularization of human myocardium in vitro

In this study, we report static and perfused models of human myocardial-microvascular interaction. In static culture, we observe distinct regulation of electrophysiology of human induced pluripotent stem cell derived-cardiomyocytes (hiPSC-CMs) in co-culture with human cardiac microvascular endothelial cells (hCMVECs) and human left ventricular fibroblasts (hLVFBs), including modification of beating rate, action potential, calcium handling, and pro-arrhythmic substrate. Within a heart-on-a-chip model, we subject this three-dimensional (3D) co-culture to microfluidic perfusion and vasculogenic growth factors to induce spontaneous assembly of perfusable myocardial microvasculature. Live imaging of red blood cells within myocardial microvasculature reveals pulsatile flow generated by beating hiPSC-CMs. This study therefore demonstrates a functionally vascularized in vitro model of human myocardium with widespread potential applications in basic and translational research.

Accelerating Cardiovascular Research: Recent Advances in Translational 2D and 3D Heart Models

In vitro modelling the complex (patho-) physiological conditions of the heart is a major challenge in cardiovascular research. In recent years, methods based on three-dimensional (3D) cultivation approaches have steadily evolved to overcome the major limitations of conventional adherent monolayer cultivation (2D). These 3D approaches aim to study, reproduce or modify fundamental native features of the heart such as tissue organization and cardiovascular microenvironment. Therefore, these systems have great potential for (patient-specific) disease research, for the development of new drug screening platforms, and for the use in regenerative and replacement therapy applications. Consequently, continuous improvement and adaptation is required with respect to fundamental limitations such as cardiomyocyte maturation, scalability, heterogeneity, vascularization, and reproduction of native properties. In this review, 2D monolayer culturing and the 3D in vitro systems of cardiac spheroids, organoids, engineered cardiac microtissue and bioprinting as well as the ex vivo technique of myocardial slicing are introduced with their basic concepts, advantages, and limitations. Furthermore, recent advances of various new approaches aiming to extend as well as to optimize these in vitro and ex vivo systems are presented. This article is protected by copyright. All rights reserved.

hESC derived cardiomyocyte biosensor to detect the different types of arrhythmogenic properties of drugs

In the present work, we introduce a new cell-based biosensor for detecting arrhythmias based on a novel utilization of the combination of the Atomic Force Microscope (AFM) lateral force measurement as a nanosensor with a dual 3D cardiomyocyte syncytium. Two spontaneously coupled clusters of cardiomyocytes form this. The syncytium's functional contraction behavior was assessed using video sequences analyzed with Musclemotion ImageJ/Fiji software, and immunocytochemistry evaluated phenotype composition. The application of caffeine solution induced arrhythmia as a model drug, and its spontaneous resolution was monitored by AFM lateral force recording and interpretation and calcium fluorescence imaging as a reference method describing non-synchronized contractions of cardiomyocytes. The phenotypic analysis revealed the syncytium as a functional contractile and conduction cardiac behavior model. Calcium fluorescence imaging was used to validate that AFM fully enabled to discriminate cardiac arrhythmias in this in vitro cellular model. The described novel 3D hESCs-based cellular biosensor is suitable to detect arrhythmic events on the level of cardiac contractile and conduction tissue cellular model. The resulting biosensor allows for screening of arrhythmogenic properties of tailored drugs enabling its use in precision medicine.

Tissue-engineered heart chambers as a platform technology for drug discovery and disease modeling

Current drug screening approaches are incapable of fully detecting and characterizing drug effectiveness and toxicity of human cardiomyocytes. The pharmaceutical industry uses mathematical models, cell lines, and in vivo models. Many promising drugs are abandoned early in development, and some cardiotoxic drugs reach humans leading to drug recalls. Therefore, there is an unmet need to have more reliable and predictive tools for drug discovery and screening applications. Biofabrication of functional cardiac tissues holds great promise for developing a faithful 3D in vitro disease model, optimizing drug screening efficiencies enabling precision medicine. Different fabrication techniques including molding, pull spinning and 3D bioprinting were used to develop tissue-engineered heart chambers. The big challenge is to effectively organize cells into tissue with structural and physiological features resembling native tissues. Some advancements have been made in engineering miniaturized heart chambers that resemble a living pump for drug screening and disease modeling applications. Here, we review the currently developed tissue-engineered heart chambers and discuss challenges and prospects.

Modeling hypertrophic cardiomyopathy with human cardiomyocytes derived from induced pluripotent stem cells

One of the obstacles in studying the pathogenesis of hypertrophic cardiomyopathy (HCM) is the poor availability of myocardial tissue samples at the early stages of disease development. This has been addressed by the advent of induced pluripotent stem cells (iPSCs), which allow us to differentiate patient-derived iPSCs into cardiomyocytes (iPSC-CMs) in vitro. In this review, we summarize different approaches to establishing iPSC models and the application of genome editing techniques in iPSC. Because iPSC-CMs cultured at the present stage are immature in structure and function, researchers have attempted several methods to mature iPSC-CMs, such as prolonged culture duration, and mechanical and electrical stimulation. Currently, many researchers have established iPSC-CM models of HCM and employed diverse methods for performing measurements of cellular morphology, contractility, electrophysiological property, calcium handling, mitochondrial function, and metabolism. Here, we review published results in humans to date within the growing field of iPSC-CM models of HCM. Although there is no unified consensus, preliminary results suggest that this approach to modeling disease would provide important insights into our understanding of HCM pathogenesis and facilitate drug development and safety testing.

MicroRNAs as therapeutic targets in cardiovascular disease

The discovery of microRNAs and their role in diseases was a breakthrough that inspired research into microRNAs as drug targets. Cardiovascular diseases are an area in which limitations of conventional pharmacotherapy are highly apparent and where microRNA-based drugs have appreciably progressed into preclinical and clinical testing. In this Review, we summarize the current state of microRNAs as therapeutic targets in the cardiovascular system. We report recent advances in the identification and characterization of microRNAs, their manipulation and clinical translation, and discuss challenges and perspectives toward clinical application.

Human Engineered Heart Tissue Models for Disease Modeling and Drug Discovery

The emergence of human induced pluripotent stem cells (hiPSCs) and efficient differentiation of hiPSC-derived cardiomyocytes (hiPSC-CMs) induced from diseased donors have the potential to recapitulate the molecular and functional features of the human heart. Although the immaturity of hiPSC-CMs, including the structure, gene expression, conduct, ion channel density, and Ca²⁺ kinetics, is a major challenge, various attempts to promote maturation have been effective. Three-dimensional cardiac models using hiPSC-CMs have achieved these functional and morphological maturations, and disease models using patient-specific hiPSC-CMs have furthered our understanding of the underlying mechanisms and effective therapies for diseases. Aside from the mechanisms of diseases and drug responses, hiPSC-CMs also have the potential to evaluate the safety and efficacy of drugs in a human context before a candidate drug enters the market and many phases of clinical trials. In fact, novel drug testing paradigms have suggested that these cells can be used to better predict the proarrhythmic risk of candidate drugs. In this review, we overview the current strategies of human engineered heart tissue models with a focus on major cardiac diseases and discuss perspectives and future directions for the real application of hiPSC-CMs and human engineered heart tissue for disease modeling, drug development, clinical trials, and cardiotoxicity tests.

Current state and future of 3D bioprinted models for cardiovascular research and drug development

In the last decade, 3D bioprinting technology has emerged as an innovative tissue engineering approach for regenerative medicine and drug development. This article aims at providing an overview about the most commonly used bioengineered tissues, focusing on 3D bioprinted cardiac cells and how they have been utilized for drug discovery and development. The review describes that, while this field is still developing, cardiovascular research may benefit from laboratory-engineered heart tissues built of specific cell types with precise 3D architecture mimicking the native cardiac microenvironment. It also describes the role played by regulatory agencies and potential commercialization pathways for direct translation from the bench to the bedside of studies using 3D bioprinted cardiac tissues.

Application Progress of Organoids in Colorectal Cancer

Currently, colorectal cancer is still the third leading cause of cancer-related mortality, and the incidence is rising. It is a long time since the researchers used cancer cell lines and animals as the study subject. However, these models possess various limitations to reflect the cancer progression in the human body. Organoids have more clinical significance than cell lines, and they also bridge the gap between animal models and humans. Patient-derived organoids are three-dimensional cultures that simulate the tumor characteristics in vivo and recapitulate tumor cell heterogeneity. Therefore, the emergence of colorectal cancer organoids provides an unprecedented opportunity for colorectal cancer research. It retains the molecular and cellular composition of the original tumor and has a high degree of homology and complexity with patient tissues. Patient-derived colorectal cancer organoids, as personalized tumor organoids, can more accurately simulate colorectal cancer patients’ occurrence, development, metastasis, and predict drug response in colorectal cancer patients. Colorectal cancer organoids show great potential for application, especially preclinical drug screening and prediction of patient response to selected treatment options. Here, we reviewed the application of colorectal cancer organoids in disease model construction, basic biological research, organoid biobank construction, drug screening and personalized medicine, drug development, drug toxicity and safety, and regenerative medicine. In addition, we also displayed the current limitations and challenges of organoids and discussed the future development direction of organoids in combination with other technologies. Finally, we summarized and analyzed the current clinical trial research of organoids, especially the clinical trials of colorectal cancer organoids. We hoped to lay a solid foundation for organoids used in colorectal cancer research.

A New Versatile Platform for Assessment of Improved Cardiac Performance in Human-Engineered Heart Tissues

Cardiomyocytes derived from human pluripotent stem cells (hPSC-CMs) hold a great potential as human in vitro models for studying heart disease and for drug safety screening. Nevertheless, their associated immaturity relative to the adult myocardium limits their utility in cardiac research. In this study, we describe the development of a platform for generating three-dimensional engineered heart tissues (EHTs) from hPSC-CMs for the measurement of force while under mechanical and electrical stimulation. The modular and versatile EHT platform presented here allows for the formation of three tissues per well in a 12-well plate format, resulting in 36 tissues per plate. We compared the functional performance of EHTs and their histology in three different media and demonstrated that tissues cultured and maintained in maturation medium, containing triiodothyronine (T3), dexamethasone, and insulin-like growth factor-1 (TDI), resulted in a higher force of contraction, sarcomeric organization and alignment, and a higher and lower inotropic response to isoproterenol and nifedipine, respectively. Moreover, in this study, we highlight the importance of integrating a serum-free maturation medium in the EHT platform, making it a suitable tool for cardiovascular research, disease modeling, and preclinical drug testing.

Comprehensive analyses of the inotropic compound omecamtiv mecarbil in rat and human cardiac preparations

Omecamtiv mecarbil (OM), a myosin activator, was reported to induce complex concentration- and species-dependent effects on contractile function and clinical studies indicated a low therapeutic index with diastolic dysfunction at concentrations above 1 µM. To further characterize effects of OM in a human context and under different preload conditions, we constructed a setup that allows isometric contractility analyses of human induced pluripotent stem cell (hiPSC)-derived engineered heart tissues (EHTs). The results were compared to effects of OM on the very same EHTs measured under auxotonic conditions. OM induced a sustained, concentration-dependent increase in time-to-peak under all conditions (maximally 2-3 fold). Peak force, in contrast, was increased by OM only in human, but not rat EHTs and only under isometric conditions, varied between hiPSC lines and showed a biphasic concentration-dependency with maximal effects at 1 µM. Relaxation time tended to fall under auxotonic and strongly increase under isometric conditions, again with biphasic concentration-dependency. Diastolic tension concentration-dependently increased under all conditions. The latter was reduced by an inhibitor of the mitochondrial sodium calcium exchanger (CGP-37157). OM induced increases in mitochondrial oxidation in isolated cardiomyocytes, indicating that OM, an inotrope that does not increase intracellular and mitochondrial Ca²⁺, can induce mismatch between an increase in ATP and ROS production and unstimulated mitochondrial redox capacity. Taken together, we developed a novel setup well suitable for isometric measurements of EHTs. The effects of OM on contractility and diastolic tension are complex with concentration-, time-, species- and loading-dependent differences. Effects on mitochondrial function require further studies.

Human-Engineered Atrial Tissue for Studying Atrial Fibrillation

This chapter details the generation of atrial fibrin-based engineered heart tissue (EHT) in standard 24-well format as a 3D model for the human atrium. Compared to 2D cultivation, human-induced pluripotent stem cells (hiPSCs)-derived atrial cardiomyocytes demonstrated a higher degree of maturation in 3D format. Furthermore, we have demonstrated in previous work that the model displayed atrial characteristics in terms of contraction and gene expression patterns, electrophysiology, and pharmacological response. Here, we describe how to embed atrial cardiomyocytes differentiated from hiPSCs in a fibrin hydrogel to form atrial EHT attached to elastic silicone posts, allowing auxotonic contraction. In addition, we describe how force and other contractility parameters can be derived from these beating atrial EHTs by video-optical monitoring. The presented atrial EHT model is suitable to study chamber-specific mechanisms, drug effects and to serve for disease modeling.

Engineering Biological Tissues from the Bottom-Up: Recent Advances and Future Prospects

Tissue engineering provides a powerful solution for current organ shortages, and researchers have cultured blood vessels, heart tissues, and bone tissues in vitro. However, traditional top-down tissue engineering has suffered two challenges: vascularization and reconfigurability of functional units. With the continuous development of micro-nano technology and biomaterial technology, bottom-up tissue engineering as a promising approach for organ and tissue modular reconstruction has gradually developed. In this article, relevant advances in living blocks fabrication and assembly techniques for creation of higher-order bioarchitectures are described. After a critical overview of this technology, a discussion of practical challenges is provided, and future development prospects are proposed.

Patient-Derived Organoids in Precision Medicine: Drug Screening, Organoid-on-a-Chip and Living Organoid Biobank

Organoids are in vitro self-assembling, organ-like, three-dimensional cellular structures that stably retain key characteristics of the respective organs. Organoids can be generated from healthy or pathological tissues derived from patients. Cancer organoid culture platforms have several advantages, including conservation of the cellular composition that captures the heterogeneity and pharmacotypic signatures of the parental tumor. This platform has provided new opportunities to fill the gap between cancer research and clinical outcomes. Clinical trials have been performed using patient-derived organoids (PDO) as a tool for personalized medical decisions to predict patients' responses to therapeutic regimens and potentially improve treatment outcomes. Living organoid biobanks encompassing several cancer types have been established, providing a representative collection of well-characterized models that will facilitate drug development. In this review, we highlight recent developments in the generation of organoid cultures and PDO biobanks, in preclinical drug discovery, and methods to design a functional organoid-on-a-chip combined with microfluidic. In addition, we discuss the advantages as well as limitations of human organoids in patient-specific therapy and highlight possible future directions.

Insights to Heart Development and Cardiac Disease Models Using Pluripotent Stem Cell Derived 3D Organoids

Medical research in the recent years has achieved significant progress due to the increasing prominence of organoid technology. Various developed tissue organoids bridge the limitations of conventional 2D cell culture and animal models by recapitulating in vivo cellular complexity. Current 3D cardiac organoid cultures have shown their utility in modelling key developmental hallmarks of heart organogenesis, but the complexity of the organ demands a more versatile model that can investigate more fundamental parameters, such as structure, organization and compartmentalization of a functioning heart. This review will cover the prominence of cardiac organoids in recent research, unpack current in vitro 3D models of the developing heart and look into the prospect of developing physiologically appropriate cardiac organoids with translational applicability. In addition, we discuss some of the limitations of existing cardiac organoid models in modelling embryonic development of the heart and manifestation of cardiac diseases.

Development of a 3-Dimensional Model to Study Right Heart Dysfunction in Pulmonary Arterial Hypertension: First Observations

Pulmonary arterial hypertension (PAH) patients eventually die of right heart failure (RHF). Currently, there is no suitable pre-clinical model to study PAH. Therefore, we aim to develop a right heart dysfunction (RHD) model using the 3-dimensional engineered heart tissue (EHT) approach and cardiomyocytes derived from patient-induced pluripotent stem cells (iPSCs) to unravel the mechanisms that determine the fate of a pressure-overloaded right ventricle. iPSCs from PAH and healthy control subjects were differentiated into cardiomyocytes (iPSC-CMs), incorporated into the EHT, and maintained for 28 days. In comparison with control iPSC-CMs, PAH-derived iPSC-CMs exhibited decreased beating frequency and increased contraction and relaxation times. iPSC-CM alignment within the EHT was observed. PAH-derived EHTs exhibited higher force, and contraction and relaxation times compared with control EHTs. Increased afterload was induced using 2× stiffer posts from day 0. Due to high variability, there were no functional differences between normal and stiffer EHTs, and no differences in the hypertrophic gene expression. In conclusion, under baseline spontaneous conditions, PAH-derived iPSC-CMs and EHTs show prolonged contraction compared with controls, as observed clinically in PAH patients. Further optimization of the hypertrophic model and profound characterization may provide a platform for disease modelling and drug screening.

From Spheroids to Organoids: The Next Generation of Model Systems of Human Cardiac Regeneration in a Dish

Organoids are tiny, self-organized, three-dimensional tissue cultures that are derived from the differentiation of stem cells. The growing interest in the use of organoids arises from their ability to mimic the biology and physiology of specific tissue structures in vitro. Organoids indeed represent promising systems for the in vitro modeling of tissue morphogenesis and organogenesis, regenerative medicine and tissue engineering, drug therapy testing, toxicology screening, and disease modeling. Although 2D cell cultures have been used for more than 50 years, even for their simplicity and low-cost maintenance, recent years have witnessed a steep rise in the availability of organoid model systems. Exploiting the ability of cells to re-aggregate and reconstruct the original architecture of an organ makes it possible to overcome many limitations of 2D cell culture systems. In vitro replication of the cellular micro-environment of a specific tissue leads to reproducing the molecular, biochemical, and biomechanical mechanisms that directly influence cell behavior and fate within that specific tissue. Lineage-specific self-organizing organoids have now been generated for many organs. Currently, growing cardiac organoid (cardioids) from pluripotent stem cells and cardiac stem/progenitor cells remains an open challenge due to the complexity of the spreading, differentiation, and migration of cardiac muscle and vascular layers. Here, we summarize the evolution of biological model systems from the generation of 2D spheroids to 3D organoids by focusing on the generation of cardioids based on the currently available laboratory technologies and outline their high potential for cardiovascular research.

Organoid Technology: A Reliable Developmental Biology Tool for Organ-Specific Nanotoxicity Evaluation

Engineered nanomaterials are bestowed with certain inherent physicochemical properties unlike their parent materials, rendering them suitable for the multifaceted needs of state-of-the-art biomedical, and pharmaceutical applications. The log-phase development of nano-science along with improved "bench to beside" conversion carries an enhanced probability of human exposure with numerous nanoparticles. Thus, toxicity assessment of these novel nanoscale materials holds a key to ensuring the safety aspects or else the global biome will certainly face a debacle. The toxicity may span from health hazards due to direct exposure to indirect means through food chain contamination or environmental pollution, even causing genotoxicity. Multiple ways of nanotoxicity evaluation include several in vitro and in vivo methods, with in vitro methods occupying the bulk of the "experimental space." The underlying reason may be multiple, but ethical constraints in in vivo animal experiments are a significant one. Two-dimensional (2D) monoculture is undoubtedly the most exploited in vitro method providing advantages in terms of cost-effectiveness, high throughput, and reproducibility. However, it often fails to mimic a tissue or organ which possesses a defined three-dimensional structure (3D) along with intercellular communication machinery. Instead, microtissues such as spheroids or organoids having a precise 3D architecture and proximate in vivo tissue-like behavior can provide a more realistic evaluation than 2D monocultures. Recent developments in microfluidics and bioreactor-based organoid synthesis have eased the difficulties to prosper nano-toxicological analysis in organoid models surpassing the obstacle of ethical issues. The present review will enlighten applications of organoids in nanotoxicological evaluation, their advantages, and prospects toward securing commonplace nano-interventions.

Photobiomodulation therapy preconditioning modifies nitric oxide pathway and oxidative stress in human-induced pluripotent stem cell-derived ventricular cardiomyocytes treated with doxorubicin

Doxorubicin (DOX) is an anthracycline antibiotic that exhibits high heart toxicity. Human-induced pluripotent stem cell-derived ventricular cardiomyocytes (hiPSC-vCMs) are important in vitro models for testing drug cardiotoxicity. Photobiomodulation therapy (PBMT) is a non-invasive therapy that stimulates cells growth and self-repair using light irradiation. This study aimed to investigate the in vitro effects of PBMT preconditioning on cardiotoxicity induced by DOX. HiPSC-vCMs were treated with PBMT for 500 s, followed by the addition of 2 μM DOX. LED irradiation preconditioning parameters were at 660 nm with an irradiance of 10 mW/cm², performing 5 J/cm², followed by 24-h DOX exposure (2 μM). Human iPSC-vCMs treated with 2 μM DOX or irradiated with PBMT composed the second and third groups, respectively. The control group did neither receive PBMT preconditioning nor DOX and was irradiated with a white standard lamp. Cells from all groups were collected to perform mRNA and miRNA expressions quantification. PBMT, when applied before the DOX challenge, restored the viability of hiPSC-vCMs and reduced ROS levels. Although downregulated by DOX, myocardial UCP2 mRNA expression presented marked upregulation after PBMT preconditioning. Expression of eNOS and UCP2 mRNA and NO production were decreased after DOX exposure, and PBMT preconditioning before the DOX challenge reversed these changes. Moreover, our data indicated that PBMT preconditioning lowered the miR-24 expression. Our data suggested that PBMT preconditioning ameliorated in vitro DOX-induced cardiotoxicity on transcription level, restoring NO levels and reducing oxidative stress.

Engineered models of the human heart: Directions and challenges

Human heart (patho)physiology is now widely studied using human pluripotent stem cells, but the immaturity of derivative cardiomyocytes has largely limited disease modeling to conditions associated with mutations in cardiac ion channel genes. Recent advances in tissue engineering and organoids have, however, created new opportunities to study diseases beyond "channelopathies." These synthetic cardiac structures allow quantitative measurement of contraction, force, and other biophysical parameters in three-dimensional configurations, in which the cardiomyocytes in addition become more mature. Multiple cardiac-relevant cell types are also often combined to form organized cardiac tissue mimetic constructs, where cell-cell, cell-extracellular matrix, and paracrine interactions can be mimicked. In this review, we provide an overview of some of the most promising technologies being implemented specifically in personalized heart-on-a-chip models and explore their applications, drawbacks, and potential for future development.

Human Embryos, Induced Pluripotent Stem Cells, and Organoids: Models to Assess the Effects of Environmental Plastic Pollution

For a long time, animal models were used to mimic human biology and diseases. However, animal models are not an ideal solution due to numerous interspecies differences between humans and animals. New technologies, such as human-induced pluripotent stem cells and three-dimensional (3D) cultures such as organoids, represent promising solutions for replacing, refining, and reducing animal models. The capacity of organoids to differentiate, self-organize, and form specific, complex, biologically suitable structures makes them excellent in vitro models of development and disease pathogenesis, as well as drug-screening platforms. Despite significant potential health advantages, further studies and considerable nuances are necessary before their clinical use. This article summarizes the definition of embryoids, gastruloids, and organoids and clarifies their appliance as models for early development, diseases, environmental pollution, drug screening, and bioinformatics.

Tissue engineering techniques for iPSC derived three-dimensional cardiac constructs

Recent developments in applied developmental physiology have provided well-defined methodologies for producing human stem cell derived cardiomyocytes. Cardiomyocytes produced in this way have become commonplace as cardiac physiology research models. This accessibility has also allowed for the development of tissue engineered human heart constructs for drug screening, surgical intervention, and investigating cardiac pathogenesis. However, cardiac tissue engineering is an interdisciplinary field that involves complex engineering and physiological concepts, which limits its accessibility. This review provides a readable, broad reaching, and thorough discussion of major factors to consider for the development of cardiovascular tissues from stem cell derived cardiomyocytes. This review will examine important considerations in undertaking a cardiovascular tissue engineering project, and will present, interpret, and summarize some of the recent advancements in this field. This includes reviewing different forms of tissue engineered constructs, a discussion on cardiomyocyte sources, and an in-depth discussion of the fabrication and maturation procedures for tissue engineered heart constructs.

Single and double modified salinomycin analogs target stem-like cells in 2D and 3D breast cancer models

Breast cancer remains one of the leading cancers among women. Cancer stem cells (CSCs) are tumor-initiating cells which drive progression, metastasis, and reoccurrence of the disease. CSCs are resistant to conventional chemo- and radio-therapies and their ability to survive such treatment enables tumor reestablishment. Metastasis is the main cause of mortality in women with breast cancer, thus advances in treatment will depend on therapeutic strategies targeting CSCs. Salinomycin (SAL) is a naturally occurring polyether ionophore antibiotic known for its anticancer activity towards several types of tumor cells. In the present work, a library of 17 C1-single and C1/C20-double modified SAL analogs was screened to identify compounds with improved activity against breast CSCs. Six single- and two double-modified analogs were more potent (IC50 range of 1.1 ± 0.1-1.4 ± 0.2 µM) toward the breast cancer cell line MDA-MB-231 compared to SAL (IC50 of 4.9 ± 1.6 µM). Double-modified compound 17 was found to be more efficacious than SAL against the majority of cancer cell lines in the NCI-60 Human Tumor Cell Line Panel. Compound 17 was more potent than SAL in inhibiting cell migration and cell renewal properties of MDA-MB-231 cells, as well as inducing selective loss of the CD44+/CD24/low stem-cell-like subpopulation in both monolayer (2D) and organoid (3D) culture. The present findings highlight the therapeutic potential of SAL analogs towards breast CSCs and identify select compounds that merit further study and clinical development.

In vitro models of the human heart

Cardiac congenital disabilities are the most common organ malformations, but we still do not understand how they arise in the human embryo. Moreover, although cardiovascular disease is the most common cause of death globally, the development of new therapies is lagging compared with other fields. One major bottleneck hindering progress is the lack of self-organizing human cardiac models that recapitulate key aspects of human heart development, physiology and disease. Current in vitro cardiac three-dimensional systems are either engineered constructs or spherical aggregates of cardiomyocytes and other cell types. Although tissue engineering enables the modeling of some electro-mechanical properties, it falls short of mimicking heart development, morphogenetic defects and many clinically relevant aspects of cardiomyopathies. Here, we review different approaches and recent efforts to overcome these challenges in the field using a new generation of self-organizing embryonic and cardiac organoids.

A gentle introduction to understanding preclinical data for cancer pharmaco-omic modeling

A central goal of precision oncology is to administer an optimal drug treatment to each cancer patient. A common preclinical approach to tackle this problem has been to characterize the tumors of patients at the molecular and drug response levels, and employ the resulting datasets for predictive in silico modeling (mostly using machine learning). Understanding how and why the different variants of these datasets are generated is an important component of this process. This review focuses on providing such introduction aimed at scientists with little previous exposure to this research area.

Quantifying the Compressive Force of 3D Cardiac Tissues via Calculating the Volumetric Deformation of Built-In Elastic Gelatin Microspheres

Quantifying cardiac contractile force is of paramount important in studying mechanical heart failure and screening therapeutic drugs. However, most existing methods can only measure the in-plane component of twitch force of cardiomyocytes, such that mismatching the centripetal compressive stress of heart beating in physiology. Here, a non-destructive method is developed for quantifying the compressive stress and mapping the distribution of the local stress within the 3D cardiac tissues. In detail, elastic gelatin microspheres labeled with fluorescence beads are fabricated by microfluidic chips with high throughput, and they serve as built-in pressure sensors which are wrapped by cardiomyocytes in 3D tissues. The deformation of microspheres and the displacements of fluorescent beads induced by the contraction of cardiomyocytes are demonstrated to characterize the amount and distribution of the centripetal compressive stress. Further, the method shows a potent capability to locally quantify contractile force variation of 3D cardiac tissues, which is induced by agonist (norepinephrine) and inhibitor (blebbistatin). On the whole, the method significantly improves the 3D measurement of mechanical force in vitro and provides a solution for locally quantifying the compressive stress within engineered cardiac tissues.

Scaffold-based and scaffold-free cardiac constructs for drug testing

The safety and therapeutic efficacy of new drugs are tested in experimental animals. However, besides being a laborious, costly process, differences in drug responses between humans and other animals and potential cardiac adverse effects lead to the discontinued development of new drugs. Thus, alternative approaches to animal tests are needed. Cardiotoxicity and responses of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to drugs are conventionally evaluated by cell seeding and two-dimensional (2D) culture, which allows measurements of field potential duration and the action potentials of CMs using multielectrode arrays. However, 2D-cultured hiPSC-CMs lack 3D spatial adhesion, and have fewer intercellular and extracellular matrix interactions, as well as different contractile behavior from CMsin vivo. This issue has been addressed using tissue engineering to fabricate three-dimensional (3D) cardiac constructs from hiPSC-CMs culturedin vitro. Tissue engineering can be categorized as scaffold-based and scaffold-free. In scaffold-based tissue engineering, collagen and fibrin gel scaffolds comprise a 3D culture environment in which seeded cells exhibit cardiac-specific functions and drug responses, whereas 3D cardiac constructs fabricated by tissue engineering without a scaffold have high cell density and form intercellular interactions. This review summarizes the characteristics of scaffold-based and scaffold-free cardiac tissue engineering and discusses the applications of fabricated cardiac constructs to drug screening.

Transcending toward Advanced 3D-Cell Culture Modalities: A Review about an Emerging Paradigm in Translational Oncology

Cancer is a disorder characterized by an uncontrollable overgrowth and a fast-moving spread of cells from a localized tissue to multiple organs of the body, reaching a metastatic state. Throughout years, complexity of cancer progression and invasion, high prevalence and incidence, as well as the high rise in treatment failure cases leading to a poor patient prognosis accounted for continuous experimental investigations on animals and cellular models, mainly with 2D- and 3D-cell culture. Nowadays, these research models are considered a main asset to reflect the physiological events in many cancer types in terms of cellular characteristics and features, replication and metastatic mechanisms, metabolic pathways, biomarkers expression, and chemotherapeutic agent resistance. In practice, based on research perspective and hypothesis, scientists aim to choose the best model to approach their understanding and to prove their hypothesis. Recently, 3D-cell models are seen to be highly incorporated as a crucial tool for reflecting the true cancer cell microenvironment in pharmacokinetic and pharmacodynamics studies, in addition to the intensity of anticancer drug response in pharmacogenomics trials. Hence, in this review, we shed light on the unique characteristics of 3D cells favoring its promising usage through a comparative approach with other research models, specifically 2D-cell culture. Plus, we will discuss the importance of 3D models as a direct reflector of the intrinsic cancer cell environment with the newest multiple methods and types available for 3D-cells implementation.

Human-induced pluripotent stem cell-derived cardiomyocytes, 3D cardiac structures, and heart-on-a-chip as tools for drug research

Development of new drugs is of high interest for the field of cardiac and cardiovascular diseases, which are a dominant cause of death worldwide. Before being allowed to be used and distributed, every new potentially therapeutic compound must be strictly validated during preclinical and clinical trials. The preclinical studies usually involve the in vitro and in vivo evaluation. Due to the increasing reporting of discrepancy in drug effects in animal and humans and the requirement to reduce the number of animals used in research, improvement of in vitro models based on human cells is indispensable. Primary cardiac cells are difficult to access and maintain in cell culture for extensive experiments; therefore, the human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) became an excellent alternative. This technology enables a production of high number of patient- and disease-specific cardiomyocytes and other cardiac cell types for a large-scale research. The drug effects can be extensively evaluated in the context of electrophysiological responses with a use of well-established tools, such as multielectrode array (MEA), patch clamp, or calcium ion oscillation measurements. Cardiotoxicity, which is a common reason for withdrawing drugs from marketing or rejection at final stages of clinical trials, can be easily verified with a use of hiPSC-CM model providing a prediction of human-specific responses and higher safety of clinical trials involving patient cohort. Abovementioned studies can be performed using two-dimensional cell culture providing a high-throughput and relatively lower costs. On the other hand, more complex structures, such as engineered heart tissue, organoids, or spheroids, frequently applied as co-culture systems, represent more physiological conditions and higher maturation rate of hiPSC-derived cells. Furthermore, heart-on-a-chip technology has recently become an increasingly popular tool, as it implements controllable culture conditions, application of various stimulations and continuous parameters read-out. This paper is an overview of possible use of cardiomyocytes and other cardiac cell types derived from hiPSC as in vitro models of heart in drug research area prepared on the basis of latest scientific reports and providing thorough discussion regarding their advantages and limitations.

Organoid models of the tumor microenvironment and their applications

A small percentage of data obtained from animal/2D culture models can be translated to humans. Therefore, there is a need to using native tumour microenvironment mimicking models to improve preclinical screening and reduce this attrition rate. For this purpose, currently, the utilization of organoids is expanding. Tumour organoids can recapitulate tumour microenvironment that is including cancer cells and non-neoplastic host components. Indeed, tumour organoids, both phenotypically and genetically, resemble the tumour tissue that originated from it. The unique properties of the tumour microenvironment can significantly affect drug response and cancer progression. In this review, we will discuss about various organoid culture strategies for modelling the tumour immune microenvironment, their applications and advantages in cancer research such as testing cancer immunotherapeutics, developing novel approaches for personalized medicine, testing drug toxicity, drug screening, study cancer initiation and progression, and we will also review the limitations of organoid culture systems.