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Recent progress in the production and maturation of iPSC-cardiomyocytes has facilitated major advances in building bioartificial heart tissue with functional cardiomyocytes. Despite this progress, vascularizing these constructs continues to be a barrier to clinical application. One emerging strategy for vascularization uses aligned “cords” of endothelial cells in tissue grafts to guide assembly of chimeric microvessels upon graft implantation. Here, we test whether this approach can guide vascularization of a bioartificial tissue implanted on the rat heart. We find that patterned cords of human endothelial cells anastomose and become perfused with host blood by 3 days post-implantation. Immunohistochemical staining confirmed that graft-derived micro-vessels persist in the patch for 7 days. Furthermore, we noted a shift in distribution of vessels in the patch from patterned cord-associated clustering at 3 days to a more diffuse distribution pattern at 7 days. This loss of patterning corresponded to an infiltration of CD68+ cells and an increase in collagen within the patch. Upon further engraftment of patches containing both cords and human cardiomyocytes, we identified human cardiomyocytes and graft derived vasculature at the time of explant. Our findings show that patterned endothelial cords guide transient vessel patterning on the rat heart. Our results also suggest that future work should be directed at further adapting vascularization strategies to the epicardial environment and add to an important emerging dialog in cardiac cell therapy that points to the need to characterize host response prior to or in parallel with efficacy studies.

A new open-hardware bioreactor capable of applying electrical field stimulation in conjunction with static or cyclic stretch is presented. Stretch is applied to cells by a specially designed elastomeric membrane with a central seeding region. The main interest of our approach is the fine control of the characteristics of stimulations in regard to timing and amplitude in a simple design based on affordable, easy to find components and 3D printable parts. Our approach opens the way to more complex protocols for electrical and/or mechanical stimulations, which are known important regulators of cardiac phenotypes.

One of the strategies for heart regeneration includes cell delivery to the defected heart. However, most of the injected cells do not form quick cell-cell or cell-matrix interactions, therefore, their ability to engraft at the desired site and improve heart function is poor. Here, the use of a microfluidic system is reported for generating personalized hydrogel-based cellular microdroplets for cardiac cell delivery. To evaluate the system's limitations, a mathematical model of oxygen diffusion and consumption within the droplet is developed. Following, the microfluidic system's parameters are optimized and cardiac cells from neonatal rats or induced pluripotent stem cells are encapsulated. The morphology and cardiac specific markers are assessed and cell function within the droplets is analyzed. Finally, the cellular droplets are injected to mouse gastrocnemius muscle to validate cell retention, survival, and maturation within the host tissue. These results demonstrate the potential of this approach to generate personalized cellular microtissues, which can be injected to distinct regions in the body for treating damaged tissues.

Pulsus alternans is a type of arrhythmia that shows alternate contraction forces of ventricular muscles and is a sign of cardiac complications. In this study, we investigate the parameter dependence of pulsus alternans generation using a mathematical crustacean cardiac cell model with automaticity. Specifically, we modified the parameter values in the model so that they resemble realistic waveforms of the membrane potential and then analyzed the modified model. We also conducted physiological experiment and observed pulsus alternans as irregular heartbeats. We reproduced the generation of pulsus alternans in the modified mathematical model. Numerical results showed that the conductance of the transient calcium current and the calcium-dependent potassium current for the small cell (pacemaker of crustacean heart) is the key to generating such pulsus alternans.

New computational models are able to simulate details of cardiac cell networks. Their results allow a better understanding of the functionality of the heart and suggest possible actions to reduce non-fatal premature beats that can give rise to serious diseases. We developed a user-friendly interface to organize Neuron simulations and to present in real-time a three-dimensional representation of the electrical activity due to the gap junctions which interconnect the cells inside cardiac tissues. All physiological parameters were set according to real experimental observations and compared against different types of arrhythmias, retrieved from the Physionet Data Base.

Myocardial infarction (MI), caused by coronary heart disease (CHD), remains one of the most common causes of death in the United States. Over the last few decades, scientists have invested considerable resources on the study and development of cell therapies for myocardial regeneration after MI. However, due to a number of limitations, they are not yet readily available for clinical applications. Mounting evidence supports the theory that paracrine products are the main contributors to the regenerative effects attributed to these cell therapies. The next generation of cell-based MI therapies will identify and isolate cell products and derivatives, integrate them with biocompatible materials and technologies, and use them for the regeneration of damaged myocardial tissue. This review discusses the progress made thus far in pursuit of this new generation of cell therapies. Their fundamental regenerative mechanisms, their potential to combine with other therapeutic products, and their role in shaping new clinical approaches for heart tissue engineering, are addressed.

Understanding the factors that influence the electrical excitability is important for successful engineering and therapeutic translation of cardiac tissue. Electric field excitation is widely utilized in vitro and in vivo to assess the response of cardiomyocytes to electrical excitation. The excitability of cardiac tissue is influenced by a variety of factors, including anatomic location in the heart, disease status, and age. We dissect properties that alter the electrical excitability of ventricular myocardial tissue constructs in vitro in 2D and 3D models of neonatal rat ventricular myocytes, using a custom-made integrated live-cell imaging and pacing setup. We find that for both 2D and 3D constructs, the electrical signal strength correlates negatively with the threshold stimulation duration required for pacing and driving the engineered tissue, and the resulting strength-duration curve is well approximated by the Lapicque-Hill model of electrically excitable membranes. By comparing strength-duration relationships, we find that pacing 2D constructs at 2 Hz requires 1.7 to 1.9 times the stimulus strength compared to pacing at 1 Hz (n=3, p

Cardiac cells are subjected to mechanical load during each heart-beat. Normal heart load is essential for physiological development and cardiac function. At the same time, excessive load can induce pathologies such as cardiac hypertrophy. While the forces working on the heart as an organ are well-understood, information regarding stretch response at the cellular level is limited. Since cardiac stretch-response depends on the amplitude and pattern of the applied load as well as its timing during the beating cycle, the directionality of load application and its phase relative to action potential generation must be controlled precisely. Here, we design a new experimental setup, which enables high-resolution fluorescence imaging of cultured cardiac cells under cyclic uniaxial mechanical load and electrical stimulation. Cyclic stretch was applied in different phases relative to the electrical stimulus and the effect on cardiac cell beating was monitored. The results show a clear phase-dependent response and provide insight into cardiac response to excessive loading conditions.

The increasing population of patients with heart disease and the limited availability of organs for transplantation have encouraged multiple strategies to fabricate healthy implantable cardiac tissues. One of the main challenges in cardiac tissue engineering is to direct cell behaviors to form functional three-dimensional (3D) biomimetic constructs. This article provides a brief review on various cell sources used in cardiac tissue engineering and highlights the effect of scaffold-based signals such as topographical and biochemical cues and stiffness. Then, conventional and novel micro-engineered bioreactors for the development of functional cardiac tissues will be explained. Bioreactor-based signals including mechanical and electrical cues to control cardiac cell behavior will also be elaborated in detail. Finally, the application of computational fluid dynamics to design suitable bioreactors will be discussed. This review presents the current state-of-the-art, emerging directions and future trends that critically appraise the concepts involved in various approaches to direct cells for building functional hearts and heart parts.

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The mature heart is composed primarily of four different cell types: cardiac myocytes, endothelium, smooth muscle, and fibroblasts. These cell types derive from pluripotent progenitors that become progressively restricted with regard to lineage potential, giving rise to multipotent cardiac progenitor cells and, ultimately, the differentiated cell types of the heart. Recent studies have begun to shed light on the defining characteristics of the intermediary cell types that exist transiently during this developmental process and the extrinsic and cell-autonomous factors that influence cardiac lineage decisions and cellular competence. This information will shape our understanding of congenital and adult cardiac disease and guide regenerative therapeutic approaches. In addition, cardiac progenitor specification can serve as a model for understanding basic mechanisms regulating the acquisition of cellular identity. In this review, we present the concept of “chromatin competence” that describes the potential for three-dimensional chromatin organization to function as the molecular underpinning of the ability of a progenitor cell to respond to inductive lineage cues and summarize recent studies advancing our understanding of cardiac cell specification, gene regulation, and chromatin organization and how they impact cardiac development.

Assembling three-dimensional (3D) tissues from single cells necessitates the use of various advanced technological methods because higher-density tissues require numerous complex capillary structures to supply sufficient oxygen and nutrients. Accordingly, creating healthy culture conditions to support 3D cardiac tissues requires an appropriate balance between the supplied nutrients and cell metabolism. The objective of this study was to develop a simple and efficient method for low-temperature cultivation (< 37 °C) that decreases cell metabolism for facilitating the buildup of 3D cardiac tissues. We created 3D cardiac tissues using cell sheet technology and analyzed the viability of the cardiac cells in low-temperature environments. To determine a method that would allow thicker 3D tissues to survive, we investigated the cardiac tissue viability under low-temperature culture processes at 20–33.5 °C and compared it with the viability under the standard culture process at 37 °C. Our results indicated that the standard culture process at 37 °C was unable to support higher-density myocardial tissue; however, low-temperature culture conditions maintained dense myocardial tissue and prevascularization. To investigate the efficiency of transplantation, layered cell sheets produced by the low-temperature culture process were also transplanted under the skin of nude rats. Cardiac tissue cultured at 30 °C developed denser prevascular networks than the tissue cultured at the standard temperature. Our novel findings indicate that the low-temperature process is effective for fabricating 3D tissues from high-functioning cells such as heart cells. This method should make major contributions to future clinical applications and to the field of organ engineering., Highlights • Low-temperature culture conditions maintained layered myocardial cell sheets. • Cardiac tissue cultured at 30 °C developed denser prevascular networks than the 37 °C cultivation. • Low-temperature tissue engineering could possibily improve cell delivery for transplantation.

In the last 10 years the number of studies showing the benefits of resistance training (RT) to the cardiovascular system, have grown. In comparison to aerobic training, RT-induced favorable adaptations to the cardiovascular system have been ignored for many years, thus the mechanisms of the RT-induced cardiovascular adaptations are still uncovered. The lack of animal models with comparable protocols to the RT performed by humans hampers the knowledge. We have used squat-exercise model, which is widely used by many others laboratories. However, to a lesser extent, other models are also employed to investigate the cardiovascular adaptations. In the subsequent sections we will review the information regarding cardiac morphological adaptations, signaling pathway of the cardiac cell, cardiac function and the vascular adaptation induced by RT using this animal model developed by Tamaki et al. in 1992. Furthermore, we also describe cardiovascular findings observed using other animal models of RT.

Rationale The major role of a transverse-tubular (TT) network in a cardiac cell is to facilitate effective excitation-contraction coupling and signaling. The TT network structures are heterogeneous within a single cell, and vary between different types of cells and species. They are also remodeled in cardiac diseases. However, how different TT network structures predispose cardiac cells to arrhythmogenesis remains to be revealed. Objective To systematically investigate the roles of TT network structure and the underlying mechanisms in the genesis of intracellular calcium (Ca2 +) alternans and triggered activity (TA). Methods and results Based on recent experimental observations, different TT network structures, including uniformly and non-uniformly random TT distributions, were modeled in a cardiac cell model consisting of a three-dimensional network of Ca2 + release units (CRUs). Our simulations showed that both Ca2 + alternans and Ca2 + wave-mediated TA were promoted when the fraction of orphaned CRUs was in an intermediate range, but suppressed in cells exhibiting either well-organized TT networks or low TT densities. Ca2 + alternans and TA could be promoted by low TT densities when the cells were small or the CRU coupling was strong. Both alternans and TA occurred more easily in uniformly random TT networks than in non-uniformly random TT networks. Subcellular spatially discordant Ca2 + alternans was promoted by non-uniformly random TT networks but suppressed by increasing CRU coupling strength. These mechanistic insights provide a holistic understanding of the effects of TT network structure on the susceptibility to arrhythmogenesis. Conclusions The TT network plays important roles in promoting Ca2 + alternans and TA, and different TT network structures may predispose cardiac cells differently to arrhythmogenesis.

Summary Fulfilling the potential of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes for studying conduction and arrhythmogenesis requires development of multicellular models and methods for long-term repeated tissue phenotyping. We generated confluent hiPSC-derived cardiac cell sheets (hiPSC-CCSs), expressing the genetically encoded voltage indicator ArcLight. ArcLight-based optical mapping allowed generation of activation and action-potential duration (APD) maps, which were validated by mapping the same hiPSC-CCSs with the voltage-sensitive dye, Di-4-ANBDQBS. ArcLight mapping allowed long-term assessment of electrical remodeling in the hiPSC-CCSs and evaluation of drug-induced conduction slowing (carbenoxolone, lidocaine, and quinidine) and APD prolongation (quinidine and dofetilide). The latter studies also enabled step-by-step depiction of drug-induced arrhythmogenesis ("torsades de pointes in the culture dish") and its prevention by MgSO4 and rapid pacing. Phase-mapping analysis allowed biophysical characterization of spiral waves induced in the hiPSC-CCSs and their termination by electrical cardioversion and overdrive pacing. In conclusion, ArcLight mapping of hiPSC-CCSs provides a powerful tool for drug testing and arrhythmia investigation., Graphical Abstract, Highlights • Optical mapping of hiPSC-derived cardiac cell sheets expressing ArcLight • Evaluating effects of drugs and time (weeks) on conduction and APD • Mapping drug-induced TdP and electrically induced spiral waves (rotors) • Evaluating interventions aiming to prevent or terminate arrhythmias in the model, Shaheen and Shiti et al. combine hiPSC-CMs, two-dimensional cardiac tissue models, and optical mapping of a genetically encoded voltage indicator (ArcLight) to enable both short-term and repeated tissue electrophysiological phenotyping (over weeks). This allowed tracking of electrophysiological tissue remodeling over time; drug effects on conduction, repolarization, and pro-arrhythmia; and investigation of arrhythmia mechanisms and treatments.

Since our observation that T-tubules can fail to propagate action potentials in diseased hearts (1), our studies have focused on understanding the consequences of these electrical defects for local Ca2+ release (2) and force production (3). More recently, we have started to explore the causes of electrical defects (4), focusing on the presence of electrical conduction failures, seemingly associated with a local drop in membrane excitability (5). The methodology developed through our work has allowed us to quantitatively assess T-tubular conductivity, thus permitting evaluation of the efficiency of passive spread of voltage changes across the cardiac cell. Although these passive … [↵][1]2To whom correspondence should be addressed. Email: sacconi{at}lens.unifi.it. [1]: #xref-corresp-1-1

Necrosis is an ancient topic which gains new attraction in the research area these years. There is no doubt that some necrosis can be regulated by genetic manipulation other than an accidental cell death resulting from physical or chemical stimuli. Recent advances in the molecular mechanism underlying the programmed necrosis show a fine regulation network which indicates new therapy targets in human diseases. Heart diseases seriously endanger our health and have high fatality rates in the patients. Cell death of cardiac myocytes is believed to be critical in the pathogenesis of heart diseases. Although necrosis is likely to play a more important role in cardiac cell death than apoptosis, apoptosis has been paid much attention in the past 30 years because it used to be considered as the only form of programmed cell death. However, recent findings of programmed necrosis and the related signalling pathways have broadened our horizon in the field of programmed cell death and promote new pharmacological application in the treatment of heart diseases. In this review, we summarize the advanced progress in these signalling pathways and discuss the pathos‐physiological relevance and therapeutic implication of targeting necrosis in heart diseases treatment.

The microfluidic systems are designed especially for many biological applications. An Organ-on-a-chip system, used to mimic organ functions, is one type of such microsystems. Various organs, e.g., liver, skin, lung, or breast are investigated in microscale. The microsystems designed for heart cell culture and analysis (called Heart-on-a-chip) are also fabricated. In this chapter, a characterization of the microfluidic systems for cardiac cell culture is described. Interest in this research area stems from the fact that heart diseases are the most common cause of death around the world. Therefore, research issues concerning heart diseases are presented at the beginning of this chapter. Two approaches of investigating cardiac cells in microscale are shown: the creation of a beating heart culture model, which mimics heart tissue and the creation of a whole vascular system, which mimics blood flow in vessels. Specific properties, which have to be provided in Heart-on-a-chip systems, are also presented. Features such as: perfusion conditions, electrical field, stretching, hydrogels, and nanofibres are used to mimic a native myocardium. Additionally, heart cell culture in the microsystems is often used to simulate heart diseases and investigate heart regeneration using stem cells (SCs).

Background/Aims: Diabetic cardiomyopathy is associated with increased apoptosis and suppressed autophagy in cardiac cells. The polyphenol resveratrol has shown beneficial effects in various cardiovascular diseases. This study investigated if resveratrol protected cardiac cells by modulating apoptosis and autophagy in the context of diabetes. Methods: H9c2 cardiac myoblast cells were exposed to high glucose combined with palmitate. Autophagy was evaluated by estimating LC3-II/I ratio, P62 protein levels, and LC3 fluorescent puncta. Apoptosis was assessed by using terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), flow cytometry, and analysis of the protein expression of apoptotic markers (cleavage of caspase-3 and PARP). Results: High glucose and palmitate suppressed autophagic activity and exacerbated apoptotic cell death in cardiac myoblast cells. Resveratrol restored autophagy and attenuated apoptosis in cells upon diabetic stimuli. Moreover, resveratrol activated AMPK and JNK1, thereby suppressing mTOR and its downstream effectors p70S6K1 and 4EBP1, as well as disrupting the Beclin1–Bcl-2 complex. Conclusion: Resveratrol protects cardiac cells by regulating the switch between autophagy and apoptotic machinery under diabetic conditions, which is attributed by AMPK-mediated phosphorylation of mTORC1/p70S6K1/4EBP1 and JNK-mediated dissociation of Beclin1-Bcl-2. Our study suggests that autophagy may be an important target for resveratrol in the treatment of diabetic cardiomyopathy.

Stem cells (SCs) are the main source of biological material used in cell therapy and tissue engineering. Additionally, these cells are being investigated as a potential therapy technique for cardiovascular diseases (CVDs) and heart regeneration. To improve the investigation of SC proliferation and maturation, the Lab-on-a-Chip systems are being developed. There are many reports, which have proven that such microsystems have been successfully used for SC differentiation into different cell lineages. In this chapter, we present Heart-on-a-chip systems based on stem cells—the microsystems utilized for SC differentiation into cardiomyocytes (CMs). Various types of SC differentiation performed in Lab-on-a-chip systems are presented at the beginning of this chapter. Next, biochemical, physical and mechanical stimulations are presented as techniques to perform cardiogenesis. Other promising methods, especially the use of graphene and their other forms, which could be used for cardiac differentiation, are presented at the end of this chapter. Finally, we summarize the research focused on heart regeneration using the Lab-on-a-chip systems, and we outline future perspectives for microsystem usage for SC differentiation into CMs.

To meet the need of a large quantity of hPSC-derived cardiomyocytes (CM) for pre-clinical and clinical studies, a robust and scalable differentiation system for CM production is essential. With a human pluripotent stem cells (hPSC) aggregate suspension culture system we established previously, we developed a matrix-free, scalable, and GMP-compliant process for directing hPSC differentiation to CM in suspension culture by modulating Wnt pathways with small molecules. By optimizing critical process parameters including: cell aggregate size, small molecule concentrations, induction timing, and agitation rate, we were able to consistently differentiate hPSCs to >90% CM purity with an average yield of 1.5 to 2 × 109 CM/L at scales up to 1 L spinner flasks. CM generated from the suspension culture displayed typical genetic, morphological, and electrophysiological cardiac cell characteristics. This suspension culture system allows seamless transition from hPSC expansion to CM differentiation in a continuous suspension culture. It not only provides a cost and labor effective scalable process for large scale CM production, but also provides a bioreactor prototype for automation of cell manufacturing, which will accelerate the advance of hPSC research towards therapeutic applications.

Cell sheet engineering allows investigators/clinicians to prepare cell-dense three-dimensional (3-D) tissues, and various clinical trials with these fabricated tissues have already been performed for regenerating damaged tissues. Cell sheets are easily manipulated and 3-D tissues can be rapidly fabricated by layering the cell sheets. This study used optical coherence tomography (OCT) to noninvasively analyze the following processes: (1) adhesions between layered cell sheets, and (2) the beating and functional interaction of cardiac cell sheet-tissues for fabricating functional thicker 3-D tissues. The tight adhesions and functional couplings between layered cell sheets could be observed cross-sectionally and in real time. Importantly, the noninvasive and cross-sectional analyses of OCT make possible to fabricate 3-D tissues by confirming the adherence and functional couplings between layered cell sheets. OCT technology would contribute to cell sheet engineering and regenerative medicine., Highlights • Development of an OCT system to noninvasively analyze three-dimensional cell sheet-tissues. • Noninvasive and cross-sectional observation of the adhesions between layered cell sheets in detail. • Noninvasive and cross-sectional observation of beating three-dimensional cardiac tissues.

Stem cell regenerative therapies hold promise for treating diseases across the spectrum of medicine. Recent clinical trials have confirmed the safety of stem cell delivery to the heart with promising but variable results. While significant progress has been made in the preclinical stages, the clinical application of cardiac cell therapy is limited by technical challenges, including inability to isolate a pure population of cardiac-specific progenitors capable of robust engraftment and regeneration, lack of appropriate pre-clinical animal models, uncertainty about the best mode of delivery, paucity of adequate imaging modalities, and lack of knowledge about the fate of transplanted cells. The inability of transplanted cells to structurally and functionally integrate into the host myocardium may pose arrhythmogenic risk to patients. This is in part dependent on the type of cell transplanted, where the expression of gap junctions such as connexin-43 is essential not only for electromechanical integration, but has also been found to be protective against electrical instability post-transplant. Additionally, certain methods of cell delivery, such as intramyocardial injection, carry a higher rate of arrhythmias. Other potential contributors to the arrhythmogenicity of cell transplantation include re-entrant pathways due to heterogeneity in conduction velocities between graft and host as well as graft automaticity. In this paper, we discuss the arrhythmogenic potential of cell delivery to the heart.

Defects in intercellular coupling in the heart play a key role in the initiation and persistence of malignant arrhythmias. Such disorders result from abnormal expression and distribution of connexins, the major constituents of cardiac gap junction channels. The alterations of myocardial connexin are well established as a consistent feature of both human and animal heart disease and aging. Following these facts, the modulation of connexin mediated intercellular coupling is suggested as a new antiarrhythmic approach. This review provides recent data supporting this concept. It can be challenging for the development of new antiarrhythmic drugs. Moreover, findings point out the implication of some endogenous compounds in protection from life-threatening arrhythmias via preservation of myocardial connexin.

Nanofibrous structure developed by electrospinning technology provides attractive extracellular matrix conditions for the anchorage, migration and differentiation of stem cells, including those responsible for regenerative medicine. Recently, biocomposite nanofibers consisting of two or more polymeric blends are electrospun more tidily in order to obtain scaffolds with desired functional and mechanical properties depending on their applications. The study focuses on one such an attempt of using copolymer Poly(l-lactic acid)-co-poly (ε-caprolactone) (PLACL), silk fibroin (SF) and Aloe Vera (AV) for fabricating biocomposite nanofibrous scaffolds for cardiac tissue engineering. SEM micrographs of fabricated electrospun PLACL, PLACL/SF and PLACL/SF/AV nanofibrous scaffolds are porous, beadless, uniform nanofibers with interconnected pores and obtained fibre diameter in the range of 459 ± 22 nm, 202 ± 12 nm and 188 ± 16 nm respectively. PLACL, PLACL/SF and PLACL/SF/AV electrospun mats obtained at room temperature with an elastic modulus of 14.1 ± 0.7, 9.96 ± 2.5 and 7.0 ± 0.9 MPa respectively. PLACL/SF/AV nanofibers have more desirable properties to act as flexible cell supporting scaffolds compared to PLACL for the repair of myocardial infarction (MI). The PLACL/SF and PLACL/SF/AV nanofibers had a contact angle of 51 ± 12° compared to that of 133 ± 15° of PLACL alone. Cardiac cell proliferation was increased by 21% in PLACL/SF/AV nanofibers compared to PLACL by day 6 and further increased to 42% by day 9. Confocal analysis for cardiac expression proteins myosin and connexin 43 was observed better by day 9 compared to all other nanofibrous scaffolds. The results proved that the fabricated PLACL/SF/AV nanofibrous scaffolds have good potentiality for the regeneration of infarcted myocardium in cardiac tissue engineering.

Hypocalcaemia is known for its neuromuscular symptoms, which are rapidly alleviated by intravenous supplementation. Calcium is also essential for both cardiac cell excitability and contraction. We present a case of acute heart failure due to hypocalcaemia in a young male with a complex medical history. LEARNING POINTS Hypocalcaemia is a rare cause of acute heart failure. All clinical decisions, although correct and necessary, may have grave consequences in the short and long term. Childhood cancer survivors have an excess risk of developing multiple complications, namely heart failure and lung fibrosis.

Drug-induced Torsade-de-Pointes (TdP) has been responsible for the withdrawal of many drugs from the market and is therefore of major concern to global regulatory agencies and the pharmaceutical industry. The Comprehensive in vitro Proarrhythmia Assay (CiPA) was proposed to improve prediction of TdP risk, using in silico models and in vitro multi-channel pharmacology data as integral parts of this initiative. Previously, we reported that combining dynamic interactions between drugs and the rapid delayed rectifier potassium current (IKr) with multi-channel pharmacology is important for TdP risk classification, and we modified the original O'Hara Rudy ventricular cell mathematical model to include a Markov model of IKr to represent dynamic drug-IKr interactions (IKr-dynamic ORd model). We also developed a novel metric that could separate drugs with different TdP liabilities at high concentrations based on total electronic charge carried by the major inward ionic currents during the action potential. In this study, we further optimized the IKr-dynamic ORd model by refining model parameters using published human cardiomyocyte experimental data under control and drug block conditions. Using this optimized model and manual patch clamp data, we developed an updated version of the metric that quantifies the net electronic charge carried by major inward and outward ionic currents during the steady state action potential, which could classify the level of drug-induced TdP risk across a wide range of concentrations and pacing rates. We also established a framework to quantitatively evaluate a system's robustness against the induction of early afterdepolarizations (EADs), and demonstrated that the new metric is correlated with the cell's robustness to the pro-EAD perturbation of IKr conductance reduction. In summary, in this work we present an optimized model that is more consistent with experimental data, an improved metric that can classify drugs at concentrations both near and higher than clinical exposure, and a physiological framework to check the relationship between a metric and EAD. These findings provide a solid foundation for using in silico models for the regulatory assessment of TdP risk under the CiPA paradigm.

Increased protein phosphatase-1 in heart failure (HF) induces molecular changes deleterious to the cardiac cell. Inhibiting protein phosphatase-1 through the overexpression of a constitutively active inhibitor-1 (I-1c) has been shown to reverse cardiac dysfunction in a model of ischemic HF.This study sought to determine the therapeutic efficacy of a re-engineered adenoassociated viral vector carrying I-1c (BNP116.I-1c) in a preclinical model of nonischemic HF, and to assess thoroughly the safety of BNP116.I-1c gene therapy.Volume-overload HF was created in Yorkshire swine by inducing severe mitral regurgitation. One month after mitral regurgitation induction, pigs were randomized to intracoronary delivery of either BNP116.I-1c (n = 6) or saline (n = 7). Therapeutic efficacy and safety were evaluated 2 months after gene delivery. Additionally, 24 naive pigs received different doses of BNP116.I-1c for safety evaluation.At 1 month after mitral regurgitation induction, pigs developed HF as evidenced by increased left ventricular end-diastolic pressure and left ventricular volume indexes. Treatment with BNP116.I-1c resulted in improved left ventricular ejection fraction (-5.9 ± 4.2% vs. 5.5 ± 4.0%; p 0.001) and adjusted dP/dt maximum (-3.39 ± 2.44 sIntracoronary delivery of BNP116.I-1c was safe and improved contractility of the left ventricle and atrium in a large animal model of nonischemic HF.

Purpose: Biochemical markers such as cardiac troponin I (cTnI) and N-terminal pro B-type natriuretic peptide (NT-proBNP) have become indispensable tools for the diagnosis of myocardial injury, providing highly sensitive and specific information about cardiac cell damage and wall stress. The purpose of the present research was to examine the response of cardiac biomarkers to a soccer game in adolescent male soccer players. Methods: Twenty-two trained adolescent male soccer players (14–16 y) were selected in a purposive manner. Blood samples were taken before, immediately after, and 2 and 24 hours after the game for the determination of cTnI and NT-proBNP. Results: Serum concentration of cTnI and NT-proBNP increased immediately and 2 hours after the soccer game (P P = .002), whereas serum NT-proBNP levels returned to baseline. At no time point did any of the values exceed the upper reference value. Conclusions: This is the first study to investigate the acute responses of cardiac biomarkers to a soccer game in adolescent male players. The postgame elevation of cardiac biomarkers and their rapid recovery are indicative of a physiological rather than a pathological response.

In developed countries cardiac diseases are still the number one cause of death. For this reason, research aims to understand physiological and pathological processes of the heart. Proper functioning of the heart and therefore, the supply of organs with blood is triggered by electrical activity. For each contraction of ventricles an excitation of action potentials through the cardiac cells has preceded. Research to model the excitation of the heart is a relevant topic in order to understand ongoing coherences in the heart and be able to test cardiac devices in vitro. Therefore, in this model we demonstrate a physiological motivated abstracted simulation of the vectorcardiogram (VCG). In this model, we developed the conduction pathway of action potentials in the heart by applying a predefined propagation direction. The segmentation of heart was performed in order to distinguish between the different existing heart tissues. A tree structure was implemented, in-which each node of the tree represents a cardiac cell and each edge of the tree structure the transition between cells. Therefore, the edges of the conduction tree are weighted with the conduction velocity in the considered heart area. Due to the predefined conduction orientation a reduction in complexity can be achieved. The choice of a simple volume conductor facilitates the transfer from the source signals to the chosen observing points on the volume conductor. The simulation of a lead system similar to the Frank lead system shows morphological reasonable results, so that for further investigation the simulation of pathological scenarios is conceivable. Typical characteristics of the VCG like P-Loop, QRS-Loop and the T-Loop are clearly identifiable. The reduction of complexity promises to reach real-time capability using this model for testing in ECG-triggered medical devices [1].

Cardiac failure is a quite severe condition that can result in life-threatening consequences. Cardiac tissue engineering is thought to be one of the most promising technologies to reconstruct damaged cardiac muscles and facilitate myocardial tissue regeneration. We report a new nanofiber bundle substrate for three-dimensional (3D) cardiac cell culture as a platform to investigate cell morphology and contraction. Polymeric nanofiber bundles with various patterns act as physical cues to align the cardiac cell sheets. Comparing the uniaxial alignment with the randomly distributed pattern, we found that the bundles with the former pattern have more “grooves” for the settlement of cardiomyocytes in a 3D structure than the latter. The cardiomyocytes loaded on the aligned nanofiber bundles tend to grow along the fiber axis. The interfacial structure between a single cardiomyocyte in the cardiac cell sheet and the attached nanofibers was observed using environmental scanning electron microscope. Immunofluorescence imaging showed that the uniaxially aligned nanofibers greatly promoted cell attachment and alignment of the cardiomyocytes because of the matching morphology between the nanofiber pattern and the biological components. Moreover, we concluded that the aligned polymeric nanofibers could be a promising substrate suitable for the anisotropic contraction of cardiac cell sheets.

International audience; Cardiac cell therapy holds a real promise for improving heart function and especially of the chronically failing myocardium. Embedding cells into 3D biodegradable scaffolds may better preserve cell survival and enhance cell engraftment after transplantation, consequently improving cardiac cell therapy compared with direct intramyocardial injection of isolated cells.The primary objective of a scaffold used in tissue engineering is the recreation of the natural 3D environment most suitable for an adequate tissue growth. An important aspect of this commitment is to mimic the fibrillar structure of the extracellular matrix, which provides essential guidance for cell organization, survival, and function. Recent advances in nanotechnology have significantly improved our capacities to mimic the extracellular matrix. Among them, electrospinning is well known for being easy to process and cost effective. Consequently, it is becoming increasingly popular for biomedical applications and it is most definitely the cutting edge technique to make scaffolds that mimic the extracellular matrix for industrial applications.Here, the desirable physico-chemical properties of the electrospun scaffolds for cardiac therapy are described, and polymers are categorized to natural and synthetic. Moreover, the methods used for improving functionalities by providing cells with the necessary chemical cues and a more in vivo-like environment are reported.

Cardiovascular disease is a significant global Cardiovascular disease is a significant global health problem. Effectively treating it and exercise, but also demands the development of novel tools for rapid diagnosis and new therapeutics for treatment. The field of nanomaterials is making significant contributions to multiple health care problems in the areas of disease detection, imaging and drug delivery. Gold nanoparticles are particularly promising due to their ease of synthesis, biocompatibility and unique optical properties. In particular, gold nanorods having received much attention for their potential in the diagnosis and treatment of cancer, are now being examined for other biomedical applications. This chapter highlights efforts using gold nanorods in cardiovascular research in such areas as detection of cardiovascular disease, understanding cardiac cell response to nanomaterials and the ability of gold nanorods to alter the mechanical properties of model tissue constructs and cardiac valves .

Significance: Antineoplastic therapies have significantly improved the prognosis of oncology patients. However, these treatments can bring to a higher incidence of side-effects, including the worrying cardiovascular toxicity (CTX). Recent Advances: Substantial evidence indicates multiple mechanisms of CTX, with redox mechanisms playing a key role. Recent data singled out mitochondria as key targets for antineoplastic drug-induced CTX; understanding the underlying mechanisms is, therefore, crucial for effective cardioprotection, without compromising the efficacy of anti-cancer treatments. Critical Issues: CTX can occur within a few days or many years after treatment. Type I CTX is associated with irreversible cardiac cell injury, and it is typically caused by anthracyclines and traditional chemotherapeutics. Type II CTX is generally caused by novel biologics and more targeted drugs, and it is associated with reversible myocardial dysfunction. Therefore, patients undergoing anti-cancer treatments should be closely monitored, and patients at risk of CTX should be identified before beginning treatment to reduce CTX-related morbidity. Future Directions: Genetic profiling of clinical risk factors and an integrated approach using molecular, imaging, and clinical data may allow the recognition of patients who are at a high risk of developing chemotherapy-related CTX, and it may suggest methodologies to limit damage in a wider range of patients. The involvement of redox mechanisms in cancer biology and anticancer treatments is a very active field of research. Further investigations will be necessary to uncover the hallmarks of cancer from a redox perspective and to develop more efficacious antineoplastic therapies that also spare the cardiovascular system.

Cardiac beneficial effects of chronic exercise is well admitted. These effects mainly studied at the organ and organism integrated levels find their origin in cardiomyocyte adaptation. This chapter try to highlight the main trends of the data related to the different parameters subject to such adaptations. This is addressed through cardiomyocytes size and structure, calcium and contractile properties, and finally electrophysiological alterations induced by training as they transpire from the literature. Despite the clarifications needed to decipher healthy cardiomyocyte remodeling, this overview clearly show that cardiac cell plasticity ensure the cardiac adaptation to exercise training and offers an interesting mean of action to counteract physiological disturbances induced by cardiac pathologies.

The field of heart regeneration has witnessed significant advancements toward developing new therapeutics in the past decade. Strategies to regenerate the adult human heart are in constant development in both the experimental and clinical arenas. Although stem cell therapies remain controversial, cell-based heart repair is a promising approach toward regenerating the adult human heart. Experience with cell therapy has resulted in several important milestones in clinical studies. There are still important roadblocks ahead before cell therapy can achieve the regeneration potential for broad numbers of patients. In this chapter, we focus on the history of cardiac cell repair and therapeutic strategies and discuss the lessons learned in cell-based heart regeneration.

The role of small, non-coding microRNAs (miRNAs) has recently emerged as fundamental in the regulation of the physiology of the cardiovascular system. Several specific miRNAs were found to be expressed in embryonic, postnatal, and adult cardiac tissues. In the present review, we will provide an overview about their role in controlling the different pathways regulating cell identity and fate determination. In particular, we will focus on the involvement of miRNAs in pluripotency determination and reprogramming, and specifically on cardiac lineage commitment and cell direct transdifferentiation into cardiomyocytes. The identification of cardiac-specific miRNAs and their targets provide new promising insights into the mechanisms that regulate cardiac development, function and dysfunction. Furthermore, due to their contribution in reprogramming, they could offer new opportunities for developing safe and efficient cell-based therapies for cardiovascular disorders.

Calcium dynamics in a cardiac cell are described by a system of 3-D non-linear stochastic partial differential equations. To obtain solutions that have biophysical properties, it is necessary to explore the model parameter space. To decrease the complexity of the parameter search, we reduce the 3-D stochastic model to a 1-D deterministic model. The reduction of the problem from 3-D to 1-D is done through an asymptotic approximation after non-dimensionalization and based on rational biophysical assumptions of the 3-D domain; the stochastic to deterministic transformation is based on the regular property of the 3-D solution. The result of the model reduction proves very effective in reducing the time required to get qualitative as well as quantitative information about parameter regions in the 3-D stochastic model including calcium dynamics (sparks, wave propagation, and recovery) observed in cardiac cells.

This review article discusses a recent work using engineered cardiac cells to study the function of the intercalated disc putting emphasis on mechanical and electrical coupling.

In the past decade, optical mapping provided crucial mechanistic insight into electromechanical function and the mechanism of ventricular fibrillation. Therefore, to date, optical mapping dominates experimental cardiac electrophysiology. The first cardiac measurements involving optics were done in the early 1900s using the fast cinematograph that later evolved into methods for high-resolution activation and repolarization mapping and stimulation of specific cardiac cell types. The field of "optocardiography," therefore, emerged as the use of light for recording or interfering with cardiac physiology. In this review, we discuss how optocardiography developed into the dominant research technique in experimental cardiology. Furthermore, we envision how optocardiographic methods can be used in clinical cardiology.