The effect of topographical and mechanical stimulation on the structural and functional anisotropy of cardiomyocytes grown on a circular PDMS diaphragm

Integrating melt electrospinning writing and microfluidics to engineer a human cardiac microenvironment for high-fidelity drug screening

The preclinical evaluation of drug-induced cardiotoxicity is critical for developing novel drug, helping to avoid drug wastage and post-marketing withdrawal. Although human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and the engineered heart organoid have been used for drug screening and mimicking disease models, they are always limited by the immaturity and lack of functionality of the cardiomyocytes. In this study, we constructed a Cardiomyocytes-on-a-Chip (CoC) that combines micro-grooves (MGs) and circulating mechanical stimulation to recapitulate the well-organized structure and stable beating of myocardial tissue. The phenotypic changes and maturation of CMs cultured on the CoC have been verified and can be used for the evaluation of cardiotoxicity and cardioprotective drug responses. Taken together, these results highlight the ability of our myocardial microarray platform to accurately reflect clinical behaviour, underscoring its potential as a powerful pre-clinical tool for assessing drug response and toxicity.

Pseudo-3D Topological Alignments Regulate Mechanotransduction and Maturation of Smooth Muscle Cells

Smooth muscle cells (SMCs) sense and respond to mechanical stimuli in their extracellular microenvironments (ECMs), playing a crucial role in muscle tissue engineering. Increasing evidence from topological cues-mediated mechanotransduction of SMCs in ECMs has suggested some potential underlying mechanisms of how SMC functions and maturation are regulated by their mechanosensing leading to transduction. However, how the expression of yes-associated protein 1 (YAP) influences the phenotypic shift from synthetic to contractile is still controversial. Here, pseudo-3D topological alignments mimicking native muscle tissues are generated using laser-cutter engraving to explore the influence of topological cues on SMC mechanotransduction and maturation. The analysis of topological cue-mediated mechanotransduction and maturation marker expression revealed YAP is involved in mechanotransduction for SMCs cultured on cross-patterned substrates in the presence of cell-cell interactions. Moreover, these SMCs with YAP-linked mechanosensing showed higher expression of calponin, indicating a shift toward contractile phenotypes in vitro and in vivo. Furthermore, it showed skeletal muscle cells has different mechanosensing and maturation mechanisms compared to SMCs, revealing muscle type-dependent different sensing of topological cues, and converting into maturation-associated signaling cascades. This study provides insights into the regulation of SMC mechanotransduction and maturation by topological cues, suggesting the involvement of YAP-linked signaling pathways in this process.

3D-Printed Myocardium-Specific Structure Enhances Maturation and Therapeutic Efficacy of Engineered Heart Tissue in Myocardial Infarction

Despite advancements in engineered heart tissue (EHT), challenges persist in achieving accurate dimensional accuracy of scaffolds and maturing human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), a primary source of functional cardiac cells. Drawing inspiration from cardiac muscle fiber arrangement, a three-dimensional (3D)-printed multi-layered microporous polycaprolactone (PCL) scaffold is created with interlayer angles set at 45° to replicate the precise structure of native cardiac tissue. Compared with the control group and 90° PCL scaffolds, the 45° PCL scaffolds exhibited superior biocompatibility for cell culture and improved hiPSC-CM maturation in calcium handling. RNA sequencing demonstrated that the 45° PCL scaffold promotes the mature phenotype in hiPSC-CMs by upregulating ion channel genes. Using the 45° PCL scaffold, a multi-cellular EHT is successfully constructed, incorporating human cardiomyocytes, endothelial cells, and mesenchymal stem cells. These complex EHTs significantly enhanced hiPSC-CM engraftment in vivo, attenuated ventricular remodeling, and improved cardiac function in mouse myocardial infarction. In summary, the myocardium-specific structured EHT developed in this study represents a promising advancement in cardiovascular regenerative medicine.

Nanogrooved Elastomeric Diaphragm Arrays for Assessment of Cardiomyocytes under Synergistic Effects of Circular Mechanical Stimuli and Electrical Conductivity to Enhance Intercellular Communication

Cardiovascular diseases remain the leading cause of mortality, necessitating advancements in in vitro cardiac tissue engineering platforms for improved disease modeling, drug screening, and regenerative therapies. The chief challenge to recapitulating the beating behavior of cardiomyocytes is creation of the circular stress profile experienced by hollow organs in the natural heart due to filling pressure and integrated strategies for intercellular communication to promote cell-to-cell connections. We present a platform featuring addressable arrays of nanogrooved polydimethylsiloxane (PDMS) diaphragms for cell alignment and circular mechanical stimulation, with embedded silver nanowires (AgNWs) for electrical cues, so that cardiomyocyte functionality can be assessed under these synergistic influences. Central to our innovation is a two-layer PDMS diaphragm design that electrically isolates the liquid metal (EGaIn) strain sensor in the bottom layer to enable detection and control of mechanical stimulation from conductive portions of embedded AgNWs in the top layer that supports cardiomyocyte culture and communication. In this manner, through localized detection and control of the circular mechanical stimulation, the essential role of multiaxial stretching on cardiomyocyte function is elucidated based on their contractility, sarcomere length, and connexin-43 expression. This in vitro platform can potentially transform cardiac tissue engineering, drug screening, and precision medicine approaches.

Advancing 3D Engineered In Vitro Models for Heart Failure Research: Key Features and Considerations

Heart failure is characterized by intricate myocardial remodeling that impairs the heart's pumping and/or relaxation capacity, ultimately reducing cardiac output. It represents a major public health burden, given its high prevalence and associated morbidity and mortality rates, which continue to challenge healthcare systems worldwide. Despite advancements in medical science, there are no treatments that address the disease at its core. The development of three-dimensional engineered in vitro models that closely mimic the (patho)physiology and drug responses of the myocardium has the potential to revolutionize our insights and uncover new therapeutic avenues. Key aspects of these models include the precise replication of the extracellular matrix structure, cell composition, micro-architecture, mechanical and electrical properties, and relevant physiological and pathological stimuli, such as fluid flow, mechanical load, electrical signal propagation, and biochemical cues. Additionally, to fully capture heart failure and its diversity in vivo, it is crucial to consider factors such as age, gender, interactions with other organ systems and external influences-thereby recapitulating unique patient and disease phenotypes. This review details these model features and their significance in heart failure research, with the aim of enhancing future platforms that will deepen our understanding of the disease and facilitate the development of novel, effective therapies.

The development, use, and challenges of electromechanical tissue stimulation systems

BACKGROUND

Tissue stimulations greatly affect cell growth, phenotype, and function, and they play an important role in modeling tissue physiology. With the goal of understanding the cellular mechanisms underlying the response of tissues to external stimulations, in vitro models of tissue stimulation have been developed in hopes of recapitulating in vivo tissue function.

METHODS

Herein we review the efforts to create and validate tissue stimulators responsive to electrical or mechanical stimulation including tensile, compression, torsion, and shear.

RESULTS

Engineered tissue platforms have been designed to allow tissues to be subjected to selected types of mechanical stimulation from simple uniaxial to humanoid robotic stain through equal-biaxial strain. Similarly, electrical stimulators have been developed to apply selected electrical signal shapes, amplitudes, and load cycles to tissues, lending to usage in stem cell-derived tissue development, tissue maturation, and tissue functional regeneration. Some stimulators also allow for the observation of tissue morphology in real-time while cells undergo stimulation. Discussion on the challenges and limitations of tissue simulator development is provided.

CONCLUSIONS

Despite advances in the development of useful tissue stimulators, opportunities for improvement remain to better reproduce physiological functions by accounting for complex loading cycles, electrical and mechanical induction coupled with biological stimuli, and changes in strain affected by applied inputs.

Architecture design and advanced manufacturing of heart-on-a-chip: scaffolds, stimulation and sensors

Heart-on-a-chip (HoC) has emerged as a highly efficient, cost-effective device for the development of engineered cardiac tissue, facilitating high-throughput testing in drug development and clinical treatment. HoC is primarily used to create a biomimetic microphysiological environment conducive to fostering the maturation of cardiac tissue and to gather information regarding the real-time condition of cardiac tissue. The development of architectural design and advanced manufacturing for these "3S" components, scaffolds, stimulation, and sensors is essential for improving the maturity of cardiac tissue cultivated on-chip, as well as the precision and accuracy of tissue states. In this review, the typical structures and manufacturing technologies of the "3S" components are summarized. The design and manufacturing suggestions for each component are proposed. Furthermore, key challenges and future perspectives of HoC platforms with integrated "3S" components are discussed. Architecture design concepts of scaffolds, stimulation and sensors in chips.

Strain sensor on a chip for quantifying the magnitudes of tensile stress on cells

During cardiac development, mechanotransduction from the in vivo microenvironment modulates cardiomyocyte growth in terms of the number, area, and arrangement heterogeneity. However, the response of cells to different degrees of mechanical stimuli is unclear. Organ-on-a-chip, as a platform for investigating mechanical stress stimuli in cellular mimicry of the in vivo microenvironment, is limited by the lack of ability to accurately quantify externally induced stimuli. However, previous technology lacks the integration of external stimuli and feedback sensors in microfluidic platforms to obtain and apply precise amounts of external stimuli. Here, we designed a cell stretching platform with an in-situ sensor. The in-situ liquid metal sensors can accurately measure the mechanical stimulation caused by the deformation of the vacuum cavity exerted on cells. The platform was applied to human cardiomyocytes (AC16) under cyclic strain (5%, 10%, 15%, 20 and 25%), and we found that cyclic strain promoted cell growth induced the arrangement of cells on the membrane to gradually unify, and stabilized the cells at 15% amplitude, which was even more effective after 3 days of culture. The platform's precise control and measurement of mechanical forces can be used to establish more accurate in vitro microenvironmental models for disease modeling and therapeutic research.

Enhanced cardiomyocyte structural and functional anisotropy through synergetic combination of topographical, conductive, and mechanical stimulation

Drug-induced cardiotoxicity, a significant concern in the pharmaceutical industry, often results in the withdrawal of drugs from the market. The main cause of drug-induced cardiotoxicity is the use of immature cardiomyocytes during in vitro drug screening procedures. Over time, several methods such as topographical, conductive, and mechanical stimulation have been proposed to enhance both maturation and contractile properties of these cardiomyocytes. However, the synergistic effects of integrating topographical, conductive, and mechanical stimulation for cardiomyocyte maturation remain underexplored and poorly understood. To address this limitation, herein, we propose a grooved polydimethylsiloxane (PDMS) membrane embedded with silver nanowires (AgNWs-E-PDMS). The proposed AgNWs-E-PDMS membrane enhances the maturation of cardiomyocytes and provides a more accurate evaluation of drug-induced cardiotoxicity. When subjected to 10% tensile stress on the AgNWs-E-PDMS membrane, cardiomyocytes displayed substantial enhancements. Specifically, the contraction force, sarcomere length, and connexin-43 (Cx43) expression are increased by 2.0-, 1.5-, and 2.4-times, respectively, compared to the control state. The practical feasibility of the proposed device as a drug screening platform is demonstrated by assessing the adverse effects of lidocaine on cardiomyocytes. The contraction force and beat rate of lidocaine treated cardiomyocytes cultured on the AgNWs-E-PDMS membrane under mechanical stimulation decreased to 0.9 and 0.64 times their initial values respectively, compared to 0.6 and 0.51 times in the control state. These less pronounced changes in the contraction force and beat rate signify the superior drug response in the cardiomyocytes, a result of their enhanced maturation and growth on the AgNWs-E-PDMS membrane combined with mechanical stimulation.