Human induced pluripotent stem cell-derived cardiomyocytes to study inflammation-induced aberrant calcium transient.

Heart failure with preserved ejection fraction (HFpEF) is commonly found in persons living with HIV (PLWH) even when antiretroviral therapy suppresses HIV viremia. However, studying this condition has been challenging because an appropriate animal model is not available. In this article, we studied calcium transient in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in culture to simulate the cardiomyocyte relaxation defect noted in PLWH and HFpEF and assess whether various drugs have an effect.

Independent compartmentalization of functional, metabolic, and transcriptional maturation of hiPSC-derived cardiomyocytes.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) recapitulate numerous disease and drug response phenotypes, but cell immaturity may limit their accuracy and fidelity as a model system. Cell culture medium modification is a common method for enhancing maturation, yet prior studies have used complex media with little understanding of individual component contribution, which may compromise long-term hiPSC-CM viability. Here, we developed high-throughput methods to measure hiPSC-CM maturation, determined factors that enhanced viability, and then systematically assessed the contribution of individual maturation medium components.

Functional Validation of Doxorubicin-Induced Cardiotoxicity-Related Genes.

Background: Genome-wide association studies and candidate gene association studies have identified more than 180 genetic variants statistically associated with anthracycline-induced cardiotoxicity (AIC). However, the lack of functional validation has hindered the clinical translation of these findings.

Objectives: The aim of this study was to functionally validate all genes associated with AIC using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs).

Nutritional requirements of human induced pluripotent stem cells.

The nutritional requirements for human induced pluripotent stem cell (hiPSC) growth have not been extensively studied. Here, building on our prior work that established the suitable non-basal medium components for hiPSC growth, we develop a simplified basal medium consisting of just 39 components, demonstrating that many ingredients of DMEM/F12 are either not essential or are at suboptimal concentrations. This new basal medium along with the supplement, which we call BMEM, enhances the growth rate of hiPSCs over DMEM/F12-based media, supports derivation of multiple hiPSC lines, and allows differentiation to multiple lineages.

A review of protocols for human iPSC culture, cardiac differentiation, subtype-specification, maturation, and direct reprogramming.

The methods for the culture and cardiomyocyte differentiation of human embryonic stem cells, and later human induced pluripotent stem cells (hiPSC), have moved from a complex and uncontrolled systems to simplified and relatively robust protocols, using the knowledge and cues gathered at each step. HiPSC-derived cardiomyocytes have proven to be a useful tool in human disease modelling, drug discovery, developmental biology, and regenerative medicine. In this protocol review, we will highlight the evolution of protocols associated with hPSC culture, cardiomyocyte differentiation, sub-type specification, and cardiomyocyte maturation.

An updated protocol for the cost-effective and weekend-free culture of human induced pluripotent stem cells.

The protocol provided here describes methodologies for making a highly cost-effective, chemically defined medium for culturing hiPSCs we call B8 medium. The typical cost of B8 medium is US$10 per liter, which with modifications included here is more affordable than standard media. We provide simple protocols for making B8 supplement aliquots, making the basal media DMEM/F12, Matrigel-coated plates, thawing, passaging, culturing, and cryopreserving hiPSCs.

Mitochondrial architecture in cardiac myocytes depends on cell shape and matrix rigidity.

Contraction of cardiac myocytes depends on energy generated by the mitochondria. During cardiac development and disease, the structure and function of the mitochondrial network in cardiac myocytes is known to remodel in concert with many other factors, including changes in nutrient availability, hemodynamic load, extracellular matrix (ECM) rigidity, cell shape, and maturation of other intracellular structures. However, the independent role of each of these factors on mitochondrial network architecture is poorly understood.

Pluripotent Stem Cell Modeling of Anticancer Therapy-Induced Cardiotoxicity.

Purpose Of Review: In this article, we review the different model systems based on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and how they have been applied to identify the cardiotoxic effects of anticancer therapies.

Recent Findings: Developments on 2D and 3D culture systems enabled the use of hiPSC-CMs as screening platforms for cardiotoxic effects of anticancer therapies such as anthracyclines, monoclonal antibodies, and tyrosine kinase inhibitors. Combined with computational approaches and higher throughput screening technologies, they have also enabled mechanistic studies and the search for cardioprotective strategies.

Generating a Cost-Effective, Weekend-Free Chemically Defined Human Induced Pluripotent Stem Cell (hiPSC) Culture Medium.

We have previously developed a cost-effective chemically defined medium formula for weekend-free culture of human induced pluripotent stem cells (hiPSCs), costing ∼3% of the price of commercial medium. This medium, which we termed B8, is specifically optimized for robust and fast growth of hiPSCs and for a weekend-free medium change regimen. We demonstrated that this medium is suitable for reprogramming of somatic cells into hiPSCs and for differentiation into a variety of lineages.

Regulation of calcium dynamics and propagation velocity by tissue microstructure in engineered strands of cardiac tissue.

Disruptions to cardiac tissue microstructure are common in diseased or injured myocardium and are known substrates for arrhythmias. However, we have a relatively coarse understanding of the relationships between myocardial tissue microstructure, propagation velocity and calcium cycling, due largely to the limitations of conventional experimental tools. To address this, we used microcontact printing to engineer strands of cardiac tissue with eight different widths, quantified several structural and functional parameters and established correlation coefficients.

Matrix-guided control of mitochondrial function in cardiac myocytes.

In ventricular myocardium, extracellular matrix (ECM) remodeling is a hallmark of physiological and pathological growth, coincident with metabolic rewiring of cardiac myocytes. However, the direct impact of the biochemical and mechanical properties of the ECM on the metabolic function of cardiac myocytes is mostly unknown. Furthermore, understanding the impact of distinct biomaterials on cardiac myocyte metabolism is critical for engineering physiologically-relevant models of healthy and diseased myocardium.

Engineering cardiac microphysiological systems to model pathological extracellular matrix remodeling.

Many cardiovascular diseases are associated with pathological remodeling of the extracellular matrix (ECM) in the myocardium. ECM remodeling is a complex, multifactorial process that often contributes to declines in myocardial function and progression toward heart failure. However, the direct effects of the many forms of ECM remodeling on myocardial cell and tissue function remain elusive, in part because conventional model systems used to investigate these relationships lack robust experimental control over the ECM.

Microenvironmental Modulation of Calcium Wave Propagation Velocity in Engineered Cardiac Tissues.

Introduction: In the myocardium, rapid propagation of action potentials and subsequent calcium waves is critical for synchronizing the contraction of cardiac myocytes and maximizing cardiac output. In many pathological settings, diverse remodeling of the tissue microenvironment is correlated with arrhythmias and decreased cardiac output, but the precise impact of tissue remodeling on propagation is not completely understood. Our objective was to delineate how multiple features within the cardiac tissue microenvironment modulate propagation velocity.

Mitochondrial function in engineered cardiac tissues is regulated by extracellular matrix elasticity and tissue alignment.

Mitochondria in cardiac myocytes are critical for generating ATP to meet the high metabolic demands associated with sarcomere shortening. Distinct remodeling of mitochondrial structure and function occur in cardiac myocytes in both developmental and pathological settings. However, the factors that underlie these changes are poorly understood.

Engineering micromyocardium to delineate cellular and extracellular regulation of myocardial tissue contractility.

Cardiovascular diseases are a leading cause of death, in part due to limitations of existing models of the myocardium. Myocardium consists of aligned, contractile cardiac myocytes interspersed with fibroblasts that synthesize extracellular matrix (ECM). The cellular demographics and biochemical and mechanical properties of the ECM remodel in many different cardiac diseases.

Parallel imaging acceleration of spiral Fourier velocity encoded MRI using SPIRiT.

This paper demonstrates parallel imaging acceleration of spiral Fourier velocity encoded MRI using the iterative self-consistent parallel imaging reconstruction (SPIRiT) technique. Magnitude images and time-velocity distributions obtained with image domain SPIRiT and sum-of-squares reconstruction are compared, for 2-fold and 4-fold undersampling. We show that SPIRiT is able to reduce spatial aliasing from undersampled time-velocity distributions, with good results for 2-fold undersampling, and moderately good results for 4-fold undersampling.