Miniaturized iPS-Cell-Derived Cardiac Muscles for Physiologically Relevant Drug Response Analyses

Abstract

Tissue engineering approaches have the potential to increase the physiologic relevance of human iPS-derived cells, such as cardiomyocytes (iPS-CM). However, forming Engineered Heart Muscle (EHM) typically requires >1 million cells per tissue. Existing miniaturization strategies involve complex approaches not amenable to mass production, limiting the ability to use EHM for iPS-based disease modeling and drug screening. Micro-scale cardiospheres are easily produced, but do not facilitate assembly of elongated muscle or direct force measurements. Here we describe an approach that combines features of EHM and cardiospheres: Micro-Heart Muscle (μHM) arrays, in which elongated muscle fibers are formed in an easily fabricated template, with as few as 2,000 iPS-CM per individual tissue. Within μHM, iPS-CM exhibit uniaxial contractility and alignment, robust sarcomere assembly, and reduced variability and hypersensitivity in drug responsiveness, compared to monolayers with the same cellular composition. μHM mounted onto standard force measurement apparatus exhibited a robust Frank-Starling response to external stretch, and a dose-dependent inotropic response to the β-adrenergic agonist isoproterenol. Based on the ease of fabrication, the potential for mass production and the small number of cells required to form μHM, this system provides a potentially powerful tool to study cardiomyocyte maturation, disease and cardiotoxicology in vitro.

Advanced maturation of human cardiac tissue grown from pluripotent stem cells

“…Because a functional β-adrenergic receptor system is dependent on both intracellular calcium reserves and the proximity of Ca V 1.2 channels and t-tubules 4,26,27 , comprehensive responses to β-adrenergic agonists are an indicator of phenotypic maturation 28 . We examined if early/intensity tissues had ability for ionotropic response to isoproterenol, since current efforts to capture this effect have been unsuccessful 2,10 .…”

A BAG3 chaperone complex maintains cardiomyocyte function during proteotoxic stress

“…To determine whether the decrease in contractility caused by bortezomib was a result of disruption of myofilament structure, we expressed a fluorescently tagged ACTN2 to label Z-disks in live cells (36). Cells expressing the transgene were viable and continued to contract normally (Supplemental Video 1).…”

Mechanotransduction and Metabolism in Cardiomyocyte Microdomains

“…Among nonvascularized 2D and thin-3D platforms, microstructured chambers coated with extracellular matrix proteins, and dog-bone shaped thin gels promoted the alignment of hiPSC-derived cardiomyocytes. In these studies, cells were genetically engineered to express a calcium-sensitive fluorescent protein, enabling the assessment of contractility and calcium cycling parameters in vitro [197, 198]. Additionally, micropillars-based platforms were manufactured in a range of pathophysiological stiffness to study single cardiomyocytes [199] and tissues [200].…”