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Growth of engineered human myocardium with mechanical loading and vascular coculture.

ABSTRACT: The developing heart requires both mechanical load and vascularization to reach its proper size, yet the regulation of human heart growth by these processes is poorly understood.We seek to elucidate the responses of immature human myocardium to mechanical load and vascularization using tissue engineering approaches.Using human embryonic stem cell and human induced pluripotent stem cell-derived cardiomyocytes in a 3-dimensional collagen matrix, we show that uniaxial mechanical stress conditioning promotes 2-fold increases in cardiomyocyte and matrix fiber alignment and enhances myofibrillogenesis and sarcomeric banding. Furthermore, cyclic stress conditioning markedly increases cardiomyocyte hypertrophy (2.2-fold) and proliferation rates (21%) versus unconditioned constructs. Addition of endothelial cells enhances cardiomyocyte proliferation under all stress conditions (14% to 19%), and addition of stromal supporting cells enhances formation of vessel-like structures by ?10-fold. Furthermore, these optimized human cardiac tissue constructs generate Starling curves, increasing their active force in response to increased resting length. When transplanted onto hearts of athymic rats, the human myocardium survives and forms grafts closely apposed to host myocardium. The grafts contain human microvessels that are perfused by the host coronary circulation.Our results indicate that both mechanical load and vascular cell coculture control cardiomyocyte proliferation, and that mechanical load further controls the hypertrophy and architecture of engineered human myocardium. Such constructs may be useful for studying human cardiac development as well as for regenerative therapy.

SUBMITTER: Tulloch NL

PROVIDER: S-EPMC3140796 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Growth of engineered human myocardium with mechanical loading and vascular coculture.

Tulloch Nathaniel L NL Muskheli Veronica V Razumova Maria V MV Korte F Steven FS Regnier Michael M Hauch Kip D KD Pabon Lil L Reinecke Hans H Murry Charles E CE

Circulation research 20110519 1

<h4>Rationale</h4>The developing heart requires both mechanical load and vascularization to reach its proper size, yet the regulation of human heart growth by these processes is poorly understood.<h4>Objective</h4>We seek to elucidate the responses of immature human myocardium to mechanical load and vascularization using tissue engineering approaches.<h4>Methods and results</h4>Using human embryonic stem cell and human induced pluripotent stem cell-derived cardiomyocytes in a 3-dimensional colla ...[more]

PMID: 21597009

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Project description:Engineered cardiac tissues (ECTs) are platforms to investigate cardiomyocyte maturation and functional integration, to evaluate the feasibility of generating implantable tissues for cardiac repair and regeneration, and may be useful models for pharmacology and toxicology bioassays. These ECTs rapidly mature in vitro to acquire the features of functional cardiac muscle and respond to mechanical load with increased proliferation and maturation. ECTs can be generated from various immature cardiac cell sources and little is known regarding the broad changes in regulatory transcript expression that occur in these in vitro tissues during normal maturation and in response to mechanical or pharmacologic interventions. We tested the hypothesis that global ECT gene expression patterns are sensitive to mechanical loading conditions and tyrosine kinase inhibitors, similar to the maturing myocardium. We generated 3D ECTs from day 14.5 rat embryo ventricular cells, as previously published, and then treated constructs after 5 days in culture for 48 hours with mechanical stretch (5%, 0.5 Hz) and/or the p38MAPK (p38 mitogen-activated protein kinase) selective inhibitor BIRB796. RNA was isolated from 3 sets of experiments and assayed using a standard Agilent rat 4x44k V3 microarray and Pathway Analysis software for transcript expression fold changes and changes in regulatory molecules and networks. At the threshold of a 1.5 fold change in expression, mechanical stretch altered 1,559 transcripts, versus 1,411 for BIRB796, and 1,846 for stretch plus BIRB796. As anticipated, top pathways altered in response to these stimuli include Cellular Development, Cellular Growth and Proliferation; Tissue Development; Cell Death, Cell Signaling, and Small Molecule Biochemistry as well as numerous other pathways. Changes in transcript expression were confirmed by quantitative-PCR for selected regulatory molecules. Thus, ECTs display a broad spectrum of altered gene expression in response to mechanical load and/or tyrosine kinase inhibition, reflecting the complex regulation of proliferation, differentiation, and architectural alignment that occurs during ECT maturation and adaptation. This approach can now be used to test the role of individual molecules and pathways on the regulation of ECT maturation and remodeling. 7 and 4 biological replicates with four groups (control, mechanical stretch, BIRB and mechanical stretch with BIRB)

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Growth of engineered human myocardium with mechanical loading and vascular coculture.

Publications

Growth of engineered human myocardium with mechanical loading and vascular coculture.

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