Construction of Defined Human Engineered Cardiac Tissues to Study Mechanisms of Cardiac Cell Therapy

Abstract

Human cardiac tissue engineering can fundamentally impact therapeutic discovery through the development of new species-specific screening systems that replicate the biofidelity of three-dimensional native human myocardium, while also enabling a controlled level of biological complexity, and allowing non-destructive longitudinal monitoring of tissue contractile function. Initially, human engineered cardiac tissues (hECT) were created using the entire cell population obtained from directed differentiation of human pluripotent stem cells, which typically yielded less than 50% cardiomyocytes. However, to create reliable predictive models of human myocardium, and to elucidate mechanisms of heterocellular interaction, it is essential to accurately control the biological composition in engineered tissues. To address this limitation, we utilize live cell sorting for the cardiac surface marker SIRPα and the fibroblast marker CD90 to create tissues containing a 3:1 ratio of these cell types, respectively, that are then mixed together and added to a collagen-based matrix solution. Resulting hECTs are, thus, completely defined in both their cellular and extracellular matrix composition. Here we describe the construction of defined hECTs as a model system to understand mechanisms of cell-cell interactions in cell therapies, using an example of human bone marrow-derived mesenchymal stem cells (hMSC) that are currently being used in human clinical trials. The defined tissue composition is imperative to understand how the hMSCs may be interacting with the endogenous cardiac cell types to enhance tissue function. A bioreactor system is also described that simultaneously cultures six hECTs in parallel, permitting more efficient use of the cells after sorting.

Transplantation of human induced pluripotent stem cell-derived cardiomyocytes improves myocardial function and reverses ventricular remodeling in infarcted rat hearts

“…A well-established method of cardiomyocyte differentiation from PSCs provides an ideal source of cardiomyocytes and makes regenerative therapy for myocardial muscle damage a promising strategy. The methods of cardiomyocyte differentiation, purification, and maturation from iPSCs or ESCs have been established both by our lab [9][10][11][12] and other labs [13][14][15][16][17]. Recently, transplantation of human ESC-derived cardiomyocytes (ESC-CMs) has been proven to significantly improve cardiac function in infarcted rat and nonhuman primate hearts [18,19] due to the capacity of PSC-CMs to remuscularize the infarcted hearts and form electromechanical junctions with the host hearts [15].…”

Experimental and Computational Insight Into Human Mesenchymal Stem Cell Paracrine Signaling and Heterocellular Coupling Effects on Cardiac Contractility and Arrhythmogenicity

“…Our custom bioreactor system 38 facilitates simultaneous culture of six hECTs that are each comprised of either unsupplemented (-hMSC) or 10% hMSC-supplemented (+hMSC) cellular composition. hMSCs were employed from lots used in recently published clinical trials.…”

Physiologic, Pathologic, and Therapeutic Paracrine Modulation of Cardiac Excitation-Contraction Coupling

“…A major advancement in the cardiac research field has been the growing sophistication of in vitro models of functional human myocardium by combining tissue engineering technology with human stem cell biology, 156–158 as recently reviewed. 159–161 In our laboratory, hECTs are created, cultured, and tested using a custom bioreactor 162 with integrated force-sensing end-posts. As the tissue beats (either spontaneously or by electrical pacing), deflections of the end-posts are tracked in real time by high-speed video to non-invasively monitor contractile performance throughout a sequence of twitch cycles (Figure 3A).…”

“…To this end, in the cardiac tissue engineering field, we are one of the first groups to model familial dilated cardiomyopathy 165 and to test stem cell therapies. 54,162,164 In the context of this review, our hECT system is advantageous for uniquely providing a configuration of co-cultured tissues in a shared bath in order to investigate paracrine signaling effects on cardiac contractility. Its ability to non-invasively measure contractile function facilitates the collection of multi-day longitudinal data on the effects of paracrine factors on contractile function.…”