With the aim of processing and culturing a multitude of tissue specimens, we set out to provide physiological conditions in exchangeable incubation chambers that should permit parallel, easily expandable operation within a standard CO 2 incubator. Multifactorial incubation systems providing mechanical load, excitation and oxygen supply to adult myocardial tissue preparations have been shown to support viability and force development for up to 6 days, but these systems were based on technically demanding incubators and permitted maintenance of few samples at a time 13, 17. These requirements, however, are not met by adult myocardial tissue slices. Most of them have been built with the intention of promoting differentiation or maturation of stem cell-derived cardiomyocytes, and rely on developmental properties of those tissues, such as spontaneous excitation, substrate adhesion or adaptive growth. In view of the essential impact of excitation and contraction for the maintenance and development of myocardial differentiation 12, 13, 14, we hypothesized that close simulation of biomechanical and electrical conditions might be adequate for resolving the limitations of unloaded tissue culture.īioreactors for the cultivation of muscle tissue have been constructed in many variations 12, 15, 16. While this technology indicated the requirement of mechanical forces for the maintenance of cultivated myocardium, it did neither permit excitation and active contraction of the tissue, nor could it prevent the rapid decline of contractile force in vitro. Initial attempts of organotypic cultivation utilized the adherence on a filter surface to stabilize tissue dimensions, thus achieving survival of human myocardial slices for up to 4 weeks 7. Such complex tissue models have been proposed for disease and drug research 10, 11, but the limited stability has restricted their use to short-term experiments.
With the aim to facilitate the use of adult myocardium, methods have been developed for the automated preparation of viable tissue slices from animal and human hearts 7, 8, 9. Viability and function of trabecular muscle strips and of isolated cardiomyocytes decline rapidly 3, whilst the artificial myocardial tissue composed of differentiated stem cells still represents an immature phenotype 4, 5, even though cardiomyocyte maturation can be greatly improved by advanced biomimetic stimulation 6. Unfortunately, current experimental models of human myocardium involve severe limitations. Such in vitro systems may include cells and tissues of human origin, a feature that is important in cardiac research since species-related peculiarities of mechanical load, heart rate and electrophysiology impede interpretation of findings obtained, e.g., in mouse models 1, 2.
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Prior to the involvement of in vivo studies, experimental systems would be desired that provide intact, multicellular, three-dimensional tissue composition in combination with free choice of external manipulation, thus enabling disease modelling and therapy simulation. Biomimetic tissue culture will provide new opportunities to study drug targets, gene functions, and cellular plasticity in adult human myocardium.Įfficient translation of basic biomedical research requires information on the impact of molecular targets in systems with increasing complexity, progressing from cultured cells to isolated organs and living subjects. The suitability of the model for drug safety evaluation is exemplified by repeated assessment of refractory period that permits sensitive analysis of repolarization impairment induced by the multimodal hERG-inhibitor pentamidine. Cultured myocardium undergoes particular alterations in biomechanics, structure, and mRNA expression. In biomimetic culture, tissue slices prepared from explanted failing human hearts attain a stable state of contractility that can be monitored for up to 4 months or 2000000 beats in vitro. Here, we report preservation of structure and performance of human myocardium under conditions of physiological preload, compliance, and continuous excitation. Whilst vital slices of human myocardium approach these demands, their rapid degeneration in tissue culture precludes long-term experimentation. In vitro models incorporating the complexity and function of adult human tissues are highly desired for translational research.
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