Multi-organ platform with tissue-specific niches linked by vascular flow for studies of systemic disease.

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Engineering of human cardiac muscle electromechanically matured to an adult-like phenotype

Author ManuscriptThe application of tissue-engineering approaches to human induced pluripotent stem (hiPS) cells enables the development of physiologically relevant human tissue models for in vitro studies of development, regeneration, and disease. However, the immature phenotype of hiPS-derived cardiomyocytes (hiPS-CMs) limits their utility. We have developed a protocol to generate engineered cardiac tissues from hiPS cells and electromechanically mature them toward an adult-like phenotype. This protocol also provides optimized methods for analyzing these tissues' functionality, ultrastructure, and cellular properties. The approach relies on biological adaptation of cultured tissues subjected to biomimetic cues, applied at an increasing intensity, to drive accelerated maturation. hiPS cells are differentiated into cardiomyocytes and used immediately after the first contractions are observed, when they still have developmental plasticity. This starting cell population is combined with human dermal fibroblasts, encapsulated in a fibrin hydrogel and allowed to compact under passive tension in a custom-designed bioreactor. After 7 d of tissue formation, the engineered tissues are matured for an additional 21 d by increasingly intense electromechanical stimulation. Tissue properties can be evaluated by measuring contractile function, responsiveness to electrical stimuli, ultrastructure properties (sarcomere length, mitochondrial density, networks of transverse tubules), force-frequency and force-length relationships, calcium handling, and responses to β-adrenergic agonists. Cell properties can be evaluated by monitoring gene/protein expression, oxidative metabolism, and electrophysiology. The protocol takes 4 weeks and requires experience in advanced cell culture and machining methods for bioreactor fabrication. We anticipate that this protocol will improve modeling of cardiac diseases and testing of drugs.NIBIB and NCATS grant EB17103 (G.V.-N.); NIBIB, NCATS, NIAMS, NIDCR, and NIEHS grant EB025765 (G.V.-N.); NHLBI grants HL076485 (G.V.-N.) and HL138486 (M.Y.); NSF grant 16478 (G.V.-N.); the University of Minho MD/PhD program (D.T.); a Japan Society for the Promotion of Science fellowship (K.M.); and the Columbia University Stem Cell Initiative (L.S., M.Y.

Advanced maturation of human cardiac tissue grown from pluripotent stem cells

Cardiac tissues generated from human induced pluripotent stem cells (iPSCs) can serve as platforms for patient-specific studies of physiology and disease1-6. However, the predictive power of these models is presently limited by the immature state of the cells1, 2, 5, 6. Here we show that this fundamental limitation can be overcome if cardiac tissues are formed from early-stage iPSC-derived cardiomyocytes soon after the initiation of spontaneous contractions and are subjected to physical conditioning with increasing intensity over time. After only four weeks of culture, for all iPSC lines studied, such tissues displayed adult-like gene expression profiles, remarkably organized ultrastructure, physiological sarcomere length (2.2 µm) and density of mitochondria (30%), the presence of transverse tubules, oxidative metabolism, a positive force-frequency relationship and functional calcium handling. Electromechanical properties developed more slowly and did not achieve the stage of maturity seen in adult human myocardium. Tissue maturity was necessary for achieving physiological responses to isoproterenol and recapitulating pathological hypertrophy, supporting the utility of this tissue model for studies of cardiac development and disease.The authors acknowledge funding support from the National Institutes of Health of the USA (NIBIB and NCATS grant EB17103 (G.V.-N.); NIBIB, NCATS, NIAMS, NIDCR and NIEHS grant EB025765 (G.V.-N.); NHLBI grants HL076485 (G.V.-N.) and HL138486 (M.Y.); Columbia University MD/PhD program (S.P.M., T.C.); University of Minho MD/PhD program (D.T.); Japan Society for the Promotion of Science fellowship (K.M.); and Columbia University Stem Cell Initiative (D.S., L.S., M.Y.). We thank S. Duncan and B. Conklin for providing human iPSCs, M.B. Bouchard for assistance with image and video analysis, and L. Cohen-Gould for transmission electron microscopy services.info:eu-repo/semantics/publishedVersio

Monitoring contractility in cardiac tissue with cellular resolution using biointegrated microlasers

Funding: This research was financially supported by the European Research Council under the European Union’s Horizon 2020 Framework Programme (FP/2014-2020)/ERC grant agreement no. 640012 (ABLASE), by EPSRC (grant no. EP/P030017/1) and by the RS Macdonald Charitable Trust. S.J.P. acknowledges funding by the Royal Society of Edinburgh (Biomedical Fellowship) and the British Heart Foundation (grant no. FS/17/9/32676). S.J.P. and G.B.R. acknowledge support from The Wellcome Trust Institutional Strategic Support Fund to the University of St Andrews (grant no. 204821/Z/16/A). M.S. acknowledges funding by the European Commission (Marie Skłodowska-Curie Individual Fellowship, 659213) and the Royal Society (Dorothy Hodgkin Fellowship, DH160102; grant no. RGF\R1\180070).The contractility of cardiac cells is a key parameter that describes the biomechanical characteristics of the beating heart, but functional monitoring of three-dimensional cardiac tissue with single-cell resolution remains a major challenge. Here, we introduce microscopic whispering-gallery-mode lasers into cardiac cells to realize all-optical recording of transient cardiac contraction profiles with cellular resolution. The brilliant emission and high spectral sensitivity of microlasers to local changes in refractive index enable long-term tracking of individual cardiac cells, monitoring of drug administration, accurate measurements of organ-scale contractility in live zebrafish, and robust contractility sensing through hundreds of micrometres of rat heart tissue. Our study reveals changes in sarcomeric protein density as an underlying factor to cardiac contraction. More broadly, the use of novel micro- and nanoscopic lasers as non-invasive, biointegrated optical sensors brings new opportunities to monitor a wide range of physiological parameters with cellular resolution.PostprintPeer reviewe

Mitochondrial Function and Dysfunction in Dilated Cardiomyopathy

Cardiac tissue requires a persistent production of energy in order to exert its pumping function. Therefore, the maintenance of this function relies on mitochondria that represent the "powerhouse" of all cardiac activities. Mitochondria being one of the key players for the proper functioning of the mammalian heart suggests continual regulation and organization. Mitochondria adapt to cellular energy demands via fusion-fission events and, as a proof-reading ability, undergo mitophagy in cases of abnormalities. Ca2+ fluxes play a pivotal role in regulating all mitochondrial functions, including ATP production, metabolism, oxidative stress balance and apoptosis. Communication between mitochondria and others organelles, especially the sarcoplasmic reticulum is required for optimal function. Consequently, abnormal mitochondrial activity results in decreased energy production leading to pathological conditions. In this review, we will describe how mitochondrial function or dysfunction impacts cardiac activities and the development of dilated cardiomyopathy

Electromechanical stimulation advances maturation of human cardiac tissues grown from pluripotent stem cells

Data used to generate the figures in the manuscript Electromechanical stimulation advances maturation of human cardiac tissues grown from pluripotent stem cells

New EMPIR project – Metrology for Drug Delivery

This document presents the scientific and technical objectives, state of the art and expected progress beyond it, and most importantly the expected impact on metrology, science, standards, and society of the new joint research project MeDD II, Metrology for drug delivery (follow up of project MeDD I). It was selected for funding through the EURAMET EMPIR program of the European Commission and the participating countries. The project starts in June 2019 and will last for three years. It involves 15 partners from National and Designated Metrology Institutes, companies, and academia. The main objective is to enable traceable measurements of volume, flow and pressure of existing drug delivery devices (for example infusion pumps and analysers) and inline sensors that work at flow rates lower than 100 nL/min, in order to prevent inaccurate measurement results. This project will also investigate fast changing flow rates, liquid mixing behaviour and occlusion phenomena in multi-infusion systems with the purpose of improving dosing accuracy in each infusion line