Despite proven efficacy of pharmacotherapies targeting primarily global neurohormonal dysregulation, heart failure (HF) is a growing pandemic with increasing burden. Treatments mechanistically focusing at the cardiomyocyte level are lacking. MicroRNAs (miRNA) are transcriptional regulators and essential drivers of disease progression. We previously demonstrated that miR-132 is both necessary and sufficient to drive the pathological cardiomyocytes growth, a hallmark of adverse cardiac remodelling. Therefore, miR-132 may serve as a target for HF therapy. Here we report further mechanistic insight of the mode of action and translational evidence for an optimized, synthetic locked nucleic acid antisense oligonucleotide inhibitor (antimiR-132). We reveal the compound's therapeutic efficacy in various models, including a clinically highly relevant pig model of HF. We demonstrate favourable pharmacokinetics, safety, tolerability, dose-dependent PK/PD relationships and high clinical potential for the antimiR-132 treatment scheme.

Human pluripotent stem cell (hPSC)-derived cardiomyocytes hold great potential for in vitro modeling of diseases like cardiomyopathies. Yet, knowledge about expression and functional impact of sarcomeric protein isoforms like the myosin heavy chain (MyHC) in hPSC-cardiomyocytes is scarce. We hypothesized that ventricular β-MyHC expression alters contraction and calcium kinetics and drives morphological and electrophysiological differentiation towards ventricular-like cardiomyocytes. To address this, we (1) generated human embryonic stem cell-derived cardiomyocytes (hESC-CMs) that switched towards exclusive β-MyHC, and (2) functionally and morphologically characterized these hESC-CMs at the single-cell level. MyHC-isoforms and functional properties were investigated during prolonged in vitro culture of cardiomyocytes in floating cardiac bodies (soft conditions) vs. culture on a stiff matrix. Using a specific anti-β-MyHC and a newly generated anti-α-MyHC-antibody, we found individual cardiomyocytes grown in cardiac bodies to mostly express both α- and β-MyHC-protein isoforms. Yet, 35 and 75 days of cultivation on laminin-coated glass switched 66 and 87 % of all cardiomyocytes to exclusively express β-MyHC, respectively. Twitch contraction and calcium transients were faster for CMs on laminin-glass. Surprisingly, both parameters were only little affected by the MyHC-isoform, although hESC-CMs with only β-MyHC had much lower ATP-turnover and tension cost, just as in human ventricular cardiomyocytes. Spontaneous contractions and no strict coupling of β-MyHC to ventricular-like action potentials suggest that MyHC-isoform expression does not fully determine the hESC-CM differentiation status. Stiff substrate-induced pure β-MyHC-protein expression in hESC-CMs, with several contractile parameters close to ventricular cardiomyocytes, provides a well-defined in vitro system for modeling of cardiomyopathies and drug screening approaches.

Aiming at clinical translation, robust directed differentiation of human pluripotent stem cells (hPSCs), preferentially in chemically defined conditions, is a key requirement. Here, feasibility of suspension culture based hPSC-cardiomyocyte (hPSC-CM) production in low-cost, xeno-free media compatible with good manufacturing practice standards is shown. Applying stirred tank bioreactor systems at increasing dimensions, our advanced protocol enables routine production of about 1 million hPSC-CMs/mL, yielding $1.3 3 10 8 CM in 150 mL and $4.0 3 10 8 CMs in 350-500 mL process scale at >90% lineage purity. Process robustness and efficiency is ensured by uninterrupted chemical WNT pathway control at early stages of differentiation and results in the formation of almost exclusively ventricular-like CMs. Modulated WNT pathway regulation also revealed the previously unappreciated role of ROR1/CD13 as superior surrogate markers for predicting cardiac differentiation efficiency as soon as 72 h of differentiation. This monitoring strategy facilitates process upscaling and controlled mass production of hPSC derivatives.

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