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Background: Because adult cardiomyocytes have little regenerative capacity, resident cardiac fibroblasts (CFs) synthesize extracellular matrix after myocardial infarction (MI) to form fibrosis, leading to cardiac dysfunction and heart failure. Therapies that can regenerate the myocardium and reverse fibrosis in chronic MI are lacking. The overexpression of cardiac transcription factors, including Mef2c/Gata4/Tbx5/Hand2 (MGTH), can directly reprogram CFs into induced cardiomyocytes (iCMs) and improve cardiac function under acute MI. However, the ability of in vivo cardiac reprogramming to repair chronic MI with established scars is undetermined. Methods: We generated a novel Tcf21 iCre /reporter/MGTH2A transgenic mouse system in which tamoxifen treatment could induce both MGTH and reporter expression in the resident CFs for cardiac reprogramming and fibroblast lineage tracing. We first tested the efficacy of this transgenic system in vitro and in vivo for acute MI. Next, we analyzed in vivo cardiac reprogramming and fusion events under chronic MI using Tcf21 iCre /Tomato/MGTH2A and Tcf21 iCre /mTmG/MGTH2A mice, respectively. Microarray and single-cell RNA sequencing were performed to determine the mechanism of cardiac repair by in vivo reprogramming. Results: We confirmed the efficacy of transgenic in vitro and in vivo cardiac reprogramming for acute MI. In chronic MI, in vivo cardiac reprogramming converted ≈2% of resident CFs into iCMs, in which a majority of iCMs were generated by means of bona fide cardiac reprogramming rather than by fusion with cardiomyocytes. Cardiac reprogramming significantly improved myocardial contraction and reduced fibrosis in chronic MI. Microarray analyses revealed that the overexpression of MGTH activated cardiac program and concomitantly suppressed fibroblast and inflammatory signatures in chronic MI. Single-cell RNA sequencing demonstrated that resident CFs consisted of 7 subclusters, in which the profibrotic CF population increased under chronic MI. Cardiac reprogramming suppressed fibroblastic gene expression in chronic MI by means of conversion of profibrotic CFs to a quiescent antifibrotic state. MGTH overexpression induced antifibrotic effects partly by suppression of Meox1, a central regulator of fibroblast activation. Conclusions: These results demonstrate that cardiac reprogramming could repair chronic MI by means of myocardial regeneration and reduction of fibrosis. These findings present opportunities for the development of new therapies for chronic MI and heart failure.

In this study, deep learning (DL)-based estimation of the Flory–Huggins χ parameter of A-B diblock copolymers from two-dimensional cross-sectional images of three-dimensional (3D) phase-separated structures were investigated. 3D structures with random networks of phase-separated domains were generated from real-space self-consistent field simulations in the 25–40 χN range for chain lengths (N) of 20 and 40. To confirm that the prepared data can be discriminated using DL, image classification was performed using the VGG-16 network. We comprehensively investigated the performances of the learned networks in the regression problem. The generalization ability was evaluated from independent images with the unlearned χN. We found that, except for large χN values, the standard deviation values were approximately 0.1 and 0.5 for A-component fractions of 0.2 and 0.35, respectively. The images for larger χN values were more difficult to distinguish. In addition, the learning performances for the 4-class problem were comparable to those for the 8-class problem, except when the χN values were large. This information is useful for the analysis of real experimental image data, where the variation of samples is limited.

Summary Direct cardiac reprogramming holds great potential for regenerative medicine. However, it remains inefficient, and induced cardiomyocytes (iCMs) generated in vitro are less mature than those in vivo, suggesting that undefined extrinsic factors may regulate cardiac reprogramming. Previous in vitro studies mainly used hard polystyrene dishes, yet the effect of substrate rigidity on cardiac reprogramming remains unclear. Thus, we developed a Matrigel-based hydrogel culture system to determine the roles of matrix stiffness and mechanotransduction in cardiac reprogramming. We found that soft matrix comparable with native myocardium promoted the efficiency and quality of cardiac reprogramming. Mechanistically, soft matrix enhanced cardiac reprogramming via inhibition of integrin, Rho/ROCK, actomyosin, and YAP/TAZ signaling and suppression of fibroblast programs, which were activated on rigid substrates. Soft substrate further enhanced cardiac reprogramming with Sendai virus vectors via YAP/TAZ suppression, increasing the reprogramming efficiency up to ∼15%. Thus, mechanotransduction could provide new targets for improving cardiac reprogramming., Graphical Abstract, Highlights • Hydrogel culture reveals the role of mechanotransduction in cardiac reprogramming • Soft ECM comparable with native myocardium promotes cardiac reprogramming • Soft ECM promotes cardiac reprogramming via YAP/TAZ/fibroblast signaling inhibition • Soft ECM promotes Sendai virus vector-mediated cardiac reprogramming, In this article, Ieda and colleagues showed that a soft matrix, which is comparable with native myocardium, efficiently promoted cardiac reprogramming. This soft matrix enhanced cardiac reprogramming via inhibition of integrin, Rho/ROCK, actomyosin, and YAP/TAZ signaling and subsequent suppression of fibroblast programs, which were activated on conventional rigid substrates, thus demonstrating that mechanotransduction plays a critical role in cardiac reprogramming.

Introduction: The incidence of arterial thrombosis increases with age, but its underlying mechanisms are unclear. Myocardial infarction is associated with increased von Willebrand factor (VWF) and decreased a disintegrin-like and metalloproteinase with thrombospondin type-1 motif 13 (ADAMTS13) levels. We aimed to examine the relationship between the VWF-ADAMTS13 axis and age in ST-elevation myocardial infarction (STEMI). Methods: Patients who underwent endovascular arterial recanalization for STEMI or acute ischemic stroke (AIS) and had aspirated thrombi at our institute between June 2019 and August 2020 were enrolled. Seventy-one patients were divided into two age groups— Results: Among all patients (STEMI and AIS), ADAMTS13 levels were significantly lower in the ≥65 years group than in the Conclusions: Our study demonstrated low ADAMTS13 levels in elderly patients with STEMI, but not in those with AIS. The VWF-ADAMTS13 axis may be more involved in the pathogenesis of STEMI than in that of AIS among elderly patients.

Graphical abstract, Highlights • Permeability values of 90 industry chemicals were measured by a Caco-2 system. • A multivariate prediction equation for permeability of chemicals was proposed. • Chemical permeability coefficients were inversely associated with hepatic NOELs., Apparent permeability coefficients (Papp) across a human intestinal epithelial Caco-2 cell monolayer were measured for a range of industrial/drug chemicals. A predictive equation for determining in vitro Papp values of fifty-six substances was set up using multivariate regression analysis based on in silico-estimated physicochemical properties (molecular weights and water distribution coefficients for apical and basal pH environments) (r = 0.77, p

While the vascular healing process after drug-eluting stent implantation is not fully elucidated, it is generally accepted that macrophages play an important role in inflammation. It is also known that macrophages involved in the pathogenesis of atherosclerosis may stem from several origins, that is, monocyte-derived macrophages versus resident macrophages. However, little is known about the role of human macrophages on reperfusion of culprit coronary arteries in patients with atherosclerotic disease who have sustained acute coronary syndrome. In this present case report, we describe the presence of cluster of differentiation (CD) 163-positive macrophages in close proximity to the stent struts at the luminal site 72 hours after drug-eluting stent implantation in the culprit coronary lesion for ST elevation myocardial infarction by postmortem examination.

The native core light-harvesting complex (LH1) from the thermophilic purple phototrophic bacterium Thermochromatium tepidum requires Ca2+ for its thermal stability and characteristic absorption maximum at 915 nm. To explore the role of specific amino acid residues of the LH1 polypeptides in Ca-binding behavior, we constructed a genetic system for heterologously expressing the Tch. tepidum LH1 complex in an engineered Rhodobacter sphaeroides mutant strain. This system contained a chimeric pufBALM gene cluster (pufBA from Tch. tepidum and pufLM from Rba. sphaeroides) and was subsequently deployed for introducing site-directed mutations on the LH1 polypeptides. All mutant strains were capable of phototrophic (anoxic/light) growth. The heterologously expressed Tch. tepidum wild-type LH1 complex was isolated in a reaction center (RC)-associated form and displayed the characteristic absorption properties of this thermophilic phototroph. Spheroidene (the major carotenoid in Rba. sphaeroides) was incorporated into the Tch. tepidum LH1 complex in place of its native spirilloxanthins with one carotenoid molecule present per αβ-subunit. The hybrid LH1-RC complexes expressed in Rba. sphaeroides were characterized using absorption, fluorescence excitation, and resonance Raman spectroscopy. Site-specific mutagenesis combined with spectroscopic measurements revealed that α-D49, β-L46, and a deletion at position 43 of the α-polypeptide play critical roles in Ca binding in the Tch. tepidum LH1 complex; in contrast, α-N50 does not participate in Ca2+ coordination. These findings build on recent structural data obtained from a high-resolution crystallographic structure of the membrane integrated Tch. tepidum LH1-RC complex and have unambiguously identified the location of Ca2+ within this key antenna complex.