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We report the case of a 79-year-old woman with essential thrombocythemia who presented with simultaneous two-vessel acute myocardial infarction (AMI) in the subacute phase of takotsubo cardiomyopathy. Despite sufficient anticoagulation therapy with warfarin to prevent thrombus formation in the left ventricle, the patient developed simultaneous two-vessel AMI in the right and left circumflex coronary arteries 16 days after the onset of takotsubo cardiomyopathy. Thromboembolism from the left ventricle associated with takotsubo cardiomyopathy was considered a potential cause of this event. However, macroscopic and pathological findings of the aspirated thrombi revealed that the primary cause of AMI was non-organized white platelet thrombi associated with essential thrombocythemia. In addition to oral anticoagulation therapy with warfarin, low-dose aspirin was started. The patient was discharged without any symptoms, and the clinical course has been uneventful for >5 years. This case highlights the potential risk of fatal complications associated with essential thrombocythemia, including simultaneous multivessel AMI. Additionally, pathological findings of the thrombi may play a crucial role in clarifying the etiology in such complicated cases. Appropriate antithrombotic therapy should be selected according to the pathogenesis of the condition. LEARNING OBJECTIVE: We describe a 79-year-old woman with essential thrombocythemia complicated with simultaneous two-vessel acute myocardial infarction (AMI) in the subacute phase of takotsubo cardiomyopathy. Although patients with essential thrombocythemia are highly predisposed to thrombotic events including AMI, the appropriate antithrombotic regimen remains controversial. The macroscopic and pathological findings of the thrombi play a pivotal role in clarifying the etiology, which may lead to the appropriate antithrombotic therapy.

Spontaneous coronary artery dissection (SCAD) is the most important cause of acute coronary syndrome in pregnant women. Pregnancy-associated SCAD frequently occurs in the third trimester or postpartum period. However, little is known regarding the relationship between the occurrence of SCAD and stillbirth. We describe here a 41-year-old woman complicated by sudden cardiac arrest owing to SCAD in the distal segment of the right coronary artery 13 days after stillbirth. After contacting emergency medical services, she was resuscitated by an automated external defibrillator because the initial electrocardiographic waveform was ventricular fibrillation. After cardiopulmonary resuscitation, the diagnosis of SCAD was confirmed by coronary angiography and intracoronary imaging, including intravascular ultrasound and optical coherence tomography. The patient was managed with conservative medical therapy because the culprit lesion was present in the distal segment of the right coronary artery and coronary blood flow was preserved. No major adverse cardiovascular events, including recurrent ventricular arrhythmia, were observed during hospitalization. Our findings indicate that pregnancy-associated SCAD leading to sudden cardiac arrest may occur in the postpartum period, even after stillbirth. Intravascular imaging plays a pivotal role in diagnosing SCAD.

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.

Aortic stenosis (AS), a late complication of thoracic radiation therapy for chest lesions, is often coincident with porcelain aorta or hostile thorax. We herein report a 59-year-old man with a history of mediastinal Hodgkin lymphoma treated with radiation therapy but later presenting with heart failure caused by severe AS. Severe calcification in the mediastinum and around the ascending aorta made it difficult to perform surgical aortic valve replacement. The patient therefore underwent transcatheter aortic valve implantation (TAVI). It is important to recognize radiation-induced AS early, now that TAVI is a well-established treatment required by increasing numbers of successfully treated cancer patients.

The Academic Research Consortium (ARC) recently published a definition of patients at high bleeding risk (HBR) undergoing percutaneous coronary intervention. However, the prevalence of the ARC-HBR criteria in patients undergoing endovascular therapy (EVT) for peripheral artery disease in lower extremities has not been thoroughly investigated. This study sought to investigate the prevalence and impact of the ARC-HBR criteria in patients undergoing EVT. We analyzed 277 consecutive patients who underwent their first EVT from July 2011 to September 2019. We applied the full ARC-HBR criteria to the study population. The primary end point was a composite outcome of all-cause mortality, Bleeding Academic Research Consortium 3 or 5 bleeding, and lower limb amputation within 12 months of EVT. Among the 277 patients, 193 (69.7%) met the ARC-HBR criteria. HBR patients had worse clinical outcomes compared with non-HBR patients at 12 months after EVT, including a higher incidence of the composite primary outcome (19.2% vs. 3.6%, p

Cardiovascular disease is a leading cause of death worldwide. Mammalian cardiomyocytes (CMs) proliferate during embryonic development, whereas they largely lose their regenerative capacity after birth. Defined factors expressed in cardiac progenitors or embryonic CMs may activate the cell cycle and induce CM proliferation in postnatal and adult hearts. Here, we report that the overexpression of Tbx6, enriched in the cardiac mesoderm (progenitor cells), induces CM proliferation in postnatal and adult mouse hearts. By screening 24 factors enriched in cardiac progenitors or embryonic CMs, we found that only Tbx6 could induce CM proliferation in primary cultured postnatal rat CMs. Intriguingly, it did not induce the proliferation of cardiac fibroblasts. We next generated a recombinant adeno-associated virus serotype 9 vector encoding Tbx6 (AAV9-Tbx6) for transduction into mouse CMs in vivo. The subcutaneous injection of AAV9-Tbx6 into neonatal mice induced CM proliferation in postnatal and adult mouse hearts. Mechanistically, Tbx6 overexpression upregulated multiple cell cycle activators including Aurkb, Mki67, Ccna1, and Ccnb2 and suppressed the tumor suppressor Rb1. Thus, Tbx6 promotes CM proliferation in postnatal and adult mouse hearts by modifying the expression of cell cycle regulators.

The mesoderm arises from pluripotent epiblasts and differentiates into multiple lineages; however, the underlying molecular mechanisms are unclear. Tbx6 is enriched in the paraxial mesoderm and is implicated in somite formation, but its function in other mesoderms remains elusive. Here, using direct reprogramming-based screening, single-cell RNA-seq in mouse embryos, and directed cardiac differentiation in pluripotent stem cells (PSCs), we demonstrated that Tbx6 induces nascent mesoderm from PSCs and determines cardiovascular and somite lineage specification via its temporal expression. Tbx6 knockout in mouse PSCs using CRISPR/Cas9 technology inhibited mesoderm and cardiovascular differentiation, whereas transient Tbx6 expression induced mesoderm and cardiovascular specification from mouse and human PSCs via direct upregulation of Mesp1, repression of Sox2, and activation of BMP/Nodal/Wnt signaling. Notably, prolonged Tbx6 expression suppressed cardiac differentiation and induced somite lineages, including skeletal muscle and chondrocytes. Thus, Tbx6 is critical for mesoderm induction and subsequent lineage diversification.

The coronary vascular system is critical for myocardial growth and cardiomyocyte survival. However, the molecular mechanism regulating coronary angiogenesis remains elusive. Vascular endothelial growth factor (VEGF) regulates angiogenesis by binding to the specific receptors Flk1 and Flt1, which results in different functions. Despite the importance of Flk1 and Flt1, their expression in the coronary vasculature remains largely unknown due to the lack of appropriate antibodies for immunostaining. Here, we analyzed multiple reporter mice including Flk1-GFP BAC transgenic (Tg), Flk1-LacZ knock-in, Flt1-DsRed BAC Tg, and Flk1-GFP/Flt1-DsRed double Tg animals to determine expression patterns in mouse hearts during cardiac growth and after myocardial infarction (MI). We found that Flk1 was expressed in endothelial cells (ECs) with a pattern of epicardial-to-endocardial transmural gradients in the neonatal mouse ventricle, which was downregulated in adult coronary vessels with development. In contrast, Flt1 was homogeneously expressed in the ECs of neonatal mouse hearts and expression was maintained until adulthood. After MI, expression of both Flk1 and Flt1 was induced in the regenerating coronary vessels at day 7. Intriguingly, Flk1 expression was downregulated thereafter, whereas Flt1 expression was maintained in the newly formed coronary vessels until 30 days post-MI, recapitulating their expression kinetics during development. This is the first report demonstrating the spatiotemporal expression patterns of Flk1 and Flt1 in the coronary vascular system during development and after MI; thus, this study suggests that these factors have distinct and important functions in coronary angiogenesis.

Direct reprogramming is a promising approach in regenerative medicine. Overexpression of the cardiac transcription factors Gata4, Mef2c, and Tbx5 (GMT) or GMT plus Hand2 (GHMT) directly reprogram fibroblasts into cardiomyocyte-like cells (iCMs). However, the critical timing of transgene expression and the molecular mechanisms for cardiac reprogramming remain unclear. The conventional doxycycline (Dox)-inducible temporal transgene expression systems require simultaneous transduction of two vectors (pLVX-rtTA/pLVX-cDNA) harboring the reverse tetracycline transactivator (rtTA) and the tetracycline response element (TRE)-controlled transgene, respectively, leading to inefficient cardiac reprogramming. Herein, we developed a single-construct-based polycistronic Dox-inducible vector (pDox-cDNA) expressing both the rtTA and TRE-controlled transgenes. Fluorescence activated cell sorting (FACS) analyses, quantitative RT-PCR, and immunostaining revealed that pDox-GMT increased cardiac reprogramming three-fold compared to the conventional pLVX-rtTA/pLVX-GMT. After four weeks, pDox-GMT-induced iCMs expressed multiple cardiac genes, produced sarcomeric structures, and beat spontaneously. Co-transduction of pDox-Hand2 with retroviral pMX-GMT increased cardiac reprogramming three-fold compared to pMX-GMT alone. Temporal Dox administration revealed that Hand2 transgene expression is critical during the first two weeks of cardiac reprogramming. Microarray analyses demonstrated that Hand2 represses cell cycle-promoting genes and enhances cardiac reprogramming. Thus, we have developed an efficient temporal transgene expression system, which could be invaluable in the study of cardiac reprogramming.

Cardiac disease remains a major cause of death worldwide. Direct cardiac reprogramming has emerged as a promising approach for cardiac regenerative therapy. After the discovery of MyoD, a master regulator for skeletal muscle, other single cardiac reprogramming factors (master regulators) have been sought. Discovery of cardiac reprogramming factors was inspired by the finding that multiple, but not single, transcription factors were needed to generate induced pluripotent stem cells (iPSCs) from fibroblasts. We first reported a combination of cardiac-specific transcription factors, Gata4, Mef2c, and Tbx5 (GMT), that could convert mouse fibroblasts into cardiomyocyte-like cells, which were designated as induced cardiomyocyte-like cells (iCMs). Following our first report of cardiac reprogramming, many researchers, including ourselves, demonstrated an improvement in cardiac reprogramming efficiency, in vivo direct cardiac reprogramming for heart regeneration, and cardiac reprogramming in human cells. However, cardiac reprogramming in human cells and adult fibroblasts remains inefficient, and further efforts are needed. We believe that future research elucidating epigenetic barriers and molecular mechanisms of direct cardiac reprogramming will improve the reprogramming efficiency, and that this new technology has great potential for clinical applications.

Accepted: 2006-09-12, 資料番号: SA1000698000

In order to simulate the interaction between the solar wind and the artificially deployed magnetic field produced around a magnetic sail spacecraft, a laboratory simulator was designed and constructed inside the space chamber (2m in diameter) at ISAS. As a solar wind simulator, a high-power magnetoplasmadynamic arcjet is operated in a quasisteady mode of ∼0.8ms duration. It can generate a simulated solar wind flow that is a high-speed (above 20km/s), high-density (above 1017m-3) hydrogen plasma plume of ∼70cm in diameter. A small coil (18mm in diameter), which is to simulate a magnetic sail spacecraft and can obtain 1.9-T magnetic field strength at its center, was immersed inside the simulated solar wind. Using these devices, the formation of a magnetic cavity (∼8cm in radius) was observed around the coil, which indicates successful simulation of the plasma flow around the coil (simulated magnetic sail spacecraft) in the laboratory.

Summary Direct cardiac reprogramming holds great promise for regenerative medicine. We previously generated directly reprogrammed induced cardiomyocyte-like cells (iCMs) by overexpression of Gata4, Mef2c, and Tbx5 (GMT) using retrovirus vectors. However, integrating vectors pose risks associated with insertional mutagenesis and disruption of gene expression and are inefficient. Here, we show that Sendai virus (SeV) vectors expressing cardiac reprogramming factors efficiently and rapidly reprogram both mouse and human fibroblasts into integration-free iCMs via robust transgene expression. SeV-GMT generated 100-fold more beating iCMs than retroviral-GMT and shortened the duration to induce beating cells from 30 to 10 days in mouse fibroblasts. In vivo lineage tracing revealed that the gene transfer of SeV-GMT was more efficient than retroviral-GMT in reprogramming resident cardiac fibroblasts into iCMs in mouse infarct hearts. Moreover, SeV-GMT improved cardiac function and reduced fibrosis after myocardial infarction. Thus, efficient, non-integrating SeV vectors may serve as a powerful system for cardiac regeneration.

This study was designed to examine immunological changes in maternal peripheral blood and the relationship of these changes with the amount of fetal cells in the blood.The expression of interleukin-4 (IL-4), IL-8, IL-18 and fetal hemoglobin gamma chain (HbF-gamma chain) messenger RNAs (mRNAs) in maternal peripheral blood was measured by a quantitative reverse transcription-polymerase chain reaction method.In maternal peripheral blood, the expression of IL-4 mRNA was up-regulated from the second gestational month (GM) to delivery. The expression of IL-8 and IL-18 mRNAs was down-regulated from the third or fourth GM until the eighth or ninth GM, respectively, and both increased before the onset of labor, though IL-4 mRNA decreased. The expression of IL-8 and IL-18, but not IL-4, mRNAs was correlated with that of HbF-gamma chain mRNA.Immunological interactions between maternal peripheral immune cells and fetal cells appear to be related to the onset of labor.