Laura Padrón-Barthe

New treatments are still necessary to eradicate tuberculosis disease. Macrophages derived from human induced pluripotent stem cells (hiPSC-Macs) offer a physiological niche to identify potential new drugs in the context of Mycobacterium tuberculosis (Mtb) infection. Here, we describe the scale-up of hiPSC-Macs production in 5-stack chambers for high-throughput drug screening against Mtb. A rate of approximately 100 million hiPSC-Macs was generated with optimal quality for a period of up to 12 weeks. Moreover, the infection model was optimized using a luminescence-based Mtb reporter strain. The assay showed enough sensitivity to identify compounds that could target host-pathogen interactions during Mtb infection. We interrogated a library of 200,000 compounds in Mtb-infected hiPSC-Macs with a Z-score above 0.3 in all plates analyzed. After secondary assays, 223 qualified hits were selected for further progression.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetically-determined cardiac heart muscle disorder characterized by fibro-fatty replacement of the myocardium that results in heart failure and sudden cardiac death (SCD), predominantly in young males. The disease is often caused by mutations in genes encoding proteins of the desmosomal complex, with a significant minority caused by mutations in non-desmosomal proteins. Existing treatment options are based on SCD prevention with the implantable cardioverter defibrillator, antiarrhythmic drugs, and anti-heart failure medication. Heart transplantation may also be required and there is currently no cure. Several genetically modified animal models have been developed to characterize the disease, assess its progression, and determine the influence of potential environmental factors. These models have also been very valuable for translational therapeutic approaches, to screen new treatment options that prevent and/or reverse the disease. Here, we review the available ARVC animal models reported to date, highlighting the most important pathophysiological findings and discussing the effect of treatments tested so far in this setting. We also describe gaps in our knowledge of the disease, with the goal of stimulating research and improving patient outcomes.

Heart failure (HF) has become an epidemic and constitutes a major medical, social, and economic problem worldwide. Despite advances in medical treatment, HF prognosis remains poor. The development of efficient therapies is hampered by the lack of appropriate animal models in which HF can be reliably determined, particularly in mice. The development of HF in mice is often assumed based on the presence of cardiac dysfunction, but HF itself is seldom proved. Lung ultrasound (LUS) has become a helpful tool for lung congestion assessment in patients at all stages of HF. We aimed to apply this non-invasive imaging tool to evaluate HF in mouse models of both systolic and diastolic dysfunction. We used LUS to study HF in a mouse model of systolic dysfunction, dilated cardiomyopathy, and in a mouse model of diastolic dysfunction, diabetic cardiomyopathy. LUS proved to be a reliable and reproducible tool to detect pulmonary congestion in mice. The combination of LUS and echocardiography allowed discriminating those mice that develop HF from those that do not, even in the presence of evident cardiac dysfunction. The study showed that LUS can be used to identify the onset of HF decompensation and to evaluate the efficacy of therapies for this syndrome. This novel approach in mouse models of cardiac disease enables for the first time to adequately diagnose HF non-invasively in mice with preserved or reduced ejection fraction, and will pave the way to a better understanding of HF and to the development of new therapeutic approaches.

This study sought to determine the usefulness of genetic testing to predict evolution in hypertrophic cardiomyopathy (HCM) and to assess the role of genetic testing in clinical practice. Genetic results of 100 HCM patients tested for mutations in ≥10 HCM-causing genes were evaluated. Patients were classified as with poor (group A) or favourable (group B) clinical course. Forty-five pathogenic mutations (PM) were identified in 28 patients (56 %) from group A and in 23 (46 %) from group B (p = 0.317). Only 40 patients (40 %) exhibited PM that had been previously reported and only 15 (15 %) had PM reported in ≥10 individuals. PM associated with poor prognosis were identified in just five patients from group A (10 %). Genetic findings are not useful to predict prognosis in most HCM patients. By contrast, real-world data reinforce the usefulness of genetic testing to provide genetic counselling and to enable cascade genetic screening.

Key Points: Single cell lineage tracing shows early separation of blood-endothelial precursors in the mouse embryo. Hemogenic endothelium in the YS generates the blood-endothelial common lineage and produces definitive precursors.

The first endothelial and blood cells of amniote embryos appear in close association in the blood islands of the yolk sac. This association and in vitro lineage analyses have suggested a common origin from mesodermal precursors called haemangioblasts, specified in the primitive streak during gastrulation. Fate mapping and chimera studies, however, failed to provide strong evidence for a common origin in the early mouse yolk sac. Additional in vitro studies suggest instead that mesodermal precursors first generate haemogenic endothelium, which then generate blood cells in a linear sequence. We conducted an in vivo clonal analysis to determine the potential of individual cells in the mouse epiblast, primitive streak and early yolk sac. We found that early yolk sac blood and endothelial lineages mostly derive from independent epiblast populations, specified before gastrulation. Additionally, a subpopulation of the yolk sac endothelium has haemogenic activity and displays characteristics similar to those found later in the embryonic haemogenic endothelium. Our results show that the earliest endothelial and blood cell populations in the mouse embryo are specified independently, and that haemogenic endothelium first appears in the yolk sac and produces blood precursors with markers related to definitive haematopoiesis.