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La edad es un factor de riesgo arrítmico que, en especies animales, está asociado a la remodelación del colágeno. En este trabajo caracterizamos la dinámica tisular del colágeno asociada a la edad en el ventrículo izquierdo humano y utilizamos estos resultados para simular su efecto sobre la generación de arritmias ventriculares.

La desregulación de microRNAs (miRNAs) se asocia con múltiples procesos incluidos el envejecimiento cardiaco y las enfermedades cardiovasculares (ECV). Por ello, se posicionan como prometedoras dianas terapéuticas. Para superar limitaciones en su uso como tal, se propone la creación de nanoestructuras de DNA (DNS) biocompatibles para crear terapias efectivas y seguras.

Pese a la relevancia de la edad como factor de riesgo de las enfermedades cardiovasculares, sus bases moleculares y funcionales están poco caracterizadas en humanos. Para mejorar esta comprensión hemos estudiado su dinámica transcripcional cronológica y biológica en ventrículo izquierdo humano y hemos desarrollado un modelo de envejecimiento celular cardiaco.

Simple Summary Prion diseases are neurodegenerative disorders affecting humans and animals. The development of in vitro cellular models from naturally susceptible species like humans or ruminants can potentially make a great contribution to the study of many aspects of these diseases, including the ability of prions to infect and replicate in cells and therapeutics. Our study shows for the first time how ovine mesenchymal stem cells derived from bone marrow and their neural-like progeny are able to react to scrapie prion infection in vitro and assesses the effects of this infection on cell viability and proliferation. Finally, we observe that the differentiation of ovine mesenchymal stem cells into neuron-like cells makes them more permissive to prion infection. Abstract Scrapie is a prion disease affecting sheep and goats and it is considered a prototype of transmissible spongiform encephalopathies (TSEs). Mesenchymal stem cells (MSCs) have been proposed as candidates for developing in vitro models of prion diseases. Murine MSCs are able to propagate prions after previous mouse-adaptation of prion strains and, although ovine MSCs express the cellular prion protein (PrPC), their susceptibility to prion infection has never been investigated. Here, we analyze the potential of ovine bone marrow-derived MSCs (oBM-MSCs), in growth and neurogenic conditions, to be infected by natural scrapie and propagate prion particles (PrPSc) in vitro, as well as the effect of this infection on cell viability and proliferation. Cultures were kept for 48–72 h in contact with homogenates of central nervous system (CNS) samples from scrapie or control sheep. In growth conditions, oBM-MSCs initially maintained detectable levels of PrPSc post-inoculation, as determined by Western blotting and ELISA. However, the PrPSc signal weakened and was lost over time. oBM-MSCs infected with scrapie displayed lower cell doubling and higher doubling times than those infected with control inocula. On the other hand, in neurogenic conditions, oBM-MSCs not only maintained detectable levels of PrPSc post-inoculation, as determined by ELISA, but this PrPSc signal also increased progressively over time. Finally, inoculation with CNS extracts seems to induce the proliferation of oBM-MSCs in both growth and neurogenic conditions. Our results suggest that oBM-MSCs respond to prion infection by decreasing their proliferation capacity and thus might not be permissive to prion replication, whereas ovine MSC-derived neuron-like cells seem to maintain and replicate PrPSc.

Cardiac tissue slices preserve the heterogeneous structure and multicellularity of the myocardium and allow its functional characterization. However, access to human ventricular samples is scarce. We aim to demonstrate that slices from small transmural core biopsies collected from living donors during routine cardiac surgery preserve structural and functional properties of larger myocardial specimens, allowing accurate electrophysiological characterization. In pigs, we compared left ventricular transmural core biopsies with transmural tissue blocks from the same ventricular region. In humans, we analyzed transmural biopsies and papillary muscles from living donors. All tissues were vibratomesliced. By histological analysis of the transmural biopsies, we showed that tissue architecture and cellular organization were preserved. Enzymatic and vital staining methods verifed viability. Optically mapped transmembrane potentials confrmed that action potential duration and morphology were similar in pig biopsies and tissue blocks. Action potential morphology and duration in human biopsies and papillary muscles agreed with published ranges. In both pigs and humans, responses to increasing pacing frequencies and β-adrenergic stimulation were similar in transmural biopsies and larger tissues. We show that it is possible to successfully collect and characterize tissue slices from human myocardial biopsies routinely extracted from living donors, whose behavior mimics that of larger myocardial preparations both structurally and electrophysiologically. Fil: Oliván Viguera, Aida. Universidad de Zaragoza; España Fil: Pérez Zabalza, María. Universidad de Zaragoza; España Fil: García Mendívil, Laura. Universidad de Zaragoza; España Fil: Mountris, Konstantinos A.. Universidad de Zaragoza; España Fil: Orós Rodrigo, Sofía. Universidad de Zaragoza; España Fil: Ramos Marquès, Estel. Universidad de Zaragoza; España Fil: Vallejo Gil, José María. University Hospital Miguel Servet; España Fil: Fresneda Roldán, Pedro Carlos. University Hospital Miguel Servet; España Fil: Fañanás Mastral, Javier. University Hospital Miguel Servet; España Fil: Vázquez Sancho, Manuel. University Hospital Miguel Servet; España Fil: Matamala Adell, Marta. University Hospital Miguel Servet; España Fil: Sorribas Berjón, Fernando. University Hospital Miguel Servet; España Fil: Bellido Morales, Javier André. University Hospital Miguel Servet; España Fil: Mancebón Sierra, Francisco Javier. University Hospital Miguel Servet; España Fil: Vaca Núñez, Alexánder Sebastián. University Hospital Miguel Servet; España Fil: Ballester Cuenca, Carlos. University Hospital Miguel Servet; España Fil: Marigil, Miguel Ángel. Hospital San Jorge; España Fil: Pastor, Cristina. Aragón Institute of Health Sciences; España Fil: Ordovás, Laura. Aragón Agency for Research and Development; España. Universidad de Zaragoza; España Fil: Köhler, Ralf. Aragón Institute of Health Sciences; España. Aragón Agency for Research and Development; España Fil: Diez, Emiliano Raúl. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Cátedra de Fisiología Humana Normal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentina Fil: Pueyo, Esther. Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina; España. Universidad de Zaragoza; España

Cardiomyocytes&rsquo, geometry and connexin 43 (CX43) amount and distribution are structural features that play a pivotal role in electrical conduction. Their quantitative assessment is of high interest in the study of arrhythmias, but it is usually hampered by the lack of automatic tools. In this work, we propose a software algorithm (Myocyte Automatic Retrieval and Tissue Analyzer, MARTA) to automatically detect myocytes from fluorescent microscopy images of cardiac tissue, measure their morphological features and evaluate the expression of CX43 and its degree of lateralization. The proposed software is based on the generation of cell masks, contouring of individual cells, enclosing of cells in minimum area rectangles and splitting of these rectangles into end-to-end and middle compartments to estimate CX43 lateral-to-total ratio. Application to human ventricular tissue images shows that mean differences between automatic and manual methods in terms of cardiomyocyte length and width are below 4 &mu, m. The percentage of lateral CX43 also agrees between automatic and manual evaluation, with the interquartile range approximately covering from 3% to 30% in both cases. MARTA is not limited by fiber orientation and has an optimized speed by using contour filtering, which makes it run hundreds of times faster than a trained expert. Developed for CX43 studies in the left ventricle, MARTA is a flexible tool applicable to morphometric and lateralization studies of other markers in any heart chamber or even skeletal muscle. This open-access software is available online.

Aging leads to structural and electrophysiological changes that increase the risk of postoperative atrial arrhythmias; however, noninvasive preoperative markers of atrial proarrhythmic conditions are still needed. This study is aimed at assessing whether interatrial dyssynchrony determined using two-dimensional speckle tracking echocardiography relates to proarrhythmic structural and functional remodeling. A cohort of 45 patients in sinus rhythm referred for cardiac surgery was evaluated by echocardiography and surface electrocardiogram the day before the intervention. Transmembrane potential, connexin, and potassium channel distribution, inflammatory, and nitrooxidative markers were measured from right atrial tissue obtained from patients. A difference greater than 40 milliseconds between right and left atrial free wall contraction confirmed the presence of interatrial dyssynchrony in 21 patients. No difference in relation with age, previous diseases, and 2-dimensional echocardiographic findings as well as average values of global longitudinal right and left atrial strain were found between synchronic and dyssynchronic patients. Postoperative atrial fibrillation incidence increased from 8.3% in the synchronic group to 33.3% in the dyssynchronic ones. P wave duration showed no difference between groups. Action potentials from dyssynchronous patients decreased in amplitude, maximal rate of depolarization, and hyperpolarized. Duration at 30% of repolarization increased, being markedly shorter at 90% of repolarization. Only the dyssynchronous group showed early and delayed afterdepolarizations. Atrial tissue of dyssynchronous patients displayed lateralization of connexin 40 and increased connexin 43 expression and accumulation of tumor necrosis factor-α in the intercalated disc. Tumor necrosis factor-α did not colocalize, however, with lateralized connexin 40. Nitroxidative marks and KATP channels increased perivascularly and in myocytes. Our results demonstrate that, as compared to a traditional surface electrocardiogram, the novel noninvasive echocardiographic evaluation of interatrial dyssynchrony provides a better identification of nonaged-related proarrhythmic atrial remodeling with increased susceptibility to postoperative atrial fibrillation.

Aging is the main risk factor for cardiovascular diseases. In humans, cardiac aging remains poorly characterized. Most studies are based on chronological age (CA) and disregard biological age (BA), the actual physiological age (result of the aging rate on the organ structure and function), thus yielding potentially imperfect outcomes. Deciphering the molecular basis of ventricular aging, especially by BA, could lead to major progresses in cardiac research. We aim to describe the transcriptome dynamics of the aging left ventricle (LV) in humans according to both CA and BA and characterize the contribution of microRNAs, key transcriptional regulators. BA is measured using two CA‐associated transcriptional markers: CDKN2A expression, a cell senescence marker, and apparent age (AppAge), a highly complex transcriptional index. Bioinformatics analysis of 132 LV samples shows that CDKN2A expression and AppAge represent transcriptomic changes better than CA. Both BA markers are biologically validated in relation to an aging phenotype associated with heart dysfunction, the amount of cardiac fibrosis. BA‐based analyses uncover depleted cardiac‐specific processes, among other relevant functions, that are undetected by CA. Twenty BA‐related microRNAs are identified, and two of them highly heart‐enriched that are present in plasma. We describe a microRNA‐gene regulatory network related to cardiac processes that are partially validated in vitro and in LV samples from living donors. We prove the higher sensitivity of BA over CA to explain transcriptomic changes in the aging myocardium and report novel molecular insights into human LV biological aging. Our results can find application in future therapeutic and biomarker research., The biological age, measured by transcriptional markers, explains better than the chronological age the transcriptional dynamics of the human aging myocardium. microRNAs that change expression in the aging left ventricle are identified. Such microRNAs potentially regulate genes with cardiac‐specific functions. Cardiac‐enriched microRNAs that increase or decrease with biological age are present in plasma. They are thus candidate biomarkers to represent the biological age of the heart.