Atomic Force Microscopy: an innovative technology to explore cardiomyocyte cell surface in cardiac physio/pathophysiology

International audienceAtomic Force Microscopy (AFM) has emerged these recent years as a multifunctional toolbox for studying biological samples in physiological conditions. Although its use has spread among biologists community, cardiology remains a scientific field where not been extensively used yet. Heart diseases are nowadays a major human threat, and cause the death of millions of people each year. A convergent point to all heart diseases seems to be related to the defect of the cardiomyocyte, the contractile unit of the he reason, many scientists got interested in this cell type. However, very few studies use a technology such as AFM and its derivatives (force spectroscopy, multiparametric imaging) to explore this cell. The aim of this review is thus to give a comprehensive an interest of the biophysical approach made possible by AFM studies. We will show how AFM has been and can be used to study fix living cardiomyocytes, and, how combined with other types of microscopy, it can help getting a better understanding o pathologies or drugs. This review is the first dedicated to the use of AFM technics in cardiology, and gives new insights in fundamental questions surrounding cardiomyocytes, that can be answered using such a technology

Atomic Force Microscopy: an innovative technology to explore cardiomyocyte cell surface in cardiac physio/pathophysiology

International audienceAtomic Force Microscopy (AFM) has emerged these recent years as a multifunctional toolbox for studying biological samples in physiological conditions. Although its use has spread among biologists community, cardiology remains a scientific field where not been extensively used yet. Heart diseases are nowadays a major human threat, and cause the death of millions of people each year. A convergent point to all heart diseases seems to be related to the defect of the cardiomyocyte, the contractile unit of the he reason, many scientists got interested in this cell type. However, very few studies use a technology such as AFM and its derivatives (force spectroscopy, multiparametric imaging) to explore this cell. The aim of this review is thus to give a comprehensive an interest of the biophysical approach made possible by AFM studies. We will show how AFM has been and can be used to study fix living cardiomyocytes, and, how combined with other types of microscopy, it can help getting a better understanding o pathologies or drugs. This review is the first dedicated to the use of AFM technics in cardiology, and gives new insights in fundamental questions surrounding cardiomyocytes, that can be answered using such a technology

Études autopsiques des matières organiques conservées : Louise de Quengo et les cœurs issus des cardiotaphes

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The last battle of Anne of Brittany: Solving mass grave through an interdisciplinary approach (paleopathology, biological anthropology, history, multiple isotopes and radiocarbon dating)

International audienceMass graves are usually key historical markers with strong incentive for archeological investigations. The identification of individuals buried in mass graves has long benefitted from traditional historical, archaeological, anthropological and paleopathological techniques. The addition of novel methods including genetic, genomic and isotopic geochemistry have renewed interest in solving unidentified mass graves. In this study, we demonstrate that the combined use of these techniques allows the identification of the individuals found in two Breton historical mass graves, where one method alone would not have revealed the importance of this discovery. The skeletons likely belong to soldiers from the two enemy armies who fought during a major event of Breton history: the siege of Rennes in 1491, which ended by the wedding of the Duchess of Brittany with the King of France and signaled the end of the independence of the region. Our study highlights the value of interdisciplinary approaches with a particular emphasis on increasingly accurate isotopic markers. The development of the sulfur isoscape and testing of the triple isotope geographic assignment are detailed in a companion paper [13]

Structural evidence for a new elaborate 3D-organization of the cardiomyocyte lateral membrane in adult mammalian cardiac tissues

International audienceAims: This study explored the lateral crest structures of adult cardiomyocytes (CMs) within healthy and diseased cardiac tissue.Methods and results: Using high-resolution electron and atomic force microscopy, we performed an exhaustive quantitative analysis of the three-dimensional (3D) structure of the CM lateral surface in different cardiac compartments from various mammalian species (mouse, rat, cow, and human) and determined the technical pitfalls that limit its observation. Although crests were observed in nearly all CMs from all heart compartments in all species, we showed that their heights, dictated by the subsarcolemmal mitochondria number, substantially differ between compartments from one species to another and tightly correlate with the sarcomere length. Differences in crest heights also exist between species; for example, the similar cardiac compartments in cows and humans exhibit higher crests than rodents. Unexpectedly, we found that lateral surface crests establish tight junctional contacts with crests from neighbouring CMs. Consistently, super-resolution SIM or STED-based immunofluorescence imaging of the cardiac tissue revealed intermittent claudin-5-claudin-5 interactions in trans via their extracellular part and crossing the basement membrane. Finally, we found a loss of crest structures and crest–crest contacts in diseased human CMs and in an experimental mouse model of left ventricle barometric overload.Conclusion: Overall, these results provide the first evidence for the existence of differential CM surface crests in the cardiac tissue as well as the existence of CM–CM direct physical contacts at their lateral face through crest–crest interactions. We propose a model in which this specific 3D organization of the CM lateral membrane ensures the myofibril/myofiber alignment and the overall cardiac tissue cohesion. A potential role in the control of sarcomere relaxation and of diastolic ventricular dysfunction is also discussed. Whether the loss of CM surface crests constitutes an initial and common event leading to the CM degeneration and the setting of heart failure will need further investigation

Ephrin-B1 regulates the adult diastolic function through a late postnatal maturation of cardiomyocyte surface crests

The rod-shaped adult cardiomyocyte (CM) harbors a unique architecture of its lateral surface with periodic crests, relying on the presence of subsarcolemmal mitochondria (SSM) with unknown role. Here, we investigated the development and functional role of CM crests during the postnatal period. We found in rodents that CM crest maturation occurs late between postnatal day 20 (P20) and P60 through both SSM biogenesis, swelling and crest-crest lateral interactions between adjacent CM, promoting tissue compaction. At the functional level, we showed that the P20-P60 period is dedicated to the improvement of relaxation. Interestingly, crest maturation specifically contributes to an atypical CM hypertrophy of its short axis, without myofibril addition, but relying on CM lateral stretching. Mechanistically, using constitutive and conditional CM-specific knock-out mice, we identified ephrin-B1, a lateral membrane stabilizer, as a molecular determinant of P20-P60 crest maturation, governing both the CM lateral stretch and the diastolic function, thus highly suggesting a link between crest maturity and diastole. Remarkably, while young adult CM-specific Efnb1 KO mice essentially exhibit an impairment of the ventricular diastole with preserved ejection fraction and exercise intolerance, they progressively switch toward systolic heart failure with 100% KO mice dying after 13 months, indicative of a critical role of CM-ephrin-B1 in the adult heart function. This study highlights the molecular determinants and the biological implication of a new late P20-P60 postnatal developmental stage of the heart in rodents during which, in part, ephrin-B1 specifically regulates the maturation of the CM surface crests and of the diastolic function

Apelin prevents cardiac fibroblast activation and collagen production through inhibition of sphingosine kinase 1

Activation of cardiac fibroblasts and their differentiation into myofibroblasts is a key event in the progression of cardiac fibrosis that leads to end-stage heart failure. Apelin, an adipocyte-derived factor, exhibits a number of cardioprotective properties; however, whether apelin is involved in cardiac fibroblast activation and myofibroblast formation remains unknown. The aim of this study was to determine the effects of apelin in activated cardiac fibroblasts, the potential related mechanisms and impact on cardiac fibrotic remodelling process