221 research outputs found

    Building blocks of microphysiological system to model physiology and pathophysiology of human heart

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    Microphysiological systems (MPS) are drawing increasing interest from academia and from biomedical industry due to their improved capability to capture human physiology. MPS offer an advanced in vitro platform that can be used to study human organ and tissue level functions in health and in diseased states more accurately than traditional single cell cultures or even animal models. Key features in MPS include microenvironmental control and monitoring as well as high biological complexity of the target tissue. To reach these qualities, cross-disciplinary collaboration from multiple fields of science is required to build MPS. Here, we review different areas of expertise and describe essential building blocks of heart MPS including relevant cardiac cell types, supporting matrix, mechanical stimulation, functional measurements, and computational modelling. The review presents current methods in cardiac MPS and provides insights for future MPS development with improved recapitulation of human physiology.Peer reviewe

    Optical mapping of contracting hearts

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    Optical mapping is a widely used tool to record and visualize the electrophysiological properties in a variety of myocardial preparations such as Langendorff-perfused isolated hearts, coronary-perfused wedge preparations, and cell culture monolayers. Motion artifact originating from the mechanical contraction of the myocardium creates a significant challenge to performing optical mapping of contracting hearts. Hence, to minimize the motion artifact, cardiac optical mapping studies are mostly performed on non-contracting hearts, where the mechanical contraction is removed using pharmacological excitation–contraction uncouplers. However, such experimental preparations eliminate the possibility of electromechanical interaction, and effects such as mechano-electric feedback cannot be studied. Recent developments in computer vision algorithms and ratiometric techniques have opened the possibility of performing optical mapping studies on isolated contracting hearts. In this review, we discuss the existing techniques and challenges of optical mapping of contracting hearts

    Hands-on Science. Celebrating Science and Science Education

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    The book herein aims to contribute to the improvement of Science Education in our schools and to an effective implementation of a sound widespread scientific literacy at all levels of society

    Electrical Communication and its Physiological Relevance in Retinal Pigment Epithelium

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    Verkkokalvon pigmenttiepiteeli (eng. retinal pigment epithelium, RPE) tekee tiivistä yhteistyötä verkkokalvon kanssa turvatakseen näköaistin toiminnan. Useita RPE:n tärkeimpiä tehtäviä, kuten valoa aistivien näköaistinsolujen uusiutumista, säädellään ionikanavien avulla. Näiden kanavien toimintaa ja RPE:n kykyä säädellä kalvopotentiaaliaan ei kuitenkaan vielä täysin ymmärretä. Tässä väitöskirjatyössä tutkittiin jänniteherkkien ionikanavien toimintaa sekä RPE:n sähköistä kytkeytyvyyttä käyttäen mallina ihmisen alkion kantasoluista erilaistettuja RPE-soluja sekä hiiren RPE-kudosta. Jänniteherkät natriumkanavat (NaV) tunnetaan parhaiten osallisuudestaan aktiopotentiaalin synnyssä hermosoluissa, mutta näiden kanavien tiedetään esiintyvän myös useissa muissa solutyypeissä, kuten makrofageissa ja astrosyyteissä, joissa aktiopotentiaaleja ei lähtökohtaisesti muodostu. NaV kanavien ei kuitenkaan uskottu esiintyvän RPE-kudoksessa huolimatta siitä, että niitä on toisinaan havaittu RPE-soluviljelmissä. Tämä väitöskirjatyö osoitti, että sekä kantasoluista erilaistetuissa RPE-soluissa että hiiren RPE-soluissa ilmentyy useita NaV- kanavaperheen alatyyppejä. Samalla havaittiin, että aikaisempi virheellinen johtopäätös aiheutui tutkimusten suorittamisesta yksittäisillä soluilla toiminnallisen kudoksen sijaan. Tässä työssä osoitettiin myös löydettyjen Nav-kanavatyyppien toiminnallisuus sähköfysiologisilla mittauksilla. Merkittävimpien kanavatyyppien (NaV1.4–NaV1.6 sekä NaV1.8) havaittiin sijoittuvan solu-soluliitoksiin tai RPE:n apikaaliselle solukalvolle. RPE-solujen sähköfysiogisia mittauksia on tyypillisesti tehty yksittäisistä eristetyistä soluista. Tästä johtuen RPE-solujen sähköistä kytkeytyvyyttä ei ole selvitetty nisäkkäillä, vaikka tiedetään, että aukkoliitoksilla on tärkeitä tehtäviä silmän kehityksessä. Tämä väitöskirjatyö osoitti, että solujen merkittävin aukkoliitosproteiini (engl. Connexin, Cx) on Cx43, jonka havaittiin muodostavan sekä aukkoliitoksia että puolikkaita hemikanavia solujen apikaalisella pinnalla. Sähköfysiologiset mittaukset osoittivat, että RPE:n laajasta aukkoliitosten verkostosta huolimatta RPE-solujen välinen kytkeytyvyys on suhteellisen alhainen. Kytkeytyvyyttä voitiin kuitenkin säädellä aukkoliitosten farmakologisilla estäjillä, tai estämällä tietyn Cdk5 (engl. cyclin-dependent kinase 5) kinaasi-entsyymin toimintaa. NaV-kanavien ja aukkoliitosten merkitystä RPE:n fysiologiassa tutkittiin keskittymällä näköaistinsolujen kalvojen uusiutumiseen, jossa RPE:n solusyönti eli fagosytoosi on merkittävässä roolissa. Tulokset osoittivat, että fagosytoosin aikana NaV-alatyypit NaV1.4 ja NaV1.8 esiintyvät lähellä näköaistinsolujen kalvopartikkeleita. NaV-kanavien toiminnan estäminen farmakologisesti tai geneettisesti (engl. short hairpin RNA, shRNA) vähensi merkittävästi fagosytoosin tehokkuutta. Lisäksi näiden kanavien havaittiin paikantuvan sekä apikaalipinnalle muodostuviin fagosytoosi-kuppeihin, että jo sisään otettuihin fagosomeihin yhdessä endosomien markkeriproteiinien (engl. rat sarcoma virus-related protein, Rab7) kanssa. Nämä tulokset antavat viitteitä siitä, että NaV-kanavilla olisi monipuolisia tehtäviä fagosytoosin aikana. NaV-kanavien lisäksi myös Cx43:n havaittiin esiintyvän näköaistinsolujen kalvopartikkelien kanssa fagosytoosissa ja tulokset antavat viitteitä siitä, että aukkoliitoksia otetaan solujen sisälle prosessin aikana. Fosforylaation havaittiin säätelevän tätä aukkoliitosten siirtymää ja erityisesti Cdk5-, ja proteiinikinaasi C- entsyymeillä oli merkittävä rooli tässä säätelyssä. Tämän työn tulokset osoittivat, että Cx43 liittyy fagosytoosikuppien muodostukseen sekä solujen aktiini-tukirangan uudelleen järjestymiseen. Fagosytoosin säätelyn tiedetään perustuvan vuorokausirytmiin ja mielenkiintoista on, että Cdk5-kinaasin on osoitettu vaikuttavan tähän rytmiin. On siis mahdollista, että Cdk5 auttaa myös fagosytoosin ajoituksen säätelyssä. Kokonaisuutena työni osoittaa RPE:n fysiologian ja sen ionikanavakoneiston säätelyn monimutkaisuuden. Nav-kanavien roolin on havaittu olevan huomattavasti monipuolisempi kuin aktiopotentiaalien muodostus hermosoluissa ja tuloksemme vahvistavat tätä käsitystä. Yksi työni yllättävimmistä ja merkittävimmistä tuloksista oli, että RPE voi säädellä kalvojännitettään ja epiteelikudoksen solujen välistä viestintäänsä nopeasti. Tarkemmat tiedot tämän ionisignaloinnin roolista fagosytoosissa lisäävät ymmärrystämme prosessista, joka on merkittävä näkökyvyllemme. Yhteenvetona tämä työ osoittaa, että RPE:n rooli yhteistyössä verkkokalvon kanssa on paljon aktiivisempi kuin on aikaisemmin luultu.Retinal pigment epithelium (RPE) is a tissue that preserves the health and functionality of its closely associated neural tissue, the retina. Many of the essential functions of RPE, including the renewal of light-sensing retinal photoreceptors, are regulated by ion channels. Yet, the involved ionic mechanisms, the extent of membrane potential dynamics, and the intercellular communication are not entirely understood. In this thesis, I studied the voltage-gated ion channels and electrical coupling of RPE in both human embryonic stem cell-derived and mouse RPE. Voltage-gated sodium channels (NaV), while best known for their role in action potential generation, are expressed in several non-excitable cell types such as macrophages and astrocytes. Yet, these channels had not been considered to exist in native RPE, although they had occasionally been detected in cell culture. This thesis demonstrates that stem cell-derived and mouse RPE exhibit several subtypes of NaV channels and that their earlier dismissal was due to cell isolation procedures. Our electrophysiological recordings showed that these identified NaV channels are functional. The main channel subtypes NaV1.4–NaV1.6 and NaV1.8 were found to localize in the cell-cell junctions or apical membrane in RPE. As the conventional method to carry out electrophysiological recordings in RPE is to use single cells, the electrical connectivity had not been characterized in mammalian RPE, despite the importance of gap junctions in ocular development. In this thesis, we showed that the major connexin (Cx) isoform was Cx43 which was found to form both gap junctions and apical hemichannels. The electrophysiological recordings demonstrated that the electrical connectivity was relatively low despite the extensive network of gap junctions in RPE. Yet, it was modifiable by gap junction blockers or by inhibiting a specific kinase known as cyclin-dependent kinase 5 (Cdk5). The significance of NaV channels and gap junctions to RPE physiology was investigated by focusing on the renewal of photoreceptor outer segments, where phagocytosis by RPE plays a key role. The results demonstrated that NaV subtypes NaV1.4 and NaV1.8 localize with the outer segments during phagocytosis. Moreover, inhibiting the activity of NaV channels with pharmacological modulators or short hairpin RNA (shRNA) significantly impaired phagocytosis efficiency. Furthermore, Nav channels were found to localize to the forming phagocytic cups in the apical membrane and the ingested phagosomes together with an endosomal marker Rab7. The results obtained in this thesis imply that NaV channels have versatile roles in phagocytosis. In addition to NaV channels, Cx43 localized adjacent to outer segments during phagocytosis, and the results indicate that gap junctions are internalized during the process. This translocation of gap junctions was shown to be regulated by phosphorylation, particularly by kinases such as Cdk5 and protein kinase C. The results obtained in this thesis imply that Cx43 is involved in the formation of phagocytic cups. As phagocytosis is known to be under circadian control, and Cdk5 has previously been shown to regulate this cycle, it is plausible that Cdk5 helps to control the rhythm of photoreceptor renewal. Our results highlight the complexity of RPE physiology and its ion channel machinery. The findings add to the growing body of evidence demonstrating that NaV channels' role is much more diverse than action potential generation. The results show that RPE can generate fast changes in voltage and rapidly modify its cell-cell connectivity across the epithelium. Gaining a deeper understanding of the involvement of ionic mechanisms in phagocytosis could help us to understand the phagocytosis pathway both in the healthy and diseased eye. Ultimately, this work highlights that RPE's role in its interaction with the neural retina is far more active than was previously thought

    Modelling the interaction between induced pluripotent stem cells derived cardiomyocytes patches and the recipient hearts

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    Cardiovascular diseases are the main cause of death worldwide. The single biggest killer is represented by ischemic heart disease. Myocardial infarction causes the formation of non-conductive and non-contractile, scar-like tissue in the heart, which can hamper the heart's physiological function and cause pathologies ranging from arrhythmias to heart failure. The heart can not recover the tissue lost due to myocardial infarction due to the myocardium's limited ability to regenerate. The only available treatment is heart transpalant, which is limited by the number of donors and can elicit an adverse response from the recipients immune system. Recently, regenerative medicine has been proposed as an alternative approach to help post-myocardial infarction hearts recover their functionality. Among the various techniques, the application of cardiac patches of engineered heart tissue in combination with electroactive materials constitutes a promising technology. However, many challenges need to be faced in the development of this treatment. One of the main concerns is represented by the immature phenotype of the stem cells-derived cardiomyocytes used to fabricate the engineered heart tissue. Their electrophysiological differences with respect to the host myocardium may contribute to an increased arrhythmia risk. A large number of animal experiments are needed to optimize the patches' characteristics and to better understand the implications of the electrical interaction between patches and host myocardium. In this Thesis we leveraged cardiac computational modelling to simulate \emph{in silico} electrical propagation in scarred heart tissue in the presence of a patch of engineered heart tissue and conductive polymer engrafted at the epicardium. This work is composed by two studies. In the first study we designed a tissue model with simplified geometry and used machine learning and global sensitivity analysis techniques to identify engineered heart tissue patch design variables that are important for restoring physiological electrophysiology in the host myocardium. Additionally, we showed how engineered heart tissue properties could be tuned to restore physiological activation while reducing arrhythmic risk. In the second study we moved to more realistic geometries and we devised a way to manipulate ventricle meshes obtained from magnetic resonance images to apply \emph{in silico} engineered heart tissue epicardial patches. We then investigated how patches with different conduction velocity and action potential duration influence the host ventricle electrophysiology. Specifically, we showed that appropriately located patches can reduce the predisposition to anatomical isthmus mediated re-entry and that patches with a physiological action potential duration and higher conduction velocity were most effective in reducing this risk. We also demonstrated that patches with conduction velocity and action potential duration typical of immature stem cells-derived cardiomyocytes were associated with the onset of sustained functional re-entry in an ischemic cardiomyopathy model with a large transmural scar. Finally, we demonstrated that patches electrically coupled to host myocardium reduce the likelihood of propagation of focal ectopic impulses. This Thesis demonstrates how computational modelling can be successfully applied to the field of regenerative medicine and constitutes the first step towards the creation of patient-specific models for developing and testing patches for cardiac regeneration.Open Acces

    Physics-informed neural networks for blood flow inverse problems

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    Physics-informed neural networks (PINNs) have emerged as a powerful tool for solving inverse problems, especially in cases where no complete information about the system is known and scatter measurements are available. This is especially useful in hemodynamics since the boundary information is often difficult to model, and high-quality blood flow measurements are generally hard to obtain. In this work, we use the PINNs methodology for estimating reduced-order model parameters and the full velocity field from scatter 2D noisy measurements in the ascending aorta. The results show stable and accurate parameter estimations when using the method with simulated data, while the velocity reconstruction shows dependence on the measurement quality and the flow pattern complexity. The method allows for solving clinical-relevant inverse problems in hemodynamics and complex coupled physical systems

    3-я Міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні аспекти (ICSF 2022) 24-27 травня 2022 року, м. Кривий Ріг, Україна

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    Матеріали 3-ої Міжнародної конференції зі сталого майбутнього: екологічні, технологічні, соціальні та економічні аспекти (ICSF 2022) 24-27 травня 2022 року, м. Кривий Ріг, Україна.Proceedings of the 3rd International Conference on Sustainable Futures: Environmental, Technological, Social and Economic Matters (ICSF 2022) 24-27 May 2022, Kryvyi Rih, Ukraine

    Advances in Computer Recognition, Image Processing and Communications, Selected Papers from CORES 2021 and IP&C 2021

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    As almost all human activities have been moved online due to the pandemic, novel robust and efficient approaches and further research have been in higher demand in the field of computer science and telecommunication. Therefore, this (reprint) book contains 13 high-quality papers presenting advancements in theoretical and practical aspects of computer recognition, pattern recognition, image processing and machine learning (shallow and deep), including, in particular, novel implementations of these techniques in the areas of modern telecommunications and cybersecurity
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