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A limitation in the application of pluripotent stem cell-derived cardiomyocytes (PSC-CMs) is the failure of these cells to achieve full functional maturity. The mechanisms by which directed differentiation differs from endogenous development, leading to consequent PSC-CM maturation arrest, remain unclear. Here, we generate a single-cell RNA sequencing (scRNA-seq) reference of mouse in vivo CM maturation with extensive sampling of previously difficult-to-isolate perinatal time periods. We subsequently generate isogenic embryonic stem cells to create an in vitro scRNA-seq reference of PSC-CM-directed differentiation. Through trajectory reconstruction, we identify an endogenous perinatal maturation program that is poorly recapitulated in vitro. By comparison with published human datasets, we identify a network of nine transcription factors (TFs) whose targets are consistently dysregulated in PSC-CMs across species. Notably, these TFs are only partially activated in common ex vivo approaches to engineer PSC-CM maturation. Our study can be leveraged toward improving the clinical viability of PSC-CMs.
Assuntos
Células-Tronco Pluripotentes Induzidas , Células-Tronco Pluripotentes , Humanos , Animais , Camundongos , Miócitos Cardíacos , Diferenciação Celular , Células-Tronco Embrionárias , Fatores de Transcrição/genéticaRESUMO
PURPOSE: This study aims to evaluate the value of tissue inhibitors of MMPs-2 (TIMP-2) to indicate 5-Fluorouracil (5-Fu) resistance status in colorectal cancer. METHODS: The 5-Fu resistance of colorectal cancer cell lines was detected using Cell-Counting Kit-8 (CCK-8) and calculated using IC50. Enzyme-linked immunosorbent assay (ELISA) and real time-quantitative polymerase chain reaction (RT-qPCR) were used to detect TIMP-2 expression level in the culture supernatant and serum. Twenty-two colorectal cancer patients' TIMP-2 levels and clinical characteristics were analyzed before and after chemotherapy. Additionally, the patient-derived xenograft (PDX) model of 5-Fu resistance was used to evaluate the feasibility of TIMP-2 as a predictive biomarker of 5-Fu resistance. RESULTS: Our experimental results display that TIMP-2 expression is elevated in colorectal cancer drug-resistant cell lines, and its expression level is closely related to 5-Fu resistance. Moreover, TIMP-2 in colorectal cancer patient serum undergoing 5-Fu-based chemotherapy could indicate their drug resistance status, and its efficacy is higher than CEA and CA19-9. Finally, PDX model animal experiments reveal that TIMP-2 can detect 5-Fu resistance in colorectal cancer earlier than tumor volume. CONCLUSION: TIMP-2 is a good indicator of 5-Fu resistance in colorectal cancer. Monitoring the serum TIMP-2 level can help the clinician identify 5-Fu resistance in colorectal cancer patients earlier during chemotherapy.
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Antimetabólitos Antineoplásicos , Neoplasias Colorretais , Inibidor Tecidual de Metaloproteinase-2 , Animais , Humanos , Antimetabólitos Antineoplásicos/farmacologia , Antimetabólitos Antineoplásicos/uso terapêutico , Biomarcadores , Linhagem Celular Tumoral , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/patologia , Resistencia a Medicamentos Antineoplásicos , Fluoruracila/farmacologia , Fluoruracila/uso terapêutico , Inibidor Tecidual de Metaloproteinase-2/uso terapêuticoRESUMO
The concept of carbon neutrality has been promoted and implemented in increasing countries since the twenty-first century. In-depth research on carbon neutrality has helped improve the environmental conditions and played a particular role in sustaining economic and social development. However, there is a less comprehensive review of the status in this field; therefore, this article uses the information visualization software CiteSpace to thoroughly analyze carbon neutrality research from multiple perspectives. This study aims to reveal the current research evolutions and hotspots in this field, predict future research trends, and construct the framework for better understanding. The results find that the number of papers published on carbon neutrality keeps increasing annually, and carbon neutrality has been the widely participated domain. In addition, publications by organizations and in top journals have aroused wide attention, and the hot spots on carbon neutrality have shifted to policy, recovery, and efficiency. Based on the results, a knowledge framework of this domain is constructed to give readers a clearer understanding of the evolvement and trends, which will also provide targeted references and help for future researchers.
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Bibliometria , Carbono , Publicações , EficiênciaRESUMO
The dominant rumen bacteria in Gayals, Yaks and Yunnan Yellow Cattle were investigated using PCR-DGGE approach. The analysis of DGGE profiles, identification of dominant bands and phylogenetic analysis 16S rDNA sequences in DGGE profiles were combined to reveal the dominant bacterial communities and compared the differences between those cattle species. DGGE profiles revealed that Gayals had the most abundant dominant bacteria and the lowest similarity of intraspecies between individuals than other two cattle species. A total of 45 sequences were examined and sequence similarity analysis revealed that Gayals had the most sequences appeared to uncultured bacteria, accounting for 85.0% of the total sequences, Yaks and Yunnan Yellow Cattle had 44.4 and 68.8% uncultured bacterial sequences, respectively. According to phylogenetic analysis, the rumen dominant bacteria of Gayals were mainly phylogenetically placed within phyla firmicutes and bacteroidetes, and the known bacteria were mainly belonged to the genera Lachnospiraceae bacterium, Ruminococcus flavefaciens and Clostridium celerecrescens. Moreover, the dominant bacteria of Yaks were also mainly belonged to phyla firmicutes and bacteroidetes, and the known dominant bacteria were including Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, Pseudobutyrivibrio ruminis, Schwartzia succinivorans and Clostridiales bacterium, most of them are common rumen bacteria. In addition, the dominant bacteria in Yunnan Yellow Cattle were belonged to phyla firmicutes, bacteroidetes and Actinobacteria, and the known dominant bacteria containing Prevotella sp., Staphylococci lentus, Staphylococcus xylosus and Corynebacterium casei. Present study first detected Staphylococcus lentus and Staphylococcus xylosus in the rumen of cattle.
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Bactérias/crescimento & desenvolvimento , Bovinos/microbiologia , Eletroforese em Gel de Gradiente Desnaturante/métodos , Rúmen/microbiologia , Animais , Sequência de Bases , China , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Cardiomyocytes undergo significant structural and functional changes after birth, and these fundamental processes are essential for the heart to pump blood to the growing body. However, due to the challenges of isolating single postnatal/adult myocytes, how individual newborn cardiomyocytes acquire multiple aspects of the mature phenotype remains poorly understood. Here we implement large-particle sorting and analyze single myocytes from neonatal to adult hearts. Early myocytes exhibit wide-ranging transcriptomic and size heterogeneity that is maintained until adulthood with a continuous transcriptomic shift. Gene regulatory network analysis followed by mosaic gene deletion reveals that peroxisome proliferator-activated receptor coactivator-1 signaling, which is active in vivo but inactive in pluripotent stem cell-derived cardiomyocytes, mediates the shift. This signaling simultaneously regulates key aspects of cardiomyocyte maturation through previously unrecognized proteins, including YAP1 and SF3B2. Our study provides a single-cell roadmap of heterogeneous transitions coupled to cellular features and identifies a multifaceted regulator controlling cardiomyocyte maturation.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Miócitos Cardíacos/metabolismo , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Fatores de Processamento de RNA/metabolismo , Fatores de Transcrição/metabolismo , Animais , Cálcio/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Diferenciação Celular , Redes Reguladoras de Genes , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Camundongos , Receptores Ativados por Proliferador de Peroxissomo/genética , Células-Tronco Pluripotentes/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Transcriptoma , Proteínas de Sinalização YAPRESUMO
BACKGROUND: To make nutrients more accessible and further increase biological activity, cooked black soybeans were inoculated with Bacillus natto and fermented at 37 degrees C for 48 h. The changes in physiochemical properties of fermented black soybean natto were investigated. RESULTS: The inoculation procedure significantly increased moisture, viscosity, color, polyphenol compounds and anthocyanin, and significantly decreased hardness after 48 h fermentation. Fibrinolytic and caseinolytic protease, beta-glucosidase activities, TCA-soluble nitrogen, and ammonia nitrogen contents in the inoculated samples significantly increased as fermentation time increased. Genistin and daidzin concentrations gradually decreased with increased fermentation time. However, genistein and daidzein increased with fermentation time, which reached 316.8 and 305.2 microg g(-1) during 48 h fermentation, respectively. DPPH radical scavenging activities of the fermented black soybeans increased linearly with fermentation time and concentration. Compared with the soaked black soybeans and cooked black soybeans, the fermented black soybeans with B. natto resulted in higher scavenging activity towards DPPH radicals, which correlated well with the content of total phenols (r = 0.9254, P < 0.05) and aglycone isoflavone (r = 0.9861, P < 0.05). CONCLUSION: Black soybean natto fermented by B. natto has the potential to become a functional food because of its high antioxidant activity.
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Antioxidantes/farmacologia , Bacillus/metabolismo , Glycine max , Preparações de Plantas/farmacologia , Sementes , Alimentos de Soja/análise , Cor , Fermentação , Alimento Funcional , Isoflavonas/análise , Sementes/química , Sementes/metabolismo , Sementes/microbiologia , Alimentos de Soja/microbiologia , Glycine max/química , Glycine max/metabolismo , Glycine max/microbiologiaRESUMO
BACKGROUND AND PURPOSE: The electrophysiological properties of human pluripotent stem cell-derived cardiomyocytes (CMs) have not yet been characterized in a syncytial context. This study systematically characterized the contributions of different repolarizing potassium currents in human embryonic stem cell-derived CMs (hESC-CMs) during long-term culture as cell monolayers. EXPERIMENTAL APPROACH: The H9 hESC line was differentiated to CMs and plated to form confluent cell monolayers. Optical mapping was used to record the action potentials (APs) and conduction velocity (CV) during electrophysiological and pharmacological experiments. RT-PCR and Western blot were used to detect the presence and expression levels of ion channel subunits. KEY RESULTS: Long-term culture of hESC-CMs led to shortened AP duration (APD), faster repolarization rate, and increased CV. Selective block of IKr , IKs , IK1 , and IKur significantly affected AP repolarization and APD in a concentration- and culture time-dependent manner. Baseline variations in APD led to either positive or negative APD dependence of drug response. Chromanol 293B produced greater relative AP prolongation in mid- and late-stage cultures, while DPO-1 had more effect in early-stage cultures. CV in cell monolayers in early- and late-stage cultures was most susceptible to slowing by E-4031 and BaCl2 respectively. CONCLUSIONS AND IMPLICATIONS: IKr , IKs , IK1 , and IKur all play an essential role in the regulation of APD and CV in hESC-CMs. During time in culture, increased expression of IKr and IK1 helps to accelerate repolarization, shorten APD, and increase CV. We identified a new pro-arrhythmic parameter, positive APD dependence of ion channel block, which can increase APD and repolarization gradients.
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Potenciais de Ação/fisiologia , Miócitos Cardíacos/fisiologia , Canais de Potássio/fisiologia , Linhagem Celular , Células-Tronco Embrionárias Humanas/citologia , HumanosRESUMO
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold great promise for cardiac studies, but their structural and functional immaturity precludes their use as faithful models of adult myocardium. Here we describe engineered heart slices (EHS), preparations of decellularized porcine myocardium repopulated with hiPSC-CMs that exhibit structural and functional improvements over standard culture. EHS exhibited multicellular, aligned bundles of elongated CMs with organized sarcomeres, positive inotropic responses to isoproterenol, anisotropic conduction of action potentials, and electrophysiological functionality for more than 200 days. We developed a new drug assay, GRIDS, that serves as a "fingerprint" of cardiac drug sensitivity for a range of pacing rates and drug concentrations. GRIDS maps characterized differences in drug sensitivity between EHS and monolayers more clearly than changes in action potential durations or conduction velocities. EHS represent a tissue-like model for long-term culture, structural, and functional improvement, and higher fidelity drug response of hiPSC-CMs.
Assuntos
Coração/fisiologia , Células-Tronco Pluripotentes Induzidas/citologia , Miocárdio/citologia , Miócitos Cardíacos/citologia , Engenharia Tecidual/métodos , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Cardiotônicos/farmacologia , Técnicas de Cultura de Células/métodos , Diferenciação Celular/fisiologia , Células Cultivadas , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Coração/efeitos dos fármacos , Humanos , Isoproterenol/farmacologia , SuínosRESUMO
IMPACT STATEMENT: Genetic heart diseases such as arrhythmogenic cardiomyopathy (AC), a common genetic cause of sudden cardiac death, can be modeled using patient-specific induced pluripotent stem cell-derived cardiac myocytes (CMs). However, it is important to culture these cells in a multicellular syncytium with exposure to surrounding matrix cues to create more accurate and robust models of the disease due to the importance of cell-cell and cell-matrix interactions. The engineered heart slice, constructed by seeding CMs on intact decellularized matrix slices, allows molecular and functional studies on an aligned multilayered syncytium of CMs. This study reveals the potential for an improved disease-in-a-dish model of AC.
Assuntos
Arritmias Cardíacas , Cardiomiopatias , Células-Tronco Pluripotentes Induzidas , Modelos Cardiovasculares , Mutação , Miocárdio , Placofilinas , Engenharia Tecidual , Animais , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/patologia , Cardiomiopatias/genética , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/patologia , Miocárdio/metabolismo , Miocárdio/patologia , Placofilinas/genética , Placofilinas/metabolismo , SuínosRESUMO
INTRODUCTION: Voltage-sensitive optical (VSO) sensors offer a minimally invasive method to study the time course of repolarization of the cardiac action potential (AP). This Comprehensive in vitro Proarrhythmia Assay (CiPA) cross-platform study investigates protocol design and measurement variability of VSO sensors for preclinical cardiac electrophysiology assays. METHODS: Three commercial and one academic laboratory completed a limited study of the effects of 8 blinded compounds on the electrophysiology of 2 commercial lines of human induced pluripotent stem-cell derived cardiomyocytes (hSC-CMs). Acquisition technologies included CMOS camera and photometry; fluorescent voltage sensors included di-4-ANEPPS, FluoVolt and genetically encoded QuasAr2. The experimental protocol was standardized with respect to cell lines, plating and maintenance media, blinded compounds, and action potential parameters measured. Serum-free media was used to study the action of drugs, but the exact composition and the protocols for cell preparation and drug additions varied among sites. RESULTS: Baseline AP waveforms differed across platforms and between cell types. Despite these differences, the relative responses to four selective ion channel blockers (E-4031, nifedipine, mexiletine, and JNJ 303 blocking IKr, ICaL, INa, and IKs, respectively) were similar across all platforms and cell lines although the absolute changes differed. Similarly, four mixed ion channel blockers (flecainide, moxifloxacin, quinidine, and ranolazine) had comparable effects in all platforms. Differences in repolarisation time course and response to drugs could be attributed to cell type and experimental method differences such as composition of the assay media, stimulated versus spontaneous activity, and single versus cumulative compound addition. DISCUSSION: In conclusion, VSOs represent a powerful and appropriate method to assess the electrophysiological effects of drugs on iPSC-CMs for the evaluation of proarrhythmic risk. Protocol considerations and recommendations are provided toward standardizing conditions to reduce variability of baseline AP waveform characteristics and drug responses.
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A total of 6,219 positive clones were obtained by constructing a BAC library of uncultured ruminal fungi of gayal, and two clones (xynF1 and eglF2) with lignocellulolytic enzyme activity were selected. The sequencing results showed that xynF1 and eglF2 had 903-bp, and 1,995-bp, open reading frames likely to encode ß-xylanase (XynF1) and ß-glucosidase (EglF2), respectively. The amino acid sequence of XynF1 had 99% coverage and 95% homology to the endo-ß-1,4-xylanase encoded by the cellulase gene of Orpinomyces sp. LT-3 (GenBank accession No. AEO51791.1). The amino acid sequence of EglF2 had 99% coverage and 93% homology to the ß-glucosidase encoded by the cellulase gene of Piromyces sp. E2 (GenBank accession No. CAC34952.1). Analysis using the SMART software showed that XynF1 contains a glycoside hydrolase family 11 functional module and a carbohydrate-binding module, while EglF2 contains a glycoside hydrolase family 1 functional module. XynF1 showed the highest relative enzymatic activity, up to 95%, at 45°C and pH 4.2, while EglF2 showed the highest relative enzymatic activity, up to 95%, at 55°C and pH 6.2. In this study, we achieved efficient expression of the xynF1 and eglF2 genes in Pichia pastoris, which laid a foundation for the practical application of the lignocellulolytic enzymes.
Assuntos
Celulases/genética , Endo-1,4-beta-Xilanases/química , Fungos/enzimologia , Regulação Enzimológica da Expressão Gênica , Rúmen/enzimologia , Ruminantes/microbiologia , beta-Glucosidase/química , Sequência de Aminoácidos , Animais , Celulases/metabolismo , Celulose/metabolismo , Clonagem Molecular , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/isolamento & purificação , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fungos/genética , Biblioteca Gênica , Genes Fúngicos/genética , Fases de Leitura Aberta , Pichia/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Rúmen/microbiologia , Homologia de Sequência de Aminoácidos , beta-Glucosidase/genética , beta-Glucosidase/isolamento & purificaçãoRESUMO
Electrophysiological variability in cardiomyocytes derived from pluripotent stem cells continues to be an impediment for their scientific and translational applications. We studied the variability of action potentials (APs) recorded from clusters of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using high-resolution optical mapping. Over 23,000 APs were analyzed through four parameters: APD30, APD80, triangulation and fractional repolarization. Although measures were taken to reduce variability due to cell culture conditions and rate-dependency of APs, we still observed significant variability in APs among and within the clusters. However, similar APs were found in spatial locations with close proximity, and in some clusters formed distinct regions having different AP characteristics that were reflected as separate peaks in the AP parameter distributions, suggesting multiple electrophysiological phenotypes. Using a recently developed automated method to group cells based on their entire AP shape, we identified distinct regions of different phenotypes within single clusters and common phenotypes across different clusters when separating APs into 2 or 3 subpopulations. The systematic analysis of the heterogeneity and potential phenotypes of large populations of hESC-CMs can be used to evaluate strategies to improve the quality of pluripotent stem cell-derived cardiomyocytes for use in diagnostic and therapeutic applications and in drug screening.
Assuntos
Potenciais de Ação , Diferenciação Celular , Células-Tronco Embrionárias Humanas/citologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/fisiologia , Estimulação Elétrica , Fenômenos Eletrofisiológicos , HumanosRESUMO
Neurons derived from human pluripotent stem cells (hPSCs) are powerful tools for studying human neural development and diseases. Robust functional coupling of hPSC-derived neurons with target tissues in vitro is essential for modeling intercellular physiology in a dish and to further translational studies, but it has proven difficult to achieve. Here, we derive sympathetic neurons from hPSCs and show that they can form physical and functional connections with cardiac muscle cells. Using multiple hPSC reporter lines, we recapitulated human autonomic neuron development in vitro and successfully isolated PHOX2B::eGFP+ neurons that exhibit sympathetic marker expression and electrophysiological properties and norepinephrine secretion. Upon pharmacologic and optogenetic manipulation, PHOX2B::eGFP+ neurons controlled beating rates of cardiomyocytes, and the physical interactions between these cells increased neuronal maturation. This study provides a foundation for human sympathetic neuron specification and for hPSC-based neuronal control of organs in a dish.
Assuntos
Diferenciação Celular , Miócitos Cardíacos/citologia , Neurônios/citologia , Células-Tronco Pluripotentes/citologia , Sistema Nervoso Simpático/citologia , Animais , Animais Recém-Nascidos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular/genética , Linhagem Celular , Citometria de Fluxo , Regulação da Expressão Gênica no Desenvolvimento , Genes Reporter , Proteínas de Fluorescência Verde/metabolismo , Ventrículos do Coração/citologia , Proteínas Hedgehog/metabolismo , Proteínas de Homeodomínio/metabolismo , Humanos , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/metabolismo , Neurônios/metabolismo , Optogenética , Fenótipo , Células-Tronco Pluripotentes/metabolismo , Fatores de Transcrição/metabolismo , Via de Sinalização Wnt/genéticaRESUMO
Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are the most promising source of cardiomyocytes (CMs) for experimental and clinical applications, but their use is largely limited by a structurally and functionally immature phenotype that most closely resembles embryonic or fetal heart cells. The application of physical stimuli to influence hPSC-CMs through mechanical and bioelectrical transduction offers a powerful strategy for promoting more developmentally mature CMs. Here we summarize the major events associated with in vivo heart maturation and structural development. We then review the developmental state of in vitro derived hPSC-CMs, while focusing on physical (electrical and mechanical) stimuli and contributory (metabolic and hypertrophic) factors that are actively involved in structural and functional adaptations of hPSC-CMs. Finally, we highlight areas for possible future investigation that should provide a better understanding of how physical stimuli may promote in vitro development and lead to mechanistic insights. Advances in the use of physical stimuli to promote developmental maturation will be required to overcome current limitations and significantly advance research of hPSC-CMs for cardiac disease modeling, in vitro drug screening, cardiotoxicity analysis and therapeutic applications.
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Miócitos Cardíacos/citologia , Células-Tronco Pluripotentes/citologia , Diferenciação Celular/fisiologia , HumanosRESUMO
Methods for obtaining cardiomyocytes from human embryonic stem cells (hESCs) are improving at a significant rate. However, the characterization of these cardiomyocytes (CMs) is evolving at a relatively slower rate. In particular, there is still uncertainty in classifying the phenotype (ventricular-like, atrial-like, nodal-like, etc.) of an hESC-derived cardiomyocyte (hESC-CM). While previous studies identified the phenotype of a CM based on electrophysiological features of its action potential, the criteria for classification were typically subjective and differed across studies. In this paper, we use techniques from signal processing and machine learning to develop an automated approach to discriminate the electrophysiological differences between hESC-CMs. Specifically, we propose a spectral grouping-based algorithm to separate a population of CMs into distinct groups based on the similarity of their action potential shapes. We applied this method to a dataset of optical maps of cardiac cell clusters dissected from human embryoid bodies. While some of the nine cell clusters in the dataset are presented with just one phenotype, the majority of the cell clusters are presented with multiple phenotypes. The proposed algorithm is generally applicable to other action potential datasets and could prove useful in investigating the purification of specific types of CMs from an electrophysiological perspective.
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Potenciais de Ação/fisiologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/fisiologia , Processamento de Sinais Assistido por Computador , Algoritmos , Inteligência Artificial , Técnicas Eletrofisiológicas Cardíacas , Células-Tronco Embrionárias , HumanosRESUMO
BACKGROUND: We recently demonstrated that high frequency alternating current (HFAC) electric fields can reversibly block propagation in the heart by inducing an oscillating, elevated transmembrane potential (Vm) that maintains myocytes in a refractory state for the field duration and can terminate arrhythmias, including ventricular fibrillation (VF). OBJECTIVES: To quantify and characterize conduction block (CB) induced by HFAC fields and to determine whether the degree of CB can be used to predict defibrillation success. METHODS: Optical mapping was performed in adult guinea pig hearts (n = 14), and simulations were performed in an anatomically accurate rabbit ventricular model. HFAC fields (50-500 Hz) were applied to the ventricles. A novel power spectrum metric of CB-the loss of spectral power in the 1-30 Hz range, termed loss of conduction power (LCP)-was assessed during the HFAC field and compared with defibrillation success and VF vulnerability. RESULTS: LCP increased with field strength and decreased with frequency. Optical mapping experiments conducted on the epicardial surface showed that LCP and the size of CB regions were significantly correlated with VF initiation and termination. In simulations, subsurface myocardial LCP and CB sizes were more closely correlated with VF termination than surface values. Multilinear regression analysis of simulation results revealed that while CB on both the surface and the subsurface myocardium was predictive, subsurface myocardial CB was the better predictor of defibrillation success. CONCLUSIONS: HFAC fields induce a field-dependent state of CB, and defibrillation success is related to the degree and location of the CB.
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Bloqueio Atrioventricular/terapia , Cardioversão Elétrica/métodos , Coração/fisiopatologia , Fibrilação Ventricular/terapia , Imagens com Corantes Sensíveis à Voltagem/métodos , Animais , Bloqueio Atrioventricular/fisiopatologia , Simulação por Computador , Eletrocardiografia , Cobaias , Técnicas In Vitro , Coelhos , Fibrilação Ventricular/fisiopatologiaRESUMO
Since the first description of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), these cells have garnered tremendous interest for their potential use in patient-specific analysis and therapy. Additionally, hiPSC-CMs can be derived from donor cells from patients with specific cardiac disorders, enabling in vitro human disease models for mechanistic study and therapeutic drug assessment. However, a full understanding of their electrophysiological and contractile function is necessary before this potential can be realized. Here, we review this emerging field from a functional perspective, with particular emphasis on beating rate, action potential, ionic currents, multicellular conduction, calcium handling and contraction. We further review extant hiPSC-CM disease models that recapitulate genetic myocardial disease.
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Fenômenos Eletrofisiológicos , Cardiopatias/patologia , Cardiopatias/fisiopatologia , Células-Tronco Pluripotentes Induzidas/citologia , Contração Miocárdica , Miócitos Cardíacos/citologia , Animais , Coração/fisiologia , Coração/fisiopatologia , Humanos , Células-Tronco Pluripotentes Induzidas/patologia , Ácido Láctico , Miócitos Cardíacos/patologiaRESUMO
Human embryonic stem cells have emerged as the prototypical source from which cardiomyocytes can be derived for use in drug discovery and cell therapy. However, such applications require that these cardiomyocytes (hESC-CMs) faithfully recapitulate the physiology of adult cells, especially in relation to their electrophysiological and contractile function. We review what is known about the electrophysiology of hESC-CMs in terms of beating rate, action potential characteristics, ionic currents, and cellular coupling as well as their contractility in terms of calcium cycling and contraction. We also discuss the heterogeneity in cellular phenotypes that arises from variability in cardiac differentiation, maturation, and culture conditions, and summarize present strategies that have been implemented to reduce this heterogeneity. Finally, we present original electrophysiological data from optical maps of hESC-CM clusters.
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Fenômenos Eletrofisiológicos , Células-Tronco Embrionárias/citologia , Contração Miocárdica , Miócitos Cardíacos/citologia , Animais , Bioengenharia , HumanosRESUMO
Left ventricular-assist devices (LVADs) are used to supply blood to the body of patients with heart failure. Pressure unloading is greater for counter-pulsating LVADs than for continuous LVADs. However, several clinical trials have demonstrated that myocardial recovery is similar for both types of LVAD. This study examined the contractile energy consumption of the myocardium with continuous and counter-pulsating LVAD support to ascertain the effect of the different LVADs on myocardial recovery. We used a three-dimensional electromechanical model of canine ventricles, with models of the circulatory system and an LVAD. We compared the left ventricular peak pressure (LVPP) and contractile ATP consumption between pulsatile and continuous LVADs. With the continuous and counter-pulsating LVAD, the LVPP decreased to 46 and 10%, respectively, and contractile ATP consumption decreased to 60 and 50%. The small difference between the contractile ATP consumption of these two types of LVAD may explain the comparable effects of the two types on myocardial recovery.