No description available.

No description available.

Yes / We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9Hz. Action potential waveforms recorded at 1Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na+-channel blocker (5μM) ranolazine or the intracellular Ca2+ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller inMCTmyocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus, our study links electrical restitution remodeling to a defining mechanical characteristic of heart failure, the reduced ability to respond to an increase in demand.

No / Evaluation of drug candidates in in-vitro assays of action potential duration (APD) is one component of preclinical safety assessment. Current assays are limited by technically-demanding, time-consuming electrophysiological methods. This study aimed to assess whether a voltage-sensitive dye-based assay could be used instead. Methods Optical APs were recorded using di-4-ANEPPS in electrically field stimulated Beagle left ventricular midmyocardial myocytes (LVMMs). Pharmacological properties of di-4-ANEPPS on the main cardiac ion channels that shape the ventricular AP were investigated using IonWorks™ and conventional electrophysiology. Effects of 9 reference drugs (dofetilide, E4031, d-sotalol, ATXII, cisapride, terfenadine, alfuzosin, diltiazem and pinacidil) with known APD-modulating effects were assessed on optically measured APD at 1 Hz. Results Under optimum conditions, 0.1 μM di-4-ANEPPS could be used to monitor APs paced at 1 Hz during nine, 5 s exposures without altering APD. di-4-ANEPPS had no effect on either hIERG, hINa, hIKs and hIto currents in transfected CHO cells (up to 10 µM) or ICa,L current in LVMMs (at 16 µM). di-4-ANEPPS had no effect on APs recorded with microelectrodes at 1 or 0.5 Hz over a period of 30 min di-4-ANEPPS displayed the sensitivity to record changes in optically measured APD in response to altered pacing frequencies and sequential vehicle additions did not affect the optically measured APD. APD data obtained with 9 reference drugs were as expected except (i) d-sotalol-induced increases in duration were smaller than those caused by other IKr blockers and (ii) increases in APD were not detected using low concentrations of terfenadine. Discussion Early in drug discovery, the di-4-ANEPPS-based method can reliably be used to assess drug effects on APD as part of a cardiac risk assessment strategy.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Lesão do DNA mitocondrial (mtDNA) promove disfunção desta organela, contribuindo para a gênese do envelhecimento e fisiopatologia de doenças como aterosclerose e diabetes. A mitocôndria é a principal fonte quantitativa de espécies reativas de oxigênio (ROS) em células, e o complexo NAD(P)H oxidase a principal fonte de ROS envolvidas na sinalização celular. A possível inter-relação entre estas duas importantes vias produtoras de ROS não está definida. O objetivo deste estudo foi investigar o perfil de alterações na expressão e atividade da NAD(P)H oxidase de células musculares lisas vasculares (VSMC) em resposta a perturbações mínimas da função mitocondrial análogas às esperadas em doenças crônico-degenerativas vasculares. Inicialmente, validamos modelo in vitro de disfunção mitocondrial induzida por incubação de VSMC com brometo de etídio (24 - 72 h). Lesões mínimas do mtDNA foram documentadas por alterações nos produtos de amplificação (PCR) da região repetitiva da D-loop e redução da taxa de consumo de oxigênio total em ~15% vs. basal (p<0,05). Este grau de lesão não foi suficiente para induzir alterações morfológicas evidentes ou apoptose, e foi associado ao retardo de 25 - 30% no aumento de população celular induzido por soro fetal bovino. Nestas condições, não se detectou aumento da produção basal de superóxido ou mudanças nos níveis de glutationa, óxidos de nitrogênio, ou da atividade superóxido dismutase. A produção basal de peróxido de hidrogênio aumentou ~15%. Após disfunção mitocondrial, houve significativo aumento (30 - 45%) na atividade basal do complexo NAD(P)H oxidase em fração de membrana de VSMC. Entretanto, a ativação da oxidase pela AII, conhecido agonista da oxidase vascular, foi essencialmente abolida, indicando dependência funcional da ativação da oxidase com a integridade da mitocôndria. Em sintonia com esses dados, na condição basal, ocorreu aumento de expressão da isoforma Nox4 da oxidase, enquanto o aumento do mRNA da Nox1 normalmente visto após AII foi minimizado. Por outro lado, o aumento da atividade da NADPH oxidase causado pelo estressor do RE tunicamicina (indutor de Nox4) foi também abolido pela disfunção mitocondrial, entretanto, ocorreu aumento do mRNA da Nox4, indicando que as alterações funcionais da oxidase nesta situação não decorrem apenas de mudanças da expressão. Dissociação semelhante entre expressão e atividade ocorreu após exposição de 72 horas ao EtBr (i.e., durante adaptação). Nesta, ocorreu maior expressão do mRNA de Nox1 e Nox4 com AII, sem aumento da atividade da oxidase em membranas. Incubação do EtBr por 24 horas não induziu per se aumento consistente nos índices de estresse do RE e induziu inversão do padrão do tráfego subcelular da dissulfeto isomerase protéica (PDI), uma chaperona redox descrita recentemente como reguladora da NADPH oxidase. Após 72 horas de incubação com EtBr, a expressão de chaperonas marcadoras de estresse do RE foi bastante diminuída e o tráfego da PDI teve o padrão restaurado. Demonstramos por microscopia confocal evidências preliminares de possível co-localização entre Nox1 e mitocôndria. Estes dados sugerem uma relevante inter-relação funcional entre mitocôndria e complexo NAD(P)H oxidase, associada pelo menos a alterações de expressão e/ou tráfego subcelular de subunidades catalíticas e reguladoras desse complexo. / Mitochondrial DNA (mtDNA) damage induces dysfunction of this organelle, contributing to the genesis of aging and to the pathophysiology of diseases such as atherosclerosis and diabetes. Mitochondria are the main quantitative source of reactive oxygen species (ROS) in cells, while NAD(P)H oxidase complex is a major source of cell signaling-associated ROS. The possible crosstalk between these two relevant sources of ROS is unclear. The aim of this study was to investigate changes in activity and/or expression of vascular smooth muscle cell (VSMC) NAD(P)H oxidase in response to minor perturbations of mitochondrial function similar to those expected to occur in chronic degenerative vascular diseases. Initially, we validated an in vitro model of mitochondrial dysfunction in VSMC, through incubation with ethidium bromide (24 - 72 h). Minimal mtDNA damage after EtBr was shown by distinct amplification patterns (at PCR) of D-loop repetitive region and by ~ 15% oxygen consumption decrease vs. basal (p<0.05). Such mtDNA damage was not sufficient to induce morphologic changes or apoptosis, whereas serum-stimulated increase in cell number was prevented by 25-30%. Under those conditions, baseline superoxide production, as well as levels of glutathione or nitrogen oxides or superoxide dismutase activity were unchanged. Baseline hydrogen peroxide production increased ~15%. VSMC membrane fraction NADPH oxidase activity was increased by 30-45% after mitochondrial dysfunction. However, oxidase activation due to AII (100 nM, 4h) was markedly abrogated, indicating that A-II-driven oxidase activation requires integrity of mitochondrial function. Accordingly, there were increases in baseline mRNA expression of Nox4 oxidase isoform, while the expected increase in Nox1 by AII was minimized. On the other hand, the NADPH oxidase activity induced by the endoplasmic reticulum stressor tunicamycin (Nox4 inducer) after mitochondrial dysfunction was abrogated, however simultaneously with increased Nox4 mRNA, thus indicating that the observed functional alterations in the oxidase complex in these conditions cannot be associated only to mRNA expression changes. After VSMC EtBr incubation for 72 h, similar dissociation between expression and activity was observed, with increase in Nox 1 and Nox4 mRNA by AII, without parallel increase in membrane fraction oxidase activity. Although there was little change in ER stress markers after 24h EtBr, protein disulfide isomerase (PDI), a redox chaperone recently described by us as a novel NAD(P)H oxidase regulator, exhibited a reversal of its subcellular traffic pattern. After 72 h EtBr, the expression of ER markers was strongly decreased and normal PDI traffic was restored. Confocal microscopy suggested possible co-localization between Nox1 and mitochondria. These results suggest a functionally relevant crosstalk between mitochondria and NADPH oxidase complex associated at least to changes in expression and/or subcellular traffic of catalytic or regulatory subunits of this complex.

O estudo de mutações genéticas como causa das cardiomiopatias teve início com a descoberta de mutações em proteínas sarcoméricas que levavam à Cardiomiopatia Hipertrófica, desde então, alterações em diversos genes, de proteínas contráteis ou não, foram descobertas e listadas como a responsável pelo desenvolvimento de diferentes cardiomiopatias. Estudar o efeito destas mutações nos cardiomiócitos destes pacientes permanecia um desafio devido ao difícil acesso às células cardíacas. Em 2007, a técnica de reprogramação de células somáticas em células-tronco pluripotentes foi descoberta. Pelo fato das células-tronco pluripotentes serem capazes de ser diferenciadas em cardiomiócitos, surgiu-se a possibilidade de se estudar essas células de indivíduos portadores das mutações genéticas. Esta tese teve como objetivo a criação de um modelo celular para estudar a Cardiomiopatia Hipertrófica causada por mutações genéticas. Inicialmente foi estabelecido um protocolo de reprogramação celular para se estabelecer linhagens celulares das células-tronco induzidas de um paciente com mutação no gene MYH7. Tendo as células caracterizadas, elas foram diferenciadas em cardiomiócitos através de um protocolo adaptado de protocolos de diferenciação direta em cardiomiócitos. Os cardiomiócitos gerados apresentaram características moleculares e funcionais semelhantes à cardiomiócitos primários humanos e foi visualizado, através de microscopia eletrônica de transmissão, que os cardiomiócitos do paciente com alteração genética possuíam grande proporção de sarcômeros desorganizados em comparação a cardiomiócitos de indivíduos saudáveis. Em conclusão, o modelo celular desenvolvido sugere ser possível o estudo do efeito de mutações genéticas em Cardiomiopatia Hipertrófica. / The study of genetic mutations as the cause of cardiomyopathies initiates with the discovery of mutations in sarcomeric proteins genes that lead to Hypertrophic Cardiomyopathy. Since then, mutations in several genes, coding to sarcomeric proteins or not, were discovered and listed as the reason to the cardiomyopathies. To study the effect of these mutations was a challenge due the difficulty to accesses cardiac cells. In 2007, the technique of reprogramming somatic cells into pluripotent stem cells was discovered. The fact that the pluripotent stem cells are capable of differentiating into cardiomyocytes opened the opportunity to study these cells from individuals with genetic mutations. This thesis aimed to create a cellular model to study Hypertrophic Cardiomyopathy caused by genetic mutations. Initially we established a cell reprogramming protocol to establish induced stem cells lines from a patient with mutation in MYH7 gene. Having characterized the cells, they were differentiated into cardiomyocytes using an adapted protocol from direct differentiation protocols. Cardiomyocytes generated showed molecular and functional characteristics similar to human primary cardiomyocytes and were visualized by means of transmission electron microscopy. The patient\'s cardiomyocytes had a large proportion of disorganized sarcomeres compared to cardiomyocytes from healthy individuals. In conclusion, the cell model developed suggests that it is possible to study the effect of genetic mutation in Hypertrophic Cardiomyopathy using induced pluripotent stem cells derived cardiomyocytes.

A substituição de cardiomiócitos na vida pós-natal tem sido um dos maiores desafios da medicina regenerativa. O conceito de que os cardiomiócitos proliferam ativamente durante o desenvolvimento, mas perdem completamente esse potencial logo após o nascimento, foi recentemente questionado quando as primeiras evidências mostraram a existência de mecanismos endógenos de regeneração cardíaca em camundongos com um dia de vida. Nós avaliamos esse fenômeno em ratos de um dia de vida (P1) e investigamos o impacto da regeneração inicial na perfusão tecidual em longo prazo e a função cardíaca global em resposta ao stress. A homogeneidade da cirurgia de ressecção apical foi comprovada através do exame de ressonância magnética (MRI) e demonstramos que os ratos P1 apresentaram evidências de neoformação de cardiomiócitos a partir da marcação de Troponina I e Conexina 43 na àrea da lesão 21 dias após a cirurgia de ressecção, enquanto os ratos de sete dias de idade (P7) apresentaram a substituição do tecido principalmente por deposição de colágeno. De maneira interessate, as células recém-formadas apresentaram uma aparente falta de alinhamento uniforme nos ratos P1, e a hipoperfusão do tecido cardíaco foi detectada para ambos os grupos de pós-ressecção 21 e aos 60 dias do exame de SPECT. A função cardíaca basal direta aos 60 dias apresentou-se preservada em todos os grupos, enquanto sob estresse hemodinâmico, o grau de mudança na LVDEP, Volume Sitólico e Trabalho Sistólico indicaram função cardíaca diminuída nos ratos P7. Além disso, a relação pressão-volume diastólica final e o aumento da deposição de colágeno intersticial no P7 são consistentes com o aumento da rigidez da câmara. Coletivamente, nós mostramos que o potencial regenerativo com ausência de remodelamento cardíaco adverso é restrito aos ratos P1. Em seguida, procurou-se avaliar os mecanismos moleculares que regulam esse fenômeno através da combinação de ferramentas exploratórias. Embora tenha sido descrito anteriormente que o sistema imunológico não é totalmente maduro ao nascimento, o sequenciamento do RNA total de corações de ratos sham-operados, P1 e P7 mostrou que o procedimento cirúrgico foi suficiente para ativar algumas vias ligadas à resposta inflamatória e considerando as subpopulações de macrófagos pró (M1) e anti-inflamatórios (M2), sugerimos que o perfil de macrófagos anti-inflamatórios (M2) infiltrados no coração de ratos P1 são diferentes das células adultas pró-fibróticas regulares. Os meios condicionados M1 e M2 elevaram a taxa de proliferação de cardiomiócitos em condições de normóxia, mas somente o M2 apresentou resposta proliferativa em hipóxia e preveniu a diferenciação-induzida de fibroblastos cardíacos por menor expressão ?SMA. Por membranas array de citocinas, 15 citocinas apresentaram-se comuns aos dois meios condicionados, mas apenas 4 citocinas, sendo elas IL-4, IL-1?, IL-6 e Fractalkine, foram exclusivas ao meio condicionado M2, e que poderiam ser possíveis candidatos aos efeitos regenerativos encontrados. Nesse sentido, experimentos futuros fazem-se necessários a fim de explorar os efeitos dessas citocinas e desenvolver novas estratégias terapêuticas / The replacement of cardiomyocytes in postnatal life has proven to be one of the biggest challenges in regenerative medicine. The concept that cardiomyocytes proliferate actively during development but cease completely right after birth has been recently questioned when first evidences showed the existence of endogenous mechanisms of cardiac regeneration in one-day-old mice. We sought to evaluate this phenomenon in one-day-old rats (P1) and to assess the impact of the early regenerative process on long-term tissue perfusion and overall cardiac function in response to stress. We confirmed the successful apical resection surgery through magnetic resonance imaging (MRI) and that P1 heart was associated with evidence of cardiomyocytes neoformation as indicated by Troponin I and Connexin 43 expression at 21 days postresection, while in seven-day-old rats (P7) mainly scar tissue replacement ensued. Interestingly, there was an apparent lack of uniform alignment of newly formed cells in P1, and cardiac tissue hypoperfusion has been detected for both groups at 21 postresection and at 60 days through SPECT scanning. Direct basal cardiac function at 60 days, was preserved in all groups, whereas under hemodynamic stress the degree of change on LVDEP, Stroke Volume and Stroke Work indicated diminished overall cardiac function in P7. Furthermore, the End-Diastolic Pressure-Volume relationship and increased interstitial collagen deposition in P7 is consistent with increased chamber stiffness. Collectively, we showed that regenerative potential with slight collagen deposition is restricted to P1 rats. Then we sought to evaluate the molecular mechanisms that regulate this phenomenon through explorative tools. Although it has been previously described that the immune system is not fully mature at birth, total RNA sequenced from sham-operated, P1 and P7 heart rats showed that surgery is sufficient to activate inflammatory pathways, and considering pro (M1) and anti-inflammatory (M2) macrophages subpopulations, we suggested that invaded macrophages in resected P1 hearts are different from the traditional pro-fibrotic M2-like adult cells. Conditioned M1 and M2 medium elevated cardiomyocytes proliferative rate under basal conditions, but only M2 produced the same effect in cardiomyocytes under hypoxia and prevented myofibroblasts-induced differentiation through ?SMA intensity expression. Membrane array for cytokines showed 15 common cytokines for both M1 and M2 conditioned medium, but only 4, as IL-4, IL-1?, IL-6 and Fractalkine, were M2 exclusive and possible candidates to the regenerative potential. Additional experiments are needed to further explore these cytokines and to maybe develop new therapeutic strategies

by Au Ka Wing. / "June 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 153-162). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Ng, Sze Ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 110-124). / Abstract also in Chinese. / Thesis Committee --- p.i / Acknowledgements --- p.ii / Contents --- p.iii / Abstract --- p.vii / 論文摘要 --- p.x / Abbreviations --- p.xi / List of Figures --- p.xiii / List of Tables --- p.xvii / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter 1.1 --- Embryonic Stem Cells (ESCs) --- p.1 / Chapter 1.1.1 --- What are ESCs and the characteristics of ESCs --- p.1 / Chapter 1.1.1.1 --- Pluripotent markers --- p.2 / Chapter 1.1.1.2 --- Germ layers' markers --- p.3 / Chapter 1.1.2 --- Mouse ESCs (mESCs) --- p.4 / Chapter 1.1.2.1 --- mESCs co-culture with mitotically inactivated mouse embryonic fibroblast (MEF) feeder layers --- p.4 / Chapter 1.1.2.2 --- Feeder free mESCs --- p.4 / Chapter 1.1.3 --- Promising uses of ESCs and their shortcomings --- p.5 / Chapter 1.1.4 --- Characteristics of ESC-derived cardiomyocytes (ESC-CMs) --- p.6 / Chapter 1.2 --- Cardiovascular diseases (CVD) --- p.7 / Chapter 1.2.1 --- Background --- p.7 / Chapter 1.2.2 --- Current treatments --- p.8 / Chapter 1.2.3 --- Potential uses of ESC-CMs for basic science research and therapeutic purposes --- p.9 / Chapter 1.2.4 --- Current hurdles in application of ESC-CMs for clinical uses --- p.10 / Chapter 1.3 --- Cardiac gene markers --- p.13 / Chapter 1.3.1 --- Atrial-specific --- p.13 / Chapter 1.3.2 --- Ventricular-specific --- p.19 / Chapter 1.4 --- Lentiviral vector-mediated gene transfer --- p.27 / Chapter 1.5 --- Cell cycle in ESCs --- p.29 / Chapter 1.5.1 --- Cell cycle --- p.29 / Chapter 1.5.2 --- Characteristics of cell cycle in ESCs --- p.30 / Chapter 1.6 --- Potassium (K+) channels --- p.31 / Chapter 1.6.1 --- Voltage gated potassium (Kv) channels --- p.32 / Chapter 1.6.2 --- Role of Kv channels in maintenance of membrane potential --- p.32 / Chapter 1.7 --- Objectives and significances --- p.33 / Chapter CHAPTER TWO --- MATERIALS AND METHODS --- p.35 / Chapter 2.1 --- Mouse embryonic fibroblast (MEF) culture --- p.35 / Chapter 2.1.1 --- Derivation of MEF --- p.3 5 / Chapter 2.1.2 --- MEF culture --- p.37 / Chapter 2.1.3 --- Irradiation of MEF --- p.37 / Chapter 2.2 --- mESC culture and their differentiation --- p.38 / Chapter 2.2.1 --- mESC culture --- p.38 / Chapter 2.2.2 --- Differentiation of mESCs --- p.39 / Chapter 2.3 --- Subcloning --- p.40 / Chapter 2.3.1 --- Amplification of Irx4 --- p.40 / Chapter 2.3.2 --- Purification of DNA products --- p.41 / Chapter 2.3.3 --- Restriction enzyme digestion --- p.42 / Chapter 2.3.4 --- Ligation of Irx4 with iDuet101A vector --- p.43 / Chapter 2.3.5 --- Transformation of ligation product into competent cells --- p.43 / Chapter 2.3.6 --- Small scale preparation of bacterial plasmid DNA --- p.44 / Chapter 2.3.7 --- Confirmation of positive clones by restriction enzyme digestion --- p.45 / Chapter 2.3.8 --- DNA sequencing of the cloned plasmid DNA --- p.45 / Chapter 2.3.9 --- Large scale preparation of target recombinant expression vector --- p.45 / Chapter 2.4 --- Lentiviral vector-mediated gene transfer to mESCs --- p.47 / Chapter 2.4.1 --- Lentivirus packaging --- p.47 / Chapter 2.4.2 --- Lentivirus titering --- p.48 / Chapter 2.4.3 --- Multiple transduction to mESCs --- p.48 / Chapter 2.4.4 --- Hygromycin selection on mESCs --- p.49 / Chapter 2.5 --- Selection of stable clone --- p.49 / Chapter 2.5.1 --- Monoclonal establishment and clone selection --- p.49 / Chapter 2.6 --- Differentiation of cell lines after selection --- p.50 / Chapter 2.7 --- Gene expression study on control and Irx4-overexpressed mESC lines --- p.50 / Chapter 2.8 --- Analysis of mESCs at different phases of the cell cycle --- p.55 / Chapter 2.8.1 --- Go/Gi and S phase synchronization --- p.55 / Chapter 2.8.2 --- Cell cycle analysis by propidium iodide (PI) staining followed by flow cytometric analysis --- p.55 / Chapter 2.8.3 --- Gene expression study by qPCR of Kv channel isoforms --- p.56 / Chapter 2.8.4 --- Membrane potential measurement by membrane potential-sensitive dye followed by flow cytometry --- p.57 / Chapter 2.9 --- Apoptotic study --- p.58 / Chapter 2.10 --- Determination of pluripotent characteristic of mESCs --- p.59 / Chapter 2.10.1 --- Expression of germ layers' markers by qPCR --- p.59 / Chapter 2.10.2 --- Differentiation by hanging drop method and suspension method --- p.61 / Chapter CHAPTER THREE --- RESULTS --- p.62 / Chapter 3.1 --- mESC culture --- p.62 / Chapter 3.1.1 --- Cell colony morphology of feeder free mESCs --- p.62 / Chapter 3.2 --- Subcloning --- p.63 / Chapter 3.2.1 --- PCR cloning of Irx4 --- p.63 / Chapter 3.2.2 --- Restriction digestion on iDuet101A --- p.64 / Chapter 3.2.3 --- Ligation of Irx4 to iDuet101A backbone --- p.66 / Chapter 3.2.4 --- Confirmation of successful ligation --- p.67 / Chapter 3.3 --- Lentivirus packaging --- p.68 / Chapter 3.3.1 --- Transfection --- p.68 / Chapter 3.4 --- Multiple transduction of mESCs and hygromycin selection of positively-transduced cells --- p.69 / Chapter 3.5 --- FACS --- p.70 / Chapter 3.6 --- Irx4 and iduet clone selection --- p.71 / Chapter 3.7 --- Characte rization of mESCs after clone selection --- p.74 / Chapter 3.7.1 --- Immunostaining of pluripotent and differentiation markers --- p.74 / Chapter 3.8 --- Differentiation of cell lines after selection --- p.77 / Chapter 3.8.1 --- Size of EBs of the cell lines during differentiation --- p.77 / Chapter 3.9 --- Gene expression study by qPCR --- p.79 / Chapter 3.10 --- Kv channel expression and membrane potential of mESCs at Go/Gi phase and S phases --- p.84 / Chapter 3.10.1 --- Expression of Kv channels subunits at G0/Gi phase and S phase --- p.86 / Chapter 3.10.2 --- Membrane potential at Go/Gi phase and S phase --- p.87 / Chapter 3.11 --- Effects of TEA+ on feeder free mESCs --- p.89 / Chapter 3.11.1 --- Apoptotic study --- p.89 / Chapter 3.11.2 --- Expression of germ layers´ة markers --- p.91 / Chapter 3.11.3 --- Embryo id bodies (EBs) measurement after differentiation --- p.92 / Chapter CHAPTER FOUR --- DISCUSSION --- p.95 / Chapter 4.1 --- Effect of overexpression of Irx4 on the cardiogenic potential of mESCs --- p.95 / Chapter 4.2 --- Role of Kv channels in maintaining the chacteristics of mESCs --- p.99 / Chapter 4.2.1 --- Inhibition of Kv channels led to a redistribution of the proportion of cells in different phases of the cell cycle: importance of Kv channels in cell cycle progression in native ESCs --- p.99 / Chapter 4.2.2 --- Inhibition of Kv channels led to a loss of pluripotency at molecular and functional levels: importance of Kv channels in the fate determination of mESCs --- p.102 / Chapter 4.3 --- Insights from the present investigation on the future uses of ESCs --- p.105 / Conclusions --- p.108 / References --- p.110