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Hypoxia can aggravate tumor occurrence, development, invasion, and metastasis, and greatly inhibit the photodynamic therapy (PDT) effect. Herein, carbon nitride (CNs)-based DNA and photosensitizer co-delivery systems (BPSCNs) with oxygen-producing functions are developed to address this problem. Selenide glucose (Seglu) is used as the dopant to prepare red/NIR-active CNs (SegluCNs). The tumor-targeting unit Bio-PEG2000 is utilized to construct BPSCNs nanoparticles through esterification reactions. Furthermore, DNA hydrophobization is realized via mixing P53 gene with a positively charged mitochondrial-targeted near-infrared (NIR) emitting photosensitizer (MTTPY), which is encapsulated in non-cationic BPSCNs for synergistic delivery. Ester bonds in BPSCNs@MTTPY-P53 complexes can be disrupted by lipase in the liver to facilitate P53 release, upregulated P53 expression, and promoted HIF-1α degradation in mitochondria. In addition, the oxygen produced by the complexes improved the hypoxic microenvironment of hepatocellular carcinoma (HCC), synergistically downregulated HIF-1α expression in mitochondria, promoted mitochondrial-derived ferroptosis and enhanced the PDT effect of the MTTPY unit. Both in vivo and in vitro experiments indicated that the transfected P53-DNA, produced O2 and ROS by these complexes synergistically led to mitochondrial-derived ferroptosis in hepatoma cells through the HIF-1α/SLC7A11 pathway, and completely avoiding PDT resistance caused by hypoxia, exerting a significant therapeutic role in HCC treatment.
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BACKGROUND: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) show tremendous promise for cardiac regeneration, but the successful development of hESC-CM-based therapies requires improved tools to investigate their electrical behavior in recipient hearts. While optical voltage mapping is a powerful technique for studying myocardial electrical activity ex vivo, we have previously shown that intra-cardiac hESC-CM grafts are not labeled by conventional voltage-sensitive fluorescent dyes. We hypothesized that the water-soluble voltage-sensitive dye di-2-ANEPEQ would label engrafted hESC-CMs and thereby facilitate characterization of graft electrical function and integration. METHODS: We developed and validated a novel optical voltage mapping strategy based on the simultaneous imaging of the calcium-sensitive fluorescent protein GCaMP3, a graft-autonomous reporter of graft activation, and optical action potentials (oAPs) derived from di-2-ANEPEQ, which labels both graft and host myocardium. Cardiomyocytes from three different GCaMP3+ hESC lines (H7, RUES2, or ESI-17) were transplanted into guinea pig models of subacute and chronic infarction, followed by optical mapping at 2 weeks post-transplantation. RESULTS: Use of a water-soluble voltage-sensitive dye revealed pro-arrhythmic properties of GCaMP3+ hESC-CM grafts from all three lines including slow conduction velocity, incomplete host-graft coupling, and spatially heterogeneous patterns of activation that varied beat-to-beat. GCaMP3+ hESC-CMs from the RUES2 and ESI-17 lines both showed prolonged oAP durations both in vitro and in vivo. Although hESC-CMs partially remuscularize the injured hearts, histological evaluation revealed immature graft structure and impaired gap junction expression at this early timepoint. CONCLUSION: Simultaneous imaging of GCaMP3 and di-2-ANEPEQ allowed us to acquire the first unambiguously graft-derived oAPs from hESC-CM-engrafted hearts and yielded critical insights into their arrhythmogenic potential and line-to-line variation.
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Células-Tronco Embrionárias Humanas , Miócitos Cardíacos , Animais , Diferenciação Celular , Células-Tronco Embrionárias , Cobaias , MiocárdioRESUMO
Evidence to date suggests that ß-arrestins act beyond their role as adapter proteins. Arginine vasopressin (AVP) may be a factor in inflammation and fibrosis in the pathogenesis of heart failure. In the present study we investigated the effect of AVP on inflammatory cytokine IL-6 production in murine hearts and the impact of ß-arrestin 2-dependent signaling on AVP-induced IL-6 production. We found that administration of AVP (0.5 U/kg, iv) markedly increased the levels of IL-6 mRNA in rat hearts with the maximum level occurred at 6 h. In ß-arrestin 2 KO mouse hearts, deletion of ß-arrestin 2 decreased AVP-induced IL-6 mRNA expression. We then performed in vitro experiments in adult rat cardiac fibroblasts (ARCFs). We found that AVP (10-9-10-6 M) dose-dependently increased the expression of IL-6 mRNA and protein, activation of NF-κB signaling and ERK1/2 phosphorylation, whereas knockdown of ß-arrestin 2 blocked AVP-induced IL-6 increase, NF-κB activation and ERK1/2 phosphorylation. Pharmacological blockade of ERK1/2 using PD98059 diminished AVP-induced NF-κB activation and IL-6 production. The selective V1A receptor antagonist SR49059 effectively blocked AVP-induced NF-κB phosphorylation and activation as well as IL-6 expression in ARCFs. In AVP-treated mice, pre-injection of SR49059 (2 mg/kg, iv) abolished AVP-induced NF-κB activation and IL-6 production in hearts. The above results suggest that AVP induces IL-6 induction in murine hearts via the V1A receptor-mediated ß-arrestin2/ERK1/2/NF-κB pathway, thus reveal a novel mechanism of myocardial inflammation in heart failure involving the V1A/ß-arrestin 2/ERK1/2/NF-κB signaling pathway.
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Arginina Vasopressina/farmacologia , Coração/fisiopatologia , Interleucina-6/metabolismo , beta-Arrestina 2/genética , Animais , Arginina Vasopressina/administração & dosagem , Relação Dose-Resposta a Droga , Fibroblastos/metabolismo , Técnicas de Silenciamento de Genes , Insuficiência Cardíaca/fisiopatologia , Masculino , Camundongos , Camundongos Knockout , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , NF-kappa B/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Vasopressinas/metabolismoRESUMO
Background Protein posttranslational modifications by O-linked ß-N-acetylglucosamine (O-GlcNAc) increase with cardiac hypertrophy, yet the functional effects of these changes are incompletely understood. In other organs, O-GlcNAc promotes adaptation to acute physiological stressors; however, prolonged O-GlcNAc elevations are believed to be detrimental. We hypothesize that early O-GlcNAcylation improves cardiac function during initial response to pressure overload hypertrophy, but that sustained elevations during established pathological hypertrophy negatively impact cardiac function by adversely affecting calcium handling proteins. Methods and Results Transverse aortic constriction or sham surgeries were performed on littermate controls or cardiac-specific, inducible O-GlcNAc transferase knockout (OGTKO) mice to reduce O-GlcNAc levels. O-GlcNAc transferase deficiency was induced at different times. To evaluate the initial response to pressure overload, OGTKO was completed preoperatively and mice were followed for 2 weeks post-surgery. To assess prolonged O-GlcNAcylation during established hypertrophy, OGTKO was performed starting 18 days after surgery and mice were followed until 6 weeks post-surgery. In both groups, OGTKO with transverse aortic constriction caused significant left ventricular dysfunction. OGTKO did not affect levels of the calcium handling protein SERCA2a. OGTKO reduced phosphorylation of phospholamban and cardiac troponin I, which would negatively impact cardiac function. O-GlcNAcylation of protein kinase A catalytic subunit, a kinase for phospholamban, decreased with OGTKO. Conclusions O-GlcNAcylation promotes compensated cardiac function in both early and established pathological hypertrophy. We identified a novel O-GlcNAcylation of protein kinase A catalytic subunit, which may regulate calcium handling and cardiac function.
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Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Hipertrofia Ventricular Esquerda/enzimologia , Miocárdio/enzimologia , N-Acetilglucosaminiltransferases/metabolismo , Disfunção Ventricular Esquerda/enzimologia , Função Ventricular Esquerda , Remodelação Ventricular , Animais , Sinalização do Cálcio , Proteínas de Ligação ao Cálcio/metabolismo , Modelos Animais de Doenças , Glicosilação , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Hipertrofia Ventricular Esquerda/patologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Camundongos Knockout , Miocárdio/patologia , N-Acetilglucosaminiltransferases/deficiência , N-Acetilglucosaminiltransferases/genética , Fosforilação , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Fatores de Tempo , Troponina I/metabolismo , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/patologia , Disfunção Ventricular Esquerda/fisiopatologiaRESUMO
Chronic mountain sickness (CMS) is estimated at 1.2% in Tibetans living at the Qinghai-Tibetan Plateau. Eighteen single-nucleotide polymorphisms (SNPs) from nine nuclear genes that have an association with CMS in Tibetans have been analyzed by using pairwise linkage disequilibrium (LD). The SNPs included are the angiotensin-converting enzyme (rs4340), the angiotensinogen (rs699), and the angiotensin II type 1 receptor (AGTR1) (rs5186) from the renin-angiotensin system. A low-density lipoprotein apolipoprotein B (rs693) SNP was also included. From the hypoxia-inducible factor oxygen signaling pathway, the endothetal Per-Arnt-Sim domain protein 1 (EPAS1) and the egl nine homolog 1 (ENGL1) (rs480902) SNPs were included in the study. SNPs from the vascular endothelial growth factor (VEGF) signaling pathway included are the v-akt murine thymoma viral oncogene homolog 3 (rs4590656 and rs2291409), the endothelial cell nitric oxide synthase 3 (rs1007311 and rs1799983), and the (VEGFA) (rs699947, rs34357231, rs79469752, rs13207351, rs28357093, rs1570360, rs2010963, and rs3025039). An increase in LD occurred in 40 pairwise comparisons, whereas a decrease in LD was found in 55 pairwise comparisons between the controls and CMS patients. These changes were found to occur within and between signaling pathways, which suggests that there is an interaction between SNP alleles from different areas of the genome that affect CMS.
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Cardiomyocytes derived from human pluripotent stem cells show tremendous promise for the replacement of myocardium and contractile function lost to infarction. However, until recently, no methods were available to directly determine whether these stem cell-derived grafts actually couple with host myocardium and fire synchronously following transplantation in either intact or injured hearts. To resolve this uncertainty, our group has developed techniques for the intravital imaging of hearts engrafted with stem cell-derived cardiomyocytes that have been modified to express the genetically encoded protein calcium sensor, GCaMP. When combined with the simultaneously recorded electrocardiogram, this protocol allows one to make quantitative assessments as to the presence and extent of host-graft electrical coupling as well as the timing and pattern of graft activation. As described here, this system has been employed to investigate the electromechanical integration of human embryonic stem cell-derived cardiomyocytes in a guinea pig model of cardiac injury, but analogous approaches should be applicable to other human graft cell types and animal models.
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Eletroporação , Fenômenos Mecânicos , Miócitos Cardíacos/citologia , Células-Tronco Pluripotentes/citologia , Células-Tronco Pluripotentes/transplante , Transplante de Células-Tronco/métodos , Animais , Linhagem Celular , Criopreservação , Desoxirribonucleases/química , Desoxirribonucleases/metabolismo , Cobaias , Traumatismos Cardíacos/patologia , Humanos , Masculino , Imagem Molecular , Células-Tronco Pluripotentes/metabolismo , Dedos de ZincoRESUMO
Mountain sickness (MS) occurs among humans visiting or inhabiting high altitude environments. We conducted genetic analyses of seven single nucleotide polymorphisms (SNPs) in the promoter region of VEGFA gene for lowland (Han) and highland (Tibetan) Chinese. The seven SNPs were evaluated in Han and Tibetan patients with acute (A) and chronic (C) MS. We compared 64 patients with AMS with 64 Han unaffected with MS, as well as 48 CMS patients with 32 unaffected Tibetans. The SNPs studied are rs699947, rs34357231, rs79469752, rs13207351, rs28357093, rs1570360, and rs2010963 which are found in the promoter ranging from -2,578 to -634 bp from the transcriptional start site (TSS), respectively. Direct sequencing was used to identify individual genotypes for these SNPs. Arterial oxygen saturation of hemoglobin (SaO2) was found to be significantly associated with the rs699947, rs34357231, rs13207351, and rs1570360 SNPs in Han patients with AMS, while the rs2010963 SNP was found to approach significance in the AMS study group, but found to be significantly associated in the normal Tibetan study group. The Han and Tibetan control groups were found to diverge significantly for the rs28357093 and rs2010963 SNPs, as measured by genetic distances of 0.073 and 0.054, respectively. All the SNPs are found in transcriptional factor binding sites (TFBS), and their possible role in gene regulation was evaluated with regard to MS. MS was found to be significantly associated with these SNPs compared with their Han and Tibetan control groups, indicating that these nucleotide substitutions result in TFBS changes which apparently have a physiological effect on the development of high altitude sickness.
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Doença da Altitude/genética , Povo Asiático/genética , Fator A de Crescimento do Endotélio Vascular/genética , Doença Aguda , Adulto , Sequência de Bases , Sítios de Ligação/genética , Etnicidade/genética , Feminino , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Fatores de Transcrição/metabolismoRESUMO
Transplantation studies in mice and rats have shown that human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) can improve the function of infarcted hearts, but two critical issues related to their electrophysiological behaviour in vivo remain unresolved. First, the risk of arrhythmias following hESC-CM transplantation in injured hearts has not been determined. Second, the electromechanical integration of hESC-CMs in injured hearts has not been demonstrated, so it is unclear whether these cells improve contractile function directly through addition of new force-generating units. Here we use a guinea-pig model to show that hESC-CM grafts in injured hearts protect against arrhythmias and can contract synchronously with host muscle. Injured hearts with hESC-CM grafts show improved mechanical function and a significantly reduced incidence of both spontaneous and induced ventricular tachycardia. To assess the activity of hESC-CM grafts in vivo, we transplanted hESC-CMs expressing the genetically encoded calcium sensor, GCaMP3 (refs 4, 5). By correlating the GCaMP3 fluorescent signal with the host ECG, we found that grafts in uninjured hearts have consistent 1:1 hostgraft coupling. Grafts in injured hearts are more heterogeneous and typically include both coupled and uncoupled regions. Thus, human myocardial grafts meet physiological criteria for true heart regeneration, providing support for the continued development of hESC-based cardiac therapies for both mechanical and electrical repair.
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Arritmias Cardíacas/terapia , Fenômenos Eletrofisiológicos , Células-Tronco Embrionárias/citologia , Traumatismos Cardíacos/fisiopatologia , Miocárdio/patologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/transplante , Animais , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/fisiopatologia , Cálcio/análise , Cálcio/metabolismo , Estimulação Elétrica , Corantes Fluorescentes/análise , Cobaias , Traumatismos Cardíacos/complicações , Traumatismos Cardíacos/patologia , Humanos , Medições Luminescentes , Masculino , Contração Miocárdica/fisiologia , Miocárdio/citologia , Miócitos Cardíacos/fisiologia , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/fisiopatologia , Taquicardia Ventricular/terapiaRESUMO
Mountain sickness (MS) occurs among humans visiting or inhabiting high altitude environments. We conducted genetic analyses of the AKT3, ANGPTL4, eNOS3 and VEGFA genes in lowland (Han) and highland (Tibetan) Chinese. Ten single nucleotide polymorphisms (SNPs) were evaluated in Han and Tibetan patients with acute (A) and chronic (C) MS. We compared 74 patients with AMS to 79 Han unaffected with MS, as well as 48 CMS patients to 31 unaffected Tibetans. The ten SNPs studied are AKT3 (rs4590656, rs2291409), ANGPTL4 (rs1044250), eNOS3 (rs1007311, rs1799983) and VEGFA (rs79469752, rs13207351, rs28357093, rs1570360, rs3025039). Direct sequencing was used to identify individual genotypes for these SNPs. Hemoglobin (Hb), hematocrit (Hct), and red blood cell count (RBC) were found to be significantly associated with the AKT3 SNP (rs4590656), Hb was found to be associated with the eNOS3 SNP (rs1007311), and RBC was found to be significantly associated with the VEGFA SNP (rs1570360) in Tibetan patients with CMS. CMS patients were found to diverge significantly for both eNOS3 SNPs as measured by genetic distance (0.042, 0.047) and for the VEGFA SNP (rs28357093) with a genetic distance of 0.078 compared to their Tibetan control group. Heart rate (HR) was found to be significantly associated with the eNOS3 SNP (rs1799983) and arterial oxygen saturation of hemoglobin (SaO2) was found to be significantly associated with the VEGFA SNPs (rs13207351, rs1570360) in Han patients with AMS. The Han and Tibetan control groups were found to diverge significantly for the ANGPTL4 SNP and VEGFA SNP (rs28357093), as measured by genetic distances of 0.049 and 0.073, respectively. Seven of the SNPs from non-coding regions are found in the transcriptional factor response elements and their possible role in gene regulation was evaluated with regard to MS. AMS and CMS were found to be significantly associated with the four genes compared to their Han and Tibetan control groups, respectively, indicating that these nucleotide alterations have a physiological effect for the development of high altitude sickness.
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Doença da Altitude/genética , Altitude , Angiopoietinas/genética , Povo Asiático/genética , Óxido Nítrico Sintase Tipo III/genética , Proteínas Proto-Oncogênicas c-akt/genética , Fator A de Crescimento do Endotélio Vascular/genética , Alelos , Proteína 4 Semelhante a Angiopoietina , China , Feminino , Frequência do Gene , Genótipo , Humanos , Desequilíbrio de Ligação , Masculino , Polimorfismo de Nucleotídeo Único , Elementos de RespostaRESUMO
Cardiac resynchronization therapy (CRT), in which both ventricles are paced to recoordinate contraction in hearts that are dyssynchronous from conduction delay, is the only heart failure (HF) therapy to date to clinically improve acute and chronic function while also lowering mortality. CRT acutely enhances chamber mechanical efficiency but chronically alters myocyte signaling, including improving ß-adrenergic receptor reserve. We speculated that the latter would identify unique CRT effects that might themselves be effective for HF more generally. HF was induced in dogs by 6 weeks of atrial rapid pacing with (HFdys, left bundle ablated) or without (HFsyn) dyssynchrony. We used dyssynchronous followed by resynchronized tachypacing (each 3 weeks) for CRT. Both HFdys and HFsyn myocytes had similarly depressed rest and ß-adrenergic receptor sarcomere and calcium responses, particularly the ß2-adrenergic response, whereas cells subjected to CRT behaved similarly to those from healthy controls. CRT myocytes exhibited suppressed Gαi signaling linked to increased regulator of G protein (heterotrimeric guanine nucleotide-binding protein) signaling (RGS2, RGS3), yielding Gαs-biased ß2-adrenergic responses. This included increased adenosine cyclic AMP responsiveness and activation of sarcoplasmic reticulum-localized protein kinase A. Human CRT responders also showed up-regulated myocardial RGS2 and RGS3. Inhibition of Gαi (with pertussis toxin, RGS3, or RGS2 transfection), stimulation with a Gαs-biased ß2 agonist (fenoterol), or transient (2-week) exposure to dyssynchrony restored ß-adrenergic receptor responses in HFsyn to the values obtained after CRT. These results identify a key pathway that is triggered by restoring contractile synchrony and that may represent a new therapeutic approach for a broad population of HF patients.
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Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/terapia , Receptores Adrenérgicos beta 2/metabolismo , Transdução de Sinais/fisiologia , Animais , Terapia de Ressincronização Cardíaca , Células Cultivadas , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Cães , Transferência Ressonante de Energia de Fluorescência , Proteínas de Ligação ao GTP/metabolismo , Proteínas Ativadoras de GTPase/metabolismo , Proteínas Heterotriméricas de Ligação ao GTP/metabolismo , Humanos , Técnicas In Vitro , Células Musculares/metabolismo , Miocárdio/metabolismo , Proteínas RGS/metabolismoRESUMO
The availability of human cardiomyocytes derived from embryonic stem cells (ESCs) has generated -considerable excitement, as these cells are an excellent model system for studying myocardial development and may have eventual application in cell-based cardiac repair. Cardiomyocytes derived from the related induced pluripotent stem cells (iPSCs) have similar properties, but also offer the prospects of patient-specific disease modeling and cell therapies. Unfortunately, the methods by which cardiomyocytes have been historically generated from pluripotent stem cells are unreliable and typically result in preparations of low cardiac purity (typically <1% cardiomyocytes). We detail here the methods for a recently reported directed cardiac differentiation protocol, which involves the serial application of two growth factors known to be involved in early embryonic heart development, activin A, and bone morphogenetic protein-4 (BMP-4). This protocol reliably yields preparations of 30-60% cardiomyocytes, which can then be further enriched to >90% cardiomyocytes using straightforward physical methods.
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Técnicas de Cultura de Células/métodos , Miócitos Cardíacos/citologia , Células-Tronco Pluripotentes/citologia , Ativinas/farmacologia , Animais , Proteína Morfogenética Óssea 4/farmacologia , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Centrifugação com Gradiente de Concentração , Colágeno/farmacologia , Criopreservação , Meios de Cultivo Condicionados/farmacologia , Combinação de Medicamentos , Embrião de Mamíferos/citologia , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Laminina/farmacologia , Camundongos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Células-Tronco Pluripotentes/efeitos dos fármacos , Células-Tronco Pluripotentes/metabolismo , Povidona , Proteoglicanas/farmacologia , Dióxido de SilícioRESUMO
AIM: Human embryonic stem cells (hESCs) represent a novel cell source to treat diseases such as heart failure and for use in drug screening. In this study, we aim to promote efficient generation of cardiomyocytes from hESCs by combining the current optimal techniques of controlled growth of undifferentiated cells and specific induction for cardiac differentiation. We also aim to examine whether these methods are scalable and whether the differentiated cells can be cryopreserved. METHODS & RESULTS: hESCs were maintained without conditioned medium or feeders and were sequentially treated with activin A and bone morphogenetic protein-4 in a serum-free medium. This led to differentiation into cell populations containing high percentages of cardiomyocytes. The differentiated cells expressed appropriate cardiomyocyte markers and maintained contractility in culture, and the majority of the cells displayed working chamber (atrial and ventricular) type electrophysiological properties. In addition, the cell growth and differentiation process was adaptable to large culture formats. Moreover, the cardiomyocytes survived following cryopreservation, and viable cardiac grafts were detected after transplantation of cryopreserved cells into rat hearts following myocardial infarctions. CONCLUSION: These results demonstrate that cardiomyocytes of high quality can be efficiently generated and cryopreserved using hESCs maintained in serum-free medium, a step forward towards the application of these cells to human clinical use or drug discovery.
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Criopreservação/métodos , Células-Tronco Embrionárias/citologia , Miócitos Cardíacos , Animais , Diferenciação Celular , Linhagem Celular , Proliferação de Células , Meios de Cultura Livres de Soro , Humanos , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , RatosRESUMO
RATIONALE: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) exhibit either a "working" chamber or a nodal-like phenotype. To generate optimal hESC-CM preparations for eventual clinical application in cell-based therapies, we will need to control their differentiation into these specialized cardiac subtypes. OBJECTIVE: To demonstrate intact neuregulin (NRG)-1ß/ErbB signaling in hESC-CMs and test the hypothesis that this signaling pathway regulates cardiac subtype abundance in hESC-CM cultures. METHODS AND RESULTS: All experiments used hESC-CM cultures generated using our recently reported directed differentiation protocol. To support subsequent action potential phenotyping approaches and provide a higher-throughput method of determining cardiac subtype, we first developed and validated a novel genetic label that identifies nodal-type hESC-CMs. Next, control hESC-CM preparations were compared to those differentiated in the presence of exogenous NRG-1ß, an anti-NRG-1ß neutralizing antibody, or the ErbB antagonist AG1478. We used 3 independent approaches to determine the ratio of cardiac subtypes in the resultant populations: direct action potential phenotyping under current-clamp, activation of the aforementioned genetic label, and subtype-specific marker expression by RT-PCR. Using all 3 end points, we found that inhibition of NRG-1ß/ErbB signaling greatly enhanced the proportion of cells showing the nodal phenotype. CONCLUSIONS: NRG-1ß/ErbB signaling regulates the ratio of nodal- to working-type cells in differentiating hESC-CM cultures and presumably functions similarly during early human heart development. We speculate that, by manipulating NRG-1ß/ErbB signaling, it will be possible to generate preparations of enriched working-type myocytes for infarct repair, or, conversely, nodal cells for potential use in a biological pacemaker.
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Diferenciação Celular/fisiologia , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Receptores ErbB/fisiologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Neuregulina-1/fisiologia , Transdução de Sinais/fisiologia , Animais , Linhagem Celular , Células Cultivadas , Células-Tronco Embrionárias/fisiologia , Humanos , Camundongos , Miócitos Cardíacos/classificação , Nó Sinoatrial/citologia , Nó Sinoatrial/embriologia , Nó Sinoatrial/metabolismoRESUMO
1. G-Protein-coupled receptors (GPCR) and electrical field stimulation (EFS) regulate cardiac function and pathological remodelling, including cardiac hypertrophy. Cardiac Ca(2+)/calmodulin-dependent protein kinase (CaMK) IIdelta expression and activity are altered in cardiac hypertrophy and heart failure. The aim of the present study was to determine the effects of CaMKIIdelta isoforms on neonatal rat cardiomyocyte hypertrophy induced by GPCR and EFS. 2. Cardiac hypertrophy was induced by angiotensin II, phenylephrine or EFS and was confirmed by increases in cell volume, [(3)H]-leucine incorporation, sarcomere assembly and mRNA expression of atrial natriuretic factor and beta-myosin heavy chain. The effects of the CaMKII inhibitors KN93 and autocamtide 2-related inhibitory peptide (AIP) on cardiomyocyte hypertrophy were investigated, as was the effect of overexpression of dominate negative CaMKIIdelta. 3. Cardiomyocyte hypertrophy was inhibited by the CaMKII inhibitors KN93 and AIP and by overexpression of dominate negative CaMKIIdelta, but was potentiated by overexpression of wild-type CaMKIIdeltaB or CaMKIIdeltaC. Activation of CaMKII by GPCR agonists or EFS was inhibited by the CaMKII inhibitors. 4. The GPCR agonists and EFS synergistically activated CaMKII and upregulated CaMKIIdeltaB and CaMKIIdeltaC mRNA expression and protein synthesis. All these effects were abolished by the CaMKII inhibitors. 5. The findings of the present study indicate that CaMKII orchestrates additive prohypertrophic factors between GPCR agonists and EFS. Thus, CaMKII may be a useful target in the clinical treatment of hypertrophy and cardiac remodelling.
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Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/fisiologia , Miócitos Cardíacos/fisiologia , Miócitos Cardíacos/ultraestrutura , Receptores Acoplados a Proteínas G/fisiologia , Adenoviridae/genética , Angiotensina II/farmacologia , Animais , Animais Recém-Nascidos , Western Blotting , Proteínas de Ligação ao Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Tamanho Celular/efeitos dos fármacos , Células Cultivadas , Estimulação Elétrica , Imuno-Histoquímica , Leucina/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Peptídeos/metabolismo , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
We recently described a murine embryonic stem cell (ESC) line engineered to express the activated Notch 4 receptor in a tetracycline (doxcycline; Dox) regulated fashion (tet-notch4 ESCs). Notch 4 induction in Flk1(+) hematopoietic and vascular progenitors from this line respecified them to a cardiovascular fate. We reasoned that these cells would be ideal for evaluating the contribution of the cardiomyocyte and vascular lineages to the functional improvement noted following stem cell transplantation in infarcted hearts. Flk-1(+) Tet-notch4 cells from d 3 embryoid bodies exposed to doxycycline (Dox(+)) were compared to uninduced (Dox(-)) Flk-1(+) cells. Mice underwent transplantation of 5 x 10(5) Dox(+) cells, Dox(-)cells, or an equal volume of serum-free medium after surgically induced myocardial infarction. The mean ejection fraction was 59 + or - 15, 46 + or - 17, and 39 + or - 13% in the Dox(+), Dox(-), and serum-free medium groups, respectively (P<0.05 for the differences among all 3 groups). Immunohistochemistry of hearts injected with Dox(+) grafts expressed myocardial and vascular markers, whereas grafts of Dox(-) cells expressed primarily vascular markers. We conclude that cardiovascular progenitors are more effective than vascular progenitors in improving function after myocardial infarction. The transplantation of appropriate cell types is critical for maximizing the benefit of cardiovascular cell therapy.-Adler, E. D., Chen, V. C., Bystrup, A., Kaplan, A. D., Giovannone, S., Briley-Saebo, K., Young, W., Kattman, S., Mani, V., Laflamme, M., Zhu, W.-Z., Fayad, Z., Keller, G. The cardiomyocyte lineage is critical for optimization of stem cell therapy in a mouse model of myocardial infarction.
Assuntos
Células-Tronco Embrionárias/metabolismo , Células-Tronco Embrionárias/transplante , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/terapia , Miócitos Cardíacos/metabolismo , Transplante de Células-Tronco , Animais , Antígenos de Diferenciação/biossíntese , Linhagem Celular , Modelos Animais de Doenças , Regulação da Expressão Gênica , Camundongos , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Miócitos Cardíacos/patologia , Volume SistólicoRESUMO
Calcium-calmodulin-dependent protein kinase II (CaMKII) is one of the main protein kinases mediating intracellular Ca changes. It is also involved in the process of cardiac diseases, such as cardiac hypertrophy, but its effects on myocardial fibrosis remain unclear. The present study investigates whether CaMKII is involved in cardiac fibroblast proliferation and extracellular matrix (ECM) secretion induced by angiotensin II (AngII) or electrical field stimulation (EFS) in cultured neonatal rat cardiac fibroblasts. Cardiac fibroblast proliferation was assessed by a cell survival assay (MTT) and manual cell enumeration. Cellular matrix production was demonstrated by matrix metalloproteinases (MMP) 1, 2, 9, and collagen I/III messenger RNA expression, MMP-2, 9 protein expression, and secretion of transforming growth factor beta1 and tumor necrosis factor alpha. Either AngII or EFS promoted cardiac fibroblast proliferation and ECM secretion, while also up-regulating expression of CaMKII deltaB and deltaC. More importantly, CaMKII inhibitors, autocamtide-2-related inhibitory peptide (AIP 5 microM) or KN93 (0.5 microM), suppressed cardiac fibroblast proliferation, inhibited the excretion of transforming growth factor beta1 and tumor necrosis factor alpha, decreased the messenger RNA expression of MMP-1, 2, 9 and collagen I/III, and decreased the protein expression of MMP-2, 9. These results suggest that CaMKII mediates cardiac fibroblast proliferation and ECM secretion induced by either AngII or EFS.
Assuntos
Angiotensina II/farmacologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Matriz Extracelular/metabolismo , Fibroblastos/metabolismo , Animais , Animais Recém-Nascidos , Benzilaminas/farmacologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Proliferação de Células/efeitos dos fármacos , Estimulação Elétrica , Matriz Extracelular/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Peptídeos/farmacologia , Ratos , Ratos Sprague-Dawley , Sulfonamidas/farmacologiaRESUMO
The muscle lost after a myocardial infarction is replaced with noncontractile scar tissue, often initiating heart failure. Whole-organ cardiac transplantation is the only currently available clinical means of replacing the lost muscle, but this option is limited by the inadequate supply of donor hearts. Thus, cell-based cardiac repair has attracted considerable interest as an alternative means of ameliorating cardiac injury. Because of their tremendous capacity for expansion and unquestioned cardiac potential, pluripotent human embryonic stem cells (hESCs) represent an attractive candidate cell source for obtaining cardiomyocytes and other useful mesenchymal cell types for such therapies. Human embryonic stem cell-derived cardiomyocytes exhibit a committed cardiac phenotype and robust proliferative capacity, and recent testing in rodent infarct models indicates that they can partially remuscularize injured hearts and improve contractile function. Although the latter successes give good reason for optimism, considerable challenges remain in the successful application of hESCs to cardiac repair, including the need for preparations of high cardiac purity, improved methods of delivery, and approaches to overcome immune rejection and other causes of graft cell death. This review will describe the phenotype of hESC-derived cardiomyocytes and preclinical experience with these cells and will consider strategies to overcoming the aforementioned challenges.
Assuntos
Blastocisto/citologia , Células-Tronco Embrionárias , Cardiopatias/cirurgia , Infarto do Miocárdio/cirurgia , Miócitos Cardíacos/transplante , Transplante de Células-Tronco/métodos , Técnicas de Cultura de Células , Diferenciação Celular , Separação Celular/métodos , Coração Fetal/citologia , Coração Fetal/fisiologia , Humanos , Miócitos Cardíacos/citologia , Fenótipo , Regeneração , CicatrizaçãoRESUMO
In recent years, cell transplantation has drawn tremendous interest as a novel approach to preserving or even restoring contractile function to infarcted hearts. A typical human infarct involves the loss of approximately 1 billion cardiomyocytes, and, therefore, many investigators have sought to identify endogenous or exogenous stem cells with the capacity to differentiate into committed cardiomyocytes and repopulate lost myocardium. As a result of these efforts, dozens of stem cell types have been reported to have cardiac potential. These include pluripotent embryonic stem cells, as well various adult stem cells resident in compartments including bone marrow, peripheral tissues, and the heart itself. Some of these cardiogenic progenitors have been reported to contribute replacement muscle through endogenous reparative processes or via cell transplantation in preclinical cardiac injury models. However, considerable disagreement exists regarding the efficiency and even the reality of cardiac differentiation by many of these stem cell types, making these issues a continuing source of controversy in the field. In this review, we consider approaches to cell fate mapping and establishing the cardiac phenotype, as well as the present state of the evidence for the cardiogenic and regenerative potential of the major candidate stem cell types.
Assuntos
Diferenciação Celular , Infarto do Miocárdio/terapia , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Transplante de Células-Tronco , Células-Tronco/metabolismo , Animais , Transdiferenciação Celular , Modelos Animais de Doenças , Humanos , Contração Miocárdica , Infarto do Miocárdio/metabolismo , RegeneraçãoRESUMO
1. In coronary artery disease, the typical atheromatous plaque consists of a lipid core containing various inflammatory cells and a fibrous cap composed mostly of extracellular matrix. Both matrix metalloproteinases (MMPs) and inflammation are involved in the initiation of atherosclerotic plaques and plaque instability. 2. 2,3,4 cent,5-Tetrahydroxystilbene-2-O-beta-D-glucoside (TSG) reduces the blood lipid content and prevents the atherosclerotic process, but the mechanism of action of TSG is unclear. The purpose of the present study was to test whether TSG can suppress MMP activation and inflammation in atherosclerotic rats. 3. Sixty male Sprague-Dawley rats were randomly divided into six groups. Atherosclerosis was induced by feeding rats a hyperlipidaemic diet; TSG (120, 60 or 30 mg/kg per day) was administered by oral gavage. After 12 weeks of treatment, rats were killed (ethyl carbamate 1200 mg/kg) and serum lipids, C-reactive protein (CRP), interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha were measured. Haematoxylin-eosin (H&E) staining was used to examine histopathological changes in the aorta. The mRNA and protein expression of MMPs were assayed by reverse transcription-polymerase chain reaction, immunohistochemistry and western blotting. Simvastatin (2 mg/kg per day) was administered as a positive control, whereas the vehicle (0.9% NaCl) group served as the untreated control. 4. In the present study, TSG significantly and dose-dependently attenuated the hyperlipidaemic diet-induced alterations in serum lipid profile and increases in CRP, IL-6 and TNF-a levels. In addition, TSG normalized the structure of the aortic wall and suppressed the expression of MMP-2 and MMP-9 at both the mRNA and protein level in the rat aortic wall. 5. In summary, TSG suppresses the expression of MMP-2 and MMP-9 and inhibits inflammation in the diet-induced atherosclerotic rats.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Aterosclerose/tratamento farmacológico , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Glucosídeos/uso terapêutico , Inflamação/tratamento farmacológico , Estilbenos/uso terapêutico , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Relação Dose-Resposta a Droga , Glucosídeos/administração & dosagem , Masculino , Metaloproteinases da Matriz/metabolismo , Ratos , Ratos Sprague-Dawley , Sinvastatina , Estilbenos/administração & dosagemRESUMO
The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta(C) (CaMKIIdelta(C)) is found in the macromolecular complex of type 2 ryanodine receptor (RyR2) Ca(2+) release channels in the heart. However, the functional role of CaMKII-dependent phosphorylation of RyR2 is highly controversial. To address this issue, we expressed wild-type, constitutively active, or dominant-negative CaMKIIdelta(C) via adenoviral gene transfer in cultured adult rat ventricular myocytes. CaMKII-mediated phosphorylation of RyR2 was reduced, enhanced, or unaltered by dominant-negative, constitutively active, or wild-type CaMKIIdelta(C) expression, whereas phosphorylation of phospholamban at Thr17, an endogenous indicator of CaMKII activity, was at 73%, 161%, or 115% of the control group expressing beta-galactosidase (beta-gal), respectively. In parallel with the phospholamban phosphorylation, the decay kinetics of global Ca(2+) transients was slowed, accelerated, or unchanged, whereas spontaneous Ca(2+) spark activity was hyperactive, depressed, or unchanged in dominant-negative, constitutively active, or wild-type CaMKIIdelta(C) groups, respectively. When challenged by high extracellular Ca(2+), both wild-type and constitutively active CaMKIIdelta(C) protected the cells from store overload-induced Ca(2+) release, manifested by a approximately 60% suppression of Ca(2+) waves (at 2 to 20 mmol/L extracellular Ca(2+)) in spite of an elevated sarcoplasmic reticulum Ca(2+) content, whereas dominant-negative CaMKIIdelta(C) promoted Ca(2+) wave production (at 20 mmol/L Ca(2+)) with significantly depleted sarcoplasmic reticulum Ca(2+). Taken together, our data support the notion that CaMKIIdelta(C) negatively regulates RyR2 activity and spontaneous sarcoplasmic reticulum Ca(2+) release, thereby affording a negative feedback that stabilizes local and global Ca(2+)-induced Ca(2+) release in the heart.