Abstract 23: Overexpression Of Tbx20 In Adult Cardiomyocytes Promotes Cardiomyocyte Proliferation And Improves Cardiac Function Post Myocardial Infarction

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Fu-li Xiang ◽  
Katherine Yutzey
Keyword(s):  
Myocardial Infarction ◽  
Cell Cycle ◽  
Cardiac Function ◽  
Heart Development ◽  
Weight Ratio ◽  
Negative Regulator ◽  
Proliferation Markers ◽  
Post Surgery ◽  
Adult Cardiomyocytes ◽  
Scar Size

Background: Adult mammalian cardiomyocytes (CM) have the potential to proliferate, but this is not sufficient to compensate for the massive loss of functional CMs after myocardial infarction (MI), which remains a leading cause of death in the US. During embryonic heart development, the transcription factor Tbx20 is required for CM proliferation, and Tbx20 overexpression promotes fetal characteristics in adult CMs when initiated before birth in mice. We hypothesize that Tbx20 overexpression (Tbx20OE), when induced in adult CMs after injury, improves cardiac function and repair via dedifferentiation of CMs, thus promoting cell cycle re-entry and repair in mice post-MI. Methods and Results: αMHCMerCreMer (STG) and the inducible cardiomyocyte-specific Tbx20 transgenic (αMHCMerCreMer/CAG-CAT-Tbx20, DTG) mice were subjected to MI or sham surgeries. Tbx20OE was induced 3 days post-surgery via tamoxifen to specifically target cardiac repair post-MI. In sham-operated mice, no difference in cardiac function or morphology was observed between DTG and STG groups. However, more proliferating CMs as labeled by Ki67 were found in DTG sham myocardium compared to STG. Expression of cyclin D1, E1 (cell cycle markers) and IGF1 mRNA was increased, while p21 (cell cycle inhibitor) and Meis1 (negative regulator of proliferation) were decreased, in DTG sham hearts compared to STG controls. In mice subjected to MI, cardiac function, as measured by echocardiography, was significantly improved, and the infarct scar size was smaller (58.1% vs 38.3%) in the DTG group compared to STG controls 2 and 4 weeks post-MI. Myocardial hypertrophy determined by heart to body weight ratio and myocyte diameter was also significantly reduced in DTG heart compared to STG 4 weeks post-MI. Thus, induction of Tbx20OE post-MI injury leads to improved cardiac performance, decreased scar size, and decreased maladaptive cardiac remodeling. Ongoing studies will determine if proliferation indices (Ki67, pHH3, aurora kinase B) and cytokinesis of CM post-MI are increased in myocardium and isolated adult cardiomyocytes with Tbx20OE. Conclusions: Tbx20OE in adult CM activates cell proliferation markers and also improves cardiac function and repair in mice when induced post-MI.

scholarly journals Quantitative and qualitative composition of the innate immune response are equally important in wound healing after myocardial infarction

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
J Wrobel ◽  
J Rettkowski ◽  
H Seung ◽  
C Wadle ◽  
P Stachon ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cell Cycle ◽  
Wound Healing ◽  
Innate Immunity ◽  
Cardiac Function ◽  
Ventricular Remodeling ◽  
Myeloid Cells ◽  
Fold Increase ◽  
Remote Myocardium ◽  
Inflammatory Phenotype

Abstract Background Emergency hematopoiesis (EH) serves as the foundation of monocyte-derived and macrophage (Mφ) driven efferocytosis and ventricular remodeling after myocardial infarction (MI). Excessive myelopoiesis, however, can stipulate maladaptive wound healing and its therapeutic reduction may be a novel approach to preserve cardiac function. All-trans retinoic acid (ATRA) is a pleiotropic modulator of EH and innate immunity shielding hematopoietic stem cells from activation and driving survival and differentiation of myeloid cells. Purpose This study aimed to investigate this intriguing interplay of ATRA in wound healing after MI. Methods MI was induced by permanent coronary ligation in C57BL/6 mice and treated with daily injections of either ATRA (30mg/kg) or DMSO (vehicle) up to five days, starting 24h after ligation. Flow cytometry (FACS) was used for cell cycle analysis and immunophenotyping of leukocytes in bone marrow (BM), blood and heart. Immunohistochemistry (IH), masson trichrome (MT) staining and echocardiography evaluated inflammatory-fibrotic and functional development. Cytokine expression was analyzed by qPCR in bulk infarct and isolated, polarized Mφ-populations of BM-derived and cardiac resident origin. Results On day 2 after MI, EH was significantly reduced in ATRA-treated mice as compared to vehicle controls by means of cell cycle activity (n=6–13 per group; p<0,01) and myeloid cells in BM, blood and infarct tissue (n=5–13; p<0,05). Consequently, mRNA-expression of key inflammatory cytokines, IL-1β and TNFα, was diminished in the infarct tissue in this early phase (n=5–12; p<0,05). These changes, however, failed to preserve cardiac function and ventricular remodeling, 21 days after MI (n=10–11; not significant). By qPCR, non-canonical activation of recruited ATRA-primed monocyte-derived Mφ, was found to propagate a pro-inflammatory phenotype with higher expression of MMP2 and MMP9 in sorted cardiac Mφ (n=4–5; p<0,001). Furthermore, prominent IL-1β-expression in M2-polarized BM-derived Mφ indicated an impaired anti-inflammatory phenotype after ATRA treatment (n=4–6; p<0,05). Strikingly, these changes also occurred in remote myocardium where IH revealed a 2-fold increase of CD11b - positive myeloid cells accompanied by increased expression of TNFα and TGFβ (n=9; p<0,001). MT-staining, performed 21 days after MI, demonstrated an almost 3-fold increase in collagen deposition in remote myocardium of ATRA treated mice in contrast to vehicle controls (n=4–6; p<0,0001). Conclusion Despite a beneficial reduction of EH after MI, short-term treatment with ATRA induced profound and persisting changes in the cytokine expression of monocyte-derived Mφ, which significantly altered their function and thus prevented improvements in cardiac function. Our data provide evidence that quantitative and qualitative changes in innate immunity are equally important for cardiac remodeling after MI. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft

scholarly journals Loss of Endogenously Cycling Adult Cardiomyocytes Worsens Myocardial Function

2020 ◽  
Author(s):  
Leigh A Bradley ◽  
Alexander Young ◽  
Hongbin Li ◽  
Helen O Billcheck ◽  
Matthew J Wolf
Keyword(s):  
Myocardial Infarction ◽  
Cell Cycle ◽  
Myocardial Function ◽  
Cultured Cells ◽  
Left Ventricular ◽  
Left Ventricular Chamber ◽  
Adult Cardiomyocytes ◽  
Border Zones ◽  
And Function ◽  
Chamber Size

Rationale: Endogenously cycling adult cardiomyocytes (CMs) increase after myocardial infarction (MI) but remain scare, and are generally thought not to contribute to myocardial function. However, this broadly held assumption has not been tested, mainly because of the lack of transgenic reporters that restrict Cre expression to adult CMs that reenter the cell cycle. Objective: We created and validated a new transgenic mouse, αMHC-MerDreMer-Ki67p-RoxedCre::Rox-Lox-tdTomato-eGFP (denoted αDKRC) that restricts Cre expression to cycling adult CMs and uniquely integrates spatial and temporal adult CM cycling events based on the DNA specificities of orthologous Dre- and Cre recombinases. We then created mice that expressed an inducible Diphtheria toxin (DTA), αDKRC::DTA mice, in adult cycling CMs and examined the effects of ablating these endogenously cycling CMs on myocardial function after Ischemic-Reperfusion (I/R) MI. Methods and Results: A tandem αDKRC transgene was designed, validated in cultured cells, and used to make transgenic mice. The αDKRC transgene integrated between MYH6 and MYH7 and did not disrupt expression of the surrounding genes. Compared to controls, αDKRC::RLTG mice treated with Tamoxifen expressed tdTomato+ in CMs with rare Bromodeoxyuridine (BrdU)+, eGFP+ CMs, consistent with reentry of the cell cycle. We then pre-treated αDKRC::RLTG mice with Tamoxifen to activate the reporter before sham or reperfusion (I/R) myocardial infarction (MI) surgeries. Compared to Sham surgery, the I/R MI group had increased single and paired eGFP+ CMs predominantly in the border zones (5.8 {plus minus} 0.5 vs. 3.3 {plus minus} 0.3 CMs per ten-micron section, N = 8-9 mice per group, n = 16-24 sections per mouse), indicative of cycled CMs. The single to paired eGFP+ CM ratio was ~9 to 1 (5.2 {plus minus} 0.4 single vs. 0.6 {plus minus} 0.2 paired CMs) in the I/R MI group after MI, suggesting that cycling CMs were more likely to undergo polyploidy than replication. The ablation of endogenously cycling adult CMs in αDKRC::DTA mice caused progressive worsening left ventricular chamber size and function after I/R MI, compared to controls. Conclusions: Although scarce, endogenously cycling adult CMs contribute to myocardial function after injury, suggesting that these cells may be physiologically relevant.

S6K inhibition renders cardiac protection against myocardial infarction through PDK1 phosphorylation of Akt

2011 ◽  
Vol 441 (1) ◽  
pp. 199-207 ◽  
Author(s):  
Ruomin Di ◽  
Xiangqi Wu ◽  
Zai Chang ◽  
Xia Zhao ◽  
Qiuting Feng ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Function ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Cardiac Remodelling ◽  
Heart Weight ◽  
S6 Kinase ◽  
Beneficial Effects ◽  
Therapeutic Value ◽  
Specific Deletion

In the present study, we observed a rapid and robust activation of the ribosomal protein S6K (S6 kinase) provoked by MI (myocardial infarction) in mice. As activation of S6K promotes cell growth, we hypothesized that increased S6K activity contributes to pathological cardiac remodelling after MI and that suppression of S6K activation may prevent aberrant cardiac remodelling and improve cardiac function. In mice, administration of rapamycin effectively suppressed S6K activation in the heart and significantly improved cardiac function after MI. The heart weight/body weight ratio and fibrotic area were substantially reduced in rapamycin-treated mice. In rapamycin-treated mice, decreased cardiomyocyte remodelling and cell apoptosis were observed compared with vehicle-treated controls. Consistently, inhibition of S6K with PF-4708671 displayed similar protection against MI as rapamycin. Mechanistically, we observed significantly enhanced Thr308 phosphorylation and activation of Akt in rapamycin- and PF-4708671-treated hearts. Cardiomyocyte-specific deletion of PDK1 (phosphoinositide-dependent kinase 1) and Akt1/3 abolished cardioprotection after MI in the presence of rapamycin administration. These results demonstrate that S6K inhibition rendered beneficial effects on left ventricular function and alleviated adverse remodelling following MI in mice by enhancing Akt signalling, suggesting the therapeutic value of both rapamycin and PF-4708671 in treating patients following an MI.

Role of D-type cyclins in heart development and disease

2012 ◽  
Vol 90 (9) ◽  
pp. 1197-1207 ◽  
Author(s):  
Adam Hotchkiss ◽  
Jessica Robinson ◽  
Jessica MacLean ◽  
Tiam Feridooni ◽  
Karim Wafa ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Heart Development ◽  
Cardiac Development ◽  
Perinatal Period ◽  
Cell Cycle Regulators ◽  
Adult Heart ◽  
Signalling Molecules ◽  
Adult Cardiomyocytes ◽  
Catalytically Active ◽  
Permanent Cell

A defining feature of embryonic cardiomyocytes is their relatively high rates of proliferation. A gradual reduction in proliferative capacity throughout development culminates in permanent cell cycle exit by the vast majority of cardiomyocytes around the perinatal period. Accordingly, the adult heart has severely limited capacity for regeneration in response to injury or disease. The D-type cyclins (cyclin D1, D2, and D3) along with their catalytically active partners, the cyclin dependent kinases, are positive cell cycle regulators that play important roles in regulating proliferation of cardiomyocytes during normal heart development. While expression of D-type cyclins is generally low in the adult heart, expression levels are augmented in association with cardiac hypertrophy, but are uncoupled from myocyte cell division. Accordingly, re-activation of D-type cyclin expression in the adult heart has been implicated in pathophysiological processes via mechanisms distinct from those that drive proliferation during cardiac development. Growth factors and other exogenous agents regulate D-type cyclin production and activity in embryonic and adult cardiomyocytes. Understanding differences in the precise intracellular mediators downstream from these signalling molecules in embryonic versus adult cardiomyocytes could prove valuable for designing strategies to reactivate the cell cycle in cardiomyocytes in the setting of cardiovascular disease in the adult heart.

Abstract 272: RBPJ Controls the Angiogenic Response of Mouse Adult Cardiomyocytes

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Ramon Diaz Trelles ◽  
Maria Cecilia Scimia ◽  
Pilar Ruiz Lozano ◽  
Mark Mercola
Keyword(s):  
Gene Expression ◽  
Myocardial Infarction ◽  
Cardiac Function ◽  
Target Genes ◽  
Notch Pathway ◽  
Oxygen Demand ◽  
Angiogenic Factors ◽  
Angiogenic Factor ◽  
Angiogenic Response ◽  
Adult Cardiomyocytes

Cardiac microvasculature density is critical for a correct cardiac function under normal and stress conditions. We found that the transcription factor RBPJ, downstream of the Notch signalling, can regulate angiogenic factors gene expression by repression (normal homeostasis) or activation (stress) and also by modulating the hypoxia induced angiogenic response. Accordingly, in normal conditions cardiomyocyte specific RBPJ KO adult mice hearts show a denser microvasculature. Isolated mouse adult cardiomyocytes show increased gene expression and promoter hyperacetylation and hypermethylation of angiogenic factors and Notch target genes (like HES1). Stress induced by myocardial infarction (MI) or cardiac overload (TAC) activate an angiogenic response to compensate the increased oxygen demand. Notch pathway is activated and RBPJ accumulated in the nucleus after MI and TAC. After TAC, deletion of RBPJ did not block hypertrophy induction, but prevented the increase in angiogenic factor production and microvessel density that normally occurs in response to increased workload. Remarkably, the KO preserved cardiac function and reduced cell death and fibrosis after myocardial infarction. Thus, RBPJ acts in cardiomyocytes as a master factor orchestrating homeostatic and disease-induced angiogenesis, and modulating RBPJ protects against ischemic injury.

scholarly journals Association of ADAMTS-7 Levels with Cardiac Function in a Rat Model of Acute Myocardial Infarction

2016 ◽  
Vol 38 (3) ◽  
pp. 950-958 ◽  
Author(s):  
Wenjing Wu ◽  
Hui Wang ◽  
Changan Yu ◽  
Jiahui Li ◽  
Yanxiang Gao ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Cardiac Function ◽  
Matrix Protein ◽  
Ventricular Remodeling ◽  
Structural Parameters ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ventricular Ejection Fraction ◽  
Post Surgery

Background/Aims: High ADAMTS-7 levels are associated with acute myocardial infarction (AMI), although its involvement in ventricular remodeling is unclear. In this study, we investigated the association between ADAMTS-7 expression and cardiac function in a rat AMI model. Methods: Sprague-Dawley rats were randomized into AMI (n = 40) and sham (n = 20) groups. The left anterior descending artery was sutured to model AMI. Before surgery and 7, 14, 28, and 42 days post-surgery, ADAMTS-7 and brain natriuretic peptide (BNP), and cartilage oligomeric matrix protein (COMP) were assessed by ELISA, western blot, real-time RT-PCR, and/or immunohistochemistry. Cardiac functional and structural parameters were assessed by M-mode echocardiography. Results: After AMI, plasma ADAMTS-7 levels increased, peaking on day 28 (AMI: 13.2 ± 6.3 vs. sham: 3.4 ± 1.3 ng/ml, P < 0.05). Compared with the sham group, ADAMTS-7 expression was higher in the infarct zone at day 28. COMP present in normal myocardium was degraded by day 28 post-AMI. Plasma ADAMTS-7 correlated positively with BNP (r = 0.642, P = 0.025), left ventricular end-diastolic diameter (r = 0.695, P = 0.041), left ventricular end-systolic diameter (r = 0.710, P = 0.039), left ventricular ejection fraction (r = 0.695, P = 0.036), and left ventricular short-axis fractional shortening (r = 0.721, P = 0.024). Conclusions: ADAMTS-7 levels may reflect the degree of ventricular remodeling after AMI.

scholarly journals PL - 027 Up-regulation of NRG1 improves cardiac repair in zebra fish and involved in the cardioprotective effects of exercise training in rats of myocardial infarction

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Mengxin Cai ◽  
Shaojun Du ◽  
Zhenjun Tian
Keyword(s):  
Myocardial Infarction ◽  
Skeletal Muscle ◽  
Exercise Training ◽  
Cardiac Function ◽  
Signaling Pathway ◽  
Heart Development ◽  
Cardiac Repair ◽  
Cardiomyocyte Proliferation ◽  
Infarcted Heart ◽  
Cardioprotective Effects

Objective Myocardial infarction (MI) remains a leading cause of morbidity and mortality worldwide. Exercise training could improve cardiac function following MI. However, the mechanisms are still not well-known. Neuregulin 1 (NRG1)plays an important role in heart development and regeneration.In this study, we investigated the effect of NRG1 on cardiac regeneration in a zebrafish model, detected whether exercise could improve cardiac function through regulating NRG1 expression in infarcted heart and explore the possible role of up-regulation of NRG1 in skeletal muscle play in the cardioprotective effects in rats with MI. Methods Transgenic zebrafish line, cmlc2:CreERandβ-act2:BSNrg1,wereusedto study the effect of NRG1 on heart growth and regeneration after injury. PCNA was detected by immunofluorescence staining andmRNAexpression of gata4, nkx2.5, tbx5, smyd1b, hsp90α and murf were tested by RT-PCR.Sprague-Dawley rats were used to establish MI model and underwent fourweeks of exercise training (ET) or pAAV-{dMCK promoter}rNRG1-eGFP intervention.AG1478 was used asan inhibitor of NRG1/ErbBs signaling pathway. Cardiac function and structure,cardiomyocyte proliferation and NRG1 expression were detected in the heart or skeletal. Results Cardiac-specific overexpression of NRG1 induced cardiac hypertrophy and cardiomyocyte proliferation, regulated the mRNA expression of gata4, nkx2.5, tbx5, smyd1b, hsp90α andmurf in uninjuriedzebrafish, and promote cardiac repair and regeneration after injury in the zebrafish.Exercise activated NRG1/ErbBs signaling pathway, improved cardiac remodeling and heart function, enhanced cardiomyocyte proliferation, reduced cardiomyocyte apoptosis, ROS level and MuRF1 protein expression in rats with MI. BlockingErbB signaling attenuated the ET-induced cardioprotection effects in rat with MI.up-regulation of NRG1 expression in skeletal muscle could increase the protein level of NRG1 in serum and infarcted heart, improve cardiomyocyte proliferation and reduce the level of cardiac fibrosis, finally promote cardiac function. Conclusions Up-regulation of NRG1 expression in the heart or skeletal musclemay be one of the underlying mechanisms of thebeneficial effects of exercise training following MI.

Abstract 17089: Cyclin D2 Overexpression Enhances the Potency of Human Induced-Pluripotent Stem Cell-Derived Cardiomyocytes for Cardiac Repair in a Porcine Model of Myocardial Infarction

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Meng Zhao ◽  
Yawen Tang ◽  
Wuqiang Zhu ◽  
Jianyi Zhang
Keyword(s):  
Myocardial Infarction ◽  
Cell Cycle ◽  
Stem Cell ◽  
Cardiac Function ◽  
Pluripotent Stem Cell ◽  
Myocardial Injury ◽  
Induced Pluripotent Stem Cell ◽  
Large Animal ◽  
Cyclin D2 ◽  
Induced Pluripotent

Introduction: Stem-cell-based therapies provide promise for the treatment of ischemic myocardial injury, but the number of cells that remain engrafted at the site of administration is exceptionally low, which is believed to limit the effectiveness of treatment. In this study, we investigated whether the number of engrafted human induced-pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) can be increased via overexpression of the cell-cycle activator cyclin D2 (CCND2) and if so, whether this increase is accompanied by improvements in myocardial recovery. Experiments were conducted in a large-animal (swine) model of myocardial injury. Methods and results: CCND2-overexpressing hiPSC-CMs (CCND2 OE CMs) were constructed via lentiviral transfection; then, myocardial infarction (MI) was surgically induced in swine, and the animals were randomly assigned to treatment with CCND2 OE CMs (i.e., the MI+CCND2 OE CM group), wild-type hiPSC-CMs (the MI+CCND2 WT CM group), or neither experimental treatment (the MI group); the cells were injected into five sites (6х10 6 cells/site) surrounding the infarct. Four weeks after MI, measurements of the heart-weight to bodyweight ratio (HW/BW), cardiac function (determined via magnetic resonance imaging), and vascularity (CD31 staining) were significantly better in MI+CCND2 OE CM animals than in the CCND2 WT CM group. HW/BW was also significantly lower in both cell-treatment groups than in MI animals, and CCND2 overexpression was associated with increases in both hiPSC-CM engraftment (mRNA levels) and cell-cycle activity (ki67 and phosphorylated histone 3 levels). Conclusion: Experiments in a large-animal MI model indicated that CCND2 overexpression in transplanted hiPSC-CMs was associated with increases in cell-cycle activity and the number of engrafted cells, as well as improvements in cardiac function, hypertrophy, and vascularity.

Therapeutic effect of a novel Wnt pathway inhibitor on cardiac regeneration after myocardial infarction

2017 ◽  
Vol 131 (24) ◽  
pp. 2919-2932 ◽  
Author(s):  
Dezhong Yang ◽  
Wenbin Fu ◽  
Liangpeng Li ◽  
Xuewei Xia ◽  
Qiao Liao ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cell Cycle ◽  
Cardiac Function ◽  
Infarct Size ◽  
Cardiac Regeneration ◽  
Border Zone ◽  
Cardiomyocyte Proliferation ◽  
Great Loss ◽  
Wnt Proteins ◽  
Phosphohistone H3

After myocardial infarction (MI), the heart is difficult to repair because of great loss of cardiomyoctyes and lack of cardiac regeneration. Novel drug candidates that aim at reducing pathological remodeling and stimulating cardiac regeneration are highly desirable. In the present study, we identified if and how a novel porcupine inhibitor CGX1321 influenced MI and cardiac regeneration. Permanent ligation of left anterior descending (LAD) coronary artery was performed in mice to induce MI injury. Cardiac function was measured by echocardiography, infarct size was examined by TTC staining. Fibrosis was evaluated with Masson’s trichrome staining and vimentin staining. As a result, CGX1321 administration blocked the secretion of Wnt proteins, and inhibited both canonical and non-canonical Wnt signaling pathways. CGX1321 improved cardiac function, reduced myocardial infarct size, and fibrosis of post-MI hearts. CGX1321 significantly increased newly formed cardiomyocytes in infarct border zone of post-MI hearts, evidenced by the increased EdU+ cardiomyocytes. Meanwhile, CGX1321 increased Ki67+ and phosphohistone H3 (PH3+) cardiomyocytes in culture, indicating enhanced cardiomyocyte proliferation. The mRNA microarray showed that CGX1321 up-regulated cell cycle regulating genes such as Ccnb1 and Ccne1. CGX1321 did not alter YAP protein phosphorylation and nuclear translocation in cardiomyocytes. In conclusion, porcupine inhibitor CGX1321 reduces MI injury by limiting fibrosis and promoting regeneration. It promotes cardiomyocyte proliferation by stimulating cell cycle regulating genes with a Hippo/YAP-independent pathway.

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