Effects of Akt on cardiac myocytes: location counts.
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Animals↗
Biomedical subjects
Gianluigi Condorelli
Publications and source records attributed to Gianluigi Condorelli.
Direct intramyocardial percutaneous delivery of autologous bone marrow in patients with refractory myocardial angina.
BACKGROUND: Intramyocardial injection of autologous bone marrow (ABM) may induce angiogenesis. We tested the safety and feasibility of catheter-based direct percutaneous intramyocardial delivery of ABM in patients with refractory angina pectoris. METHODS: Ten patients (9 men, 67 +/- 8 years) with refractory angina (Canadian Cardiovascular Society class III-IV) and documented myocardial ischemia were enrolled. After left ventricular electromechanical mapping, freshly aspirated and filtered ABM was percutaneously injected into target myocardial ischemic areas. Clinical symptoms (as assessed according to the Canadian Cardiovascular Society class), quality of life, and myocardial perfusion were evaluated before the procedure and through the follow-up. RESULTS: In all patients, ABM was successfully injected into the target regions. No periprocedural complications occurred. At 12 months, no major cardiac events (death, acute myocardial infarction, stroke, and malignant ventricular arrhythmias) occurred. Severity of angina improved of > or = 2 classes in 3 patients. Quality of life showed a significant improvement in all patients. Myocardial perfusion in the target regions improved in 4 of 8 patients. CONCLUSIONS: Direct percutaneous intramyocardial delivery of ABM appears feasible and safe. Further evaluation is warranted to test its clinical efficacy.
Aged↗
Sources of cardiomyocytes for stem cell therapy: an update.
The therapeutic use of stem cells for cardiac repair following myocardial infarction (MI) has generated a great deal of interest. Many types of stem/progenitor cells have been used in an attempt to regenerate the infarcted heart. We have reviewed the current state of progress using embryonic stem (ES) cells, hematopoietic stem and progenitor cells (HSCs/HPCs), mesenchymal stem and progenitor cells, resident and cardiac "stem" cells from other sources. Our view is that, even though the road ahead is long and tortuous, embryonic stem cells represent the most reliable font of CMC and the most promising type of cell to rely on for a future tool in heart failure treatment.
Animals↗
Relation of various plasma growth factor levels in patients with stable angina pectoris and total occlusion of a coronary artery to the degree of coronary collaterals.
We assessed (1) angiogenic factors in patients with stable angina and longstanding (> or =24 months) total occlusion of a single coronary artery and (2) the relation between plasma levels of angiogenic factors and the development of collateral vessels as evaluated by coronary angiography. Plasma concentrations of vascular endothelial growth factor (VEGF(165)), fibroblast growth factor, placenta-derived growth factors (PlGFs), and hepatocyte growth factor were assessed in 96 patients with stable angina and longstanding (> or =24 months) total occlusion of a single coronary artery. According to coronary angiographic results, 18 patients had no visible collaterals (group 0), 21 patients had visible collaterals but no filling of the recipient epicardial vessel (group 1), and 57 patients showed filling (partial or complete) of the recipient epicardial vessel by collaterals (group 2). Plasma VEGF(165) and PlGF concentrations were higher in group 1 than in groups 0 and 2 (VEGF(165) 75 pg/ml, range 24 to 105, vs 23 pg/ml, range 15 to 29, and 19 pg/ml, range 10 to 41, respectively, F = 5.53, p = 0.006; PlGF 35 pg/ml, range 3.5 to 105, vs 1 pg/ml, range 1 to 38, and 1 pg/ml, range 1 to 5, respectively, F = 7.09, p = 0.008). Plasma VEGF(165) and PlGF levels were similar in groups 0 and 2. There was no significant difference in plasma levels of fibroblast and hepatocyte growth factor concentrations across the 3 groups. In conclusion, plasma levels of angiogenic growth factors differ among patients with stable angina pectoris and longstanding total coronary occlusion.
Aged↗
Stem cells for cardiac repair: state of the art.
Stem cell research has generated great excitement over the last few years. In cardiovascular medicine, the possibility to cure heart failure with newly generated cardiomyocytes (CMCs) has sparked the interest of many scientists; as a result, different "ideal" cardiac stem cells were proposed for therapeutic use. We review here the literature in the cardiac stem cell field, which sometimes is "dialectic" in methodology and results.
Animals↗
Nephrotoxicity of low-osmolality versus iso-osmolality contrast agents: impact of N-acetylcysteine.
BACKGROUND: Recent data support that iodixanol, an iso-osmolality contrast agent, is less nephrotoxic than low-osmolality contrast agents when hydration is the only prophylactic strategy used. We evaluated the nephrotoxicity of iso- and low-osmolality contrast agents with prophylactic administration of N-acetylcysteine (NAC) along with hydration. METHODS: Two hundred and twenty-five patients with chronic renal insufficiency (serum creatinine >1.5 mg/dL or an estimated glomerular filtration rate <60 mL/min/1.73 m(2)), referred to our institution for coronary and/or peripheral procedures, were assigned to receive low-osmolality (iobitridol group; N = 115) or iso-osmolality (iodixanol group; N = 110) contrast dye. In all cases prophylactic administration of 0.45% saline intravenously and NAC (1200 mg orally twice daily) was used. RESULTS: Baseline creatinine levels were similar in the 2 groups [iobitridol group = 1.70 (IQR: 1.54-1.98) mg/dL; iodixanol group = 1.73 (IQR: 1.56-2.00) mg/dL, P = 0.33]. The risk score for contrast nephrotoxicity was 5.0 +/- 1.6 in the iobitridol group versus 5.0 +/- 1.8 in the iodixanol group (P = 0.44). Increase of at least 0.5 mg/dL of the creatinine concentration 48 hours after the procedure occurred in 4/115 patients (3.5%) in the iobitridol group and 3/110 patients (2.7%) in the iodixanol group (P = 1.00; OR 0.78; 95% CI 0.17-3.56). Amount of contrast media administration was similar in the 2 groups (iobitridol group = 167 +/- 90 mL; iodixanol group = 164 +/- 82 mL; P = 0.61). CONCLUSION: Nephrotoxicity of iso-osmolality and low-osmolality contrast agents was similar when a prophylactic strategy of hydration plus NAC was utilized.
Acetylcysteine↗
Stem cells for cardiomyocyte regeneration: state of the art.
A wide range of stem/progenitor cell types have been used for the regeneration of the infarcted heart. This review details the current status of progress concerning different strategies that have been used to manipulate cardiomyocyte cell growth in vitro, for their use in heart failure. The current status of this field involves different types of regenerating cells. Embryonic stem (ES) cells, hematopoietic stem and progenitor cells, mesenchymal stem and progenitor cells, and resident cardiac "stem" cells are discussed here.
Animals↗
Akt mediates the cross-talk between beta-adrenergic and insulin receptors in neonatal cardiomyocytes.
Upregulation of the sympathetic nervous system plays a key role in the pathogenesis of insulin resistance. Although the heart is a target organ of insulin, few studies have examined the mechanisms by which beta-adrenergic stimulation affects insulin sensitivity in cardiac muscle. In this study, we explored the molecular mechanisms involved in the regulation of the cross-talk between beta adrenergic and insulin receptors in neonatal rat cardiomyocytes and in transgenic mice with cardiac overexpression of a constitutively active mutant of Akt (E40K Tg). The results of this study show that beta-adrenergic receptor stimulation has a biphasic effect on insulin-stimulated glucose uptake. Short-term stimulation induces an additive effect on insulin-induced glucose uptake, and this effect is mediated by phosphorylation of Akt in threonine 308 through PKA/Ca2+-dependent and PI3K-independent pathway, whereas insulin-evoked threonine phosphorylation of Akt is exclusively PI3K-dependent. On the other hand, long-term stimulation of beta-adrenergic receptors inhibits both insulin-stimulated glucose uptake and insulin-induced autophosphorylation of the insulin receptor, and at the same time promotes threonine phosphorylation of the insulin receptor. This is mediated by serine 473 phosphorylation of Akt through PKA/Ca2+ and PI3K-dependent pathways. Under basal conditions, E40K Tg mice show increased levels of threonine phosphorylation of the beta subunit of the insulin receptor and blunted tyrosine autophosphorylation of the beta-subunit of the insulin receptor after insulin stimulation. These results indicate that, in cardiomyocytes, beta-adrenergic receptor stimulation impairs insulin signaling transduction machinery through an Akt-dependent pathway, suggesting that Akt is critically involved in the regulation of insulin sensitivity.
Adrenergic beta-Agonists↗
Akt/protein kinase B and endothelial nitric oxide synthase mediate muscular neovascularization induced by tissue kallikrein gene transfer.
BACKGROUND: Angiogenesis gene therapy with human tissue kallikrein (hTK) has shown promise for ischemic disease. The present study was undertaken to (1) assess an optimal gene transfer modality, (2) clarify hTK angiogenic pathways, and (3) discount possible side effects. METHODS AND RESULTS: The hTK gene was transferred to murine adductors by increasing doses of an adenovirus (Ad.hTK). Heterologous protein production was evaluated by ELISA and immunohistochemistry. Structural and functional characteristics of hTK-induced neovascularization were assessed. Muscular endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF)-A mRNA and protein content were evaluated by real-time polymerase chain reaction and Western blotting. The ability of hTK to phosphorylate-activate Akt/protein kinase B (Akt-B) and VEGF receptor 2 (VEGF-R2) was also determined. Implication of the aforementioned mechanisms in Ad.hTK-induced neovascularization was challenged by blocking Akt-B with a dominant-negative Akt construct; NOS with N(G)-nitro-L-arginine methyl ester; and VEGF-A with neutralizing antibody, VEGF-R2 antagonist, or Ad carrying soluble VEGF-R1 gene. We found that 10(7) PFU Ad.hTK led to peak increases in capillary and arteriole density. Newly developed arterioles persisted for up to 8 weeks. Ad.hTK did not change microvascular permeability. Ad.hTK upregulated eNOS mRNA and protein and activated Akt-B through Ser-473 phosphorylation. Inhibitory studies documented that these biochemical events were instrumental to Ad.hTK-induced neovascularization. In contrast, Ad.hTK neither affected VEGF-A and VEGF-R2 levels nor increased VEGF-R2 phosphorylation. Consistently, Ad.hTK-induced neovascularization was not disturbed by any of the different approaches used to block VEGF-A. CONCLUSIONS: Our findings provide new information on the pathway involved in hTK-induced neoangiogenesis and represent an advancement toward clinical applications with Ad.hTK.
Adenoviridae↗
Transplantation of low dose CD34+KDR+ cells promotes vascular and muscular regeneration in ischemic limbs.
Hematopoietic progenitor cell transplantation can contribute to revascularization of ischemic tissues. Yet, the optimal cell population to be transplanted has yet to be determined. We have compared the therapeutic potential of two subsets of human cord blood CD34+ progenitors, either expressing the VEGF-A receptor 2 (KDR) or not. In serum-free starvation culture, CD34+KDR+ cells reportedly showed greater resistance to apoptosis and ability to release VEGF-A, as compared with CD34+KDR- cells. When injected into the hind muscles in immunodeficient SCIDbg mice subjected to unilateral ischemia, a low number (10(3)) of CD34+KDR+ cells improved limb salvage and hemodynamic recovery better than a larger dosage (10(4)) of CD34+KDR- cells. The neovascularization induced by KDR+ cells was significantly superior to that promoted by KDR- cells. Similarly, endothelial cell apoptosis and interstitial fibrosis were significantly attenuated by KDR+ cells, which differentiated into mature human endothelial cells and also apparently skeletal muscle cells. This study demonstrates that a low number of CD34+KDR+ cells favors reparative neovascularization and possibly myogenesis in limb ischemia, suggesting the potential use of this cell population in regenerative medicine.
Animals↗
Heart infarct in NOD-SCID mice: therapeutic vasculogenesis by transplantation of human CD34+ cells and low dose CD34+KDR+ cells.
Hematopoietic (Hem) and endothelial (End) lineages derive from a common progenitor cell, the hemangioblast: specifically, the human cord blood (CB) CD34+KDR+ cell fraction comprises primitive Hem and End cells, as well as hemangioblasts. In humans, the potential therapeutic role of Hem and End progenitors in ischemic heart disease is subject to intense investigation. Particularly, the contribution of these cells to angiogenesis and cardiomyogenesis in myocardial ischemia is not well established. In our studies, we induced myocardial infarct (MI) in the immunocompromised NOD-SCID mouse model, and monitored the effects of myocardial transplantation of human CB CD34+ cells on cardiac function. Specifically, we compared the therapeutic effect of unseparated CD34+ cells vs. PBS and mononuclear cells (MNCs); moreover, we compared the action of the CD34+KDR+ cell subfraction vs. the CD34+KDR- subset. CD34+ cells significantly improve cardiac function after MI, as compared with PBS/MNCs. Similar beneficial actions were obtained using a 2-log lower number of CD34+KDR+ cells, while the same number of CD34+KDR- cells did not have any effects. The beneficial effect of CD34+KDR+ cells may mostly be ascribed to their notable resistance to apoptosis and to their angiogenic action, since cardiomyogenesis was limited. Altogether, our results indicate that, within the CD34+ cell population, the CD34+KDR+ fraction is responsible for the improvement in cardiac hemodynamics and hence represents the candidate active CD34+ cell subset.
Animals↗
AKT participates in endothelial dysfunction in hypertension.
BACKGROUND: In hypertension, reduced nitric oxide production and blunted endothelial vasorelaxation are observed. It was recently reported that AKT phosphorylates and activates endothelial nitric oxide synthase and that impaired kinase activity may be involved in endothelial dysfunction. METHODS AND RESULTS: To identify the physiological role of the kinase in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR), we used adenoviral vectors to transfer the human AKT1 gene selectively to the common carotid endothelium. In vitro, endothelial vasorelaxations to acetylcholine, isoproterenol, and insulin were blunted in control carotids from SHR compared with WKY rats, and human AKT1 overexpression corrected these responses. Similarly, blood flow assessed in vivo by Doppler ultrasound was reduced in SHR compared with WKY carotids and normalized after AKT1 gene transfer. In primary cultured endothelial cells, we evaluated AKT phosphorylation, activity, and compartmentalization and observed a mislocalization of the kinase in SHR. CONCLUSIONS: We conclude that AKT participates in the settings of endothelial dysfunction in SHR rats by impaired membrane localization. Our data suggest that AKT is involved in endothelium dysfunction in hypertension.
Acetylcholine↗
A nitric oxide-releasing derivative of enalapril, NCX 899, prevents progressive cardiac dysfunction and remodeling in hamsters with heart failure.
Nitric oxide (NO) production is known to be impaired in heart failure. A new compound (NCX 899), a NO-releasing derivative of enalapril was characterized, and its actions were evaluated in Bio 14.6 cardiomyopathic (CM) hamsters with heart failure. The hamsters were randomized to oral treatment for 4 weeks with vehicle (n=11), NCX 899 (NCX, 25 mg/kg, n=10), or enalapril (25 mg/kg, n=10). In the vehicle group, fractional shortening by echocardiography decreased (-23.6+/-2.0%) and LV end-diastolic dimension) increased (+10.9+/-1.0%), whereas fractional shortening increased (+17.5+/-4.4%) in NCX and was unchanged in the enalapril group (both P<0.01 vs. vehicle). End-diastolic dimension decreased only in NCX. LV contractility (LVdP/dt max and Emax) was significantly greater in NCX than in enalapril or vehicle, while relaxation (Tau) was shortened in both NCX and enalapril vs. vehicle. ACE activity was inhibited equally by NCX and enalapril in the CM hamster, and plasma nitrate levels were increased only in NCX (P<0.05 vs. enalapril and vehicle). In aortic strips endothelium-independent relaxation occurred only with NCX. The superior effects of NO-releasing enalapril (NCX) vs. enalapril alone to enhance vascular effects, increase LV contractility and prevent unfavorable remodeling and are consistent with vascular delivery of exogenous NO. NCX 899 may hold promise for the future treatment of heart failure.
Angiotensin-Converting Enzyme Inhibitors↗
Molecular determinants of the physiological adaptation to stress in the cardiomyocyte: a focus on AKT.
Cardiomyocytes (CMCs) adapt to physiological or pathological stimuli by undergoing molecular changes which differentiate according to the specificity of the stimulus and eventually generate a phenotype with peculiar molecular characteristics. Here, we review the literature on the molecular mechanisms activated in the CMC during physiologic adaptation to stress, as opposed to maladaptation. The critical role of the IGF-1 receptor/PI3K/Akt signaling pathway during this process is described, including effector targets regulating inotropism and cell size.
Adaptation, Physiological↗
Regulation of cell size and contractile function by AKT in cardiomyocytes.
AKT is a serine-threonine kinase involved in several different cellular functions, including the control of cell size and the regulation of survival and metabolism. Many studies have demonstrated that AKT also plays a critical role in the homeostasis of the cardiomyocyte. In these cells, AKT is activated by upstream molecules such as beta-adrenergic receptor, insulin-like growth factor-1 or insulin receptor, through PI3K alpha; whereas its activation is inhibited by the PTEN molecule. Downstream targets of AKT in the cardiomyocyte include glycogen-synthase kinase-3 beta and S6 kinase. Major effects of AKT activation in the cardiomyocyte are increase in cell size, prevention of apoptosis, and regulation of glucose metabolism. Interestingly, the AKT-dependent hypertrophic pathway is distinct from that activated by MAPKs. In fact, overexpression of AKT does not lead to MAPK activation. Our group has shown, moreover, that AKT exerts a positive effect on both inotropism and relaxation. In fact, mice overexpressing the E40K mutant of AKT in the heart showed improved cardiac function. Thus, AKT increases both cell size through the S6 kinase pathway and inotropism through the functional regulation of critical Ca(2+)-handling proteins. Therefore, AKT is a critical mediator of physiological hypertrophy.
Animals↗
Mechanism of enhanced cardiac function in mice with hypertrophy induced by overexpressed Akt.
Transgenic mice with cardiac-specific overexpression of active Akt (TG) not only exhibit hypertrophy but also show enhanced left ventricular (LV) function. In 3-4-month-old TG, heart/body weight was increased by 60% and LV ejection fraction was elevated (84 +/- 2%, p < 0.01) compared with nontransgenic littermates (wild type (WT)) (73 +/- 1%). An increase in isolated ventricular myocyte contractile function (% contraction) in TG compared with WT (6.1 +/- 0.2 versus 3.5 +/- 0.2%, p < 0.01) was associated with increased Fura-2 Ca2+ transients (396 +/- 50 versus 250 +/- 24 nmol/liter, p < 0.05). The rate of relaxation (+dL/dt) was also enhanced in TG (214 +/- 15 versus 98 +/- 18 microm/s, p < 0.01). L-type Ca2+ current (ICa) density was increased in TG compared with WT (-9.0 +/- 0.3 versus 7.2 +/- 0.3 pA/pF, p < 0.01). Sarcoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) protein levels were increased (p < 0.05) by 6.6-fold in TG, which could be recapitulated in vitro by adenovirus-mediated overexpression of Akt in cultured adult ventricular myocytes. Conversely, inhibiting SERCA with either ryanodine or thapsigargin affected myocyte contraction and relaxation and Ca2+ channel kinetics more in TG than in WT. Thus, myocytes from mice with overexpressed Akt demonstrated enhanced contractility and relaxation, Fura-2 Ca2+ transients, and Ca2+ channel currents. Furthermore, increased protein expression of SERCA2a plays an important role in mediating enhanced LV function by Akt. Up-regulation of SERCA2a expression and enhanced LV myocyte contraction and relaxation in Akt-induced hypertrophy is opposite to the down-regulation of SERCA2a and reduced contractile function observed in many other forms of LV hypertrophy.
Adenoviridae↗
p300/cAMP-response-element-binding-protein ('CREB')-binding protein (CBP) modulates co-operation between myocyte enhancer factor 2A (MEF2A) and thyroid hormone receptor-retinoid X receptor.
Thyroid hormone receptors (TRs) and members of the myocyte enhancer factor 2 (MEF2) family are involved in the regulation of muscle-specific gene expression during myogenesis. Physical interaction between these two factors is required to synergistically activate gene transcription. p300/cAMP-response-element-binding-protein ('CREB')-binding protein (CBP) interacting with transcription factors is able to increase their activity on target gene promoters. We investigated the role of p300 in regulating the TR-MEF2A complex. To this end, we mapped the regions of these proteins involved in physical interactions and we evaluated the expression of a chloramphenicol acetyltransferase (CAT) reporter gene in U2OS cells under control of the alpha-myosin heavy chain promoter containing the thyroid hormone response element (TRE). Our results suggested a role of p300/CBP in mediating the transactivation effects of the TR-retenoid X receptor (RxR)-MEF2A complex. Our findings showed that the same C-terminal portion of p300 binds the N-terminal domains of both TR and MEF2A, and our in vivo studies demonstrated that TR, MEF2A and p300 form a ternary complex. Moreover, by the use of CAT assays, we demonstrated that adenovirus E1A inhibits activation of transcription by TR-RxR-MEF2A-p300 but not by TR-RxR-MEF2A. Our data suggested that p300 can bind and modulate the activity of TR-RxR-MEF2A at TRE. In addition, it is speculated that p300 might modulate the activity of the TR-RxR-MEF2A complex by recruiting a hypothetical endogenous inhibitor which may act like adenovirus E1A.
Animals↗
Expansion of specific alphabeta+ T-cell subsets in the myocardium of patients with myocarditis and idiopathic dilated cardiomyopathy associated with Coxsackievirus B infection.
Idiopathic dilated cardiomyopathy (IDC) is one of the major causes of death in humans and has been linked to Coxsackievirus B (CVB) infection. The aim of this study was to analyze phenotypes of heart-infiltrating immune cells in patients suffering from myocarditis and IDC associated with CVB infections. We found that the myocardium of these patients was infiltrated by CD4(+) and CD8(+) T lymphocytes as well as macrophages. Evidence of CVB3/4 infections was also found. In the majority of patients, the T-cell receptor repertoire (TCR) of the infiltrating lymphocytes was restricted, with a polyclonal expansion of the Vbeta7 gene family. We also found that human leukocyte antigen (HLA) class II alleles associated with susceptibility to type 1 diabetes (HLA-DR4 and HLA-DQA1*04/05/06 alleles) were remarkably infrequent in IDC patients (p < 0.005), thus suggesting that they might confer protection against IDC. Finally, mRNA for interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha was detected in the cardiac specimens, although at a lower level compared with specimens from hearts without signs of viral infections. We conclude that CVB infection of the human myocardium is associated with a selective, yet polyclonal activation of different T-cell subsets in genetically susceptible individuals. This immune response may play a critical role in modulating disease progression after viral infections.
Adolescent↗