Current Drug Targets (v.16, #8)

Meet Our Editorial Board Member: by Hongmin Sun (777-777).

Stem Cell Aging and Age-Related Cardiovascular Disease: Perspectives of Treatment by Ex-vivo Stem Cell Rejuvenation by Rosalinda Madonna, Felix B. Engel, Sean M. Davidson, Peter Ferdinandy, Aniko Gorbe, Joost P.G. Sluijter, Linda W. Van Laake (780-785).
Aging affects endogenous stem cells in terms of functionality and numbers. In particular, during aging, the stemness property can decrease because of enhanced apoptotic cell death and senescence. In addition, aging and agingrelated co-morbidities affect the paracrine activity of stem cells and the efficiency of their transplantation. Collectively, this leads to a reduction of the capacity of organs to repair themselves, possibly due to a reduced functional capability of stem cells. Therefore, major efforts have been invested to improve the repair capability of stem cells in aged individuals by overexpressing antisenescence and antiapoptotic genes. In this review, we describe critical genes and signaling pathways in stem cell aging and discuss ex vivo genetic modification approaches aimed at stem cell rejuvenation that are of interest for the cardiovascular system.

Targets Involved in Cardioprotection by the Non-Anesthetic Noble Gas Helium by Nina C. Weber, Kirsten F. Smit, Markus W. Hollmann, Benedikt Preckel (786-792).
Research data from the past decade indicate that noble gases like xenon and helium exert profound cardioprotection when applied before, during or afte r organ ischemia. Of all noble gases, especially helium, has gained interest in the past years because it does not have an anesthetic “side effect” like xenon, allowing application of this specific gas in numerous clinical ischemia/reperfusion situations. Because helium has several unique characteristics and no hemodynamic side effects, helium could be administered in severely ill patients. Investigations in animals as well as in humans have proven that this noble gas is not completely inert and can induce several biological effects. Though the underlying molecular mechanisms of helium-induced cardiac protection are still not yet fully understood, recently different signaling pathways have been elucidated.

Intracellular Ca2+ Signals to Reconstruct A Broken Heart: Still A Theoretical Approach? by Francesco Moccia, Federico Alessandro Ruffinatti, Estella Zuccolo (793-815).
The infusion of autologous stem cells has recently been put forward as an alternative strategy to regenerate infarcted myocardium and restore the contractile functions of diseased hearts. A growing number of cell types have been probed to induce cardiac repair in several animal models of ischemic myocardium, including human cardiac progenitor cells (hCPCs), human embryonic stem cells (hESCs), human mesenchymal stem cells (hMSCs) and human endothelial progenitor cells (hEPCs). The enthusiasm raised by pre-clinical studies has been dampened by clinical practice, according to which the extent of cardiac repair by cell based therapy is inadequate with respect to animal models. There is no doubt that regenerative medicine of acute myocardial infarction (AMI) will greatly benefit from the full comprehension of the signal transduction pathways which guide stem cell towards the injury site and their subsequent acquisition of a therapeutically relevant phenotype. The present review will focus on the role that oscillations in intracellular Ca2+ concentration might play to promote the stem cells-dependent regrowth of ischemic myocardium. We will describe how intracellular Ca2+ spikes may be manipulated to redirect stem cell fate to the most suitable lineage to restore cardiac vascularisation and contractility.

Heat Shock Proteins: Mediators of Atherosclerotic Development by Justin F. Deniset, Grant N. Pierce (816-826).
Heat shock proteins play important housekeeping roles in a variety of cells within the body during normal control conditions. The many different functions for heat shock proteins in the cell depend upon the specific heat shock protein involved. Each protein is nominally differentiated based upon its molecular size. However, in addition to their role in normal cell function, heat shock proteins may play an even more important role as pro-survival proteins conserved through evolution to protect the cell from a variety of stresses. The ability of a cell to withstand these environmental stresses is critical to its capacity to adapt and remain viable. Loss of this ability may lead to pathological states. Abnormal localization, structure or function of the heat shock proteins has been associated with many pathologies, including those involving heart disease. Heat shock proteins like HSP60 and HSP70 in particular have been identified as playing important roles in inflammation and immune reactions. Inflammation has been identified recently as an important pathological risk factor for heart disease. It is perhaps not surprising therefore, that heat shock protein family has been increasingly identified as an important intracellular pathway associated with inflammatory-mediated heart conditions including atherosclerosis. This paper reviews the evidence in support of a role for heat shock proteins in cardiovascular disease and the potential to target these proteins to alter the progression of atherosclerotic disease.

Epigenetic Regulation of Myocardial Homeostasis, Self-Regeneration and Senescence by Marco Matteucci, Gaia Papini, Enrica Ciofini, Lucio Barile, Vincenzo Lionetti (827-842).
The adult myocardium has limited capacity to preserve, renew or rejuvenate itself. The local microenvironment may induce epigenetic changes affecting the survival, proliferation, function and senescence of cardiac cells at rest and following the exposure to different stressors. The cellular response to microenvironment is characterized by the release of ions, oxygen free radicals, auto/paracrine factors and RNAs that drive the magnitude of gene reprogramming through the interaction with specific promoters. The epigenetic alterations may act at transcriptional and post-transcriptional level and change cardiac physiological traits. The abnormal DNA methylation underlies the progressive decay of contractile function and the angiogenic ability; while, the histone acetylation promotes the survival, function and proliferation of cardiac cells in the presence of ischemic microenvironment. At least, the expression and secretion of microRNAs and long noncoding RNAs may regulate the threshold to stress tolerance of adult cardiac cells and induce the matrix turnover as well. Natural or synthetic active compounds effectively modulate the epigenetic state of cardiac cells. Plant foods contain many active compounds with epigenetic properties and might assume a clinical significance as natural cardiac regenerators or rejuvenators. Our review describes novel epigenetic mechanisms that underpin myocardial remodeling, repair/ regeneration or senescence in order to support the development of most effective and reproducible rescue therapy of adult heart.

Endogenous Cardioprotective Agents: Role in Pre and Postconditioning by Claudia Penna, Riccarda Granata, Carlo Gabriele Tocchetti, Maria Pia Gallo, Giuseppe Alloatti, Pasquale Pagliaro (843-867).
Cardiovascular diseases (CVD) are the leading cause of death, chronic illness and disability in Western countries. The most common cause of CVD derives from the harmful effects of acute myocardial ischemia and subsequent reperfusion injury. Cardioprotection against acute ischemia/ reperfusion injury is made possible by the "conditioning protocols." Conditioning is obtained by applying a few periods of brief ischemia and reperfusion in the event of prolonged (index) ischemia that may cause myocardial infarction. Whilst the conditioning stimulus is applied before the index ischemia in ischemic pre-conditioning, it is applied after the event in post-conditioning. Pre and post- conditioning stimuli can be applied in a different/remote organ (remote pre- and post-conditioning); in this case conditioning stimulus can also be applied during the index event, in the so called remote per-conditioning. All these endogenous cardioprotective strategies recruit endogenous cytoprotective agents and factors that elicit specific cardioprotective pathways. Here, we discuss many of these cardioprotective factors compared to literature and highlight their main characteristics and mechanisms of action. Enphasis is given to endogenous cardioprotective agents acting or not on surface receptors, including chromogranin A derivatives, ghrelin-associated peptides, growth factors and cytokines, and to microvesicles and exosomes. Moreover the cardioprotective effects of gasotransmitters nitric oxide, hydrogen sulphide and carbon monoxide are reviewed. The possible clinical translation of these knowledge for future successful therapies is briefly and critically discussed.

Updates on HCN Channels in the Heart: Function, Dysfunction and Pharmacology by Laura Sartiani, Maria Novella Romanelli, Alessandro Mugelli, Elisabetta Cerbai (868-876).
The hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play an important role in the generation of pacemaker activity of cardiac sinoatrial node cells and immature cardiomyocytes. HCN channels are also present in adult atrial and ventricular cardiomyocytes, where the physiological role is currently under investigation. In different cardiac pathologies, dysfunctional HCN channels have been suggested to be a direct cause of rhythm disorders. While loss-of-function mutations of HCN channels are associated with sinus bradycardia, HCN channel gain-of-function in atrial fibrillation, ventricular hypertrophy and failure might help enhance ectopic electrical activity and promote arrhythmogenesis. Blockade of HCN channels with ivabradine, a selective bradycardic agent currently available for clinical use, improves cardiac performance and counteracts functional remodeling in experimental hypertrophy. Accordingly, ivabradine ameliorates clinical outcome in patients with chronic heart failure. Novel compounds with enhanced selectivity for cardiac HCN channel isoforms are being studied as potential candidates for new drug development.

Nesfatin-1 and the Cardiovascular System: Central and Pheripheral Actions and Cardioprotection by Sandra Imbrogno, Tommaso Angelone, Maria C. Cerra (877-883).
Recently, the hypothalamic 82-aa peptide Nesfatin-1 received notable attention for its anorexigenic and anti-hyperglycemic properties. In mammalian hypothalamus, Nesfatin-1 is expressed, together with the precursor Nucleobindin 2 (NUCB2), in regions controlling water-food intake, body weight, and glucose homeostasis. The peptide is also peripherally expressed, as shown in the rat heart, in which it is present together with NUCB2. In addition to a central modulation of nutrition and energy balance, and of the nervous circuits responsible for blood pressure and heart rate control, Nesfatin-1 also acts peripherally on several districts, including the cardiovascular (CV) system. Accordingly, the peptide is regarded with interest as a multifunctional hormone not only linked to alimentary homeostasis. This review aims to analyze the literature on Nesfatin-1, with focus on its emerging CV activity. Few available studies show that the peptide affects energy metabolism of murine and human cardiomyocytes, by eliciting insulin-like effects. On the ex vivo rat heart, it directly depresses contractility and relaxation via cGMP, PKG and ERK1/2, and limits ischemia/reperfusion (I/R) damage, acting in post-conditioning protection. Nesfatin-1 actions are proposed to involve an unknown G-protein coupled receptor. However, in the rat heart, functional studies, co-immunoprecipitation and local sequence alignment analyses suggest an interaction with the Natriuretic Peptide Receptor-type A (NPR-A). These data open up novel perspectives to clarify not only the biological significance of the peptide, but also its putative biomedical potential in the presence of nutrition-dependent cardiovascular diseases.

Cardioprotection by Targeting the Pool of Resident and Extracardiac Progenitors by Konrad Urbanek, Caterina Frati, Gallia Graiani, Denise Madeddu, Angela Falco, Stefano Cavalli, Bruno Lorusso, Andrea Gervasi, Lucia Prezioso, Monia Savi, Francesca Ferraro, Federica Galaverna, Pietro Rossetti, Costanza Annamaria Lagrasta, Fancesca Re, Eugenio Quaini, Francesco Rossi, Antonella De Angelis, Federico Quaini (884-894).
The adult heart has the capacity to generate new myocytes that are markedly enhanced in acute and chronic heart failure of ischemic and non-ischemic origin. In addition, a pool of blood trafficking progenitor cells able to sense myocardial damage may home to the sites of injury participating to cardiac repair. This new view of myocardial biology leads to an expanding long-term research and therapeutic goals for cardioprotection. A fundamental concept to be analyzed is whether cardiac diseases are influenced by changes in the properties of tissue specific and circulating progenitors. Loss of self-renewal capacity, impaired growth or increased susceptibility to death may lead to a reduction of progenitors and leave myocardial damage unrepaired. Cardiac progenitors generate all myocardial cell lineages, thus impairment in their growth is expected to be critically involved in the structural and functional modifications of the heart. The fact that, in addition to well known effects of anthracyclines, also new drugs that target molecular pathways implicated in cell death and growth can be cardiotoxic further supports our hypothesis. Understanding the role of resident and extracardiac progenitors in the pathogenesis of cardiomyopathies of different etiology will provide not only a better comprehension of cardiac homeostasis but will also open new avenues for therapeutic interventions. The progress toward effective myocardial regeneration based on exploiting the self-renewal potential of the myocardium and the systemic pool of cardiogenic cells should advance the likelihood of efficient cardioprotection and restoration of cardiac function.

Nitroso-Redox Balance and Modulation of Basal Myocardial Function: An Update from the Italian Society of Cardiovascular Research (SIRC) by Carlo G. Tocchetti, Marilisa Molinaro, Tommaso Angelone, Vincenzo Lionetti, Rosalinda Madonna, Fabio Mangiacapra, Francesco Moccia, Claudia Penna, Laura Sartiani, Federico Quaini, Pasquale Pagliaro (895-903).
Reactive oxygen species and reactive nitrogen species are produced endogenously by cardiomyocytes and are fundamental signaling molecules that regulate cellular function. Production of ROS and RNS is finely tuned to maintain proper myocardial function, but is altered in many pathophysiological conditions, therefore contributing to worsening myocardial dysfunction and ultimately heart failure. Indeed, an excess of ROS and RNS is central in many pathways leading to cardiac hypertrophy and failure, and the correct regulation of the nitroso-redox balance is fundamental for the function of the main components of the EC-coupling machinery. Broad antioxidant therapies have been proposed to improve myocardial function, but these therapies blunt even physiological ROS and RNS signaling, bringing limited, if any, beneficial effect. On the other hand, more targeted interventions on specific sources or pathways may produce promising results.

Functional Genomics of Cardioprotection by Ischemic Conditioning and the Influence of Comorbid Conditions: Implications in Target Identification by Zoltan V. Varga, Zoltan Giricz, Peter Bencsik, Rosalinda Madonna, Mariann Gyongyosi, Rainer Schulz, Manuel Mayr, Thomas Thum, Laszlo G. Puskas, Peter Ferdinandy (904-911).
Ischemic heart disease including myocardial infarction develops on the basis of several risk-factors and comorbidities such as obesity, diabetes, hypertension, and hypercholesterolemia. Ischemic heart disease is the leading cause of mortality worldwide, therefore, identification of novel drug targets for cardioprotection is of great importance. Ischemic preconditioning, postconditioning, and remote conditioning trigger endogenous cardioprotective mechanisms that render the heart more resistant to lethal ischemic-reperfusion injury. However, major cardiovascular co-morbidities such as hyperlipidemia, diabetes, and their co-medications interfere with these cardioprotective mechanisms thereby limiting the efficacy of cardioprotective ischemic conditioning maneuvers. Ischemia reperfusion injury and cardioprotection by conditioning have been shown to affect global myocardial gene expression profile at the transcript level. Further understanding and the comprehensive analysis of the cardioprotective gene expression fingerprint in normal, protected, and in comorbid conditions may lead to identification of novel molecular targets for cardioprotection.

OPA1 in Cardiovascular Health and Disease by Niall Burke, Andrew R. Hall, Derek J. Hausenloy (912-920).
Mitochondria are known to play crucial roles in normal cellular physiology and in more recent years they have been implicated in a wide range of pathologies. Central to both these roles is their ability to alter their shape interchangeably between two different morphologies: an elongated interconnected network and a fragmented discrete phenotype - processes which are under the regulation of the mitochondrial fusion and fission proteins, respectively. In this review article, we focus on the mitochondrial fusion protein optic atrophy protein 1 (OPA1) in cardiovascular health and disease and we explore its role as a potential therapeutic target for treating cardiovascular and metabolic disease.