Human HGF plasmid DNA therapy of cardiomyocytes is being examined as a potential treatment for coronary artery disease (a major cause of myocardial infarction (MI)), as well as treatment for the damage that occurs to the heart after MI. [1] [2] After MI, the myocardium suffers from reperfusion injury which leads to death of cardiomyocytes and detrimental remodelling of the heart, consequently reducing proper cardiac function. [2] Transfection of cardiac myocytes with human HGF reduces ischemic reperfusion injury after MI. The benefits of HGF therapy include preventing improper remodelling of the heart and ameliorating heart dysfunction post-MI. [1] [3]
Human hepatocyte growth factor (HGF) is an 80kD [1] pleiotropic protein that is endogenously produced by a variety of cell types from the mesenchymal cell lineage (such as cardiomyocytes and neurons). [4] It is produced and proteolytically cleaved to its active state in response to cellular injury or during apoptosis. HGF binds to c-met receptors found on mesenchymal cell types to produce its many different effects such as increased cellular motility, morphogenesis, proliferation and differentiation. [5] Research has shown that HGF has potent angiogenic, anti-fibrotic, and anti-apoptotic properties. [1] [4] [5] [6] [3] [7] [8] It has also been shown to act as a chemoattractant for adult mesenchymal stem cells via c-met receptor binding. [4] [5]
Animal research has demonstrated that administration of HGF cDNA plasmids into ischemic cardiac tissue can increase cardiac function (improved left ventricular ejection fraction and fractional shortening compared to control subjects) after induced MI or ischemia. [6] [3] Transfection with HGF plasmids in damaged cardiac tissue also promotes angiogenesis (increased capillary density compared to control subjects), as well as decreasing detrimental remodelling of the tissue at the site of injury (decreased fibrotic deposition). [4] [6] [7] The increased production of HGF by transfected cardiomyocytes during injury has also shown to be a powerful chemo-attractant of adult mesenchymal stem cells via HGF/c-Met binding. [4] [5] The mitogenic and morphogenic properties of HGF induce recruited stem cells to take on cardiomyocyte phenotypes, potentially helping in the healing of ischemic tissue. [5] The benefits of HGF in experimental models have led to its investigation in clinical trials. A phase I clinical trial entailed injecting an adenovirus vector with the human HGF (Ad-hHGF) gene into the coronary vessels localized to ischemic tissue. Results demonstrate that it is in fact safe to administer the Ad-hHGF vector into patients with coronary artery disease in hopes of re-vascularizing damaged tissue in patients for which coronary artery bypass surgery (CABG) or percutaneous coronary intervention (PCI) are not available or possible. Despite the trial’s limitations (i.e. no assessment of left ventricular function and sample size was quite small), upon follow up assessments at 12 months, none of the patients receiving the treatment had been readmitted to hospital for MI, angina or aggravated heart failure. [1]
Cardiac muscle is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the outer layer of the heart wall and the inner layer, with blood supplied via the coronary circulation. It is composed of individual cardiac muscle cells joined by intercalated discs, and encased by collagen fibers and other substances that form the extracellular matrix.
Reperfusion injury, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue after a period of ischemia or lack of oxygen. The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and oxidative damage through the induction of oxidative stress rather than restoration of normal function.
Cell therapy is a therapy in which viable cells are injected, grafted or implanted into a patient in order to effectuate a medicinal effect, for example, by transplanting T-cells capable of fighting cancer cells via cell-mediated immunity in the course of immunotherapy, or grafting stem cells to regenerate diseased tissues.
Hepatocyte growth factor receptor is a protein that in humans is encoded by the MET gene. The protein possesses tyrosine kinase activity. The primary single chain precursor protein is post-translationally cleaved to produce the alpha and beta subunits, which are disulfide linked to form the mature receptor.
Myocardial stunning or transient post-ischemic myocardial dysfunction is a state of mechanical cardiac dysfunction that can occur in a portion of myocardium without necrosis after a brief interruption in perfusion, despite the timely restoration of normal coronary blood flow. In this situation, even after ischemia has been relieved and myocardial blood flow (MBF) returns to normal, myocardial function is still depressed for a variable period of time, usually days to weeks. This reversible reduction of function of heart contraction after reperfusion is not accounted for by tissue damage or reduced blood flow, but rather, its thought to represent a perfusion-contraction "mismatch". Myocardial stunning was first described in laboratory canine experiments in the 1970s where LV wall abnormalities were observed following coronary artery occlusion and subsequent reperfusion.
Ischemic preconditioning (IPC) is an experimental technique for producing resistance to the loss of blood supply, and thus oxygen, to tissues of many types. In the heart, IPC is an intrinsic process whereby repeated short episodes of ischaemia protect the myocardium against a subsequent ischaemic insult. It was first identified in 1986 by Murry et al. This group exposed anesthetised open-chest dogs to four periods of 5 minute coronary artery occlusions followed by a 5-minute period of reperfusion before the onset of a 40-minute sustained occlusion of the coronary artery. The control animals had no such period of “ischaemic preconditioning” and had much larger infarct sizes compared with the dogs that did. The exact molecular pathways behind this phenomenon have yet to be fully understood.
Hepatocyte growth factor (HGF) or scatter factor (SF) is a paracrine cellular growth, motility and morphogenic factor. It is secreted by mesenchymal cells and targets and acts primarily upon epithelial cells and endothelial cells, but also acts on haemopoietic progenitor cells and T cells. It has been shown to have a major role in embryonic organ development, specifically in myogenesis, in adult organ regeneration, and in wound healing.
In cardiology neocardiogenesis is the homeostatic regeneration, repair and renewal of sections of malfunctioning adult cardiovascular tissue. This includes a combination of cardiomyogenesis and angiogenesis.
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction to the heart muscle. The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw. Often such pain occurs in the center or left side of the chest and lasts for more than a few minutes. The discomfort may occasionally feel like heartburn. Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat, feeling tired, and decreased level of consciousness. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest.
Myocardial scarring is the accumulation of fibrous tissue resulting after some form of trauma to the cardiac tissue. Fibrosis is the formation of excess tissue in replacement of necrotic or extensively damaged tissue. Fibrosis in the heart is often hard to detect because fibromas, scar tissue or small tumors formed in one cell line, are often formed. Because they are so small, they can be hard to detect by methods such as magnetic resonance imaging. A cell line is a path of fibrosis that follow only a line of cells.
Myocardial infarction complications may occur immediately following a heart attack, or may need time to develop. After an infarction, an obvious complication is a second infarction, which may occur in the domain of another atherosclerotic coronary artery, or in the same zone if there are any live cells left in the infarct.
A diagnosis of myocardial infarction is created by integrating the history of the presenting illness and physical examination with electrocardiogram findings and cardiac markers. A coronary angiogram allows visualization of narrowings or obstructions on the heart vessels, and therapeutic measures can follow immediately. At autopsy, a pathologist can diagnose a myocardial infarction based on anatomopathological findings.
Heart nanotechnology is the "Engineering of functional systems at the molecular scale".
Endogenous cardiac stem cells (eCSCs) are tissue-specific stem progenitor cells harboured within the adult mammalian heart. It has to be noted that a scientific-misconduct scandal, involving Harvard professor Piero Anversa, might indicate that the heart stem cell concept be broken. Therefore, the following article should be read with caution, as it builds on Anversa's results.
Neural crest cells are multipotent cells required for the development of cells, tissues and organ systems. A subpopulation of neural crest cells are the cardiac neural crest complex. This complex refers to the cells found amongst the midotic placode and somite 3 destined to undergo epithelial-mesenchymal transformation and migration to the heart via pharyngeal arches 3, 4 and 6.
A Muse cell is an endogenous non-cancerous pluripotent stem cell. They reside in the connective tissue of nearly every organ including the umbilical cord, bone marrow and peripheral blood. They are collectable from commercially obtainable mesenchymal cells such as human fibroblasts, bone marrow-mesenchymal stem cells and adipose-derived stem cells. Muse cells are able to generate cells representative of all three germ layers from a single cell both spontaneously and under cytokine induction. Expression of pluripotency genes and triploblastic differentiation are self-renewable over generations. Muse cells do not undergo teratoma formation when transplanted into a host environment in vivo. This can be explained in part by their intrinsically low telomerase activity, eradicating the risk of tumorigenesis through unbridled cell proliferation. They were discovered in 2010 by Mari Dezawa and her research group. Clinical trials for acute myocardial infarction, stroke, epidermolysis bullosa, spinal cord injury, amyotrophic lateral sclerosis, acute respiratory distress syndrome (ARDS) related to novel coronavirus (SARS-CoV-2) infection, are conducted by Life Science Institute, Inc., a group company of Mitsubishi Chemical Holdings company. In february 2023, however, Mitsubishi Chemical Group decided to discontinue the development of a regenerative medicine product (CL2020) using Muse Cells. Physician-led clinical trial for neonatal hypoxic-ischemic encephalopathy was also started. The summary results of a randomized double-blind placebo-controlled clinical trial in patients with stroke was announced.
Remote ischemic conditioning (RIC) is an experimental medical procedure that aims to reduce the severity of ischaemic injury to an organ such as the heart or the brain, most commonly in the situation of a heart attack or a stroke, or during procedures such as heart surgery when the heart may temporary suffer ischaemia during the operation, by triggering the body's natural protection against tissue injury. Although noted to have some benefits in experimental models in animals, this is still an experimental procedure in humans and initial evidence from small studies have not been replicated in larger clinical trials. Successive clinical trials have failed to identify evidence supporting a protective role in humans.
Ischemia-reperfusion (IR) tissue injury is the resultant pathology from a combination of factors, including tissue hypoxia, followed by tissue damage associated with re-oxygenation. IR injury contributes to disease and mortality in a variety of pathologies, including myocardial infarction, ischemic stroke, acute kidney injury, trauma, circulatory arrest, sickle cell disease and sleep apnea. Whether resulting from traumatic vessel disruption, tourniquet application, or shock, the extremity is exposed to an enormous flux in vascular perfusion during a critical period of tissue repair and regeneration. The contribution of this ischemia and subsequent reperfusion on post-traumatic musculoskeletal tissues is unknown; however, it is likely that similar to cardiac and kidney tissue, IR significantly contributes to tissue fibrosis.
Cardiomyocyte proliferation refers to the ability of cardiac muscle cells to progress through the cell cycle and continue to divide. Traditionally, cardiomyocytes were believed to have little to no ability to proliferate and regenerate after birth. Although other types of cells, such as gastrointestinal epithelial cells, can proliferate and differentiate throughout life, cardiac tissue contains little intrinsic ability to proliferate, as adult human cells arrest in the cell cycle. However, a recent paradigm shift has occurred. Recent research has demonstrated that human cardiomyocytes do proliferate to a small extent for the first two decades of life. Also, cardiomyocyte proliferation and regeneration has been demonstrated to occur in various neonatal mammals in response to injury in the first week of life. Current research aims to further understand the biological mechanism underlying cardiomyocyte proliferation in hopes to turn this capability back on in adults in order to combat heart disease.
Arterial occlusion is a condition involving partial or complete blockage of blood flow through an artery. Arteries are blood vessels that carry oxygenated blood to body tissues. An occlusion of arteries disrupts oxygen and blood supply to tissues, leading to ischemia. Depending on the extent of ischemia, symptoms of arterial occlusion range from simple soreness and pain that can be relieved with rest, to a lack of sensation or paralysis that could require amputation.