Box 1: Cell types of the heart
The four-chambered heart consists of different cell types (see the figure). All these cell types contribute to structural, biochemical, mechanical and electrical properties of the functional heart. Atrial and ventricular cardiomyocytes form the muscular walls of the heart (that is, the myocardium). More than 50% of the cells of the heart are cardiac fibroblasts. Endothelial cells form the endocardium, the interior lining of blood vessels and cardiac valves. Smooth muscle cells contribute to the coronary arteries and inflow and outflow vasculature. The epicardium gives rise to the precursors of the coronary vasculature and cardiac fibroblasts. Pacemaker cells and Purkinje fibres in the conduction system are specialized cardiomyocytes that generate and conduct electrical impulses. The sinoatrial node (SAN), which is composed of a group of pacemaker cells, resides in the right atrium generating impulses to initiate heart contraction. The atrioventricular node (AVN) is located between the atria and ventricles, and it conducts an electrical impulse from the atria to the ventricles.
Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9148, USA.
- Mei Xin,
- Eric N. Olson &
- Rhonda Bassel-Duby
Competing interests statement
The authors declare no competing interests.
Mei Xin received her Ph.D. from the University of Texas Southwestern Medical Center, Dallas, USA. She completed her postdoctoral training in the laboratory of Eric N. Olson and is now an instructor at University of Texas Southwestern Medical Center, where she investigates microRNAs and signalling molecules regulating cardiovascular development and diseases.
Eric N. Olson
Eric N. Olson is Professor and Chair of the Department of Molecular Biology at the University of Texas Southwestern Medical Center, Dallas, USA, where he holds the Robert A. Welch Distinguished Chair in Science, the Annie and Willie Nelson Professorship in Stem Cell Research and the Pogue Distinguished Chair in Research on Cardiac Birth Defects. He received his Ph.D. in biochemistry from Wake Forest University and performed his postdoctoral training at Washington University School of Medicine, St Louis, Missouri, USA. He began his scientific career at the MD Anderson Cancer Center, Houston, Texas, USA, and in 1995, he founded the Department of Molecular Biology at the University of Texas Southwestern Medical Center. He is a member of the American Academy of Arts and Sciences, the US National Academy of Sciences and the Institute of Medicine. His awards include the Basic Research Prize, the Research Achievement Award and Inaugural Distinguished Scientist Award from the American Heart Association, as well as the Pasarow Award, the Pollin Prize in Pediatric Research and the Passano Award. In 2009, the French Academy of Science awarded him the Fondation Lefoulon-Delalande Grand Prize, and in 2013, he received the March of Dimes Prize in developmental biology.
Rhonda Bassel-Duby is a professor of molecular biology at the University of Texas Southwestern Medical Center, Dallas, USA. Her research focuses on the molecular mechanisms governing heart and skeletal muscle development and the response to physiological and pathological demands. She received her Ph.D. in biochemistry from McGill University, Montreal, Canada, and trained at Harvard Medical School, Boston, Massachusetts, and the University of Texas Southwestern Medical Center.
- Paracrine effects
The effects of a signalling factor secreted by one cell on a nearby cell.
The development of the embryonic heart.
- Myocardial infarction
Interruption of the blood flow to the heart, causing cell death and heart damage. Also known as heart attack.
- Lineage tracing
A genetic tool used to trace all progeny originating from a single cell.
- Cre–loxP recombination system
Tissue-specific expression of Cre recombinase to carry out targeted gene deletion.
- Ventricle apex
Anatomically, the lowest portion of the heart.
- Myocardial ischaemia–reperfusion
Restoration of the blood supply to the heart tissue that is ischaemic due to a decrease in this.
- Trabecular cardiomyocytes
Highly organized cardiomyocytes that form 'projections' into the lumen of the heart ventricles to increase surface area. They facilitate contractility of the heart.
- Locked nucleic acid (LNA)-modified anti-miRNAs
Chemically modified, single-stranded RNA oligonucleotides that contain an extra bridge connecting the 2′ oxygen and 4′ carbon, which 'locks' the ribose in the 3′-endo conformation. This results in high stability and affinity to inactivate specific miRNAs.
- Subcompact ventricular myocardial layers
The thick muscular walls of the heart ventricles.
The capability of producing congenital anomalies.
A cell that contains multiple genetically different nuclei.
- Gap junctions
A specialized intercellular connection that directly connects the cytoplasm of two cells, allowing various molecules and ions to pass freely between cells.
- Venous plexus
A congregation of multiple veins.