Scientists Create Detailed Cell Catalogue of Human Heart
Last week, scientists amazed us with stunning images of our body’s major organs at a microscopic level. Now, we are presented with the most detailed cell catalogue of the human heart ever produced. Researchers from UK and German institutes, as part of the Human Cell Atlas consortium, have charted eight regions of the heart and profiled 75 different cell states that play crucial roles in maintaining heart function and protecting it from infections.
Unlike visual representations, this map is more like a molecular catalogue that identifies various cell types and their active genes. However, it promises to provide valuable insights into diseases affecting heart rhythm and offer new avenues for treatments.
The heart is a complex organ, consisting of muscles in motion and electrical impulses at work. Heart contractions occur through the coordinated movement of heart muscle cells, stimulated by electrical impulses generated by pacemaker cells. Most pacemaker cells are located in the sinoatrial node, but there are other interconnected nodes and cell bundles that remain poorly understood.
“The cardiac conduction system is critical for the regular and coordinated beating of our hearts,” explains James Cranley, a cardiologist and joint lead author of the study. “Yet the cells which make it up are poorly understood.”
To shed light on these cell types, Cranley and his team used single-cell transcriptomics methods, which decode the genetic instructions within individual cells. They analyzed more than 700,000 individual cells and nuclei from 25 donor hearts that were not suitable for organ transplantation but ideal for this study.
Through their analysis, the researchers discovered a close connection between pacemaker cells and glial cells, which are usually responsible for supporting neurons in the brain and nervous system. In the sinoatrial and atrioventricular nodes, as well as the atrioventricular bundle of the heart, glial cells were found to support signaling processes in pacemaker cells. The researchers described the relationship between glial cells and pacemaker cells as resembling nerve cell synapses.
Furthermore, the researchers identified immune cells called plasma cells within the outer layer of the hearts. These plasma cells produce antibodies that protect the heart from infections originating in the nearby lungs.
Examining the myocardium, the heart’s muscular tissue, the team discovered a population of cells that showed high sensitivity to stress and inflammation. These cells expressed a significant number of genes associated with receptors for inflammatory signaling molecules. Additionally, they produced high levels of a peptide linked to heart failure.
By deciphering the genetic makeup of these cells, the researchers hope to develop novel approaches to improve heart treatments. They also categorized pacemaker cells based on the types of ion channels they express. This information could help researchers investigate heart misfires in the wiring system and understand why certain heart therapies fail to yield the desired results.
The researchers summarize their findings as a highly specific map of genes and cells within the cardiac conduction system. This study has been published in the scientific journal Nature, furthering our understanding of the human heart and bringing us one step closer to new treatments for heart-related conditions.