MicroRNA: a clinician's view of the state of the problem. Part 2. MicroRNA as a biomarker

Cardiovascular diseases are the main cause of death and disability in economically developed countries in the world. In response to the impact of various factors, the structure and function of several types of cells changes, contributing to the occurrence and progression of cardiovascular diseases. Search for sensitive and specific biomarkers is one of the most important problems in the field of diagnosis of cardiovascular diseases. In the last decade, microRNAs have more often been considered as potential biomarkers of a wide range of cardiovascular diseases, such as myocardial infarction, ischemic heart disease, heart failure, hypertension, diabetes mellitus and obstructive sleep apnoea. Early diagnosis of these diseases is essential to initiate immediate treatment, which can lead to improved outcomes. MicroRNAs are endogenous small (21-23 nucleotides) ribonucleotides involved in the regulation of protein synthesis from amino acids based on matrix RNA. MicroRNAs are involved in the regulation of expression of the majority (>60%) of genes encoding proteins, mainly due to its suppression, modulate numerous signaling pathways and cellular processes and participate in intercellular communication. There are different advantages of these biomarkers: low invasiveness during research, stability, resistance to destructive factors, for example, freeze-thaw cycles, enzymes in the blood. Some microRNAs are expressed everywhere, while others are specific to certain tissues and/or stages of development of the organism. At the same time, microRNAs were detected in various biological fluids: blood plasma, urine, seminal fluid, saliva, breast milk. Changes in both the amount and functional activity of microRNAs can lead to the development of various diseases. In the cardiovascular system, microRNAs control the functions of various cells, such as cardiomyocytes, endothelial cells, smooth muscle cells and fibroblasts. Thus, due to the stability of microRNAs, the tissue-specific nature of expression and secretion into specific fluids, it becomes possible to consider them as an attractive diagnostic. It is also particularly important that the expression levels of certain microRNAs reflect not only the presence of diseases in the early stages, but also the dynamic development of diseases in the later stages. This review presents the features of various microRNAs as biomarkers and their influence on some molecular pathways underlying cardiovascular diseases and describes the significant potential of supplementing traditionally used markers in clinical practice with microRNA biomarkers. Prospects for the development and limitations of the use of microRNAs as potential biomarkers are also described.