Exosomal Transport and Progression of Neurodegeneration in Amyotrophic Lateral Sclerosis

In recent years, increasing attention has been paid to the study of the communication between cells in the nervous system with extracellular vesicles, including exosomes, under physiological and pathological conditions. Exosomes are small extracellular vesicles ranging in size from 50 to 200 nm, which are secreted by most cell types and provide communication between cells by transporting proteins, lipids, and RNA to target cells. In addition, they perform antigen-presenting and signaling functions and can act as anti-inflammatory or pro-inflammatory agents. Data has been accumulated on the role of exosomes in the development of the pathological process in nervous system diseases, primarily brain tumors and neurodegenerative diseases. Amyotrophic lateral sclerosis (ALS) is a progressive fatal disease in which the selective death of motor neurons occurs. ALS inevitably leads to disruption of the functioning of muscles that perform vital functions and death of the patient in several years. The mechanisms that underlie the death of motor neurons and the spread of the pathological process are not clear. It is impossible to predict the rate of disease progression and the probable life expectancy of the patient. The most important mechanisms of AS development include the accumulation of aggregates of pathological proteins in neuronal bodies and impaired RNA metabolism. The possibility of transfer of pathological proteins and other molecules associated with the development of ALS through exosomes has been proven. This review provides an overview of studies on exosomes in different CNS diseases. The mechanisms of progression and spreading of the neurodegenerative process in ALS are discussed, focusing on the roles that exosomes and potential biomarkers of the disease in the exosomal fraction play.