The glymphatic system: methods of study, role in neurodegenerative diseases and brain tumors

The glymphatic system is a newly discovered macroscopic system for the excretion of soluble proteins and metabolites of the central nervous system, first described in vivo in 2012. It is formed by aquaporin-4 proteins in the legs of astroglial cells and uses a system of perivascular tunnels. From the first description to the present day, many extensive studies of the glymphatic system have been conducted, but there are still many unresolved issues. Most of the work described the composition of the glymphatic system, and recently, the genetic apparatuses responsible for the functioning of functional units responsible for the stable functioning of the system have also been actively studied. To date, disorders in the work of the glymphatic system are considered as a risk factor for the development of age-related brain changes, neurovascular and neurodegenerative diseases, as well as impaired recovery from injuries to the brain. Many studies have highlighted the relationship between glymphatic system dysfunction and neurodegeneration associated with traumatic brain injury. There is also a part of the work devoted to the role of glymphatic system in the development of peritumoral edema in tumors of brain. However, so far, there is insufficient data on the role of glymphatic system in the localization of primary and secondary brain tumors. The purpose of this review is to summarize the currently available results in the scientific community on the composition of glymphatic system, its visualization methods, and its role both in the normal state of the body and in pathological processes: traumatic brain injuries, neurodegenerative diseases and malignant neoplasms of the brain.