Mesenchymal stem cells (MSCs) are self-renewing cells found in almost all postnatal organs and tissues in the perivascular region. These cells have a high capacity for mesodermal differentiation; however, numerous studies have shown that MSCs can also differentiate into cells of endodermal and ectodermal lineages. Due to this multilineage differentiation capacity, these cells could function as restoratives of various cell populations after transplantation. However, not only their differentiation potential makes them ideal candidates for this, but also a series of trophic properties that promote regeneration in the surrounding tissue, such as their migratory capacity, secretory and immunomodulatory actions. This review analyzes several MSC transplantation trials to treat neurological diseases, such as demyelinating injury, spinal cord injury, paraplegia, Parkinson's disease, cochlear injury, and Alzheimer's disease. These cells could facilitate functional recovery in multiple models of neurodegenerative diseases and nervous system injuries by using their trophic capacities, reducing inflammation in the injured area, reducing apoptosis, and enhancing endogenous neurogenesis through the secretion of bioactive factors. Furthermore, since cells derived from patients have demonstrated disease-associated differences in various brain diseases, these cells represent an excellent candidate for the study of these diseases, functioning as "a window to the brain."