Glial Cells are a type of cell in the brain that play numerous roles in the nervous system, including neuronal metabolic support, neuroprotection, brain homeostasis and neuroinflammation. These cells do not generate electrical signals like neurons and have therefore been considered for a long time as a sort of “glue” that simply provides structural support to neurons. Research over the last three decades has shown that glial cells are actually very active elements of the brain. Glial cells outnumber neurons in the nervous system by a 1.5 to 2-fold factor.
There are three types of Glial cells in the brain:
Our interest at GliaPharm lies in particular in these ‘star-shaped’ cells that surround every neurons in the brain and are involved in many important functions. Astrocytes possess numerous processes that form highly organized anatomical domains interconnected into functional networks. Some of these processes closely ensheath neuronal synapses, whereas others are in contact with brain capillaries.
First, astrocytes play fundamental roles in providing neurons with specific nutriments, which are required to satisfy high energy demands of neurons to work and survive. Of importance, astrocytes also provide a number of neurotrophic factors and stimulate neuronal defense against stressors. Finally, they modulate neuronal activity, synaptic transmission and plasticity, hence playing a fundamental role in the highest brain functions such as memory, cognition and behavior.
Several neurological pathologies such as GLUT1 deficiency syndrome (GLUT1 DS), Alzheimer’s disease, Amyotrophic Lateral Sclerosis (ALS) and depression are caused, at least in part, by the dysfunction of astrocytes that results in neurons not working properly or, in the worst case, neuronal degeneration.
Oligodendrocytes are specific cells in the central nervous system whose role is to isolate axons, much similar to the role of Schwann cells in the peripheral nervous system. Oligodendrocytes’ primary function is to create a myelin sheath around axons that allows efficient and rapid transmission of the electrical signal over long distances. In addition to their anatomical role, oligodendrocytes provide trophic and metabolic support to neurons. Axon demyelination is the primary cause of severe neuropathologies that include multiple sclerosis (MS).
Microglia account for 10 to 15% of brain cells, and represent the immune defense in the central nervous system. Microglia respond to pathogens and injury by becoming ‘activated’, a process leading to morphological changes, proliferation and migration to the site of injury where they can destroy pathogens and remove damaged cells. In several neurological diseases including Alzheimer’s disease, Parkinson’s disease, ALS and autism spectrum disorders (ASD), overactivation of microglia leads to inflammatory responses that can become detrimental.