Which glial cell type plays a critical role in supporting and maintaining the blood-brain barrier?

Astrocytes are essential glial cells in the central nervous system that play a pivotal role in maintaining the integrity and function of the blood-brain barrier (BBB). These star-shaped cells myelinate blood vessels and form end-feet that surround them, thus providing structural support and regulating the passage of substances between the bloodstream and the brain.

Astrocytes facilitate the transport of nutrients and ions, and they help to maintain the ion homeostasis in the extracellular space, which is crucial for neuronal function. They secrete a variety of signaling molecules that influence the permeability of the BBB, ensuring that harmful substances do not enter the brain while allowing essential nutrients to pass through.

In contrast, microglia primarily act as the immune cells of the central nervous system, responding to injury and disease rather than supporting the BBB directly. Oligodendrocytes are responsible for the myelination of axons in the central nervous system, and Schwann cells perform a similar role in the peripheral nervous system, focusing on myelinating peripheral nerves. None of these other glial cell types have the same function in supporting and maintaining the blood-brain barrier as astrocytes do.