Blood-brain barrier
The blood-brain barrier is a tightly packed layer of cells that line the blood vessels in the brain and spinal cord. This barrier prevents large molecules, immune cells, and disease-causing organisms such as bacteria and viruses from passing from the blood stream into the central nervous system (CNS).
The brain and spinal cord have very specific requirements to enable them to function efficiently. Brain and nerve cells in the CNS need to be able to get oxygen and glucose from the blood but not to become infected by disease or to be influenced by hormones produced elsewhere in the body.
Throughout most of your body, the tiny blood vessels (capillaries) are lined by endothelial cells, but substances can seep in and out of them between the gaps in the cell layer. In the brain and spinal cord, the endothelial cells are tightly joined together, and substances can only cross the barrier through controlled transport channels or under special circumstances. The blood-brain barrier (BBB) is maintained by glial cells, including astrocytes.
Find out more
- What is the blood-brain barrier? Two US neurology students explain the BBB
References
- Neurobiology Of Disease 2015;74:14-24. Summary Focal disturbances in the blood-brain barrier are associated with formation of neuroinflammatory lesions.
- Archives Of Medical Research 2014;45(8):687-697. Summary Role of the blood-brain barrier in multiple sclerosis.
- FEBS Letters 2011;585(23):3770-3780. Summary How do immune cells overcome the blood-brain barrier in multiple sclerosis?


Glial cells
Glial cells make up to half of brain volume, supporting and protecting the nerve cells. Research shows they matter in multiple sclerosis. Find out more in this A-Z entry.


Drugs in development
Find out about new drugs on the horizon for multiple sclerosis.

Immune system
Your immune system detects and destroys disease organisms and damaged cells throughout your body. But what happens when it attacks your own cells?