From TSN: Understanding the Blood-Brain Barrier
The Blood-Brain Barrier
(image credit: Ben Brahim Mohammed)
Pfizer Neuroscience Scientist Mercedes Benya explains the importance of the blood-brain barrier and the bypassing approaches being investigated in order to treat diseases of the central nervous system — including brain tumors, Alzheimer's, Parkinson's and stroke.
This blog posting originally appeared on the Think Science Now (TSN) website  on October 3 and was written by Mercedes Beyna , Scientist in the Neuroscience Research Unit, as a preview to the New York Academy of Sciences October 25 meeting: Brain Barriers: A Hurdle for Drug Discovery .
Places where the brain meets the rest of the body are areas where a protective barrier is formed, the main one being the blood-brain barrier (BBB). Brain barriers restrict movement of substances into and out of the brain, thus maintaining the highly specialized environment that allows our most enigmatic organ to perform its unique tasks.
The idea that there is something special about the internal environment of the brain originated in the late 19th century; Paul Ehrlich showed that certain dyes, when injected into the blood of lab animals, dyed all organs — except the brain. Today, scientists know quite a bit more about these barriers. The BBB consists of endothelial cells lining the brain's blood vessels. The cells are cemented together so tightly that most material must pass through the cells, rather than between them. Gateways within the cells, transporters, strictly control what makes it across. Essential nutrients such as glucose are carried across while toxins are (hopefully) kept out. Via numerous mechanisms, the barriers prevent entry of large chemicals, viruses and bacteria. Fortunately for all of you fellow coffee lovers, caffeine (being lipid-soluble) passes through pretty easily (alcohol too). In this meeting, researchers will present the latest discoveries in the biology of brain barriers.
The barriers also impede many life-saving medications from penetrating into the brain. They block promising treatments for diseases of the central nervous system — brain tumors, Alzheimer's, Parkinson's, Huntington's, stroke, etc — from reaching their brain targets. It's an exciting time for the scientists developing strategies to get drugs past the BBB. Two recent breakthroughs come to mind:
- A potential Alzheimer's therapy that tricks a BBB transporter (the transferrin receptor)  into carrying an amazingly engineered antibody (anti-BACE1 with potent A?-lowering ability)  through the endothelial cells (transcytocis).
- Stimulators of a particular receptor (adenosine receptor agonists)  opened up the BBB in a general way, allowing brain-targeted therapeutic agents through.
Many other BBB bypassing approaches are being investigated and those being discussed in this meeting include: intranasal drug delivery, focused ultrasound, gene delivery, and transcytocis.
This meeting will connect scientists from both academia and industry to share their discoveries and insights, in the hope of accelerating scientific advances. The NYAS provides an intimate setting for facilitating a high level of interaction and encouraging thought-provoking conversations. Not to mention, it's also a place for networking and for young scientists, who are also encouraged to present posters, to find mentors.