[Science Daily: Blood-brain barrier breakthrough reported by researchers]
Blood brain barrier working group in Johns Hopkins
University defines the blood brain barrier (BBB) as a dynamic interface that
separates the brain from the circulatory system and protects the central
nervous system from potentially harmful chemicals while regulating transport of
essential molecules and maintaining a stable environment. Moreover, an abstract
from NCBI describes the BBB as a single layer of specialized
endothelial cells that coats the central nervous system (CNS) vasculature and
physically separates the brain environment from the blood constituents to
maintain the homeostasis of the CNS. The structure and function of the BBB
correspond to the interactions between the different cell types, and the
extracellular matrix of the brain and blood flow in the capillaries.
According
to the Society for Neuroscience, the BBB plays a potent role in protecting
against the passage of foreign substances that it hinders the entrance of
essential drugs that are able to repair the injuries and diseases appertained
to brain. Due to the selective entry of molecules, only beneficial molecules
for brain functioning such as amino acids, oxygen, glucose, and water are
allowed to penetrate through.
Those descriptions were how the field of Neuroscience identified the BBB. However,
Cornell researchers pioneered the discovery that would controvert the existing theories.
They found a way to penetrate the BBB that would facilitate the delivery of
drugs directly into the brain to treat brain disorders such as Alzheimer’s
disease and chemotherapy-resistant cancers.
The
use of FDA-approved drug called Lexiscan can open the BBB for a short time
period which is an adequate length of time to deliver such therapies into the brain.
Lexiscan is also known as Regadenoson is an A2A adenosine receptor agonist that
is a coronary vasodilator. A2A adenosine receptors are also found in the BBB
owing to the fact that adenosine acts as a neurotransmitter in the brain. Also,
A2A adenosine receptor plays an eminent role in regulating the human BBB
permeability. In reference the function of A2A adenosine receptor, one can deduct
how the use of Lexiscan is a ground breaking news for the cure of such brain
disorders that encountered difficulties delivering the treatments through the
BBB.
In
this image, we could see the arrow from the Adenosine receptor to P-glycoprotein
(P-gP). The drug efflux transporter P-gP is highly expressed on brain
endothelial cells and blocks the entry of most drugs delivered to the brain.
However, the activation of the A2A adenosine receptor (AR) with A2A AR agonist,
Lexiscan, rapidly decreases P-gP function and expression. In the presence of Lexiscan, the permeability for foreign molecules of the BBB increases
substantially.http://bloodbrainbarrier.jhu.edu/about/
http://www.ncbi.nlm.nih.gov/pubmed/25262373
http://www.brainfacts.org/brain-basics/neuroanatomy/articles/2014/blood-brain-barrier
http://www.rxlist.com/lexiscan-drug.htm
http://www.ncbi.nlm.nih.gov/pubmed/10668415
http://www.ncbi.nlm.nih.gov/pubmed/27043281
KSJ
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