Why we love and hate the blood-brain barrier
The blood-brain barrier: There are not many other natural defense mechanisms with which we humans have such a love-hate relationship. First, the love: The capillaries and blood vessels in our brains, of course, need this kind of protection from foreign invaders. After all, we have a very personal relationship with our brains and evolution has fixed it so that it is extremely difficult for unauthorized personnel to break through. Now, the hate: The BBB stands directly in the way of better treatments for Alzheimer's, Parkinson's, brain tumors and other neurological conditions. Chemistry World, in its June 2011 issue, devotes some considerable ink to attempts to break through this final frontier of the brain to treat some of the most challenging brain diseases.
William Pardridge, director of the Blood-Brain Barrier Research Laboratory at the University of California Los Angeles, tells Chemistry World that the cracking the blood-brain barrier problem, despite its obvious importance, is not a major focus among big pharma companies. In fact, they have turned a blind eye to the problem of drug delivery.
Among the methods mentioned by Chemistry World are early attempts at making "drugs more lipid soluble; this allowed them to penetrate the lipid-loving endothelial cells in the brain." This technique actually takes a page from a few of the not-so-nice drugs society is dealing with, like cocaine, heroin and alcohol--all of which are also lipophilic. The problem is that that lipophilic drugs also penetrate every organ, leading to bad side-effects. Also discussed: Creation of "temporary portals" through the BBB using focused ultrasound and turning the BBB, itself, into a drug-delivery device by engineering it to secrete a missing enzyme.
The article ends on a hopeful note, with some acknowledgment by pharmaceutical companies--mostly small ones and not the more-cautious large ones--that a focus on drug delivery to the brain will ultimately pay off in better treatments and cures.
- read the article in Chemistry World
Special Report: The blood-brain barrier - When nanotech meets biotech