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Here's One Way Doctors Might Get More Lifesaving Drugs Into Our Brains

This tiny carrier molecule can deliver drugs past the blood-brain barrier that could only be injected directly before.
May 13, 2015, 12:00pm

Scientists have long struggled with how to slow the spread of brain diseases such as Alzheimer's, Multiple Sclerosis (MS) and Parkinson's. Ideally, biologic therapeutics such as antibodies would make their way into our brains reversing the inflammation that these disorders cause—were it not for the the challenge of getting past the blood-brain barrier.

But a group of scientists, medical specialists and researchers with Canada's National Research Council (NRC) believe they have made a breakthrough.

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The blood-brain barrier is the Fort Knox of the body. Envision, if you will, a wall of army clad officers separating the brain from the circulatory system. The officers (which are actually a line of brain endothelial cells) are there to protect the central nervous system from potentially harmful invaders, like chemicals. But by only allowing a select few types of molecules to cross—for example, water, some gases, and lipid soluble molecules—the blood-brain barrier also prevents disease fighting drugs from entering the nervous system too.

The NRC's Therapeutics Beyond Brain Barriers (TBBB) program has been developing carrier molecules for the past six years that enable disease-fighting molecules to infiltrate the blood-brain barrier by essentially tricking the mind and exploiting the same mechanism that allows nutrients into the brain. The carrier molecules are referred to as Trojan horses disguising antibodies or peptides as proteins.

The unique breakthrough here isn't the Trojan horse method, however—which has been in use for nearly two decades—but the team's use of single domain antibodies.

"It really opens the possibilities to use many different types of therapeutics for different diseases that we couldn't really use before unless we inject them directly into the brain which is highly invasive," explained Dr. Danica Stanimirovic, the TBBB program's scientific lead.

Single domain antibodies are tiny fragments consisting of a single molecule, and are able to bind chemically to other molecules. The single domain antibody, smaller than an Aspirin, is able to squeeze past the barrier because of it's size and because it is familiar to some of the receptors along the blood-brain barrier.

Dr. Stanimirovic defined their technology as a "platform" similar to a "Lego building block" allowing companies to build different types of carrier molecules to target multiple diseases. For example, let's say a company wants to develop a drug that specifically treats Parkinson's disease. The company will build the therapeutic molecule. The TBBB will then engineer the molecule so it connects to the tiny Trojan Horse carrier, fine tune and and voila: a potential treatment for Parkinson's disease.

Pairing carrier molecules with therapeutic molecules, the team worked with Graham Farrington, director of the Antibody Discovery Group at biotechnology company Biogen Idec to test the approach in rats. The tests were a success, and showed that the carrier-antibody combo had a "highly potent" therapeutic effect on brain diseases. "This was a critical step in validating the efficacy of these antibodies and setting the stage for clinical trials," said Farrington in the release.

But there is one huge catch: both Farrington and Stanimirovic estimate that the clinical trials could take up to 10 years.

The World Health Organization predicts that neurodegenerative diseases such as Parkinson's and ALS are expected to surpass cancer as the second most common cause of death by the year 2040. That means that any kind of breakthrough—even one that could take more than a decade to test—is still a significant step towards opening the field of biologic therapeutics to other researchers and understanding the workings of the human mind.