A nano-sized trip to the brain

By: Mengying Zhang

As a foreign graduate student, my first journey to USA was not easy. An 11 hour long flight from Beijing to Seattle tormented my back and my sleep. Upon arrival, waiting in lines for customs to check my visa is endless, and stressful. Moreover, I got lost in Seattle, ending up getting on a wrong bus and wandering nowhere until midnight. Finding an affordable apartment is always hard in Seattle, too. I also suffered from culture shock. I simply thought people didn’t like me because I didn’t watch Star Wars during my childhood.

 During my graduate study, something interesting came up linking to my experience. The trip for a drug to enter the brain shares similarity to my journey to a foreign country! 

Neurological disease drugs may start their trip to the brain by entering blood vessels, like after an injection. The heart pumps the blood throughout the body, carrying the drugs to various organs including the brain. The drugs swim so hard to reach their destination, but they also risk getting lost in the circulatory system. When they reach the brain, the sophisticated brain has highly regulated and strict customs – blood brain barrier – to guard the entry. They give authorized “visas” to certain passengers, only allowing super small molecules such as water and glucose to get through. Most of the drugs fail to pass customs and enter the brain. Even some of the drugs sneak in, the inner brain environment is a jello-like maze full of dead ends. The drugs need to struggle to not get lost, as well as find the right cells to settle down and start working. In the meantime, the brain native police – microglia, are alert about any suspects. They wander inside the brain, hunt the suspects, copy more of them to help searching. When the drugs are found unfortunately, they will likely be eaten by the microglia and lose their ability to fight the disease.

The outcome of the challenging trip is cruel. Brain disease ranked as the leading group of overall disease, and it can cost American society nearly 800 million dollars every year.

What if the trip for drugs to the brain becomes easier? Like what we humans do before and during travel: what if there is a guide for the drugs? 

A nano sized carrier might be the answer! They can be particles smaller than one-thousandth of the thickness of one single human hair. Actually, being small give them big abilities. They can be made from multiple materials, easy to add properties as wanted, or interact easily with small subjects such as cells.

With the nano sized carriers as a vehicle, the drugs travel more stably in the bloodstream. When they achieve the blood brain barrier, the nano carriers present a prepared visa to the “customs”. The nano carriers are wrapped with certain molecules that can penetrate the blood brain barrier, increasing the probability for the drugs to get inside the brain. When the drugs get into the brain maze, the nano carriers with a protective shell, can move stealthily in the brain environment with minimal trouble of getting stuck on the way. At the same time, the protective shell is acting as Harry Potter’s invisibility Cloak, helping the drugs avoid the brain police – microglia – without alerting them. What’s more interesting, is the nano carrier can be engineered to have different chemical “arms” or with different shapes, guiding them to interact and enter into different type of cells for specific targeting. With all of these benefits by loading the drugs into the nano carrier, the trip for the drugs to get into the brain is much easier and more efficient.

If you want to learn more about the nano-sized trip to the brain, how in details they help the drugs to travel, and what are the beneficial outcomes for the treatment of brain diseases, please come to my Town Hall Talk on 4/23 at Ada’s Technical Books (Capitol Hill) (https://townhallseattle.org/event/uw-science-now-4-23-2019/). With travel tips, we have a more enjoyable exotic trip. That’s how nano-sized carrier can help drugs for their brain trip!

Engage Science