The blood brain barrier (BBB) is a highly organized and specialized system comprising of capillary endothelial cells which act as a guard to protect foreign substances from entering the circulatory system. There are several ways in opening the BBB, although doing so opens the brain to a host of potential ailments, such as hypoxia and cerebral ischemia. The point to opening the BBB is to facilitate the transfer of drugs, and now a new method to bypassing the permeability is in the introduction of natural microbubbles in conjunction with ultrasound treatment to increase permeability in certain regions. This treatment can provide a new wave of drug treatment that was previously unavailable to researchers.

The BBB is a mechanism which also allows for efficient flow of nutrients to the brain while controlling transport through tight junctions. It acts as a rate limiting step for the introduction of substances into the brain, but has been, for the most part, ineffective in allowing drugs for therapy and diseases to pass through. Essentially, the BBB is important for the central nervous system, creating a large portion of the complex physiology which constitute the brain.

In the past, there was success in bypassing the BBB, although such methods were followed by side effects of the experiment which were unwanted. Chemical therapy introduced to reduce the size of the endothelial cells created a dangerous environment for the patient which could lead to hypoxia in the brain. More recently, microbubbles were the new form of bypassing permeability, although the negative affects where the drugs infused microbubbles would travel throughout the brain and body, causing treatment in unwanted areas, thus, lacking highly specificity.

Now, researchers at the University of Columbia have found a methodology based on the previous microbubble technique which would incorporate lipid coverings over the microbubbles. The study was conducted four mice brains by coating microbubble vesicles in a lipid coating and fluorescents to track the movement, as well as applying a 5Hz frequency to the right side of the brain for 5 minutes, while the left side received no ultrasound treatment.

In the end of the experiment, the researchers identified that the introduction of ultrasound and lipid coverings provided a new highly predictable way of providing drug treatments. It has yet to be conducted on humans, but the applications could be used to treat Alzheimer’s, Parkinson’s, brain tumors and more.

 

COPYRIGHT: This article is property of We Speak Science, a non profit institution co-fonded by Dr. Detina Zalli (Harvard University) and Dr. Argita Zalli (Imperial College London). The article is written by Detina Zalli and Antonio Del Vecchio (Cornell University).

 

Reference:

Sierra, C., Acosta, C., Chen, C., Wu, S. Y., Karakatsani, M. E., Bernal, M., &Konofagou, E. E. (2016). Lipid microbubbles as a vehicle for targeted drug delivery using focused ultrasound-induced blood–brain barrier opening. Journal of Cerebral Blood Flow & Metabolism, 0271678X16652630.

Ballabh, P., Braun, A., &Nedergaard, M. (2004). The blood–brain barrier: an overview: structure, regulation, and clinical implications. Neurobiology of disease16(1), 1-13.

Meairs, S., & Alonso, A. (2007). Ultrasound, microbubbles and the blood–brain barrier. Progress in biophysics and molecular biology93(1), 354-362.

Dijkmans, P. A., Juffermans, L. J. M., Musters, R. J. P., van Wamel, A., Ten Cate, F. J., van Gilst, W., … & Kamp, O. (2004). Microbubbles and ultrasound: from diagnosis to therapy. European Heart Journal-Cardiovascular Imaging5(4), 245-246.

http://www.agenciasinc.es/en/News/Microbubbles-and-ultrasound-open-the-blood-brain-barrier-to-administer-drugs

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