FEB 29, 2016

Using Lasers To Open The Blood Brain Barrier

WRITTEN BY: Brenda Kelley Kim
The blood brain barrier, or BBB is what protects the brain from harmful substances that enter the bloodstream. It acts as a filter, keeping out toxins that could damage the brain. This form of protection becomes a problem when someone has brain cancer. While there have been a number of drug therapies developed for different forms of brain cancer, most of them have not been successful.
The BBB works like an intricate net of blood vessels that screen out certain substances. In most parts of the body, the smallest blood vessels, called capillaries, are lined with endothelial cells. These cells have spaces between them so that anything ingested can pass in to or out of the blood stream. Capillaries in the brain are different though. Endothelial cells there are joined together tightly, essentially saying ‘None shall pass’ so most substances cannot get through.  In addition there are Glial cells (astrocytes) that form a layer around brain blood vessels and these cells make the barrier even more difficult to cross.  
 
New research from Washington University School of Medicine might offer new hope. Laser probes have been used by a team of neurosurgeons to open the barrier . The goal of this technology is to see if chemotherapy drugs can be delivered directly to brain tumors.
 
In the study, researchers had 14 patients who’d experienced recurrences of glioblastoma, a common and fast growing form of brain cancer, go through a minor surgery. Heat from laser beams is known to kill circulating tumor cells in the brain, but the researchers found a side benefit to the laser treatment. The heat also kept the BBB open for a period of 4-6 weeks.
 
Doctors from the University of Florida also collaborated on the study. David D. Tran, M.D., Ph.D., chief of neuro-oncology at the UF College of Medicine said in a press release, “The hope is that we can help patients live longer. We know that there are several drugs out there that should work on brain tumors.” ()
 
Washington University study author Eric C. Leuthardt, MD, a neurosurgeon said, “The laser treatment kept the blood-brain barrier open for four to six weeks, providing us with a therapeutic window of opportunity to deliver chemotherapy drugs to the patients. This is crucial because most chemotherapy drugs can’t get past the protective barrier, greatly limiting treatment options for patients with brain tumors.”
 
The laser technique has been around since 2009 as a way to treat brain tumors. This new research was the first time the disruption of the BBB was noticed and used for a therapeutic purpose.
 
Out of the 14 study participants, 12 showed no tumor progression during the 10 week treatment period. The trial was small, so the team hopes to be able to conduct a larger study. Check out the video to get more information about how the blood brain barrier works.