A team of Canadian scientists has done something completely extraordinary and has permeated the blood-brain barrier (BBB) inside of a living patient to administer chemotherapy medication.
The BBB is an important physiological feature that keeps the brain, a human's most important organ, safe. The barrier is a selectively permeable membrane, which means that while some things from the blood stream — such as oxygen and certain nutrients — are let through, others are shielded out. This prevents toxins or other components in the blood that could be potentially harmful from gaining access to the brain. It's an evolutionary adaptation that has served humanity well, but it does make it exponentially more difficult to administer medications that target the brain.
In recent years, scientists have been working toward getting medication through, which needs to be delicately balanced. If the method used is too harmful, it could damage the BBB and leave the patient at increased risk of infection or brain damage. While many labs have been working on this approach with samples that aren't inside a living human brain, they proved to be too damaging.
The method used by the scientists in Canada seeks to ease chemotherapy through the BBB in order to administer medication to a patient with a brain tumor with the assistance of ultrasound waves. The medication was packaged into nanobubbles for easier transport. The focused ultrasound waves then vibrated the barrier, opening the permeation points enough for the medicine to slip through, gaining access to the tumor. Rather than being filtered out, the medication could have unprecedented direct access to the area that requires treatment. The sound waves are targeted in order to cut down on the possibility of a threat.
"The blood-brain barrier (BBB) has been a persistent obstacle to delivering valuable therapies to treat disease such as tumours," principal investigator Todd Mainprize explained in a statement. "We are encouraged that we were able to temporarily open this barrier in a patient to deliver chemotherapy directly to the brain tumour."
Less than a day after breaking the BBB, the researchers performed brain surgery, extracting a sample from the area that was treated and one that wasn't. The samples will be sent for analysis, where the researchers will determine how much of the medication was able to reach the tumor.
Ultimately, the approach is non-invasive. It is believed that once the ultrasound waves stop, the BBB is able to function normally. It is also hoped that potentially harmful substances were not able to bypass the membrane during the course of the treatment.
Of course, there are still much to know before this becomes a commonplace treatment. It will still be quite some time before the pathology results return from this patient, as well as the six to 10 other patients who will undergo the procedure in the coming months. The full report will detail the sample analysis by investigating its safety and efficacy.
This announcement is an important step on the journey toward next-level care for patients not only suffering from tumors, but other brain disorders as well, including Alzheimer's, epilepsy, and more.