It’s not by accident that chemotherapy drugs fail to treat most brain tumors and cancers. The organ sits behind a blood-brain barrier that has a short list of substances allowed through, and unfortunately it does not include medicine — at least not yet.

BrainCraft host Vanessa Hill cites that the blood-brain barrier blocks roughly 95 percent of medicine taken orally or intravenously. It’s a gate, so to speak, mostly made up of endothelial cells that form tightly together to limit what is and is not allowed to leave your blood supply and enter the brain. So at the same time the barrier keeps out foreign pathogens and toxins, it also holds back cancer treatment.

Iron and glucose are two examples of substances allowed through the barrier. On the surfaces of their cells, there are specialized proteins that the barrier recognizes and therefore allows access. In which case, scientists have started to disguise new medications inside nanoparticles coated in iron-like proteins so that they have a chance to enter the brain, too. Other scientists are experimenting with ways to force the barrier open, with one ongoing study testing the power of tiny bubbles.

"As scientists come up with more clever ways to get across the blood-brain barrier, there will be more trials to come," Hill said. "...other patients suffering from brain disorders will hopefully have better treatment options to choose from in the future, and that's what I would call a breakthrough."