Why We Can’t Deliver Drugs to the Brain

Why We Can’t Deliver Drugs to the Brain

This is Elise. She suffers from a brain tumor,
which causes blurred vision and confusion. But when doctors try and treat brain cancers
and other disorders, the brain blocks roughly 95% of medicine taken orally or intravenously. That’s a problem! So what is going on inside
your brain? And why is it just ignoring medicine? In your body, you have (on average) 5 litres
of blood that travels through 96,000 kilometres of blood vessels every day and it’s full
of different types of cells, nutrients, hormones, and gases. In their journey, they travel to your brain
and come face to face with the Blood Brain Barrier. It’s what’s stopping that 95%
of medicine getting in – it’s tough! It controls what is and what is not allowed
to leave your blood supply and enter your brain. The Blood Brain Barrier is made up of endothelial
cells and other specialised cells. The endothelial cells form tight junctions, like small gates,
between each other to restrict the transport of substances that can pass through. The barrier needs to recognize the substance
before letting it in. Luckily, iron and nutrients like glucose have
a way of getting through. They’re both recognized by specialized proteins on the surface of
the cells. When glucose or iron bind to these proteins,
they get shuttled through the gatekeeper cells and into the brain. But when the majority of medicines try to
get through, they get rejected! The gatekeeper cells treat them like blood-borne
pathogens or toxins. It’s like a paradox of our biology: The
blood brain barrier protects your brain from harm, but it’s also keeps out medicine when
people need it the most. And this is where the scientists step in – to
try and sneak medicine into your brain. One way is to disguise medicine as substances
the barrier does let through. Some scientists package medicine in nanoparticles
coated in proteins that look similar to the iron-carrying protein; in the hope it’ll
“trick” the gatekeeper cells to bind with it and let the nanoparticle into the brain,
just like they let in iron. Similarly, other scientists engineer harmless
viruses, hijacking their natural ability to enter cells. And they work as delivery vehicles
to transport medicine across the barrier. And more scientists are trying to push through
the barrier, by using magnetic nanoparticles to heat up and open the gate. Or, tiny bubbles to force it open. Seeing if these tiny bubbles can help deliver
a chemotherapy drug across the barrier is being tested right now to treat brain tumors. And as scientists continue to come up with
clever ways of getting medicine into the brain, there will be many more trials to come. Elise
and other patients suffering from brain disorders will hopefully have better treatment options
to choose from. And that’s what I would call a breakthrough!


  1. About the tiny bubbles, I actually listened to Radiolab podcast a while ago about it.
    Apparently the idea was sprung from a peculiar small crustation that can make amazingly loud noises with its claw.
    I knew about the animal, but I didn't know how the thing actually worked. Apparently it was bubbles.

  2. Did you hear about the ultrasound method using sound to temporarily let down the blood brain barrier? News of it spread to me just before this video came up

  3. The way you presented this video was a little bit different. More seamless and fluid it felt like. Either way, very cool!

  4. Lipophilic and non-polar molecules can pass through, provided they are not too big. It's how all the precursor chemicals which are processed by neurons to make all your neurotransmitters, and collagen and all that stuff. Plus, the endothelial cell's get their precursor chemicals for those protein transferases, and all the things they need to be living cells as well. It is of course also how O2 and CO2 and other essential molecules pass through as well, and no doubt initially why endothelial cells evolved in the first place.

    I've always thought the BBB was fascinating, as is the BCFB and BRB. I didn't even know most people didn't know about it. So all the better Vanessa made this video, to help educate the world.

    I learned something too, as I didn't know about the nanoparticle trials.

  5. Wow and I thought my epilepsy being controlled by medication was no big deal, thanks for another thing to be impressed by.

  6. As someone who gets incredibly squeamish, I have never seen blood cells so adorable in all my life. 💕

  7. The Title is misleading, most of the legal (or illegal) drugs, that are taken by the people on a regular bases, are easily delivered to the brain…

  8. Could you please go further into the " brain buisness", it is so interesting and does concern everybody, dorsn't it? I am suffering from migraine and this annoying disease would be a rewarding topic for a video, too. Love your wonderful work, thank you!

  9. I'm a little concerned about the "magnetic-mannered particles" and bubbles that could "force [the gates] open". I'm not sure if it's just moral judgement or not, but I'm concerned that if the gates to the brain are forced open, it could eventually do more harm than help.

  10. I have type 1 diabetes (so I'm depenent on injecting insulin) and have been suffering from depression. And it seems that this is a pretty mean combination, because insulin is one of those vehicles that control how substances can pass the blood-brain barrier – for glucose obviously, but also for certain hormons and neurotransmitters, or the precursors thereof.

  11. well the breakthrough is already here as the scientist have discovered a lymphatic vessels hiding inside the meninges.

  12. Really great animation on this one! And I learned a lot too 🙂

    Here's an interesting thing to think about: How can Zika cross the BBB?

  13. If these "bubbles" method break in the barriers, wouldn't bad/foreign particles be able to go through as well once the barriers are broken?

  14. This morning I heard from the radio that we recently found a way to broke through the barrier and treat the tumors more efficiently using ultra-sounds.

  15. Why is ship a vessel but vein a blood vessel. Shouldn't veins be the blood rivers – canals – pipes and blood cells the vessels?

  16. Medicine: "Pizza delivery for Mr. Brain"
    Blood Brain Barrier: "Hey he didn't order no pizza. Scram!"
    Medicine: "Err.. telegram for Mr. Brain."

  17. what about epilepsy? as I understand it, it is due to excessive electrical activity in the brain. do drugs that treat it have to pass the barrier?

  18. I love your channel Vanessa. You've become one of my favorite yotuber to watch so keep up the good work! 🙂

  19. Radiolab has such a nice episode explaining more about the bubbles she mentioned.


  20. Why do so many mental health professionals seem to think that when the currently available medications fail to work the failure is somehow an indication that certain conditions are more psychological than biological in nature? Couldn't blood-brain barrier problems be playing a role in these failures? PS I realize most mental heath professionals acknowledge an interplay between nature and nurture but in practice many still seem to be overly focused on nurture and reluctant to embrace many promising aspects of neuroscience?

  21. So, the endothelial cells are basically like border control between Mexico and the US, and scientists are the drug cartel coming up with new ingenious ways to sneak drugs across the border. lol

  22. Wonderful video! The best way to understanding the way our brain 'acts' by itself… And, at least geographically and culturally speaking… I'm a real burrito!

  23. I had heard about the tiny bubbles on a Radiolab podcast about shrimps.

    Good video and animation by the way

  24. Is this the same resons to why some people doesn't get high the first time they smoke weed? the body doesnt recognise it and doesnt let the THC through to the brain.
    This never happend to me but some of my friends didnt get high the first time. Maby they where just doing it wrong.

  25. Very recently, scientists have figured out a new, more effective way to pass the Blood-Brain Barrier: put the drugs inside viruses.

  26. Cannabis oil gets through this barrier, encourages healthy apoptosis and keeps it from proliferating, but hey people do it for fun so lets make it illegal.

  27. but what about recreational drugs? shouldn't the brain block them and prevent you from getting high and therefore preventing addiction???

    i have a feeling i'm wrong somewhere
    sorry…i'm not that well-versed in science ;-;
    8/8 video by the way

  28. that defensive wall to the brain is there for a reason, when they break it, shit will happend. medicine allready fucked up the immune system in many many people. most medicine is new and they dont know long term risk like 2-3 generation from now

  29. PARADOXICAL!REALLY!REALLY! That is one of the most awesomest thing about the brain.Let me explain using an example. Gamers -they aren't know to be the healthiest of people around but at the same time they also have some of the fastest human brains in the world. Its like there diet dosen't really affect there brain, like it always gets only what it needs. And this barrier explains why.

  30. It might be because it is 3:36 in the morning and I'm tired. But that Gandalf part with the egg looking things made me fucking lose it. I'm rolling.

  31. this was a great video. I heard about your channel on TWIV (this week in virology) as one of the picks of the week. Great channel from what little I have seen!

  32. HELP-(sorry for my bad english) hey venessa, please help me, I m suffering from panic disorder, and yesterday I ran out of my tablets (lonazep), I was in panic, so I took the tablet which I keept in my drawer openly, just like I will not use it (i m going to throw it away but forgot), I was in so bad panic attack that it left me with no other option, so I took the tablet, is it ok to take a pill which where on shelf for more then a month…. I m afraid that bacteria, virus or anything like that will change the compound or any will bad microorganisms bypass my bbb…. or anything bad like this

  33. Doesn't chemo attack healthy cells too? In the rest of the body it could be somehow managed, but isn't the brain too sensitive for that? I know very little about the subject. (Could just google, but comments can invoke thoughts in others :))

  34. The blood brain barrier is also the reason why dying by fugu is so torturous.
    The poison paralyses you but can't go through the barrier which means you get slowly trapped in your body.
    Bandō Mitsugorō VIII died this way

  35. without watching the vid id say why not smoke the medication, ive smelt my neibours smokin weed un it goes straight to thier brain cos they start laughing sooo bloody loudly. anywa iwil watch vid un hopefuly iwil be . . edumacated . . lol

  36. why is it such a suprise that the blood brain barrier keeps medication out surely the barriers reaction to the meds wud be that itwud class it RIGHTLY as a toxin cos it is a foreign body after all, if it just let it in then i dont think that person wud remain healthy for long . lol .

  37. Yes, but are we prepared to see that breaking this barrier may in fact cause unwanted side effects that now need to be remedied? This sounds like a slippery slope once again.

  38. Then how does hard drugs like morphine, cocaine, methamphetamine, fentanyl, etc. get into the barrier and effect the human brain to begin with?

  39. They can educate the barrier by feeding information into them to allow them to pass. There Will be no forcing into the barrier medicine. Why can't we just get along and also scientists think on that line to better their medicine. Great video

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