Placeholder Image

Subtitles section Play video

  • Ok, so you,

  • are a 4 billion year old meat robot.

  • Yeah, you heard me right.

  • In fact, as you're made of 30-ish trillion cells,

  • and each of those have their own task,

  • you're a robot made of trillions of mini robots-

  • you are a mega-meat-bot!

  • And your mission, for the past 4 billion years or so-

  • and for as long as you keep playing this game of life-

  • is to safeguard the code.

  • To duplicate it. To pass it on.

  • The thing is, you're rubbish at copying your own code.

  • Every time it's copied, errors crop up.

  • Not good when an error makes a robot worse at surviving,

  • but sometimes a mistake helps them survive...

  • and they pass that glitch in the code on-

  • that's evolution in a nutshell, right?

  • Which means you're not the result of some fancy design, I'm afraid.

  • You're a result of billions of years of bad copies.

  • Go you.

  • Another reason you're not totally awesome

  • is because that megabot of yours often breaks down.

  • Fortunately,

  • cardiologists, immunologists, microbiologists- all the "ists"-

  • have spent centuries figuring out our sensors and wiring

  • so if something does go wrong, they can usually fix it.

  • Where they struggle, though, is when the machinery turns on itself-

  • when a copying error leads a cell to start dividing uncontrollably,

  • to grow and multiply into a tumor.

  • That's cancer.

  • And sadly, even with the might of our modern medicine,

  • some cancers evade treatment.

  • But this is where a new band of biologists step into the story:

  • The "Synthetic Biologists."

  • These biohackers are mashing up science, medicine and engineering

  • to rewrite the code and fix the un-fixable.

  • Biohackers are going into a patient's genetic code

  • and reprogramming their own immune system

  • to recognize cancer cells and destroy them.

  • It's called CAR T-cell therapy, and it's awesome.

  • See, you're constantly under attack by pathogens-

  • single-celled bacteria, viruses and fungi.

  • Despite deciding, back in the day,

  • to stay solo and not 'avengers assemble' like you did,

  • those pathogens see you, in all your mega-meat-bot glory,

  • as a fortress ripe for the plundering.

  • Thankfully, you've got a security team in place to battle these invaders-

  • your immune system-

  • and some of it's top guards are your white blood cells.

  • They trawl the darkness that is your inner space,

  • checking the IDs of any cells they pass...

  • although they're not name badges,

  • but rather protein fragments on the cell's surface called antigens.

  • There are two types of these guards: T-cells and B-cells.

  • T-cells check those antigen IDs using special claws-

  • receptors that lock with a particular antigen.

  • If they find a match, they attach and they release toxic chemicals

  • that burst open the invading cell's membrane.

  • Their B-cell workmates create antibodies-

  • loads of small proteins,

  • little claws that latch perfectly onto a particular antigen,

  • marking them for destruction.

  • These two comrades have got your back

  • and your immune system is brilliant at spotting and fighting pathogens

  • that invade from outside.

  • However,

  • they're not so good at spotting your own cells that have gone rogue.

  • The antigens on cancerous cells don't look weird,

  • they look a lot like your own cells,

  • and the T's and B's aren't programmed to attack them.

  • The usual way to deal with cancer is to try to cut the tumor out,

  • or turn to radiotherapy and then chemotherapy

  • to destroy or block the growth of cancer cells,

  • but if it's a blood cancer, if it's floating around your whole body,

  • you can't do that.

  • And if the blood cancer actually starts in your white blood cells-

  • those key guards in your immune system-

  • you'll really struggle to spot it.

  • That's the case with acute lymphoblastic leukemia,

  • and that's where CAR T-cell therapy is kicking butt.

  • The biohackers are reprogramming a patient's own immune system

  • to recognize particular antigens- those particular protein fragments-

  • on the cancer cells.

  • To do it, you first need millions of a patient's T-cells

  • Then, to get a T-cell to do something different,

  • you need to replace its normal code with something new,

  • something you've designed.

  • What synthetic biologists can now do with DNA is super cool-

  • they use a computer to put together their own sequences of bases-

  • the chemical letters that spell out the DNA-

  • then they model what that new genetic code will do on a computer

  • and then make those sequences on a DNA printer-

  • yeah, that's a thing!-

  • printing not with ink, or with a plastic polymer like in a 3D printer,

  • but with those fundamental building blocks of life,

  • with those A's and C's and T's and G's.

  • The new code they designed for a T-cell has 3 key instructions:

  • 1. It tells it how to recognize and kill a cancer cell.

  • More specifically,

  • how to modify an antibody-

  • what the B-cells make to latch onto a target antigen.

  • The antibody is modified to make a new receptor

  • that can detect the particular antigens on the specific cancer.

  • 2. It tells it to make copies of itself when it finds that cancer cell

  • and 3. It tells it to survive in the patient's body.

  • To get this new code into the patient's T-cells,

  • you use a vector-

  • it's something that will easily infect the T-cell

  • and carry that bespoke DNA in with it.

  • And voila! One CAR T-cell.

  • The name comes from a fire-breathing monster from Ancient Greece,

  • that had a lion's head, a goat's body and a serpent's tail.

  • It was called "Chimera"- a name that has now come to be used

  • for something that contains two or more different types of tissues or cells.

  • As this newly engineered cell's genetic code is part T-cell, part antibody,

  • it's a "C"himera and it goes in search of the cancer's "A"ntigen

  • using its new "R"eceptor.

  • Before you put the multiplied up T-cells back into the patient,

  • you give them a mild dose of chemotherapy to wipe their existing T-cells.

  • Then you simply reinsert the now modified T-cells-

  • the CAR T-cells-

  • and they follow their normal DNA programming to move and search.

  • However, thanks to their new butt-kicking code,

  • they've changed what they're looking for:

  • they're now on a mission to find the cancerous cells and destroy them.

  • Unlike conventional chemical-based drugs

  • that get used up or excreted from the body pretty quickly,

  • CAR T-cells are living drugs that stay in the patient's bloodstream for years.

  • That's a huge pro.

  • The flip side is that they're expensive-

  • each CAR T-cell treatment is bespoke to the patient-

  • and it's more difficult to get them to work with common cancers

  • like breast or lung, because you need a specific antigen on the cancer cells

  • for the CAR T-cell to target-

  • and it's much easier to find that in blood cancers.

  • It's still early days, though,

  • and there's an exciting future for CAR T-cell therapy.

  • Researchers like Dr. Martin Pule and his team at UCL,

  • are working on improving the leukemia and lymphoma treatments even further,

  • and there's recently been some promising work on solid cancers.

  • Thanks to CAR T-cell therapy,

  • the survival rate for B acute lymphoblastic leukemia has improved hugely

  • -nearly all patients go into remission-

  • which means that leukemia cannot be detected anymore-

  • and most patients stay in remission.

  • Biohacking is here,

  • and it can reprogram your own genetic code to enable your mega-meat-bot

  • to do things it's never been able to do before!

Ok, so you,

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B1 US TED-Ed cancer car cell patient antigen leukemia

How to biohack your cells to fight cancer - Greg Foot

  • 389 25
    ktyvr258 posted on 2019/10/30
Video vocabulary