The Interstitium (Radiolab)

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Speaker 2 Hey, Gazja Squad.

Speaker 5 Happy summer to those of you in the northern hemisphere. May the popsicles be plentiful.

Speaker 7 I'm Nicola Twilley. And I'm Cynthia Graber, and you're listening to Gastropod, the podcast that looks at food through the lens of science and history.

Speaker 7 We have actually snuck a popsicle break here at Gastropod headquarters, but in this case, we're enjoying them while working hard on our next season.

Speaker 5 I'm so excited about what we have coming up that even a popsicle can't chill me out.

Speaker 5 We've got the weird story behind how the pumpkin became the king of fall, and the science behind whether your cold cuts are trying to kill you, and tons more besides.

Speaker 7 But while we're out and about reporting, we have a couple of special episodes for you. These are some of our favorite recent episodes from Friends of the Show.

Speaker 7 This week, it's an episode of Radiolab about how scientists recently discovered an entirely new, previously hidden part of the human body.

Speaker 5 Truly, an entirely new organ that scientists had somehow overlooked. We'll be back with our own fresh episode soon, but for now, enjoy this gripping medical mystery.

Speaker 10 Oh, you wait. You're listening.
Okay.

Speaker 10 All right.

Speaker 10 Okay.

Speaker 10 All right.

Speaker 10 You're listening

Speaker 11 to Radio Lab. Lab.

Speaker 10 Radio Lab. From

Speaker 13 WN Weiss.

Speaker 3 This is Radio Lab.

Speaker 14 I'm Lula Miller.

Speaker 15 I'm Latif Nasser.

Speaker 10 Oh, hello.

Speaker 14 Along with reporter Jen Brandell.

Speaker 10 Hi.

Speaker 6 Latif.

Speaker 3 Jen, have you guys met?

Speaker 15 We have not.

Speaker 15 No.

Speaker 3 So, So, Jen is a radio reporter who I've known for a long time.

Speaker 3 But these days.

Speaker 2 I'm a little hard to explain. I have been a journalist.
I'm a CEO of a tech company right now. I work between a few worlds, between entrepreneurship, democracy, media, blah, blah, blah.

Speaker 10 Yeah.

Speaker 15 Well,

Speaker 15 it's right.

Speaker 2 I'm an annoying person to talk to at a cocktail party because I can't really say it succinctly. I'm not like, I'm an astronaut.

Speaker 15 I'm a firefighter.

Speaker 3 Right. And that'll maybe come back.
Okay. So, I don't know.
Shall we just shall we begin? Are you ready for

Speaker 3 a journey?

Speaker 10 Yeah. Okay.

Speaker 16 So

Speaker 3 we're going to just to kick it off.

Speaker 2 Caffeinated, bageled, ready to go.

Speaker 3 We are going to start inside a hospital.

Speaker 14 On the fourth floor. Fourth floor.
Going up.

Speaker 9 Jen and I are walking around.

Speaker 3 It's NYU hospital. We're trailing some doctors and we're in this part of the hospital I had never thought about that exists, but it very much exists.

Speaker 17 So this is Lulu. This is Jen.

Speaker 18 We have permission to be here.

Speaker 3 So we walk into this room that looks a little bit like an industrial kitchen.

Speaker 18 We just can't mention any identifiers.

Speaker 3 There are big metal counters and sinks.

Speaker 3 And anyway, these doctors, they're pulling out Tupperwares and kind of one by one they are lifting the lids and pulling out

Speaker 3 human organs.

Speaker 18 Oh, so that's small intestine coming here.

Speaker 9 Organs I've heard about but never seen before.

Speaker 17 And this is the pancreas.

Speaker 10 They pulled out a whole stomach.

Speaker 1 Just like a big orangey red chunk of meat.

Speaker 2 And they pulled out.

Speaker 18 Here's the dome of the uterus. Oh, wow.

Speaker 2 A uterus?

Speaker 6 This is your ovary.

Speaker 10 Whoa.

Speaker 3 And they pulled out.

Speaker 18 Here's a large fatty red tissue, and that's the breast tissue.

Speaker 19 A whole breast?

Speaker 15 They pulled out. Wow.
Okay. A liver.

Speaker 10 Is that brain?

Speaker 21 No, this is skin.

Speaker 3 Just organ after organ.

Speaker 13 Are these organs for training?

Speaker 2 No, no, no, no, no. These are fresh.

Speaker 1 It looks like we're seeing

Speaker 21 blood.

Speaker 3 Some of them were dripping blood.

Speaker 17 Yeah, there's blood.

Speaker 18 The red stuff is blood.

Speaker 3 Some were dripping bile.

Speaker 2 These were organs that had come out of people that day.

Speaker 18 Oh, so are you on pancreas today? Yeah.

Speaker 3 And so what that room is, is it's a pathology lab where they are looking at anything that has been taken out of or off of a patient in the hospital.

Speaker 17 Coming down from the operating room all day, hundreds of specimens a day.

Speaker 3 Because maybe that person's getting a transplant or maybe they had... And what is that?

Speaker 18 That's cancer.

Speaker 3 A tumor removed.

Speaker 10 Wow, that's a big...

Speaker 3 That's like a tennis ball image. Yeah.

Speaker 3 now here's it's like dizzying because it's these pieces of people but they hold these full you know someone like two floors above you is going through a huge day right but the reason why we were there that day was to see a body part should we just go now yeah oh okay a sort of

Speaker 3 giving consent for this procedure i am giving consent organ just tested the syringe a couple drops came out here comes the big needle inside the human body

Speaker 3 that scientist had whoa there it is

Speaker 3 completely missed is that it are we looking at it right now

Speaker 3 even though it had just been sitting there oh my gosh i'm wow all this time inside of all of us an organ yeah

Speaker 10 well

Speaker 3 a body part a big deal body part a big deal body part a big deal body part that we'd missed until like

Speaker 3 Five years ago.

Speaker 19 What?

Speaker 10 Yeah.

Speaker 3 And yeah.

Speaker 15 And so today we are going to bring B?

Speaker 10 Well, that's the story we're gonna tell you.

Speaker 3 How we missed it.

Speaker 12 People have been looking at the human body for like since the beginning.

Speaker 2 Yep, exactly. Which is why it's so bizarre that we missed it.

Speaker 19 I don't even know if I believe you. I'm like in disbelief here.

Speaker 2 As were many.

Speaker 3 Yeah, so we're gonna tell you the story of what this mysterious body part is, what its name is, what it might be doing, why we miss it, how knowing about it might change our lives, our health, and maybe even like society a little bit.

Speaker 19 Really?

Speaker 3 But I'm gonna pipe down because

Speaker 26 Jen's going to tell you the rest.

Speaker 15 All right.

Speaker 2 Oh, great. Now I just had a Google meeting pop up.
Let me just kill all these things.

Speaker 10 Stop it. Okay.

Speaker 3 From your 17 other jobs that you were.

Speaker 10 Yeah, exactly.

Speaker 2 Okay.

Speaker 15 All right. Okay.

Speaker 2 So the story starts with this guy, Neil Fieste. Hello.
Hey, Neil. How are you doing? Dr.
Neil Thiest.

Speaker 15 I'm good.

Speaker 2 Okay, let me. So Neil was actually one of the doctors.

Speaker 17 So this is Lulu. This is Jen.

Speaker 15 Hi, hi.

Speaker 2 Who is showing us around the lab?

Speaker 18 Okay.

Speaker 2 He's a kind of short, muscly fellow.

Speaker 2 He's got tattoos on his arms, and he's kind of an unlikely doctor because he studied computer science and he thought he was going to be a rabbi for part of his life.

Speaker 18 So I was sort of all over the map.

Speaker 3 The classic rabbi programmer.

Speaker 15 No, exactly.

Speaker 10 Exactly.

Speaker 2 What about why did you want to become a doctor in the first place?

Speaker 2 Sorry, I know this could be a long story, but quickly, like in summation.

Speaker 18 I was a freshman in college. I was gay and couldn't cope with it.
And I thought, and I'm a child of Holocaust survivors too. So my formula was: I'm going to get old.
I'll never get married.

Speaker 18 I'm never going to have kids. And I'll be doing Hitler's job for him because of that.

Speaker 18 And

Speaker 18 I'm going to grow old and die alone.

Speaker 2 So when he graduated with degrees in computer science and Jewish studies, he was like, what am I doing? What is my role in the world?

Speaker 18 And then one day, my mother called me up and said, oh, bad news.

Speaker 2 The doctor that she had worked for and who had delivered him and his brother in his hometown in Connecticut had died of a heart attack on the golf course that morning.

Speaker 18 And the funeral was going to be the next day. So she called me after the funeral and I said, How was Dr.
Robinson's funeral? And she said, It was just amazing.

Speaker 18 All of Hartford came out for his funeral. And I thought, oh, if you're a doctor, people come to your funeral.

Speaker 10 So that's why I went to medical

Speaker 10 school.

Speaker 3 Wait, so like most people go into medicine because they care about other people or they say that, but you went because you wanted more people to care about you.

Speaker 10 Yeah, basically.

Speaker 18 I was terrified of being alone and I thought, I won't be alone. I'll have meaningful relationships and I'll do good things in the world and my life won't be meaningless.

Speaker 2 So he goes off to med school.

Speaker 18 Discovered pathology in the middle of it and was like, oh.

Speaker 15 I like this.

Speaker 2 Which is funny because in pathology.

Speaker 18 I'm lifting up the small intestine.

Speaker 24 You're mostly dealing with...

Speaker 2 the parts of patients, not the actual people themselves.

Speaker 18 But I just really loved looking at beautiful puzzles.

Speaker 2 Because a lot of what pathology is.

Speaker 18 So I've got this big stack of slides here.

Speaker 2 Is taking an organ and making a tiny,

Speaker 18 very thin slice.

Speaker 8 Little sample of it.

Speaker 2 Putting it on a slide, adding some stains to it to give it color.

Speaker 18 And then we'll look at it under the microscope.

Speaker 2 Where he'll see.

Speaker 17 Pattern of colors.

Speaker 18 Shapes. Oh, my God.
Relationships between the shapes. Okay, Wow.
So each cell has a particular shape. The magenta stain here is the blood vessel lining cells.

Speaker 24 Sort of like a stained glass.

Speaker 18 This is an artery and this is a vein.

Speaker 10 The teal are greenish color.

Speaker 18 These white spaces here and this is fat.

Speaker 17 And so, see how that looks blue?

Speaker 18 Yeah. Sit down at my microscope and I look at the slides.
I know that's a bad side. And I make diagnoses.

Speaker 2 So he ends up becoming a liver pathologist. And like a world-renowned one at that.
But he's also super accessible and like friendly.

Speaker 2 And even though he's not working directly with patients, he has a lot of meaningful relationships with people.

Speaker 2 And they go to him for things, like if they're seeing something they've never seen before, which is what happened in 2015.

Speaker 18 When I was at Beth Israel Medical Center in New York.

Speaker 2 So he had this Kush job at Beth Israel.

Speaker 15 It was very luxurious.

Speaker 18 I had my own room with a multi-headed microscope.

Speaker 2 Removed from all the action so he could focus on his microscope all day long. And a colleague walks in one day.
David Carlock.

Speaker 2 Neil told us you are a scope jockey.

Speaker 17 He would say that.

Speaker 18 Do you know what that means?

Speaker 9 Is that a term of art?

Speaker 17 No, no, it's very, very derogatory.

Speaker 3 Is it like a dig of someone who likes looking at microscopes?

Speaker 18 No, no, no, no. An endoscope.

Speaker 10 Oh, endoscope. Oh, okay.

Speaker 3 They like to put it up the places and look around.

Speaker 18 Yeah, or down the places and look around.

Speaker 15 Down and up through all the ends. Yes.

Speaker 17 Very good. That's what I do.

Speaker 2 He's a gastroenterologist. Thank you.
And so he comes into Neil's office and he's like, hey, man.

Speaker 2 No, it's probably more like, excuse me, Dr. Thies.

Speaker 18 We've got this new scope.

Speaker 29 Until now, gastroenterologists were often in the dark.

Speaker 2 A very fancy endoscope.

Speaker 28 Basically, a miniature microscope.

Speaker 29 Enabling you to see what you've been missing so far.

Speaker 23 So you can see cells and a living person.

Speaker 29 With real-time microscopic information critical to their decision-making process.

Speaker 23 And it was showing us something that we didn't understand.

Speaker 2 In particular, particular, it was showing them something in.

Speaker 11 The bile duct has arrived. The bile duct.

Speaker 10 The bile duct.

Speaker 2 So the bile duct is this tiny, tiny organ.

Speaker 5 It looks like just a tube.

Speaker 2 We looked at it with Neil.

Speaker 5 I don't know, three inches long, two and a half, three inches long.

Speaker 2 It's like a piece of spaghetti.

Speaker 10 Oh. Like a little piece of spaghetti.

Speaker 2 Why would call it more ZD? A dried ZD, little mini ZD.

Speaker 9 Where is the bile duct?

Speaker 18 Sort of if you go about

Speaker 18 three or four inches above your belly button, straight in.

Speaker 12 And what does the bile duct do again?

Speaker 2 So the bile duct takes bile that your body produces and it sends it to your small intestine to help with things like digestion and to fight off toxins.

Speaker 10 Okay.

Speaker 2 So a super important organ.

Speaker 17 It's purely a passive tube, but it does a lot of important things.

Speaker 2 So when patients come in and have something like abdominal pain or the whites of their eyes are yellow or maybe their skin is itchy.

Speaker 17 One of the causes of problems like that is a narrowing in the bile duct, which could be benign or it could be cancerous.

Speaker 2 So the patient gets sent to David's OR.

Speaker 23 And then we give the patient an injection of something called...

Speaker 28 This is fluorescent. Fluorosine.

Speaker 2 This is actually what the microscope sees, this fluorescent liquid.

Speaker 30 It will distribute itself through the blood system and fluid spaces within seconds.

Speaker 2 It basically lights up wherever there is fluid in your body. And then after the shot, David grabs his fancy scope.

Speaker 22 So it kind of just looks like a big black hose.

Speaker 17 It's about as thick as your finger.

Speaker 3 With a flashlight at the end.

Speaker 2 And then,

Speaker 2 he threads the scope.

Speaker 17 Down the esophagus, past the stomach.

Speaker 2 Into the small intestine.

Speaker 11 And into the bile duct.

Speaker 2 So, David and his colleague Petros Benias, they're looking through this new fancy microscope, and they're seeing something they had never seen before. The walls of the bile duct were glowing.

Speaker 28 If you can imagine a sort of honeycomb appearance.

Speaker 2 Where they'd always seen just like a dark wall, there were now these glowing holes where the fluorescent was showing with these little dark fibers around them.

Speaker 28 This nice regular honeycomb shape.

Speaker 12 And this is in patients who have bile ducts that are diseased or

Speaker 10 in a normal bile duct.

Speaker 3 In a normal, healthy bile duct, he was seeing again and again, this honeycomb of lit up holes in the wall.

Speaker 17 Well, why haven't we seen this before?

Speaker 2 And so David took some pictures of the honeycomb.

Speaker 18 We went to Neil and they showed me the pictures and said, look, what is this thing?

Speaker 17 What does this correspond to that you've been looking at for the last 30 years?

Speaker 18 And I was like, I don't know what the hell I'm looking at. I just don't know what I'm looking at.

Speaker 2 I mean, Neil says, like, you know, I've looked at the walls of a bile duct under the microscope an uncountable number of times. And there's no spaces there.

Speaker 6 It's pretty much solid.

Speaker 15 Like a dense wall.

Speaker 2 So he's looking at all these lit up holes, thinking.

Speaker 24 This doesn't make any sense.

Speaker 18 Really intense cognitive dissonance,

Speaker 18 which is a lovely place to be scientifically.

Speaker 10 You know.

Speaker 10 Yeah.

Speaker 18 Well, you know, there's some really important piece here that will make sense of it. Just what is it and how do you find it out?

Speaker 2 So Neil took these images of the honeycomb.

Speaker 18 I couldn't find them in any textbook.

Speaker 2 And he would show them to colleagues on his lunch break.

Speaker 18 And people were making fun of me.

Speaker 9 They were like, Neil, he's just wild about bile.

Speaker 15 People just didn't really care. Yeah.
Yeah. So

Speaker 18 I don't know how long it took.

Speaker 2 But eventually Neil was like, wait a second. When David uses his new scope,

Speaker 2 he's looking at live live tissue.

Speaker 18 All the tissue I see is dead.

Speaker 18 So a specimen comes down from the operating room. So

Speaker 2 whenever an organ lands on the lab desk of a pathologist.

Speaker 18 So you drop it in formaldehyde.

Speaker 2 You do all this stuff to it.

Speaker 18 And you wash it.

Speaker 2 Dip it in alcohol.

Speaker 18 Put it into wax. Because you're mummifying it.

Speaker 2 You're dehydrating it.

Speaker 18 You're turning it into a mummy of itself.

Speaker 2 Then you shave off a super thin slice of it.

Speaker 18 And put it under the microscope.

Speaker 2 Neil showed us a slide of the bioductor.

Speaker 17 And now, see all these cracks?

Speaker 5 Yeah.

Speaker 2 You see all these faint little cracks in the wall.

Speaker 17 He always thought they were cracks.

Speaker 2 Now, in medical school, Neil and everybody else was taught that those cracks were caused by the heating and drying process of just making the slide.

Speaker 2 So for 30 years, he had ignored these cracks, thinking they were just an artifact of the process.

Speaker 10 But they're not.

Speaker 2 But after seeing David's pictures of the live tissue and then studying different samples that had been frozen rather than dried out, he realized those cracks.

Speaker 18 They're the remnants of the living spaces.

Speaker 2 They were what was left behind when the holes of this honeycomb dried out and would sort of collapse on itself.

Speaker 2 It's sort of like, have you seen those tiny little sponges that are dehydrated and then you put them in water and they go like

Speaker 12 the ones that are shaped like a dinosaur or something?

Speaker 10 The ones that are like a pellet and then it's like, whoa, it's a dinosaur.

Speaker 16 Right. Yeah.

Speaker 2 So you can think about the way that slides have been being made for like 100 years, like the pellet. That's what they've been looking at.
Oh.

Speaker 2 But with David's scope, they were seeing the pellet expanded into the sponge form full of holes, which is how the walls around a real living bile duct actually look.

Speaker 18 And so we realized bile ducts are not like anything we thought they were.

Speaker 10 Huh.

Speaker 3 Which, you know.

Speaker 18 Who cares about the bile duct, right?

Speaker 3 Who actually cares that the bile duct is encased in a spongy honeycomb wall?

Speaker 10 Big deal. But

Speaker 2 this is where it gets interesting.

Speaker 18 So within days, Neil is back to doing clinical work.

Speaker 11 And he started to look at tissues that he sees every day, but now with a new eye.

Speaker 2 So one day he gets sent a breast.

Speaker 18 From the woman who had breast cancer and had to have a breast taken off. And the breast always comes with a portion of the skin.

Speaker 2 So Neil did his thing.

Speaker 18 Formaldehyde, alcohol, wax.

Speaker 2 Took some of the healthy skin, put it under the microscope, and saw...

Speaker 18 It had the same cracks.

Speaker 18 So that was exciting.

Speaker 2 And it wasn't just the skin. He was seeing those cracks in the collagen, around the stomach, around the colon.
There are cracks. Tiny little cracks in a dense wall.

Speaker 18 It's not just the bile duct. Okay, now that's more interesting.
So I called the guys and I showed them and it was like, oh, this is really cool.

Speaker 17 And Neil, of course, being Neil, said, how about we use the fancy endoscope?

Speaker 2 On him.

Speaker 2 To see if the places where you're usually seeing cracks might also, not dried out, have this network of fluid-filled holes.

Speaker 18 Do it on me.

Speaker 15 Well,

Speaker 17 we have scopes that can go lots of interesting places.

Speaker 2 david said that in order to do the stomach and the colon you'd have to knock neil out but well why don't we look at the skin so we injected my vein with the dye fluorosine and david just took the scope just holding it ran it across neil's skin scanned his skin and sure enough so is that it are we looking at it right now that's it yeah yeah yeah Wow.

Speaker 10 There it was.

Speaker 23 The white spaces are fluorosine.

Speaker 14 Like the bright orbs.

Speaker 3 We actually went up to David's OR at New York Presbyterian Hospital so we could do this on Jen.

Speaker 10 Oh,

Speaker 10 that's awesome.

Speaker 19 Really? They scoped you?

Speaker 10 Yeah, it was like, it was the coolest thing.

Speaker 6 And they saw the honeycomb fluid thing?

Speaker 2 Exactly. They could see it in me, like right away.

Speaker 11 Wow.

Speaker 2 Anyway, David and Neil had now seen these honeycomb holes in the walls around the bile duct and around the skin cells.

Speaker 2 And because they knew that all these other places had the same cracks, it seemed like this honeycomb was probably surrounding all of our organs, which raised a pretty simple question.

Speaker 18 You know, it's just, what is it?

Speaker 2 What is this structure they'd never noticed before?

Speaker 31 So. Okay, so they phone a friend, Becky Wells, professor of medicine at the University of Pennsylvania.

Speaker 2 So Becky does a lot of research into how organs like hold their structure and their shape.

Speaker 31 So the body is made up of cells, but there has to be something in between cells and around cells to keep it all together.

Speaker 2 For example, if you think about an organ like the bile duct.

Speaker 31 You know, you can't just have a little layer of cells floating around in the middle of the abdominal cavity. It would, you know, things would leak out.
It would be very unstable. It'd be very fragile.

Speaker 31 So the bile duct actually has layers of collagen to keep,

Speaker 31 you know, to keep the bile duct together.

Speaker 2 And you'll find this throughout the body, not just around the bile duct, but like in the spaces around and between most of our organs, there's this. sort of thick woven mat of collagen fibers.

Speaker 31 Exactly. You know, a very dense layer of collagen that served as a barrier.

Speaker 2 But now, here, Neil had these pictures of these holes in the barrier, and he was so excited, he actually threw his slides into a backpack and hopped on a train down to Philly to Becky's lab.

Speaker 31 He came down, yes, exactly.

Speaker 2 And Becky has some really cool instruments in her lab, including a microscope that could take a set of flat slides and turn them into a 3D image of that specimen.

Speaker 31 And we sat at this microscope in this completely dark room.

Speaker 2 And they turned it on.

Speaker 31 And what we could see was it was almost like waves of hair, which was the collagen.

Speaker 2 But now in 3D, they could see it was actually like a network of tubes.

Speaker 31 And we just start, you know, yelling and high-fiving each other. Yeah.
Yeah.

Speaker 12 And

Speaker 15 why?

Speaker 2 Well, because as far as Neil could tell.

Speaker 18 That meant that every collagen layer in the entire body,

Speaker 18 the dermis, the wrappings of all your muscles and your bones, the collagen that wraps around every artery and every vein, the collagen that gives structure to every visceral organ, your lungs, your heart, your liver, your kidneys, your pancreas, your GI tract, fibrous coverings inside your skull around the brain, the fibrous coverings around the nerves coming into the brain and going out of the brain.

Speaker 2 All of these places throughout the body that they'd always thought were just solid structural stuff were actually shot through with little tubes and tunnels.

Speaker 24 And inside of those tunnels,

Speaker 2 there was this fluid. Eventually, they got a hold of some of the fluid.

Speaker 18 It's clear, but a little yellowy.

Speaker 15 Sort of like egg whites.

Speaker 31 So we have a colleague of Neil's analyze it to see what's actually in it. And they discover this fluid has water, glucose, insulin, hormones, proteins, and hyaluronic acid.
H-A, or hyaluronic acid.

Speaker 12 Never heard of that.

Speaker 2 Well, if you're a woman, you probably have because...

Speaker 25 It's the skincare ingredient that everyone is searching for.

Speaker 2 You've been marketed on Instagram that you should buy it because it'll plump up your skin.

Speaker 32 And reduces wrinkles for younger looking skin.

Speaker 31 So when people get injections, you know, to plump up their cheeks or whatever, a lot of times it's hyaluronic acid because that, you know, sort of functions like a pillow under the skin, for example.

Speaker 31 But we realized that hyaluronic acid would be a fantastic marker to map out where the fluid is going, if it's going anywhere.

Speaker 18 So here's hyaluronic acid.

Speaker 2 So they used a stain that could show them where the hyaluronic acid was, which could show them where the fluid was moving.

Speaker 18 There are all these little brown lines.

Speaker 24 That have this sort of flow.

Speaker 18 That's the hyaluronic acid. Like little tiny tributaries.

Speaker 2 From tissue to tissue, from organ to organ.

Speaker 18 Reaching bigger streams that come together in big rivers.

Speaker 17 It's this vast fluid highway through the body.

Speaker 18 that travels between organs from one organ to the other.

Speaker 2 Connecting everything to everything else.

Speaker 17 Throughout the body.

Speaker 2 And they eventually figured out 25% of the fluid going through our body is this stuff.

Speaker 2 25% of the liquid in our body is flowing through this.

Speaker 13 And they had no idea what it was or that it existed.

Speaker 12 Wait, and what percent is blood?

Speaker 2 So we don't know the exact number, but it's less than that.

Speaker 15 Less than that?

Speaker 3 It's like four. So it's four times the amount of blood.

Speaker 6 Four times the amount of blood.

Speaker 10 Four times, and also

Speaker 12 sorry, as you mention it like that, like because the circulatory system has a heart, which is like pumping stuff through.

Speaker 12 Like, what's the mechanism of stuff getting for, yeah, and like, what's the directionality? And what's yeah, and like, why wouldn't it just all settle in your feet or something, that kind of thing?

Speaker 12 Yeah.

Speaker 18 What I think we're about to show, we're working on this, is that the spaces around the heart have fluid in them. We know that.

Speaker 18 So when the heart contracts to push blood out the left ventricle, the spaces surrounding the heart get relaxed and fluid flows into them.

Speaker 25 And then when the heart relaxes, the spaces around the heart get a little tighter and the fluid flows out.

Speaker 3 That is the thinking. And they think a same thing might be going on with the lungs because the lungs also expand and contract, expand and contract.
So anyway, just a very quick recap.

Speaker 3 This tissue that everyone thought was dense like a wall and totally passive is almost like alive. It has fluids.
It has a bumping.

Speaker 15 Crazy.

Speaker 12 The walls are juicy, is what you're saying.

Speaker 2 It's a juicy wall. It's pumping everywhere that they didn't even know.

Speaker 3 And it seems to be a system, like a unified body-wide system similar to the nervous system or the circulatory system that they had totally missed.

Speaker 31 I started thinking that my understanding of anatomy was extremely incomplete.

Speaker 6 And so they're like,

Speaker 3 we got to publish. We got to publish.

Speaker 18 Now the question is, what do we call it?

Speaker 2 And they call it the interstitium.

Speaker 12 The interstitium.

Speaker 2 What comes to mind when you hear that word?

Speaker 12 Well, I mean, if I'm being honest, that's if I was making up a fake organ, like maybe that's the thing I would say.

Speaker 2 Okay, fair enough.

Speaker 2 But for me, like, I don't know. I think it's actually really evocative.
Maybe because I'm someone who like lives my life professionally between many different worlds and ways of thinking.

Speaker 2 Like, I like how it evokes spaces that are unseen and

Speaker 2 in between.

Speaker 2 But there's still this overarching question.

Speaker 15 What the is it doing?

Speaker 2 There's that noise.

Speaker 6 Sorry, in my background, it was my, I had a calendar update come on again.

Speaker 3 And we will try to figure out what the understitchium is doing after this short break.

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Speaker 32 This month on Explain It To Me, we're talking about all things wellness.

Speaker 32 We spend nearly $2 trillion on things that are supposed to make us well: collagen smoothies and cold plunges, Pilates classes, and fitness trackers. But what does it actually mean to be well?

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Speaker 3 Radiolab, Lulu here with Jen. Hello, hello.

Speaker 9 And Latif.

Speaker 10 Hello.

Speaker 3 Okay, when we left off, we had just learned about this secret inside the human body, this piece of anatomy, a system, a human body part that nobody had noticed.

Speaker 9 until like five years ago.

Speaker 2 Well, not nobody.

Speaker 3 Okay, it might not be nobody. Okay, okay.

Speaker 6 Well, tell that story.

Speaker 2 Explain that.

Speaker 18 So my real job,

Speaker 18 this is the fun fun stuff, is liver pathology.

Speaker 33 A group of scientists believes it's discovered a fluid-filled tissues that makes up a previously unknown organ.

Speaker 18 Our interstitium work broke. And shortly after Neil was in China doing collaborative stuff about liver disease.

Speaker 2 And some of the scientists and doctors there were like, hey, can you present on this interstitium stuff?

Speaker 18 And I said, sure.

Speaker 2 So he gets to the stage, he gives his presentation. And after he's done, a very high-level physician in China.
Trained in Western medicine and traditional Chinese medicine.

Speaker 18 He was given the first question, and his first question was: what has been the response to this work of yours? And I said, well, blah, blah, blah.

Speaker 33 Scientists have expressed skepticism that the interstitium is its own organ.

Speaker 2 Like the science world was arguing about what to call this thing.

Speaker 18 Is it an organ? Is it a tissue? Is it a system? But whatever it is.

Speaker 33 Med school anatomy books may soon include a new chapter.

Speaker 2 People are talking about this new exciting thing.

Speaker 18 And he said, well, we've been talking about it for 4,000 years.

Speaker 2 Because traditional Chinese medicine has been working with fluid and channels and energy and systems throughout the whole body for thousands of years.

Speaker 2 Now, we couldn't find that doctor at the conference, but we did find another doctor in China who also had a strong reaction to the interstitium.

Speaker 19 Okay. Wow.

Speaker 2 His name is Kyusheng Chen.

Speaker 26 So, our professor, Professor Chen, is not a smart ass, and he didn't have the reaction be like, da.

Speaker 2 So, we talked to Q Sheng through the help of a translator.

Speaker 10 Wow,

Speaker 26 I don't even understand what it is happening in Chinese.

Speaker 10 Like, I'm mind-blown.

Speaker 2 So, Q Sheng is a professor at a veterinary school in China.

Speaker 2 And he does a lot of research on the kidneys of camels, animal tissue,

Speaker 19 the

Speaker 16 lungs of yaks.

Speaker 10 Yes.

Speaker 2 And apparently, female turtles that can store sperm in their tissue.

Speaker 26 For up to one year long.

Speaker 10 What?

Speaker 26 And they can still be fertilized.

Speaker 15 Whoa, that's wild.

Speaker 10 Yeah, yeah.

Speaker 2 But anyway,

Speaker 2 in 2018, he's on an airplane flying somewhere for work and he comes across the interstitial paper.

Speaker 2 And he suddenly had this kind of memory of being a little boy.

Speaker 24 He grew up in a rural village in China.

Speaker 26 One day he had something that gave him food poison and it was so bad

Speaker 26 that he was having breathing problems.

Speaker 2 So his parents took him to go see a doctor

Speaker 2 who gave him acupuncture.

Speaker 2 And he had been given like a few needles on his hands, on his legs, and then he kind of like instantly felt this relief. Like

Speaker 5 sort of he sort of blushed.

Speaker 19 He was like, it was kind of like, I just took like a fart in and then like, you know,

Speaker 2 like a fart in that the sense of like this instantaneous, like the discomfort just went away. Yeah.
It wasn't actually a fart, but it was, it was a feeling of, you know, like total relief.

Speaker 2 So he's on a plane reading about the interstitium, and he was just like, God,

Speaker 2 like, it resurfaced that question he'd been carrying in his body since he was that little boy, which was like, How did that work?

Speaker 2 So he starts reading about meridians, which are basically the network of acupuncture, the pathways in the body through which life energy known as qi flows.

Speaker 26 That's according to this book called

Speaker 26 from 2005 years ago.

Speaker 2 So he picks this pathway, this meridian, that is known to help with the gut.

Speaker 2 And he can't actually do the experiment on people because it wouldn't be ethical. So he has to do it on animals.

Speaker 12 Wait, wait, wait. Is animal acupuncture a thing?

Speaker 10 I know.

Speaker 3 I didn't. Well, I didn't know that until reading this paper.

Speaker 2 I had no idea. My 14-year-old dog, we just took her to the doctor, and they're like, you could take her to acupuncture.

Speaker 10 Yeah.

Speaker 24 Really?

Speaker 16 she's got arthritis in her hind legs and the idea is like it's it's it's like the same networks and pathways isn't it yeah pretty much huh who knew okay

Speaker 2 but so

Speaker 2 q shang got some rabbits 24 rabbits then gave the rabbits colitis colitis yes yeah

Speaker 2 it's this disease that affects aligning the colon so these rabbits they're bleeding you know they're having like little ulcers they're losing weight rapidly they're not doing well. But then

Speaker 2 he takes these little tiny needles and puts them into like the joint around the rabbit's like leg, like its knee, and the acupuncture works.

Speaker 2 Like the inflammation gets better, the bleeding reduces, they start getting weight again, like they're better.

Speaker 26 And some of them are just all good, brand is new, totally cured, just returned to normal.

Speaker 10 Yeah, wow.

Speaker 2 So then he uses the interstitial paper almost like a map

Speaker 2 to see if he can find anything in the interstitium that's happening that could explain this.

Speaker 2 And he finds

Speaker 26 telecite.

Speaker 5 Telecyte.

Speaker 2 These cells. Oh, telecytes.

Speaker 7 Yes.

Speaker 2 Telecytes, yes. Called telecytes, which are a newly discovered cell.

Speaker 26 That is just one of the residents that lives in introstitium.

Speaker 2 People aren't quite sure what it does. It seems to have some role in immune response regulation, some role in like cell-to-cell communication or signaling.

Speaker 2 But what he saw was that in the rabbits who got acupuncture, their telecytes were like super activated. They were like throwing off chemical signals, talking to each other.
They were just more active.

Speaker 12 So the telecytes are always there in the interstitium, but at least in these rabbits, when they got acupuncture, they're on hyperdrive.

Speaker 10 Foom, foom, foom. Yeah, yeah.

Speaker 3 So I was excited by it. Like there are people in China who are really excited by it.
Does he feel like he has glimpsed the meridians that were proposed by Chinese medicine?

Speaker 5 Because this feels big. Like this feels very big.

Speaker 10 Yeah.

Speaker 3 But his answer was basically

Speaker 3 all I can say is that we found what we found.

Speaker 26 So I pushed again

Speaker 26 asking if he thinks this is, you know, like still a big thing.

Speaker 15 And he's like, I cannot say that myself.

Speaker 10 So

Speaker 16 yeah. Okay.

Speaker 3 Point taken. So more to learn.
He's excited by what he saw, and he offers it.

Speaker 10 to the world to learn more.

Speaker 12 Yeah, because it's true. He hasn't found where they're going or coming from or if they're what they or exactly what they do.

Speaker 10 Yeah.

Speaker 18 But when it comes to the body and modern approaches to health and healing.

Speaker 2 Neil says Western medicine has always had a difficult time talking about or understanding things like acupuncture.

Speaker 18 Because there was no Western style anatomy to explain those clinical impressions, those personal experiences.

Speaker 2 And Neil said, even though we don't know how the interstitium might be a part of acupuncture, at at the very least, it provides a cultural bridge to allow people to have these discussions.

Speaker 2 Which is kind of exactly what happened with Q Shang, who said that to him, when Neil and the team found the interstitium,

Speaker 32 they found the body, but they didn't find the soul.

Speaker 2 They didn't find like the meaning, the reason why it's doing what it's doing, what animates it, what is its purpose.

Speaker 2 But they gave him a place to look and a place to bring these different ideas, these ancient, time-tested Eastern ideas together alongside modern Western medicine.

Speaker 18 And my hope is, bit by bit, this community will be talking to people in the Chinese medicine community and the Tibetan medicine community and Ayurvedic medicine, because we're all talking about the same body.

Speaker 12 Okay, okay, I get that. I get that.
But can I just say, like, I don't know, like, it feels like we're just learning. And I don't know.

Speaker 12 It's like, it like feels like a jump to rope in this whole other ancient tradition of medicine. Like, like, maybe, like,

Speaker 12 it looks like it has a resemblance, but it seems like it's way too early to go there.

Speaker 3 No? Would you like something that's less of a maybe?

Speaker 10 Yeah.

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Speaker 10 Lulu. Lutiff.

Speaker 3 Radio Lab. And we're back.
Yeah.

Speaker 26 Yeah.

Speaker 2 Okay. I'm excited about this.
Go, Lulu.

Speaker 10 Okay.

Speaker 15 So.

Speaker 37 How is everything?

Speaker 16 We should be

Speaker 16 ready to go. Great.

Speaker 3 At the very last minute, Jen couldn't make this interview, but I talked to this guy.

Speaker 37 Yeah, my name is Peter Friedel. I'm a medical doctor by training.

Speaker 3 His name is Peter Friedel. For a long time, he was a dermatologist.

Speaker 37 But then discovered that maybe science is what I am best at.

Speaker 3 Basically, he had seen so much skin cancer, melanoma. He'd seen so many people dying.
And so

Speaker 3 he became a scientist. He kind of left practicing medicine behind and he became like cancer scientist.
Cancer scientist. Yeah.
And so he.

Speaker 37 At the end of the day, I switched from applying knowledge to generating knowledge.

Speaker 3 And he was curious about like basically one of the most fundamental mysteries of cancer, which is how does it metastasize? Like how does it show up in the skin?

Speaker 37 And then at some point shows up in lung or liver or the brain.

Speaker 15 Like how does it spread?

Speaker 3 Yes, exactly.

Speaker 3 All throughout the body yeah so it was known that obviously once cancer gets into the blood or the lymphatic vessels it spreads all over the body and then you have to resort to chemo and things can get really really bad but what was not known was how exactly cancer goes from like your skin tissue to a blood vessel or a lymph vessel.

Speaker 9 That's hard?

Speaker 12 Like it's like harder than you would think.

Speaker 3 Yeah, because even though that might be a tiny little journey.

Speaker 37 A couple of microns, maybe millimeters.

Speaker 3 From the point of view of a cancer cell, like that journey is huge.

Speaker 37 And a very tough one.

Speaker 3 Because to a cancer cell, your body's tissue is like a thick, dense jungle.

Speaker 3 So basically, there was a hunch for a long time of how it worked. It was thought that tumor cells come tearing through tissue with, he calls them bazookas.

Speaker 37 Bazookas or bush knives.

Speaker 27 Like machetes.

Speaker 37 And scissors. All sorts of scissors.

Speaker 3 To get through this tissue.

Speaker 37 In order to move.

Speaker 3 So that they can bushwhack their way to a a vessel and then to the rest of your body.

Speaker 37 So this was the premise.

Speaker 3 And why was that the premise?

Speaker 37 Well, we saw that cancer cells in the Petri dish, they cut everything into pieces.

Speaker 3 He says, like, you can throw cancer cells and tissue cells into a Petri dish.

Speaker 37 And come back after the weekend.

Speaker 3 And the cancer will have ripped up. that tissue.

Speaker 37 And so all big pharma were on it.

Speaker 3 Peter says that's where millions of dollars of clinical trials of cancer research was focused in terms of like, okay, that's that's how it moves through. So what do you need to do?

Speaker 3 You need to disarm the cancer cell. But turned out, even if you give medicine to people that takes away the bazookas, the bush knives, the tumor cells still invade perfectly.

Speaker 3 Which was totally puzzling because they knew these cancer cells have these weapons at their disposal, but it was like they didn't actually need them to spread.

Speaker 37 And discovering that was like hundreds of million dollars were burned.

Speaker 3 Devastating to the cancer research field. I mean, it was decades of drug development, of clinical trials, of hope poured into this type of treatment.

Speaker 37 And people took a step back and wondered, okay, what did we get wrong?

Speaker 3 So early 2000s, Peter makes this jump into science.

Speaker 3 And he figures rather than studying what cancer does in a Petri dish, what he really wants to do is figure out a way to watch in real time how a cancer cell moves

Speaker 10 in the body.

Speaker 3 So what he does is he gets

Speaker 3 all these mice and then we take a mouse, cut a little hole into it, into the skin on its side, and build a frame out of plastic into this hole. And then into that, they put this little piece of glass.

Speaker 37 The glass of an aquarium, so you can look through this glass into the living tissue.

Speaker 10 Wow.

Speaker 3 Yeah. And then They take that mouse and give it a skin tumor, melanoma, and a sleeping pill.

Speaker 37 The mouse falls to sleep for three or four hours.

Speaker 3 They put the mouse on its back underneath.

Speaker 37 Like a big, huge microscope.

Speaker 14 A microscope so powerful it is the size of a room.

Speaker 10 And then

Speaker 3 they looked into the microscope through the glass portal into the mouse.

Speaker 37 And it was spectacularly colorful right from the beginning.

Speaker 3 So imagine all the skin tissue of the mouse was blue.

Speaker 15 Like a blue jungle of skin tissue.

Speaker 3 And then the cancer cells,

Speaker 3 they were like these green little dots.

Speaker 37 And the green dots were moving.

Speaker 3 But what surprised Peter was that the cancer cells weren't moving like some wild horde blowing up tissue wherever they could.

Speaker 37 They were moving like a fluid almost.

Speaker 5 Instead, they were lining up.

Speaker 37 One after the other or neighbors even together holding hands.

Speaker 14 And streaming through

Speaker 3 the mouse's skin. Basically, the cancer cells were finding little channels in the tissue where they could just zoom through it and get to

Speaker 3 a vessel.

Speaker 37 In a way, it seemed to be like a highway type system that the cells were exploiting.

Speaker 3 And what were you thinking in that moment?

Speaker 37 Oh, this is interesting. Let's, can we, can we observe it a little longer?

Speaker 3 So you're just like, you're just like fascinated.

Speaker 20 Yeah, absolutely.

Speaker 37 It's like a child

Speaker 37 in a reef. with all the fish and all the structures.
It's like fascination pure.

Speaker 3 Because remember, he's seeing this a few years before Neil's and Becky and David's paper comes out. So he still doesn't,

Speaker 3 this idea of a unified system

Speaker 3 that isn't out in the world. But he is seeing the interstitium, like the channels of the interstitium.

Speaker 12 So what did, without that information, what did he think? He thought that the cancer cells were making this channel?

Speaker 3 No, no, no. He can tell that the channels are in there in the skin.

Speaker 3 So after the kind of transfixed awe wore off, we thought, holy shit, if every tissue has these channels, how are we ever going to be able to stop the spread of cancer?

Speaker 37 There are too many channels.

Speaker 37 This is, it's like, it's, it's, it's endless.

Speaker 3 Like, there's just no way.

Speaker 37 It's clear we're not going to stop them.

Speaker 3 And so for years,

Speaker 3 Peter just sat staring. at these cancer cells moving through these highways,

Speaker 3 feeling hopeless.

Speaker 3 Until one day, he was like, What if we forget about the highways, trying to block them or stop them, and instead just go after the cancer cell?

Speaker 24 And kill it.

Speaker 3 So, what he does is he goes back to these mice and he just

Speaker 3 blasts the cancer cells with radiation. And what he discovers is that the only cells that survive the blast

Speaker 3 are the cells that are running through the interstitium. So, Peter starts pulling these cancer cells out of the mice.

Speaker 37 To find what makes the marathon runner special, different from the rest. And what he finds is that these marathon runners, they are smart, opportunistic creatures.

Speaker 3 Rather than deploying these bazookas to rip through tissue, they have these little claws that they use to get into the interstitium and move through it.

Speaker 3 And they can also use the claws to like fuel up in a way that makes them grow bigger and stronger and and harder to kill.

Speaker 37 That's already bad news, but it also is good news because if you now know what makes them special, you can take it away.

Speaker 3 Fast forward, Peter develops these antibodies that basically declaw the cancer cells. And he gives these antibodies to the mice.

Speaker 37 And you give radiation therapy at the same time. The marathon runners melt away and they die.

Speaker 37 And we can cure the mice even in tumors that otherwise are not curable.

Speaker 37 So we could, and we also followed those mice up for half a year to check whether cells had made it out into the lungs or the liver or somewhere else. And nine out of ten mice were clean.

Speaker 10 Whoa.

Speaker 37 So that means we not only we didn't need to block the roads, we bombarded the cars in a good way.

Speaker 3 And he said the difference between that and chemo, where you just flood the body

Speaker 3 with everything

Speaker 3 is like a huge world of difference, obviously, because you're not targeting the sick person's own immune system.

Speaker 2 I'm like finding myself getting

Speaker 2 emotional about this.

Speaker 2 Why?

Speaker 2 Because my mom passed away from

Speaker 2 cancer, from lymphatic leukemia and lymphoma, which are system-wide.

Speaker 2 You know, that means they've gone through the whole,

Speaker 2 they're everywhere, you know, and she got chemo and she had, she had too many white blood cells and the chemo, they were too aggressive with it and they knocked out so many white blood cells, you know, like you said, they just blast everything that then they couldn't,

Speaker 2 the white blood cell count couldn't get high enough to fight it anymore.

Speaker 24 Like they overshot it.

Speaker 15 Oh my god.

Speaker 10 Oh my God.

Speaker 3 Is that what, because I know she lived with it for a long time.

Speaker 5 She did.

Speaker 2 It was a chronic lymphatic leukemia, leukemia, which, you know, is better than the acute, where people can pass very quickly. It's really aggressive.
But

Speaker 2 it was really the chemo that ultimately killed her. And I think just hearing

Speaker 2 about

Speaker 24 Peter's work and

Speaker 2 I don't know, it gives me like a little hope.

Speaker 3 And I should say that Peter said this strategy of using antibodies and radiation.

Speaker 37 Whether then it is making it all the way into the clinics, as we know, one out of a thousand initially proposed strategies will make it to the patient.

Speaker 15 So

Speaker 16 we will have to see.

Speaker 3 It'll have to go through years of development, of trials in humans.

Speaker 37 But at least proof of concept we made, we delivered.

Speaker 3 And that's what feels big because what Peter was finding in mice.

Speaker 15 Tissues.

Speaker 18 So this is a slide of breast.

Speaker 3 Neil and Becky are now seeing in humans.

Speaker 18 And here are cancer cells walking along through the interstitium like they've got a nice little path to follow through the woods.

Speaker 18 Here they are and just marching from the interstitium to get to the lymph nodes.

Speaker 2 Yeah, so Neil and Becky, I kind of think of them as like these cartographers where they're essentially trying to make these maps.

Speaker 18 Of every single organ.

Speaker 2 Of like where the interstitium is.

Speaker 22 Where would it be in the womb?

Speaker 10 And where it isn't.

Speaker 33 There's very little, actually.

Speaker 18 It's interesting. This is one of the areas where you don't see a lot of interstitium.

Speaker 2 And it's like they are publishing as fast as they can.

Speaker 18 We've got six papers that are heading their way towards publication.

Speaker 2 And they're not claiming to know what the interstitium does or is doing throughout the body. They're just like, here are the maps.
Now, all these different fields, do with it what you will.

Speaker 2 So obviously people who are interested in acupuncture pick this up.

Speaker 18 But there's a lot of people who are focused on primarily Alzheimer's research.

Speaker 2 They've been interested in the interstitium in the skull.

Speaker 31 Neil and I both participated in a conference at the National Institutes of Health in this spring on the interstitium as it relates to the kidney.

Speaker 2 There's people looking at kidney function, there's people who hope the interstitium might help.

Speaker 31 On understanding metabolic diseases like diabetes, understanding bacteria in the body, how infections might spread in places even like your mouth.

Speaker 31 I gave a talk about this at the PennDental School, and you know, there's a lot of bacteria in the mouth, right? But

Speaker 31 we we don't know. I mean, it's, it's sort of wide open right now.

Speaker 12 Huh. It's just sort of amazing to think like this little microscope goes into the body and then opens up this whole new realm that we're just, you know, just beginning to learn about.

Speaker 12 Like, this is my favorite kind of technology story where it unlocks a whole new part of our world and literally a whole new part of ourselves that we just could not have seen otherwise.

Speaker 15 Well,

Speaker 10 about that.

Speaker 5 Turns out you didn't actually need the microscope.

Speaker 12 Wait, it's not naked eye visible, is it?

Speaker 10 No.

Speaker 10 It is?

Speaker 19 Really?

Speaker 2 So.

Speaker 18 So now what I'm going to show you, we have cut, as I said, we cut open the small intestine and the wall of the stomach.

Speaker 2 Now, this is kind of like the wildest part of the story for me. So when we were in the lab with Neil, at one one point he takes a cross-section of the small intestine in his hand.

Speaker 18 And you see this.

Speaker 2 And he started pulling at this thin

Speaker 2 like layer of almost like translucent threads encasing the intestine.

Speaker 3 That, that is the interstitium?

Speaker 18 That's the interstitium.

Speaker 10 What?

Speaker 9 Yeah.

Speaker 2 But like that was it. Like that is it.

Speaker 16 Is it okay to get that this close?

Speaker 37 See like here?

Speaker 18 When I pull it, you see little threads sort of getting tense inside there.

Speaker 15 Yeah. Yeah.
there's the interstitial.

Speaker 10 Wow. Yeah.

Speaker 10 So

Speaker 3 I thought this was like a technology.

Speaker 11 No, no, no, no.

Speaker 18 No.

Speaker 3 It's like you got a fancy scope.

Speaker 18 Any new technology that allows you to see things you didn't see before or see them in a different way is going to reveal things you hadn't noticed.

Speaker 18 Some of them may not have been available to your eye. In this case, they were available to our eye.

Speaker 17 But

Speaker 18 we had never put it together.

Speaker 2 And what Neil said was like, no one had put it together because we've been told to discount it.

Speaker 31 You know, we all read the same textbooks and look at the same drawings by the same people to explain what is seen in the human body.

Speaker 2 And all these people had decided that this thready stuff that we were seeing in the body, like, it just didn't matter.

Speaker 24 It didn't do anything important.

Speaker 2 Yeah, we were looking.

Speaker 18 We saw it. Yeah.

Speaker 6 But it had no meaning.

Speaker 2 Or even like Neil, who had been seeing cracks in tissue in slides. He'd been told since med school.

Speaker 18 This is nothing we even have to pay attention to.

Speaker 2 That the cracks in the tissue, they don't matter. Like, don't worry about the cracks.

Speaker 18 And I taught people these were just cracks for 30 years.

Speaker 3 But so it's like when Jen brought this story to us, I originally understood it as like a fancy new technology reveals this body part we've missed forever.

Speaker 3 But it sounds like you're like, no, like, is this actually a story just about beliefs getting in the way?

Speaker 9 Yep.

Speaker 18 Beliefs and training and dogma.

Speaker 18 It comes back to the Shinryu Suzuki Roshi, who was the founder of San Francisco's Ed Center, said that in the mind of the beginner, there are many possibilities, in the mind of the expert, there are few.

Speaker 18 I get choked up.

Speaker 26 Why does that choke you up?

Speaker 18 Because it's so profound.

Speaker 18 What had I been taught that got in the way?

Speaker 18 What am I missing now?

Speaker 3 The story was brought to us and reported by Jennifer Brandell. And before we go, we should say that Jen has one more kind of brain-busting chapter about the interstitium.

Speaker 3 She just published an essay about it for Orion magazine, Orion Magazine. It's called Invisible Landscapes.
Go read it.

Speaker 3 But Jen, can you just give like a cliff's note?

Speaker 2 Sure. Yeah.
So, I mean, truth be told, I'm most interested in the interstitium's metaphorical value.

Speaker 2 Like, if we've missed seeing this thing that connects so many organs in our bodies, like, might we be missing analogous things in society?

Speaker 10 Does that make sense?

Speaker 10 Not quite.

Speaker 3 Say one more beat. Say one more beat.
What is that? So an interstitium in society. Yeah, like

Speaker 2 just briefly, like I mentioned at the top, I'm a person who operates between different organs in society, like, or as we call them, organizations, you know, between journalism, tech, government, democracy.

Speaker 2 And in learning about the interstitium, it was kind of like the skeleton key for me that made me realize that, like, there's this whole invisible thing that has been discounted.

Speaker 2 The people, the roles that do this connective work, and like a kind of work.

Speaker 2 Yeah, it's like a kind of work. It's been ignored.
It's like it doesn't have a job description. It's discounted.
And like, I think it's key to the health of the whole body, like the whole economy.

Speaker 2 And so, in the essay, I give some examples of what I mean.

Speaker 3 Yeah. And I guess I just kind of want to hype you now.
Like, you talk about work you did connecting the city of Chicago during COVID to hospitals, churches, hotels to help people in need.

Speaker 3 It's very concrete stuff. It's really neat.

Speaker 10 Yeah. Yeah.
It's really neat.

Speaker 2 Oh, well, thanks, Lulu.

Speaker 2 I mean, basically, it's just making the interstitium like people visible in society and talking about how the more we value it, the more we notice, invest in it, it could have hopefully positive ramifications for the health of the economy.

Speaker 2 And I don't know, stuff, stuff like that.

Speaker 9 Stuff like that. Go check it.

Speaker 3 Again, it is called Invisible Landscapes, and you can read it at OrionMagazine.org.

Speaker 3 And if you are interested in geeking out in more scientific ideas, Neil Thies, Dr.

Speaker 3 Neil Thies just published a book that is called Notes on Complexity, a scientific theory of connection, consciousness, and being.

Speaker 3 It is really profound and great. Go check that one out as well.
Notes on Complexity by Dr. Neil Thiese.

Speaker 3 This episode was produced by Matthew Kilty with production help from Akedi Foster Keys, mixing help from Arianne Wack, fact-checking by Natalie Middleton, who was edited by Alex Neeson.

Speaker 3 Big special thanks to Jessica Clark, Erin Wickenden, Mada Zapeda, Daryl Holiday, Dr. Amy Chang, Kate Sassoon, Guy Huntley, John Jacobson, The Village Zendo, Scotty G, and

Speaker 3 rest in peace to Mavis, the 14-year-old dog.

Speaker 3 Oh, and before we go, I guess we should just... sign off with what happened after Jen was injected with fluorescent dye to get scoped.

Speaker 3 The doctors told her that if she went to a dance club, she would glow under the black light.

Speaker 3 But instead, she just went home, drank some tea.

Speaker 2 Okay. And I'm just getting back to the Airbnb I'm staying at in Brooklyn, and I have been told that the dye that was injected is gonna make my pee green.

Speaker 10 We're gonna see.

Speaker 28 I have not urinated since,

Speaker 2 well, for a while since the dye was injected.

Speaker 10 So, all right.

Speaker 28 See, here it goes.

Speaker 10 Let's take a look. Whoa.

Speaker 15 Oh, wow.

Speaker 8 It's like highlighter yellow green.

Speaker 2 It's really, yeah, it's like neon greeny yellow.

Speaker 10 It's wild.

Speaker 5 Okay, I'm gonna take a photo. This is what we get to do for work.

Speaker 1 What a privilege.

Speaker 20 Radio Lab was created by Jad Abum Rad and is edited by Soren Wheeler. Lulu Miller and Mattef Nasser are our co-hosts.
Dylan Keefe is our director of sound design.

Speaker 20 Our staff includes Simon Adler, Jeremy Bloom, Becca Bressler, Keddie Foster Keys, W.

Speaker 20 Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhu Nyana Sambadam, Matt Kilty, Annie McEwen, Alex Neeson, Alyssa Jong-Perry, Sara Kari, Sarah Sambak, Ariane Wack, Pat Walters, and Molly Webster, with help from Timmy Broderick.

Speaker 20 Our fact-checkers are Diane Kelly, Emily Krieger, and Natalie Middleton.

Speaker 38 Hi, my name is Michael Smith. I'm calling from Pennington, New Jersey.

Speaker 38 Leadership support for Radiolab science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, Simons Foundation Initiative, and the John Templeton Foundation.

Speaker 38 Foundational support for Radio Lab was provided by the Alfred P. Sloan Foundation.