The Science Of Replacing Body Parts, From Hair To Hearts

FLORA LICHTMAN: Hey, it’s Flora Lichtman. And you’re listening to Science Friday.

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On today’s episode, the science of replacing body parts from hearts to hair.

MARY ROACH: If you take armpit hair and put it on the head– this is a quote from some clinic in LA– it is difficult to style.

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FLORA LICHTMAN: It seems like every week, there is a new headline about some kind of sci-fi-sounding organ transplant– eyeballs, 3D-printed kidneys, pig hearts. In the new book, Replaceable You– Adventures in Human Anatomy, science writer Mary Roach chronicles this effort to fabricate human body parts and why it can be so monumentally difficult. The book does not skimp on the details.

And neither do we. So if you want to hear the nitty-gritty on hair transplants or vaginoplasties, today is your day. And if you don’t, don’t say we didn’t warn you. Mary, welcome to Science Friday.

MARY ROACH: Thank you, Flora.

FLORA LICHTMAN: This is your fifth book on the human body, I think, if I’m counting right. It’s a characteristically wild ride. What keeps you curious about our bodies?

MARY ROACH: Well, they’re just endlessly amazing and weird, I think, is the answer.

FLORA LICHTMAN: [CHUCKLES]

MARY ROACH: I mean, because I didn’t study biology or physiology in any formal way, every time I step into a new system of the body, whether it’s the alimentary canal, the gut, or sexual physiology or whatever it is, I’m just kind of gobsmacked by the stuff that’s going on behind the scenes, behind the curtain.

FLORA LICHTMAN: [CHUCKLES]

MARY ROACH: It’s kind of miraculous and weird but interesting.

FLORA LICHTMAN: Behind the skin drapes, yeah.

MARY ROACH: Yeah, the skin drapes– exactly. [CHUCKLES]

FLORA LICHTMAN: Mary, let’s start with a transplant that, weirdly, is dominating my social feeds right now– hair transplants. What is the state of hair transplant science?

MARY ROACH: [CHUCKLES] Yeah, hair transplants are interesting. The principle by which they work is something called donor dominance. So if you take follicles from the sides or the back of the head where they’re not sensitive to testosterone, they’re not going to fall out.

You put those on the top of the head. Now they’re going to stay permanent. They’re not going to fall out because they retain the characteristics of the back of the head– side and back of the head hair.

FLORA LICHTMAN: They’ve got that back of the head hair identity.

MARY ROACH: Yeah, exactly– exactly. So that’s kind of the principle of it. But over time, of course, if your hairline recedes and it continues behind where the new transplants were, now you’re going to have a bare patch there. So it’s kind of an ongoing relationship between the surgeon and the patient.

And I looked into the history of hair transplants. It began with a surgeon named Okuda. He was a Japanese surgeon. And I found the Okuda Papers. And he was going crazy with the donor dominance.

He was like, you can take chest hair. You can take armpit hair, put it on the head. You can take head hair and use it for pubic alopecia, which I had never heard of. But apparently, it is something that can happen.

FLORA LICHTMAN: That’s such a you book thing, Mary.

MARY ROACH: I know. The Okuda Papers, I was like, wow, he did that. He was like putting armpit hair on the mustache. And anyway, and it works. It all works.

The issue, again, with donor dominance is that say you had head hair in the pubic region. Now you need to trim it. If you take armpit hair and put it on the head– this is a quote from some clinic in LA– it is difficult to style. [CHUCKLES]

FLORA LICHTMAN: You did some self-experimentation for this book on this topic.

MARY ROACH: Yes, I did. Well, when I went out on book tour, I wanted to be able to demonstrate donor dominance. So I was at a hair transplant clinic in Southern California. And I asked if they would transplant a follicular unit from my head to my calf so that during the book tour, I could roll up my pant leg and just show them this long, luxuriant hair that was growing on my leg.

FLORA LICHTMAN: A leg pony, yeah.

MARY ROACH: Yeah, exactly. I mean, I think it had two follicles in it. So it would’ve been two hairs– long flowing hairs. Unfortunately, it didn’t take.

FLORA LICHTMAN: But they did it.

MARY ROACH: They did it.

FLORA LICHTMAN: Like, they were like, oh, sure, we’ll do it on our lunch break.

MARY ROACH: Yeah. Well, what happened, I was donating a dozen follicles to science. So they were studying just the process by which follicles grow from the basic cells– keratinocytes and dermal papilla cells– how do they grow into a follicle, so they could try to match that.

So I said, sure. I will donate a dozen hairs to you and your effort. I have now a little tiny bald spot.

FLORA LICHTMAN: Itty-bitty.

MARY ROACH: Yeah, at the top of my head. And I said, well, while you’re doing this, would you mind putting a few in my leg? And I mean, I explained I really want to be able to demonstrate donor dominance. This is educational.

FLORA LICHTMAN: Anything for sci-coms.

MARY ROACH: Yes, exactly.

FLORA LICHTMAN: –as we say.

MARY ROACH: Exactly.

FLORA LICHTMAN: [CHUCKLES] Let’s talk about Judy. Tell us about Judy.

MARY ROACH: Oh, sure, yeah, Judy is kind of the starting point for this book. She’s a reader who wrote to me going back almost four years now and said, I love your books. And would you write one about professional football referees. I don’t know why she thought that that was a good fit for me. I don’t watch football. I don’t know anything about football.

But anyway, in the course of emailing back and forth with her, she mentioned that she’s an amputee, specifically, elective amputee. It was an elective amputation. She had had spina bifida. Because of a tumor on her spinal cord, her foot was twisted.

She wasn’t able to walk on it the way she wanted to be able to walk on it. She’d had numerous surgeries that weren’t really resolving the problem. And she would see people with a prosthetic lower limb who were hiking and running and doing the things she couldn’t really do. And she was trying to find a surgeon to cut off her foot.

FLORA LICHTMAN: Trying to find a surgeon because it was hard to find a surgeon.

MARY ROACH: It was hard to find somebody because they’d say to her, well, this is a healthy foot. It has a blood supply. It’s not gangrenous.

FLORA LICHTMAN: Mmm.

MARY ROACH: You could just get more surgeries. And it took her years to find someone to do the amputation. And it’s an interesting issue. I mean, there are reasons why surgeons don’t want to do that.

FLORA LICHTMAN: Such as?

MARY ROACH: Such as, what if there’s phantom limb pain? What if the patient sues me? I can’t put this foot back on. It’s just safer to say, let’s try one more surgery, safer in the sense of, am I going to help this patient or make things worse because there’s a certain finality to cutting off a foot.

It’s also you need the insurance to cover it unless the patient wants to pay for the surgery out of pocket. So you would need to make the case that this is necessary, medically necessary. And now, if the foot is not dying, that may be hard to do.

FLORA LICHTMAN: Right. In this chapter, you write about this bias that we seem to have towards wholeness, that a whole body is better than some incomplete body. And as I was reading it, I was thinking that, culturally, like in other ways, we do accept body modification all the time– Botox, collagen, rhinoplasty. And then sometimes, we don’t at all. And I wondered what you made of that.

MARY ROACH: Well, I think we accept it if it’s making us, quote, unquote, “more attractive or more cutting edge or trendy.” I think we don’t accept it as much when it’s perceived as a disability. There are studies that look at limb salvage surgery– in other words, let’s keep the foot.

But let’s just do surgery after surgery after surgery and try and get it to the point where it’s almost as good as new, versus, let’s be realistic that this is unlikely to get to 100%. Let’s amputate now. And the person will ultimately be better off in terms of discomfort and function. And time and again, things land on the side of amputation.

But I think because it feels drastic, no matter how problematic that foot has been, it’s you. It’s you. And now it’s gone. And I think particularly, as an outsider, imagining that when you’re not dealing with the discomfort and the pain of this foot that doesn’t really work, well, you can’t imagine that. You put yourself in that position.

FLORA LICHTMAN: The book is filled with stories. What was your favorite replacement from the book?

MARY ROACH: My favorite replacement? Well, I found fascinating the ones in which some part of the human body is asked to become a different part. And there were a number of those. The body is very flexible, agreeable, you might almost say.

I had dinner with a surgeon at Cedars-Sinai Center for Transgender Health and Surgery. And one of the techniques that is sometimes used– it’s not a common first approach– but to create a neovagina for a transwoman, you can take a section of the ascending colon, I think it was. And you can keep it attached to a blood supply and kind of use it as a vagina and then also do a vulvoplasty. So you have all the other outside components.

But that’s something dating from the 1800s. There were patients who’d had cancer. And there were a couple of surgeons who had tried that. And it does work. Another one that was fascinating to me is that you could use the rectum as kind of a third lung if, in certain situations–

FLORA LICHTMAN: Yeah, tell us about that.

MARY ROACH: Not recreationally, but if you have an infant born very, very premature, so their lungs haven’t developed to the point where they’re really working, that means that you’re going to have to go in the neonatal intensive care unit and to use a ventilator. A positive pressure ventilator on an infant that young, it can damage the lungs. So if you could augment with material through the rectum, which you can, the body, the mucosa will absorb oxygen that way. Then you get a boost.

FLORA LICHTMAN: You can breathe through your butt.

MARY ROACH: You can breathe through your butt is what I’m saying.

FLORA LICHTMAN: [CHUCKLES] That is an a-ha, I would say.

MARY ROACH: You can. Yeah, you can breathe. Somebody told me about that. And I’m like, so it’s going all the way through. That’s just like constant copious farting then? That isn’t easy.

FLORA LICHTMAN: On babies, it’s cute.

MARY ROACH: It’s cute– exactly, exactly.

FLORA LICHTMAN: You know?

MARY ROACH: They get away with it, yeah.

FLORA LICHTMAN: That’s right. Hey, don’t go away because coming up after the break, just how close are we with 3D-printed organs?

MARY ROACH: We’re kind of in the Wright brothers era if you compare it to flight.

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FLORA LICHTMAN: Let’s talk about lab-grown organs. Where are we with that?

MARY ROACH: Well, bioprinted organs– I asked that exact question. I was at Carnegie Mellon, the Feinberg Lab, where they’re doing some very cool stuff printing muscle in particular. And it’s so much more complicated than you would think. It’s not like printing a four-color brochure.

And I said to Dr. Feinberg, well, how long before we’re at the point where we can print an organ that can be installed? And he said, we’re kind of in the Wright brothers era if you compare it to flight.

FLORA LICHTMAN: But that’s a big era, you know?

MARY ROACH: Yeah, and things happened fast between Wright brothers and plane flights. I mean, I don’t have the timeline. But it’s pretty quick.

And so stuff is moving. I mean, he said a couple of decades. And to me, that sounds slow because to me, that’s, well, that’s like three or four books. [CHUCKLES]

FLORA LICHTMAN: [LAUGHS]

MARY ROACH: Whoa, that’s not fast. But then he’s like, things are moving very quickly, two to three decades. No, so with printing muscle, it’s fascinating. You have to align the cells so that they will perform the function for which that muscle was intended.

For example, the heart, and I didn’t know this, when the heart squeezes blood out, it twists slightly, kind of like wringing out a sweater. You get the maximum amount of blood expelled via the musculature contraction. So if you’re printing a heart, say, or a ventricle, you print them in a helix form, as opposed to, say, a hamstring muscle where they’re kind of parallel. So you don’t really think about that.

Plus, you know, you got to feed that muscle. So are you going to print the vasculature? They’re at the point where they’re trying to figure out, OK, how much can we let the body do because the body will grow in capillaries. So some of it, you can get the body to do. But at a certain point, you’re going to have to print those. Nobody’s printing nerves quite yet.

FLORA LICHTMAN: And should I be imagining a 3D printer? Or is this more like a Chia Pet where you have some kind of scaffolding and you sprinkle the thing?

MARY ROACH: No, what I saw, it’s a printer with four extruder heads that can be printing different material, like cellular material in one, extracellular collagen material in another one. So it’s laying down one layer at a time. So it’s a printer.

Feinberg teaches a course where you can take, like, a Office Depot printer. And you can kind of rejigger it to make a 3D printer, so obviously, for simpler things than hearts. But it’s a printer.

FLORA LICHTMAN: I’m assuming the best option for transplants is there are still organ donors, though.

MARY ROACH: Yeah, the best option is right now still a human donor’s organ. One of the things going on that I found kind of exciting, because it’s a little bit simpler than printing something or growing it from scratch, at the University of Michigan Extracorporeal Life Support Laboratory– extracorporeal, meaning outside the body.

FLORA LICHTMAN: It’s a great name for a lab.

MARY ROACH: It is, totally. So one of the things they’re trying to do is extend the shelf life of a donated organ like a heart, say. OK, the traditional method where you put it on ice and you ship it out, you’ve got four to six hours to get it where it needs to go. But they’re looking at tweaking that so that they can extend it to a few days or more, which would be very cool because you could now bring in a echocardiogram machine and take a look at the heart, see how it’s pumping, how well is it, how healthy is that heart.

And if there’s an issue that could be fixed, you could fix it. So right now, there’s a age cutoff because you don’t have time to take a look and see how well it’s working. You basically say, well, these are too old, so we’re not going to take them. But if you could do it based on quality, that’d be helpful. And if you could repair them, that would also be helpful.

FLORA LICHTMAN: The title of the book is Replaceable You. Do you feel like we are replaceable or are parts, anyway?

MARY ROACH: No, the title really should be Irreplaceable You. But it doesn’t sound as good because it’s a play on this song that, of course, nobody who’s younger than 40 is going to know “Embraceable You.” It’s some old kind of standard from way back when that I happened to have heard of. But yeah, technically, the book should be called Irreplaceable You because I tried to find just what’s a simple bit of the body– is there anything simple that we can replace so that it’s 100% as good as what you were born with.

And I thought about, OK, tears. That seems pretty straightforward, like, salt water, a little bit of oil to keep it from evaporating. How hard could that be? And I contacted this researcher who has studied tears for decades. And we went on for two of the free zooms because I’m too cheap to pay for Zoom.

FLORA LICHTMAN: [LAUGHS]

MARY ROACH: We went on for two 45-minute Zooms about the tear film. And I said, so artificial tears that you buy? He goes, well, yeah, those’ll buy you a couple of hours. But they kind of wash away the good stuff.

So no, they’re not a replacement. Yeah, I mean, we as a species have gotten pretty good at coming up with substitutes when things go wrong. But in terms of plugging in something that is as good as what you started out with, I can’t name one.

FLORA LICHTMAN: Mary Roach is a science writer and author of the new book, Replaceable You– Adventures in Human Anatomy. Thanks for coming on, Mary.

MARY ROACH: Oh, thank you so much. That was really fun.

FLORA LICHTMAN: Really fun, as always.

MARY ROACH: Yeah! Yay. OK, thanks, Flora.

FLORA LICHTMAN: Thanks for listening. Don’t forget to rate and review us if you like the show. And you can always leave us a comment on this segment on Spotify. And we’d love to hear from you.

Today’s episode was produced by Rasha Aridi. I’m Flora Lichtman. Thanks for listening.

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