You know, despite many years of practicing medicine and reporting on medicine, I am continuously reminded that the body is still full of mysteries. Remarkable mysteries. We haven't figured out how to stop aging or even why we really do age. We haven't cured cancer. There's really so much about our bodies we don't know. Big fundamental questions. And yet, at the same time, we've made real progress. Progress worth celebrating. We can replace hips and limbs. And heart valves and so much more.

Just the whole notion of replacing pieces of ourselves. How do we do that? Why do we do it? Where are we at?

That's one of my favorite science writers, Mary Roach. You're in for a treat today. For years, she's explored big questions about the human body. She's written about cadavers in her book, "Stiff", the science of sex in her books, "Bonk". Yeah, she comes up with clever titles. And even wrote about what happens to us in space in her called, "Packing for Mars". This time, however, she has turned her attention to humanity's long fascination with replacing body parts and the book is called "Replaceable You". So I really wanted her to come on the show, she accepted the invitation right away, we're going to talk about what breakthroughs are already changing lives, what's still a work in progress, and what it really means to replace parts of yourself that work just as well, or maybe even better. I'm Dr. Sanjay Gupta, and this is Chasing Life.

You're a beautiful writer. It's substantive and yet so accessible and humorous. And I just, you know, the idea, I think sometimes there's the dichotomy between science and humor. And you're like, screw that, man. I'm jumping right over that line and combining those two things. And I love it.

Sadly, the word science makes people run the other way. When it comes to books, they think, oh, this is going to be a slog. I did an event with Gina Kolata, who's this wonderful reporter for the New York Times. We did an even together and Gina said, I loved your book. I thought it was going to be a real slog.

All right.

But you're a science writer.

But that's, I think, how a lot of people think about science books, though, you know? It's like eating a broccoli, you know?

Exactly.

Can you give us a little bit of background just on replacement parts, if you will? Like, how long ago did this start? How did it begin for humans?

Interestingly, if you look up the history of prosthetics, there's some foot somebody found, like a wooden foot, that may predate the noses, but in terms of a substantial number of replacements going on, noses were where it began because nasal mutilation was a form of punishment that sadly was used fairly commonly because it was not just a punishment but also deterrent because your nose is in the middle of your face and everybody sees it. And it's amazing that so far back, like 1500 BC, that there were surgical procedures, taking the flap from the cheek or the forehead and keeping it attached in one part and then swinging it down and letting the capillaries grow in on the nose and then disconnecting it up here or here. Anyway, that blew me away that that far back physicians were crafting new body parts, noses! And then they moved into, of course, the metal or the celluloid plastic.

Tell me about your friend Judy.

Judy Berna, yeah, Judy Berna, she got this whole thing rolling in a way. She's a reader who wrote to me, I guess she must have mentioned that she's an amputee. When I'm in that mode, I'm like, what's interesting in amputation? What's going on? And she said, actually, well, I am an elective amputee, and I hadn't really heard that term. She was born a spina bifida. So, she couldn't walk on it well. She couldn't run well. She just would see people with prosthetic lower limbs doing things she couldn't do. Hiking and running and she just thought, you know, your hip wears out. You get it replaced. Why can't I replace my foot? And I thought that was interesting. That notion of wholeness is something to hold on to even when the wholenes itself becomes a disability.

Yeah, right, the surgeons are reluctant, I think understandably, to remove a healthy limb. But for her, it wasn't functioning, and I printed this out from her website. "I spent almost 30 years hating my left foot, which grew crooked as a side effect of a case of spina bifida. I saw amputees doing things I could never even imagine, like running and jumping. It made me jealous and honestly a bit mad." I thought that was really interesting.

I did too. I did, too. That's where it started. And then I said, what else is going on in this community? And she mentioned osseointegration. Rather than having a socket that your residual limb goes into, you would actually implant the prosthetic right into the bone, similar to a dental implant. You're screwing it into the bones and you have much better control. You have sensation of where you're walking through the bone, you know, through the skeleton. So people are talking a lot about that in the amputee community, but there's just been a problem with infections, you know, getting into the bone. And so it's not quite there yet. So those were the things she was telling me about. And then she said, the amputee coalition has an annual conference. And why don't you just come along and talk to people? And I did. And that was fascinating.

And that was really the genesis of this book?

That's where it started, yeah, absolutely.

I think in Judy's case, anyone who reads about her, I feel like you could sort of in your own head get your mind wrapped around the idea that her left foot was not functioning well for her, and she saw what a functioning foot could do for her in terms of hiking, running, jumping, things like that. That makes sense. You get to this point in the book, I think it's around page 100, I made some notes. And you say the better prosthetics become, the easier it will be to make a case for elective amputation. And I wanted to talk about that a little bit because I think that's maybe what some of the surgeons who are reluctant to perform an amputation on what they would call a healthy limb, that's what they're sort of getting at, is that does this become a slippery slope? Do we start, as prosthetics becomes better, I mean, look, the prosthetics could always potentially be better than your existing limb, hand, foot, whatever it might be. How do you think about that?

You know, talking to surgeons about intraocular lens replacement, the procedure for cataracts has gotten so safe and so quick and reliable that there are folks who are simply very nearsighted like me, you know, I'm like 2800, who would like to just get, what's it called?

Lasik.

Lasik, yeah. Rather than getting that, they want a new lens just put in. People are asking for that. People are in their 20s and 30s and I thought, let's not get surgery quite yet for that. And then, yeah, what is the end point of that?

So my parents went through this recently, cataract surgery. And I remember the doctor said something, and my parents are in their 80s now, but they had this done about 10 years ago. And the doctor says, oh, these lenses, they last like a hundred years. And I'm like, hey, buddy, understand your patient population, right? Like, I mean, they're 70 years old. I mean I love my parents. I want them around forever, but we were building hundred year lenses for people who are getting these procedures in their 70s.

Well, it's so interesting when you talk about joint replacement. It used to be they wouldn't do it until you were in your 60s or 70s because the joint's not going to last that long. You don't want to do it twice. But now you see people getting it done in their 40s or 50s because it's much better and that's great. The other thing with Judy's case and with people in her situation, people have done studies where they look at, okay, if you do limb salvage surgery, in other words, you say, no, we're just going to keep going in and trying to fix this foot, trying to rearrange things, trying to do it surgically, and you compare the outcome and the functionality with lower limb prosthesis, you know, amputation and giving an artificial limb. The best results are with a prosthetic. I mean time and again, and there are tools, you know, to help surgeons make that decision. And, um, like you said, I can understand a surgeon's hesitation. I mean, what if the patient ends up with some kind of phantom limb pain? Insurance, you have to make the case for insurance. So that might not be easy to do. And it's just, you know, nobody's going to fault you. There was one prosthetist who was saying nobody's gonna fault you for trying to go back in and make corrections one at a time and try to fix it that way. But if you cut it off, it's a pretty final thing to do. And if things go poorly from a liability standpoint, perhaps that's worrisome.

You know, I think as a surgeon myself, I think one of the things, it's always in the back of our mind, if you're doing anything that would be remotely considered elective, not really my area, but plastic surgeons, for example, you think, god forbid something goes wrong. This person was living a perfectly fine life and now something has gone terribly wrong. It's always on the back in the mind, even though the chances of that happening are very remote, you know? Anesthesia is probably the biggest risk of a lot of these procedures. Certainly people can develop things like phantom limb pain and things like that. Where do you think we go with this as these prosthetics become better hips and knees and the guy who says hey I'm 40 years old and get new hips. They'll last me 70 years, certainly my lifespan. Do you think that that's gonna become something that's more common and done more and at a younger age?

Yes, I think that it already is, I mean, I spoke to this guy, Paul Studley, an expert in biofilms and bacteria growing on things in the body, and he painted a pretty scary picture of that process whereby, say you have an artificial hip, an implant, and bacteria set up housekeeping and they set up biofilm, so they're kind of impenetrable, they have this kind of fortress that they're in and then they can send out little scouts to go elsewhere, and there's persister cells. And it was this incredibly alarming scenario that he shared with me. And I said something to him about knowing all that you know about infection, and even though it's a low rate, but that the scenarios that you've presented to me, would you ever get an artificial hip? And he said, Oh, I have an artificial hip. The guy was barely 50. Not only that, it's metal on metal, which, you know, there had been a lot of problems. He says, those are much better now. And you know I run marathons. I run marathons and I wanted to keep running marathones. I'm like, wow, that's a great advertisement for artificial hips right there.

When we come back, if we really are replaceable, how do we decide what's really broken, what needs fixing, and what we're willing to change? That's after the break.

'The thing is that these prosthetics are in many ways, they're not just replacing what already exists. I mean, these prosthetic are getting smart. They're incorporating microprocessors as you write about. They have these sensors to adapt, but there are trade-offs. What are the trade-off you're referring to?

Sure. Well, one of those limbs with a microprocessor, you've got a battery that, you know, like having an electric car, you got to be thinking about where am I going to plug in and charge. Is it waterproof? They're heavier than a traditional limb. You know, I have very different feelings, lower limb prosthetics versus some of those arm and hand prosthetics, And that's just because the hand is so much more complicated. A hand has the indivividually, five individually moving fingers, so to be able to move it fluidly however you want rather than go through a bunch of set grips, there are grips that you choose, including one for holding a credit card, which I thought was appropriate. Judy had this comment, we walked by a display that showed one of those sort of bionic looking hands holding a raspberry. She laughed and said, are you going to spend 15 seconds manipulating that grip? No, you're going to reach over with your other hand and pick it up and eat it.

That's funny, that's right, right. And should we all live long enough, as you write in the book, we will likely have some sort of disability. And the question I think almost becomes, at what point do you define disability? If you're not 100%, is that a disability? And that might dictate when people choose to get these replacement parts.

Oh yeah, just talking to Ezra Frech about the word disability and to call him disabled. Look at what he can do versus what I can do. I'm not an athlete. I'm barely in shape, you know. Plus, I get up in the morning because I'm extremely nearsighted. So if I didn't have contact lenses, that prosthetic that I put in every morning, I would be utterly disabled. I couldn't do anything that I do.

Would you get those implantable lenses now that they do for cataracts? Would you just do that? To avoid having to put in contacts?

No, no. What's not there yet is accommodation, you know, the ability of the eye to change focus from near to far. I mean, they're getting there but that fluid shift from far away to very close, that amazing thing that the eye does automatically, that's not their yet. The lenses are great, but no, no, I wouldn't do it because I'm used to wearing contacts.

Right. No, I just think it's so fascinating. Maybe I'm perseverating on this point, but when I watched my parents go through this, first of all, they wore glasses or contacts most of their adult life. Then all of a sudden, they're not. And like everything about them changed. I mean, first of, all their vision changed, but I think how they looked even changed. They looked younger, you know? They seemed younger to me. And now they did this in their 70s, which is, you, know, I think. It seems like the right age based on their eyesight and everything at that point. And obviously they're cataracts, but I'm in my 50s now and I think, and I wear contacts and I do think to myself, they're making these lenses. They're going to get better. They're gonna be able to accommodate. So I could actually look at a bird watching like you like to do, and then also read a book with good accommodation without ever having to put on reading glasses or anything, it is an operation. It does have the attendant risks of surgery. And yet, man, Isn't that something?

It is something.

I think that's always gonna be part of the conversation is what are the risks and what is your tolerance for those risks? And at the same time, you may look at other people who get a replacement of some sort and think, wow, look at that, no need for eyeglasses, faster runner, stronger arms, whatever. You know, the whole Steve Austin bionic man sort of, you know, sensibility.

Yeah, we will be there. We're not there yet.

Not there yet. But when we get there, you anticipate that more people would probably just get replacement parts or at least get them earlier in life.

Yes, I think people have, people are very accepting and enthusiastic about surgery in ways that maybe because I see it and I read about it a lot, and I have more of an awareness of the very uncommon possibilities, infection or something with the anesthesia. I am always impressed at how willing people are to embrace a surgical option. Your neighbor and your friends, if they had it done and you see that they're moving much better, they're in less pain, you're like, I want to do that too. So I think you're going to see it more and more and more. And yes, I think that we will reach a point where people will be having it done sooner and when it's less medically necessary.

'Let's travel to China with you for a second. And I will preface by saying I got very interested in xenotransplantation and especially genetically modified pigs. One of the headlines for me immediately was that there was these companies like United Therapeutics, Martine Rothblatt. It's somewhere between 10 and 60 gene edits to these gigantic genomes and at 10 to 60 gene edits and you can essentially make a pig organ compatible with a human. I mean the human still requires anti-rejection drugs so it's not completely compatible but it's as good as a human transplant in terms of the overall genes. Why did you go to China? What were you trying to find there?

Well, two reasons. So I wanted to go to one of the facilities where they raised the pigs, I wanted to meet the pigs. And both companies said no, which isn't all that surprising. Biotech companies are pretty closed to outsiders, particularly outsiders writing books. So, I went on PubMed and sort of looked around to see who else is doing this work. And there was somebody in China who had been working on this for 30 years, xenotransplantation, it seemed like it hit the press about five years ago, but it's been in progress for 30 years. And they were quite open to my coming there and going to the facility. The other thing that occurred to me as this was going on was that China was a really good place to set this chapter because culturally there's no tradition of organ donation. People don't donate organs.

Yeah, I saw that I mean 6,000 registered organ donors in a country that has you know billion and a half people that was surprising to me.

That's yeah, it's nothing. It's nothing.

Why is that, do you think?

Well, it was explained to me by Yi Wang, who is the researcher who showed me around that it was a religious thing. It's a belief that your body and everything in it was gift from your ancestors. And so for you to mutilate it in any way, change it, take parts out and mess with them would be disrespectful. That was how she put it. And also I think because the organs that they do have come from death row prisoners, people who've been executed, it has the stigma of a punishment. There is no tradition of organ donation as an act of altruism. So it just, and I, it seems, you know, it was just talking to them about xenotransplantation, about chimerism, which is a whole other thing. You know, I thought, God, wouldn't it be simpler if you just did a bit of a, you now, this is China, you could just say, okay, it's your patriotic duty to donate, to be an organ donor. It seemed like it should be a pretty simple fix, but that's not happening.

Mary, you're a very influential person, but changing an entire government, that's challenging. We had a conference called Life Itself and they were trying to 3D print lungs. And to give context to 3d print a lung, you're talking close to a trillion voxels. It's oriented a very specific way, these cells, and obviously they all have to function as tiny blood vessels, as airways, all that sort of stuff. Fascinating. And I said, how long does it take to do this, to print one of these lungs? And she said, you know, about nine or ten months. And I said, that seems like a really long time. And she goes, how long did it take to print your lungs? And I say, yeah, good point. Yeah, that's about right. Gestation is about nine or ten months.

'Yeah, exactly. Yeah. I mean, I spent time in a bio-printing lab at Carnegie Mellon, and they were talking about how you have to, when you're printing them, the cells, you've got to align it depending on the function of the muscle. So with a heart, you print them kind of in a helix because the heart kind of twists as it pumps, as it squeezes, right? And for the deltoid muscle, a bit of like a fan shape. So, how you align these cells as you print them plus then, you know, how are you going to feed these cells? Is the body going to grow in those blood supply or you're going to have to at some point print it? What about nerves? But just an incredible, I mean, this woman showed me a, you know, she had printed a single ventricle for a mouse and it was working. You can either be like, it's just a ventricles, it didn't have valves, so it's like the blood squirting out either end. It's not terribly helpful for the mouse. The mouse kept its own heart. But still it's a ventricle that was printed on a printer an extrusion printer and it works and it pumps, you know, that's amazing. I asked the guy Adam Feinberg who runs the lab I said how long before we are printing whole organs that can be implanted into a body...

Functional organs?

Functional organs. And he said we're kind of at the Wright brothers stage.

Wow, that's interesting.

'Which is both really exciting. I mean, the Wright brothers, when that happened, that was world-changing and exciting, but still a ways to go before we have planes flying back and forth across the country.

But proof of concept is there though. I guess that's what the Wright brothers sort of, I mean, things develop pretty quickly after that.

Exactly. You know, the major breakthrough is there and same with, you know, transplantation. I think it's an end for that matter, you know, a bionic hand that it's a matter of tweaking and improving. The breakthrough concept is there. It's a matter time.

These are just wildly fascinating scientific developments. I think everyone gets excited about these things. And if not just for the gee whiz quality, the idea that it could have really objective, measurable impact on human life. The books, I love your books. And you take on topics that I mean, like at times when I'm reading it, I'd laugh and I'm like, ugh, at the same time. Whether it be a finger that's gonna be a penis or how the alimentary canal works in gulp or even some of the topics in this book. Have there ever been topics that you say, look, too much even for me, too much, even for Mary Roach, I'm not gonna do it. I mean, you've had an ultrasound while you were having sex. I mean by the way, kudos to your husband for that. He really sacrificed, I am sure for that.

I know he's such a good sport. Oh my god. I can't believe I did that to him. Oh, my god. And yeah, thank you for getting it right. It was ultrasound not an MRI people go, oh, you had sex in an MRI tube. I'm like that would have been fine, there's some privacy in an MRI tube.

Haha.

Oh my God, but has there ever been anything too much for Mary Roach even for me? No. The short answer is no.

Haha. I love it. I feel lucky every time I get to talk to you. Thanks for joining us.

Oh, thank you so much. I feel lucky too. I so enjoy this conversation and I'm a big fan and I love all that you do.

I'm gonna work on my humor a little bit.

No, no, you leave that to me. No, we can't have you being super funny. You don't cut into my turf.

Haha alright. Mary Roach, thank you for joining us. Really appreciate it.

Thank you, Sanjay.

That was my conversation with science writer, author, and friend, Mary Roach. You can get her newest book, "Replaceable You", wherever books are sold. Thanks so much for listening.