Windpipe, Grown From Stem Cells, Implanted In Man
Windpipe, Grown From Stem Cells, Implanted In Man
In June, a cancer patient with advanced tracheal cancer had a completely artificial windpipe implanted. It's the first surgery of its kind, and the windpipe was grown using the patient's own stem cells. NPR science correspondent Richard Knox talks about the future of synthetic organs.
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NEAL CONAN, host: Last month, doctors gave a man with advanced tracheal cancer a second chance. With his own windpipe blocked by an aggressive tumor, they took some of his stem cells and grew him a new one in a laboratory. Because the genetic composition is identical, surgery could proceed without concern that his body would reject the transplant.
NPR health and science correspondent Richard Knox has been reporting on this story, and he joins us now from his office near Boston. Dick, nice to have you back on the program.
RICHARD KNOX: Nice to be with you.
CONAN: And it seems like we've heard about the prospect of growing replacement body parts for years as - well, someday soon. Is this a first?
KNOX: Yeah, it's a first, I think, in several respects. First, it's certainly the biggest spare parts or replacement part grown entirely in the lab so far, and I think it's the first involving a vital organ. There have been some others involving ureters, which carry - tubes which carry urine from the bladder, blood vessels, bladders. But this is a pretty big structure. And of course it's necessary to live.
CONAN: Necessary to - we all need to breathe. And how did they do it?
KNOX: Well, it's - it's an interesting story for a couple of reasons. First of all, I really like the human aspects of it, if I can just talk about that first. Here's a 36-year-old Eritrean fellow, far from home in Iceland where he was studying geology, and he suffers a really terrible kind of cancer, the trachea. Nothing works - surgery, radiation, chemotherapy. He's having more and more difficulty breathing because the tumor's encroaching on his airway.
And this Icelandic surgeon remembers that there's an Italian guy in Stockholm who's been doing trachea transplants from cadaver donors. So he calls the guy in Stockholm, and the guy in Stockholm says he'd be willing to consider this patient. But there's really probably not enough time to get him a donor trachea. It takes a while to get these organs, and if you get one in time, it may not be the right size.
So the fellow in Stockholm, who's name is Paolo Macchiarini, decided to try, first time - he thought the time was ripe to try an experiment in which they would take a scan of his trachea to make sure they had the exact dimensions. A fellow in London has invented this spongy plastic. It's porous. Make a model of his trachea that's exactly the right size. Meanwhile, a company in Massachusetts was making an incubator.
The model and the incubator were flown to Stockholm and the patient was sent there. And they took some of his bone marrow, I think probably from the hip bone. The bone marrow contains stem cells, which can make a variety of different tissues. They combine the fellow's stem cells in this incubator with this model, which sort of serves as a scaffold for the cells to grow on, along with several growth factors that tell the cells what kind of cells to become, namely cartilage, which is what trachea, wind pipes are made of.
And within a couple of days, enough cells have grown in the surface of this thing that they could put it into his - they took out his diseased wind pipe, put this in, stitched him up, and it worked.
CONAN: And it worked. He's breathing fine.
KNOX: He seems to be breathing fine and coughing and doing other things that are necessary for a wind pipe to do. When I talked to him on Friday, he had just flown from Stockholm back to Reykjavik, and his voice was very, very low and very hoarse, and he was very tired. But he says he can breathe again, and he's very grateful.
CONAN: Now, he does not have to take the kind of anti-rejection drugs that most transplant recipients receive?
KNOX: No. There's no foreign tissue in this graft. It's either this inert plastic or it's the cells on top of it, which are grown from his own body, so they're genetically identical. So he's free of that. As I say, was able - they were able to grow it on order and in time, which is a big boon. And you know, I think we'll have to see whether he continues to do well. He's the first one of his kind.
But there's reason to think that he will because there've been 10 other patients done by Dr. Macchiarini over the - well, since 2008, so past three years, using donors from, you know, cadaver donor tracheas in which he's stripped them of their cells and left just the cartilage, and then grown stem cells on these donor cartilages - windpipe, excuse me. And all of these, he tells me, all of these 10 patients are functioning normally, are breathing, talking, and everything seems to work. So there's no reason a priori to think that this one is not going to do well as well.
CONAN: We're talking with Richard Knox, NPR health and science correspondent from his home near Boston, Massachusetts, about a man who has received a windpipe grown from his own stem cells. You're listening to TALK OF THE NATION from NPR News. And we have a caller on the line. Rita is calling from Horton in Michigan.
RITA: Hi. I have a grandson with a very rare disease in which his upper intestine does not work at all. And I know that an intestine is not the same as a windpipe - obviously there are many differences. But the family members here, of course, would love to hear about whether or not a technology like that might soon be available for something as long as an intestine and as complex as an intestine. Thanks a bunch.
CONAN: Thank you, Rita.
KNOX: Very good question. Well, I think the word soon is important. And I don't know of any laboratories around the world that are yet trying to fabricate an intestine in the lab. It's - in one sense it's a tube, but in another sense it's a very complicated tissue, has lots of functions from digestive juices and hormones and immunologic functions. And so it's a much more complicated problem. There have been transplants of intestine from donors, but they haven't, as far as I know, worked very well.
CONAN: And as you say, the question about an intestine, very different from a windpipe, which is a piece of tubing. But as you pointed out, there are any number of parts to the human body that are essentially tubes.
KNOX: Yeah. Of course the big dream of the tissue engineers is to grow more complex organs, such as this one, such as livers, hearts, lungs. And it's not clear yet whether that's going to be possible. About a year ago, there were two teams at Harvard and Yale that independently created in the laboratory lungs that worked from two to six hours in rats. And these are created sort of from live lung tissue that they've stripped the cells off of and then grown stem cells on top of. And so there is some hope that maybe lungs someday will be possible, but I think I wouldn't place your bets yet.
CONAN: And it's too early to tell on that. In the meantime, is there - I'm not sure how common trachea cancer is, but is this likely to become a preferred procedure?
KNOX: It's too soon to tell. I mean, you know, there's one patient who has gotten this entirely laboratory trachea and then there are 10 others who've gotten the cadaver trachea in a similar procedure, so we'll have to see how they all do. And I think, you know, these all need to be tried in much greater numbers over time and, you know, following these patients. This is a rare cancer. There are other cases involving the need for trachea. For instance, Dr. Macchiarini is planning to do one of these procedures on a nine-month-old infant who was born without a trachea. And he thinks he can use a biodegradable form of this plastic that would allow the graft to grow with the child. So we'll see.
CONAN: There are also other parts of the body that are composed of cartilage - our noses, for example, and important parts of our knees that athletes seem to be tearing all the time. Could this same kind of technology be appropriate for those body parts?
KNOX: Good question. I haven't asked anybody. It doesn't - there's no obvious reason why it wouldn't - I think using the same principles of developing a scaffold and seeding it with the patient's own stem cells and giving it the right recipe of growth factors to turn them into cartilage. But you may - maybe you should start a company and then see how that'll fly.
CONAN: I'll look into it, Richard. In the meantime, how long does it take once you start this process with the stem cell and the scaffold, the piece of plastic that you were talking about earlier, and that incubator from Massachusetts?
KNOX: Well, that's an amazing part of it. It really doesn't seem to take very long. It took a few days, two or three days, to grow enough of these cells on the surface of the scaffolding in order to get to the point where they could put it in. There's no objective test at this point - because it's all so new - to tell you now is the time there are enough cells on the surface of this to put it in, so it's kind of an intuitive process. And there are lots of questions - that just being one of them - that will have to be worked out before this could be standardized.
But the amazing thing is that these cells can respond to the growth factors and also to the physical, you know, properties of the scaffold, and they sort of know what to do. In order to get a blood supply to this artificial trachea in the short term, he's cut a hole in the diaphragm of this fellow and snaked a piece of tissue, it's called omentum, that lines the gut, that's very rich with blood vessels, and got of piece of this all the way up to the throat. And that provided a temporary supply, but the blood vessels then started growing in and apparently he's becoming normally vascularized.
CONAN: Richard Knox, thank you very much. Fascinating story.
KNOX: It is. Thanks.
CONAN: Dick Knox is NPR's health and science correspondent. You can read more about the artificial windpipe through our link at our website, npr.org, click on TALK OF THE NATION.
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