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Lizards Can Replace Missing Limbs - Someday Maybe We Will, Too
Medical scientists recently scored a major breakthrough when they successfully implanted several people with the world's first laboratory-grown bladders. (See the whole story on WIRED Science's "Body Building") But what about regrowing parts on the outside of the body, like fingers, arms or legs? After all, some lizards and fish can do it. What have they got that we don't?
A handful of researchers around the country are working to find out. Last year, the Defense Advanced Research Projects Agency, the Pentagon's experimental science wing, doled out multi-million dollar grants to launch two teams of scientists in pursuit of a specific goal: figure out how salamanders regenerate severed limbs, and make mice perform a similar trick. Meanwhile, the Army will soon begin an attempt to regrow the fingers of several war-maimed soldiers.
The military has thousands of reasons to be supporting such cutting-edge wound research, in the form of the ever-mounting number of severely injured soldiers being shipped home from Iraq and Afghanistan. From the American Revolution to the Persian Gulf War, the ratio of wounded to killed soldiers held steady at about 2.5 to 1. In recent years, however, advances in body armor technology have saved countless soldiers' lives - but even the best Kevlar vests still leave limbs exposed. One result is that the maimed-to-dead ratio has shot up to 9 to 1. That translates into an awful lot of veterans missing pieces of their bodies.
The salamander, the creature highest up the evolutionary scale capable of regrowing its appendages, gives a tantalizing example of the healing that might be possible for such amputees. The little lizard can fully regenerate its limbs, tail, jaws and parts of its eyes.
The basic mechanics of the process are no mystery. When a salamander's limb is lopped off, the cells around the injury don't form scar tissue, the way a mammal's would. Instead, they revert from being a component of skin or muscle back to a kind of generic state, forming a bud-like lump called a blastema. These "dedifferentiated" cells making up the blastema then multiply, re-evolving as they do into the specialized cells required to construct the new limb. Blastema know where they came from, but not necessarily where they are: Transplant one from a salamander's leg to the middle of its back, and it will grow a new leg right there.
In theory, it seems that humans should be capable of the same thing. After all, we regenerate some body parts, including liver and skin cells. More intriguingly, scientists discovered in the 1980's that human fetuses can regrow many damaged body parts with a skill to make any lizard jealous. But the gene that controls this ability somehow gets turned off after birth.
"All vertebrates seem to have that ability as embryos. But the salamander's cells are somehow able to go back to that embryonic state and access that process," says Dr. David Gardiner, a research biologist at the University of California, Irvine who is on one of the DARPA-funded teams. "The difference isn't in the genes, but in how we use them - which ones are activated and when."
In addition to the twin DARPA projects, a clinical trial aimed at regrowing fingers on amputee veterans is slated to begin soon at the Army's Institute of Surgical Research in Texas. The plan is to surgically re-open the GI's stumps, and then periodically sprinkle them with a powder made from an extract of pig bladder. As far out as that sounds, the powder has been shown to help horses regrow ligaments and to help regenerate soft tissue in humans. No one is expecting entire fingers to grow back, but even extending those finger-stumps could give the amputees back such basic capabilities as holding a car key or zipping up a fly. "The aim is just to generate enough length so that they can pinch something between thumb and finger," says David Baer, manager of the institute's bone and soft tissue program. "If you can't do that, life is awful hard."
Getting human beings to regenerate a fully-jointed finger, let alone an arm or leg, is still clearly years away - at best. (And not only because of the scientific hurdles: The Army's finger-regeneration experiment has been delayed for months because the company that makes the powder was until recently embroiled in patent litigation.) Still, as Gardiner points out, the idea of an artificially-grown bladder sounded like pure science fiction as recently as a decade ago.
"Regeneration is a basic biological property of all organisms, and with enough time and money we'll be able to figure it out," he says. "I probably won't see any actual therapies from this research. But my kids might." Here's hoping that by then there won't be quite so many soldiers returning from the Middle East needing those new appendages.
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10.23.07 7:34 AM PDT
Sergio Garcia
A very interesting topic indeed. If ever reached, this would be of extreme help to human kind. However, is this truly possible?
10.24.07 4:20 PM PDT
Darla Desautel
Loved this article. My deepest respect and admiration for those participating in this area of science. If I could start my career over, I would go into science to promote advances to help people, whether it be limb regeneration or solar energy.
10.24.07 5:58 PM PDT
Pete
Its about time!! It's just a machine, it should be able to be fixed like one for many, many years now.
Well done anyway..
10.24.07 7:46 PM PDT
Mary
Who knew that an HP printer cartridge could end up to be so important? I've always preferred HP monitors during my nursing career, but to think that the lowly printer cartridge could be so useful for regenerating parts for the human body is mind-boggling!
10.24.07 8:30 PM PDT
Ken Leach
What a fantastic show that was this evening. I would love for you to share that with the educators at SchoolTube.com. That was not only fascinating, but also inspirational and could very well be the catalyst for some young mind that hasn't had the opportunity to see it yet. Please consider uploading that to SchoolTube.com. It is a SAFE video sharing site built for schools and moderated by teachers.
Thank you again for a terrific show!
Ken Leach - Director of Education
10.24.07 9:10 PM PDT
carlina
this is amazing to me. i am 18 and myself have lost one finger. my left ring finger, i think if they ever wanted a volinteer for the regeneration of a finger, id be glad to volumteer someday. i have half un to the first knukle and to gain any of that bakc would make a big diffrence in holding a knife and cutting up food.
10.24.07 9:11 PM PDT
ted
prostate cancer is on the rise, and with that surgery will take their prostate. With this science can you replace the prostate and other parts that radiation will destroy to remove all the cancer?
10.24.07 9:32 PM PDT
Gerry
Certainly answers the question of some of what is coming next in medicine. Even beyond Star Trek's techniques.
Great article!
10.24.07 11:56 PM PDT
Allan Marsh
You have an extraordinary program. I would like more information specifically regarding the presentation on the manufacturing of an esophagus using a supporting matrix from a pig to support the regeneration of cells to create a new esophagus. Please contact me with the name and contact information of the subject as I was unable to obtain the information before the episode concluded.
Thank you for this revelation.
Yours truly,
Allan Marsh
10.25.07 4:25 AM PDT
KHALIL AHMED
This is amazing, since last six years my wife is going for dialysis. Her kidneys shrunk she have two complete kidneys i was wondering if we take one out and experiment on that one and let it grow and implant again if we can. I hope I was able to explain my situation if u need any help please email me will love to give any information u need, will really appreciate if some one can help my wife any way.
Thanks in advance.
Yours truly,
Khalil Ahmed
10.25.07 6:20 AM PDT
Gerg
Mmmm.. a little butter and garlic and those snouts would be delicious.
10.25.07 6:25 AM PDT
George Scardena
How can I obtain the info shown on Body Building on 10/24.
I have GERD and may have to have surgery and the segment about replacing part of the esophagus can be of great value if I could show my doctor. Please help.
10.25.07 6:56 AM PDT
Ed
My brother-in-law in Virginia will be going to Duke Hospital in Durham for a second opinion about a bladder replacement due to cancer. Where can I get more information about the Wake Forest bladder regeneration segment to send to him?
10.25.07 9:49 AM PDT
Bridget
I too found this program fascinating! Is there a way to find out the name of the research companies? I know so many could benefit from this technology! Thanks for the informative program!!
10.25.07 3:41 PM PDT
linda murray
This how we should fight the war on terrorism. The terror of spending a life disfigured and rejected from mainstream society. More money needs to be put into this war effort. It definately gives more bang for the buck
10.25.07 7:35 PM PDT
Bell
Why does this article not mention the part about printing out the heart
10.25.07 10:06 PM PDT
jerad
I have short gut. It would be awesome if they could regenerate stomach and intestines. I could finally know what it's like to have a normal g.i. tract.
10.26.07 4:39 PM PDT
Elaine
This is a fascinating program. I was very interested in the piece on the Esophagus. Where can we get more information?
10.26.07 9:01 PM PDT
Lee
I have regrown a finger tip with the help of two research doctors. One in PA and one in MA. I cut off the tip of my middle finger on the right hand and the tip was lost. Four weeks later, with the help of these doctors, my finger tip had completely grown back, with total feeling and figer print. In is as perfect as my orginal finger tip.
10.27.07 7:09 PM PDT
Darren
I had an acident on my farm which resulted in the loss of my right arm six inches below the elbo.The hope of this reserch may someday make me whole again.Thanks for the info.
10.28.07 3:23 PM PDT
Frances
I need a new esophagus! Please send me more info to share with my doctors! Thank you and God Bless all those in the science world who are really making a big difference!
10.28.07 7:21 PM PDT
Carol
My 11 year old son, then 8 had his middle finger tip on his riht hand cut off at school by the milk cooler unit lid. I would like to know if after 2 and 1/2 years, could his finger tip re-grow? I saw the posting from a gentleman, Lee, he had the same tip on the same hand as my son's grow back with the help of doctors in PA and MA after 4 weeks of his amputation. I would like to know more about this and the cost involved. Thank you.
10.29.07 10:27 AM PDT
Bill Ryan Free
That show, if I am correct, did show a Man who had grown a finger... that specifice information is what I am looking for here and now, and cannot see... can You direct Me to it, or send Me some information on this?
11.3.07 10:27 PM PDT
Patty
This program was fascinating, wondering if scientists will be able to eventually develop limb lengthening for children born with TAR Syndrome? Please advise!!
11.9.07 1:11 PM PST
ted
What's being done for hearing loss? I recently came upon a site "singing ear" that explains a lot about the inner ear. How long before hearing impaired can have their hearing back? Are there sites that address this issue?
12.12.07 6:10 PM PST
otto
Hurry please!!!!
12.12.07 11:35 PM PST
Christopher
I didnt see the show, but, the article was very intresting. xD
12.15.07 4:25 PM PST
Jess
About 8 months ago I was involved in an industrial accident and lost the end of my right index finger. I would be very interested in getting more info on limb regeneration. I would also like to know the cost involved in this type of procedure. I would also like to say that I would be interested in assisting in any way to help develope this procedure. Thank You.
12.16.07 3:46 AM PST
rasmasyean
Support stem cell research! Eventually we can grow entire bodies and attach our head! Personally, I rather see advances in machine interfacing with the body. Who want's a human hand when you can be a powerful cyborg!
12.17.07 1:57 PM PST
Wes
What about printing a steak?
4.18.08 6:38 AM PDT
Deepak Chand
hey it will be a great achievement when we are able to regenerate our limbs. after the invention of regeneration process in humans no one will be handicap.............
may god fulfill our dreams ....................
9.12.08 10:53 AM PDT
bubba
that would be cool
11.24.08 6:58 AM PST
pavan
My name is Pavan. I am 23 years old below knee amputee. I'd like to know if it is possible to have a leg transplantation's and go ahead. Waiting for your quick reply.
1.1.09 10:38 PM PST
jono
Well, i dont think we can grow a leg like salamanders but my uncle, who works at the cells regenerate research center of shanghai said that we can biologically make a leg from man made cells tissue and muscle and attache it to an amputee
3.6.09 4:40 PM PST
Nicholas Clancy
If only Pythagoras had the technology we have now. I think this would have happened thousands of years ago.
4.10.09 6:51 PM PDT
michael
My name is michael. Im a 24 year old male and have a right leg below the knee amputee. I'd like to know if there is a way to a leg transplantation. please email and let me know something. thank you
5.21.09 10:23 AM PDT
valentine
Jono
Please can you give me more information about the center and the work your uncle do. Please email me!! This would be very good and nice.
I think also that humans can regenerate extremeties some day, but this far far away. I need a more realistic goal.
9.27.09 4:20 AM PDT
John Fielding
Hi,
My wife had a below knee left leg amputation aged 7. She is now 37. We would be grateful for any contact regarding potential for transplant (or re growth although I think the former is more likely?!)
Thanks
John
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