The Cellular Superpowers That Heal Skin and Regrow Limbs

IRA FLATOW: This is Science Friday. I’m Ira Flatow. We’re coming to you from the Fitzgerald Theater in St. Paul, Minnesota. Are we having fun yet, everybody?

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Now, for this next segment, we asked our friends at Brains On! to help us out. Brains On! is a science podcast for kids. And we’re all kids, so it’s also for us too. And it’s produced by Minnesota Public Radio and Southern California Public Radio. They tackle questions sent in from listeners, and they invite kid co-hosts. Yeah, real kids on the show to help them find answers. Here’s Brains On! host Molly Bloom and 12-year-old co-host Maddie Sinn.

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MOLLY BLOOM: Thank you so much for having us today.

MADDIE SINN: Thank you.

MOLLY BLOOM: So our bodies have a lot of amazing superpowers. Don’t get me started on nasal mucus.

MADDIE SINN: But one of the coolest is the way their bodies heal.

MOLLY BLOOM: It is super cool. You can check out our most recent episode to find out all about how your skin heals after a cut.

MADDIE SINN: But our healing powers could be even cooler. Like what if we could regenerate body parts like Wolverine?

MOLLY BLOOM: Wolverine may be fictional. But there are some real-life creatures that have the ability to do just that.

MADDIE SINN: Starfish can do it and so can worms.

MOLLY BLOOM: And then there’s the salamander.

MADDIE SINN: We got thinking about this when one of our listeners sent in this question.

MOLLY BLOOM: 11-year-old Andrew from Pennsylvania wanted to know, how do axolotls regrow limbs? Axolotls are a kind of salamander found in Mexico.

MADDIE SINN: To find out what scientists are learning about salamander superpowers, we have Meri Firpo here today.

MOLLY BLOOM: Meri is a scientist at the University of Minnesota Stem Cell Institute. And she’s here to tell us about all the cool stuff going on in regenerative medicine today.

MADDIE SINN: So Meri, how do salamanders regrow their limbs?

MERI FIRPO: Well, salamanders, like some other animals, have this amazing capacity, if they lose a limb or their tail, to actually grow it back. And this is something that happens in the wild, where somebody– maybe another animal– takes a bite out of them. And they can actually run away and survive.

And what happens is that the edge of the wound actually turns back into the state that it had in the early embryo. And so those embryo cells– we call them blastema– actually become unspecified so that they can become any of the tissues of the limb.

The most amazing part about this, though, is that the limb can actually organize itself just like it did during the embryonic state. This is something that humans don’t have the power to do, except Wolverine, I guess.

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So the salamanders can actually take a part of their body. And then when it’s damaged, it changes back into an embryonic state and then regrows a limb just the way it happened the first time.

MADDIE SINN: So I have another question. How is this research in salamanders helping humans?

MERI FIRPO: Well, we really would like to help humans regenerate limbs as well. If you have an injury or some kind of genetic defect, we’d like to be able to take your body back to the original state and have it grow a really organized limb that will work rather than having an artificial limb. But this is far in the future.

Scientists here in Minnesota and all over the world are studying the axolotl and other amphibians and worms to try and understand how those animals have that capacity where we don’t. But we actually have superpowers of regeneration ourselves, because all of our tissues regenerate, especially tissues that are replacing themselves all the time, like our skin and our hair.

They have special cells, very rare special cells, that allow those tissues to regenerate by just wear and tear, by aging, infection, or by damage. And that allows us to heal wounds in ways that allow us to regenerate our capacity to use our skin, for example, and prevent bacteria from getting in.

We can actually replace tissues. And we use stem cells, for example, in a bone marrow transplant. We take stem cells from one person and give them to another person to allow them to regenerate all of the cells of their blood and their immune system. And we would like to be able to use stem cells to cure lots of different diseases.

One thing that we have learned that the salamanders can do is how to take any cell of the body and change it back into an embryonic state. This is a really new technology that my lab is using to take cells from a patient’s skin, turn them back into a stem cell that can become anything, and then teach those cells to recreate tissues that are needed for the same person. In my lab, we’re taking skin cells, reprogramming them back to embryonic-like stem cells, and then teaching them to make insulin to replace the insulin-producing cells that are lost in patients with diabetes.

So these types of regenerative medicine therapies are already happening. But someday, we hope that we can actually regenerate a whole organized limb so that people can walk again after if, for example, they’ve been injured.

MOLLY BLOOM: That is really cool. We have an audience question over here.

SPEAKER 1: How do you use your production in burn victims?

MERI FIRPO: Well, the way that it’s done– my lab doesn’t do that. But this was developed at Harvard University. They actually take a very small piece of skin. And they grow them in sheets in the laboratory using special growth factors that cause the cells to grow very, very fast. And they actually create sheets in a dish, like the Petri dishes you see there. And then they take the whole sheet off and then just place it over the wound. And then it will merge with the cells of the skin and heal the wound.

MOLLY BLOOM: We have another audience question.

SPEAKER 2: Yes, hi. I’ve been doing some research. I’ve got problems with a disc in my back. And there are some people that are injecting stem cells into discs to promote healing. And I’m wondering if you’re doing anything with that or if you have any knowledge of that.

MERI FIRPO: Well, I do know something about that. My lab doesn’t do this type of research. But what they are doing there is sort of a different kind of regenerative medicine. Those cells are called stem cells. They sometimes are stem cells, sometimes not.

But this type of regenerative medicine– the cells are actually not there to heal the wound. They’re there to provide signals to have the tissue where they’re placed heal itself. And this is a very powerful kind of regenerative medicine that really doesn’t require stem cells. It just requires cells that can secrete the helpful factors that can help the injury heal itself.

MADDIE SINN: So I have a question. So there’s this thing called– I think it’s called– noose game that you put over your cuts. Is that what that is?

MERI FIRPO: Yes. I use that too. But that is actually– it’s a polymer. It’s not actually cells. And that will coat your skin to protect you from infection while your skin is healing the wound.

MOLLY BLOOM: And what’s happening in our bodies when we do inject those stem cells? What is the process that’s going on?

MERI FIRPO: What happens in the body after you inject the same cells? Well, it depends on the tissue. And each tissue has its own unique characteristics. For the best understood stem cell therapy and one that has been being used widely for about 40 years, the bone marrow transplant.

The stem cells are actually just injected into a vein. And they actually know to go to the bone marrow and to take up residence there and work. So they pre-treat the bone marrow to get rid of a lot of the cells that were there. And then they just put the cells into circulation, and they know where to go.

For the stem cell therapies for diabetes, the insulin-producing cells don’t really need to be in any specific place to function. So we can put them in a place that’s easy to get for the patient, like under their skin. And then for other types of stem cell therapies, like for muscular dystrophy, where the stem cells are lost and not functioning well in the muscle, you would actually have to place the stem cells in lots of different places in the muscle for them to do their work. So depending on the tissue and the way the tissue works, the approach is going to be completely different.

MOLLY BLOOM: You’re listening to Science Friday from PRI, Public Radio International. I’m Molly Bloom from the Brains On! podcast. And we’re here with SciFri at the Fitzgerald Theater in St. Paul, Minnesota. And what other exciting research is going on in stem cells right now?

MERI FIRPO: Well, there’s so much that’s happening right now with stem cells. There are already with pluripotent stem cells, the type of cells that my lab uses that can become anything. There are already clinical trials for spinal cord injury and for diseases of the eye, like macular degeneration, that are already underway and have some very promising results.

The other types of stem cell research, the regenerative medicine research, where we can actually teach the cells within the body, the stem cells, to regenerate are also happening. And we can actually encourage those cells to heal themselves or to use cells that we make in the lab to prevent injury after a heart attack or after a stroke to allow the patient to recover with a very minimal amount of damage.

Because after the injury, then there’s a lot of information. And that information causes damage too. So we can inject cells immediately after someone has been injured by one of these types of problems, like a heart attack or a stroke, and actually help the patient prevent damage. So in addition to healing, we can actually help the patient pre-heal so they don’t actually get a large injury.

MOLLY BLOOM: Well, that is all we have time for today. I’d like to thank our guest, Meri Firpo, a scientist at the University of Minnesota Stem Cell Institute, and, of course, my co-host, Maddie Sinn.

MADDIE SINN: Thank you.

MERI FIRPO: Thank you.

IRA FLATOW: Thank you. Thank you all. They were great, weren’t they? And for more Brains On!, head on over to brainson.org or find episodes in your favorite podcast app.

That’s about all the time we have. A special thank you to Mary Ellen Berglund, who designed our wonderful science superheroes, yes, and to Molly Bloom and the Brains On! crew. Thanks also to Minnesota Public Radio, American Public Media, and the Fitz and Justin Levy, Jeff [INAUDIBLE], Stephen John, Tom Campbell, John Miller, Jennifer Larson, Dan Zimmerman, Alan [INAUDIBLE], Dietrich Poppin, Johnny Vince Evans.

Thanks also to the Brass Messengers for the musical accompaniment today and to our production partners at the studios of the City University of New York. And we cannot forget our terrific Science Friday staff– Charles Bergquist, Rachel Bouton, Danielle Dana, Brandon Echter, Jennifer Fenwick, Becky Fogel, Sarah Goldfarb, Luke Groskin, Christopher Intagliata, Jen Kwok, Julie Leibach, Alexa Lim, Annie Minoff, Annie Nero, Christian Skotte, Chau Tu, and Ariel Zych.

In St. Paul, Minnesota, I’m Ira Flatow. And as a treat, I’m going to let the Brass Messengers take us out with one last song. Goodnight, St. Paul!

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