Biology

Imagine Regrowing Lost Limbs – It’s a Step Closer With New Treatment That Helped Frogs Regenerate Amputated Legs

African Clawed Frog Leg

A new treatment helped frogs regenerate their amputated legs – taking science one step closer to helping people regrow their body parts, too.

Our bodies connect us to the world. When people lose parts of their bodies to disease or traumatic injury, they often feel that they’ve lost a part of who they are, even experiencing a grief akin to losing a loved one. Their sense of personal loss is justified because unlike salamanders or snarky comic book characters like Deadpool, adult human tissues generally do not regenerate – limb loss is permanent and irreversible.

Or is it?

While there have been significant advances in prosthetic and bionic technologies to replace lost limbs, they cannot yet restore a sense of touch, minimize the sensation of phantom pains or match the capabilities of natural limbs. Without reconstructing the limb itself, a person won’t be able to feel the touch of a loved one or the warmth of the sun.

We are researchers in regenerative and developmental biology and biomedical engineering. Our recent study in the journal Science Advances showed that just 24 hours of a treatment we designed is enough to regenerate fully functional and touch-sensitive limbs in frogs.

Kickstarting regeneration

During very early development, cells that will eventually become limbs and organs arrange themselves into precise anatomical structures using a set of chemical, biomechanical and electrical signals. In considering ways to regenerate limbs, we reasoned that it would be much easier to ask cells to repeat what they already did during early development. So we looked for ways to trigger the “build whatever normally was here” signal for cells at the site of a wound.

One of the major challenges in doing this, however, is figuring out how to create an environment that encourages the body to regenerate instead of forming scars. While scars help protect injured tissue from further damage, they also change the cellular environment in ways that prevent regeneration.


Axolotls are known for their powerful regenerative abilities.

Some aquatic animals such as the axolotl have mastered regeneration without scar formation. And even in early human development, the amniotic sac provides an environment that can facilitate regenerative mechanisms. We hypothesized that developing a similar environment could override scar formation at the time of injury and allow the body to reactivate dormant regenerative signals.

To implement this idea, we developed a wearable device made of a silk hydrogel as a way to create an isolated chamber for regeneration by blocking other signals that would direct the body to develop scars or undergo other processes. We then loaded the device with a cocktail of five drugs involved in normal animal development and tissue growth.

We chose to test the device using African clawed frogs, a species commonly used in animal research which, like humans, does not regenerate limbs in adulthood. We attached the device onto one leg stump for 24 hours. We then removed the device and observed how the site of the lost limb changed over time. Over the course of 18 months, we were amazed to find that the frogs were able to regenerate their legs, including fingerlike projections with significant nerve, bone and blood vessel regrowth. The limbs also responded to light pressure, meaning that they had a restored sense of touch, and allowed the frog to return to normal swimming behavior.

Frogs that were given the device but without the drug cocktail had limited limb regrowth without much functional restoration. And frogs that weren’t treated with the device or the drug cocktail did not regrow their limbs, leaving stumps that were insensitive to touch and functionally impaired.

Interestingly, the limbs of the frogs treated with the device and the drug cocktail weren’t perfectly reconstructed. For example, bones were sometimes fragmented. However, the incompleteness of the new limb tells us that other key molecular signals may be missing, and many aspects of the treatment can still be optimized. Once we identify these signals, adding them to the drug treatment could potentially fully reverse limb loss in the future.

While prosthetic and bionic limbs can help amputees regain their independence, they do not fully restore function.

The future of regenerative medicine

Traumatic injury is one of the leading causes of death and disability in Americans. And limb loss from severe injury is the most frequent source of lifelong disability. These traumatic injuries are often caused by automobile accidents, athletic injury, side effects of metabolic diseases such as diabetes and even battlefield injuries.

The possibility of decoding and awakening dormant signals that enable the body to regenerate parts of itself is a transformative frontier in medical science. Beyond regrowing lost limbs, regenerating heart tissue after a heart attack or brain tissue after a stroke could extend life and dramatically increase its quality. Our treatment is far from being ready to use in humans, and we only know that it works when applied immediately after injury. But uncovering and understanding the signals that allow cells to regenerate means that patients may not have to wait for scientists to really understand all the intricacies of how complex organs are constructed before they can get treated.

Making a person whole again means more than just replacing their limb. It also means restoring their sense of touch and ability to function. New approaches in regenerative medicine are now beginning to identify how that may be possible.

Written by:

  • Michael Levin – Professor of Biology, Tufts University
  • David Kaplan – Professor of Biomedical Engineering, Tufts University
  • Nirosha Murugan – Assistant Professor of Biology, Algoma University

This article was first published in The Conversation.

For more on this research, see Scientists Regrow Frog’s Lost Leg With a Five-Drug Cocktail.

Share

View Comments

  • Why haven't these evil "scientists" been arrested? Lock them up before they start inflicting amputations on mammals!

  • Very Interesing.

    On a lighter note , I always wondered why the French Considered Frogs Legs a Delicacy.
    Well , looks llike this resarch will help them to do Frog Leg Farming. Not sure how much the Frogs would would appreciate that. I can hear Kermit Protesting vehemently.

    Ona Serious Note. There are many technologies from the distant past which are lost to humans , which is why we do Scientific research, to try and rediscovver these lost technologies. This ability to regenerate lost limbs may be be one such technology.

    1. Ask a person who has lost a limb, and he/she will report that she/he thinks that he has a Ghostly Limb. Only, when the Reality of the gross world hits him/her , loss of limb hits her/him like a ton of bricks.

    2. As far as humans are concerned there are numerous reports of Couples saving the Unbilical Cord after a Child is born. Even from ancient times, the Unbilical Cord was safely stored in a amulet worn around the arm of the person after she/he grew up, and was used in medicine in ancient times to effect lots of "miracle"cures.

    3.Don't know if the same was used to regrow lost limbs.

    4.The Child in the Womb of the mother, gets her/his nutrition from the Mother, through the umbilical Cord, while floating in the amniotic Fluid after the couple concieve. The lucky sperm from millions competing to fertilize the Egg are known facts and the process of cell division and development of the Child (note I don't use the term Fetus) is also well known. Modern Science is quite judgmental abut when life actually begins.

    4. From ancient times the Vedas tell us, that Life actually begings when the the Couple decide to bring forth new life (thought) ---- after being wed in holy matrimony, as witnessed by the Gods and their fellow men and women.

    5.The act of procreation happens between consenting adults . The New Born Baby is actually concieved in the mind, before the actual physical act happens, and the Couple are lucky enough to be blessed by the almighty to concieve a physical baby.

    6. There is normally a three month Courting, Chocate, Flowers Routineamong humans before the couple decide to bring forth new life into this world (hopefully after matrimony). I do think we are a little bit more advanced than animals! Do observe the mating rituals and the song anddance among other species of life likeBirds and Animals as well. Especially the lovely birds in Madagascar!

    7. Coming back to Physical Regeneration of Lost Limbs, I suspect that the Amniotic Fluid and the Umbilical Cord which were instrumental in the physical creation of a new born after fertilization mmay have the secrets on the ability to regenerate lost limbs.

    8. We have created the Abortion PIll (RU 486 also called the "Night After Pill ") to abort the child yet tobe born, after a hedonistic night of self-indulgement and pleasure. I wonder how many such babies concieved, never see the beuatiful planet we are lucky enough to be born into and enjoy, and who could possibly contribute for the welfare of the human species.

    6. I am not being judgmental about the choices that Humans who have been granted Free Will by the Almighty God make during their lifetimes. That is their personal choice . Each Individual and has to make the same. None of us should judge their choices or actions with moral, ethical or other tinted glasses. That is their Karma Playing out I do mourn for the souls who never got to contribute to making the world slightly better, and had to rejoin the queue at the end of the line to get life again!

    Views exprssed are personaland not binding on anyone.

  • This research was done by Bob Beck. See his book THE BODY ELECTRIC. Modern medicine killed his funding. The won't make any money. Wheelchair and prosthetic companies will kill this.

By
The Conversation

Recent Posts

Staring Into Hurricane Ian’s Eye: NASA Scientists Are Analyzing the Forces That Made the Storm So Catastrophic

NASA scientists are studying the latest satellite imagery of Hurricane Ian and analyzing the forces…

September 30, 2022

NASA’s Juno Spacecraft Captures Closest View of Jupiter’s Icy Moon Europa in 22 Years

Observations from the Juno spacecraft’s close pass of the icy moon provided the first close-up…

September 30, 2022

Russian Cosmonauts Undock From Space Station and Return to Earth

Yesterday, September 29, the Soyuz spacecraft undocked from the International Space Station (ISS) at 3:34…

September 30, 2022

Ancestral Heritage and Cancer: New Connection Discovered

The study also identified a new prostate cancer taxonomy. Two groundbreaking studies recently published in the…

September 30, 2022

Scientists Discover the Secret to Making Food Seem Tastier

How does color impact how you perceive food? According to recent research, a restaurant may…

September 30, 2022

Celebrate “International Observe the Moon Night 2022” With NASA

NASA invites the public to participate in the celebration of "International Observe the Moon Night"…

September 30, 2022