Breakthrough Study Suggests Humans May One Day Regrow Limbs Like Salamanders

For centuries, the inability of humans to regrow lost limbs has been considered an unchangeable limitation. Unlike salamanders, which can regenerate entire limbs, mammals—including humans—typically heal injuries by forming scar tissue. However, new research published in Nature Communications suggests that this limitation may not be permanent.

Human Regeneration: A Hidden Capacity?

“This changes the way we think about what’s possible,” said Ken Muneoka, a professor in the Texas A&M University College of Veterinary Medicine and Biomedical Sciences (VMBS) veterinary physiology and pharmacology department (VTPP). “Why some animals can regenerate and others, particularly humans, can’t is a big question that has been asked since Aristotle. I’ve spent my career trying to understand that.”

In their study, Muneoka and his colleagues developed a two-step treatment that led to the regeneration of bone, joint structures, and ligaments in mammals. While the results were imperfect, the team believes this approach could immediately improve tissue repair after amputations and reduce scarring.

Redirecting the Body’s Natural Healing Response

In mammals, injuries trigger fibrosis, a process where fibroblast cells rapidly close wounds by forming scar tissue. This response prioritizes survival but limits the body’s ability to rebuild missing structures. In regenerative species like salamanders, the same cells organize into a blastema—a temporary structure that enables tissue regrowth.

“It’s as if these cells can move in two different directions,” Muneoka explains. “They could either make a scar or make a blastema. Our research focused on redirecting the behavior of fibroblasts already present at the injury site.”

How the Two-Step Treatment Works

The researchers tested whether mammalian healing could be shifted toward regeneration using a sequential treatment with two growth factors:

• Step 1: After a wound had already closed, fibroblast growth factor 2 (FGF2) was applied. This allowed the body to complete its typical healing response before the team “changed what happens next,” Muneoka says. FGF2 stimulated the formation of a blastema-like structure, which does not normally occur in mammals.
• Step 2: Several days later, bone morphogenetic protein 2 (BMP2) was applied, triggering the cells to begin forming new structures.

“This is really a two-step process,” Muneoka says. “You first shift the cells away from scarring, and then you provide the signals that tell them what to build.”

Challenging Long-Held Assumptions

A key implication of the study is that regeneration does not require adding external stem cells—a common approach in regenerative medicine. “You don’t have to actually get stem cells and put them back in,” Muneoka says. “They’re already there—you just need to learn how to get them to behave the way you want.”

Larry Suva, a VTPP professor who contributed to the study, emphasizes that the findings shift how we view human regenerative potential. “This research opens new doors for understanding and potentially harnessing the body’s natural healing processes,” he says.

“This changes the way we think about what’s possible.” — Ken Muneoka, Texas A&M University

Future Implications and Next Steps

While the study marks a critical step toward human limb regeneration, the researchers acknowledge that the results are not yet perfect. However, they believe the approach could soon be used to improve outcomes for amputees by reducing scarring and enhancing tissue repair.

The team plans to continue exploring how to refine the process and apply it to more complex structures, bringing us one step closer to unlocking the full potential of human regeneration.