Growth Spurt
Tadpoles regenerate new tails with sodium treatment; could limbs be next?
Just as young children can re-grow an injured fingertip, some young tadpoles can re-grow an injured tail. Recent work by Tufts scientists shows that under the proper conditions, older tadpoles can regenerate a severed tail, too—a finding that could one day lead to new treatments for older humans suffering from wounds and loss of limbs.
A key component to the regenerative response in the tadpoles was sodium ions, which were part of a drug “cocktail” that enabled the tadpoles to grow perfect new tails, including spinal cord, muscle and other tissue.
This is the first time that regeneration has been demonstrated using a specific drug-based treatment following the loss of an appendage in an animal. Until now, advances had involved administering therapies before the injury was sustained. This approach breaks new ground because it does not require gene therapy.
“We have significantly extended the effective treatment window, demonstrating that even after a scar-like wound covering begins to form, control of physiological signals can still induce regeneration,” says Michael Levin, A92, a professor of biology in the School of Arts and Sciences and director of the Center for Regenerative and Developmental Biology at Tufts.
Levin is the corresponding author on the paper detailing the work, which appeared as the cover story in the September 29 issue of the Journal of Neuroscience.
“Artificially causing an influx of sodium for just one hour can overcome a variety of problems, such as the decline in regenerative ability that comes with age and the effect of regeneration-blocking drugs,” Levin said. “This is a novel, biomedically relevant approach to inducing regeneration of a complex appendage.” The researchers discovered that the tail of the Xenopus laevis tadpole could be induced to regenerate as long as 18 hours after amputation.
The frog tail is a good model for human regeneration because it repairs injury in the same way that people do: each tissue makes more of itself. Though small, the tadpole tail is complex, with muscle, spinal cord, peripheral nerves and vasculature cells.
See an earlier story, “Grow Your Own,” about Michael Levin’s research on regeneration.