Legless frogs regrow leg-like limbs in new experiment
To stimulate regrowth in a creature that does not regenerate naturally, such as an adult frog or a human, researchers have experimented with stem cell implants or gene therapy. But these methods can be extremely complicated to implement, Dr. Murugan said.
A simpler approach, Dr. Levin suggested, is to trigger the animal’s body and cells to regenerate the limb.
To do this, the researchers had to create a protected environment around the wound to inhibit healing in the early stages of tissue repair – “to convince every cell in there that, ‘OK, we’re on the growth program of the legs'”. said Dr. Levin.
They made a wearable silicone cap called the BioDome, which was filled with a silk protein hydrogel. Dr. Murugan researched every commercially available drug known to promote regeneration before settling for a mix of five to load into the BioDome and release onto the wound.
In 2017, researchers began what would become an 18-month experiment. On the first day of the experiment, then-graduate student Annie Golding and researcher Quang L. Pham created the cocktail of drugs and BioDomes. Dr. Murugan – along with a technician, Kelsie Miller, and an undergraduate student, Hannah Vigran – performed 13 hours of surgery on 115 anesthetized female frogs.
For a year and a half, the frogs ate and swam under the supervision of an aquaculture technician, Erin Switzer, while the researchers waited patiently.
After about four months, the limbs of the frogs began to diverge, depending on which experimental group they were in, Dr Murugan said.