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Lizards regenerate perfect tails through stem-cell therapy

Although lizards can regrow amputated tails, the replacement structures are imperfect cartilage tubes lacking the dorsoventral patterning of the original tails. A research team led by the University of Southern California (USC) has recently managed to significantly improve the regeneration of lizard tails through stem-cell therapy.

To achieve this, the scientists have initially investigated how lizard tails form during adult regeneration in comparison to embryonic development. In both cases, neural stem cells (NSCs) play a crucial role. However, adult NSCs produce a molecular system blocking skeletal and nerve formation and encouraging cartilage growth, thus “ventralizing” both sides of the tail. Even if this ventralizing signal is absent, adult NSCs are still incapable of generating nerve tissue for the upper or dorsal side of the tail.

Embryonic NSCs, on the other hand, produce the ventralizing signal only in the cartilage region which becomes the lower or ventral side of the tail, allowing the dorsal side to develop skeletal and nerve tissue. Yet, even if embryonic NSCs are implanted into adult tail stumps, they still respond to the ventralizing signal and cannot develop into dorsal structures.

“Lizards have been around for more than 250 million years, and in all that time no lizard has ever regrown a tail with dorsoventral patterning, until now,” said study lead author Thomas Lozito, an assistant professor of Stem Cell Biology and Regenerative Medicine at the Keck School of Medicine at USC. “My lab has created the first regenerated lizard tails with patterned skeletons.”

Professor Lozito and his team used gene-editing tools to make embryonic NSCs unresponsive to the ventralizing signal and they implanted them into adult tail stumps. This process led to the regeneration of perfect tails with dorsoventral patterning.

“This study has provided us with essential practice on how to improve an organism’s regenerative potential,” explained Lozito. “Perfecting the imperfect regenerated lizard tail provides us with a blueprint for improving healing in wounds that don’t naturally regenerate, such as severed human limbs and spinal cords. In this way, we hope our lizard research will lead to medical breakthroughs for treating hard-to-heal injuries.”

The study is published in the journal Nature Communications

By Andrei Ionescu, Staff Writer

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