Some lizard species have an interesting defense mechanism: if a predator has them by the tail, the lizard can drop its tail and get away. Luckily, some lizard species can also then regenerate their tail, but this regeneration is not perfect. However, scientists have now discovered a way to make tail regeneration better, which may bring us closer towards one day inducing regeneration in humans.

The lizard tail has a specific pattern that gets established when the lizard develops in its egg. Tails are complicated structures that have a lot of different tissues, including bone, spinal cord, connective tissue, and skin. During development, cells send signals that cause all these different tissues in the tail to grow in the correct pattern. When a lizard regenerates its tail, however, there are some changes: it does not regrow nerves, and produces a long cartilage tube instead of bony vertebrae.

The researchers in this study first determined that during tail regeneration in adults, certain cells that exist in the developing embryo are missing. These cells are responsible for sending signals to other cells that help the tail grow in the correct pattern. The scientists isolated these key embryonic cells, edited their genes so that they would behave the same way they do in the embryo in an adult environment, and injected them into regenerating adult tails. Amazingly, these injected embryonic cells grew into new nerve cells in the regenerated tail and changed the position of the cartilage tube.

This study shows that even imperfect regeneration can be manipulated and made into a closer copy of the original. The ability to pattern regenerating limbs or tails correctly is a very important step, and could potentially help us one day learn how to regenerate limbs in humans.

This study was led by Dr. Thomas Lozito, an Assistant Professor in the Departments of Orthopaedic Surgery and Stem Cell Biology and Regenerative Medicine at the University of Southern California with colleagues based at the University of Southern California and the University of Pittsburgh.

Managing Correspondent: Gemma Johnson

Press Articles: “Aided by stem cells, a lizard regenerates a perfect tail for first time in more than 250 million years,” ScienceDaily, “Stem cells help lizard regenerate a perfect tail for first time in more than 250 million years,” SciTechDaily

Original Journal Article: “Introducing dorsoventral patterning in adult regenerating lizard tails with gene-edited embryonic neural stem cells,” Nature Communications

Image Credit: Pixabay