Genetically altered mice discovered accidentally at the Wistar Institute in Pennsylvania have the seemingly miraculous ability to regenerate like a salamander, and even regrow vital organs.

Researchers systematically amputated digits and damaged various organs of the mice, including the heart, liver and brain, most of which grew back.

The results stunned scientists because if such regeneration is possible in this mammal, it might also be possible in humans.

The researchers also made a remarkable second discovery: When cells from the regenerative mice were injected into normal mice, the normal mice adopted the ability to regenerate. And when the special mice bred with normal mice, their offspring inherited souped-up regeneration capabilities.

The mice, known as the MRL strain, were genetically engineered and inbred to develop lupus. But researchers don’t know why exactly the animals’ injuries heal so well.

“If we identified the molecules that allow mice that don’t regenerate to regenerate … and I think we could be close to doing that, then I think the next step is to consider what these molecules would do in individuals,” said Ellen Heber-Katz, a professor of molecular and cellular oncogenesis at Wistar, located on the University of Pennsylvania campus in Philadelphia.

Heber-Katz discovered the strain in 1998 accidentally while working with mice altered genetically for studying autoimmune diseases.

She had pierced holes in the ears of the genetically altered mice to distinguish them from a control group, but they healed quickly with no scarring.

She and her colleagues wanted to find out what other parts of this strain of mice would grow back, so they snipped off the tip of a tail, severed a spinal cord, poked an eye and cauterized various internal organs.

The incredible wound-healing they observed abruptly shifted the focus of Heber-Katz’s lab’s research from autoimmune disease to regenerative medicine. The researchers began hunting for the specific genes that gave the mice their special powers. They are focusing on three specific genes at the moment, but she suspects that many more likely contribute to the regenerative abilities.

By Kristen Philipkoski

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