Researchers are hard at work building biological time machines that reverse aging in some cells.

Some are trying to reset biological clocks by mimicking “magic factors” in human eggs — the only cells in a woman’s body not programmed to die. Others are identifying molecules that enable salamanders to re-grow limbs. Chemists in San Diego have created a chemical compound they call “reversine,” which resets muscle cells in mice much the same way newts restart limb cell growth after injury. A Scripps Research Institute team has created a small molecule that reverses the aging process of mouse muscle cells, turning them into “stem-like cells” and then re-growing them into different cells. And a University College London researcher has isolated an enzyme implicated in the salamander’s ability to re-grow an eye lens after it has been surgically removed.