Until just a few years ago, a severe burn was the equivalent of a death sentence. Doctors must excise the burnt skin quickly to save the patient, but they must cover the wound with something quickly; without their skin, burn victims are in constant pain and at risk for dehydration, shock and infection. In 1980, researchers Ioannis Yannas and John F. Burke published a paper about a synthetic skin membrane that could be applied to such injuries. This skin layer, made from shark and cow collagen, can serve as scaffolding while new skin cells grow. But the question of where to get these new skin cells was another problem. Doctors tried using skin from the patient's family members or from cadavers, but now it's possible to build new skin from the patient's own skin cells. Doctors can biopsy a few cells and send them to a lab where the cells divide and divide until there's an entire sheet of skin. Another source of rebuilt skin? Infant foreskins, which can grow hundreds of times their original size in the laboratory.