A California lab has cloned a human embryo, a science first; the researchers stopped short, however, of creating stem cells. Using a process called somatic cell nuclear transfer, the scientists fused DNA from a man’s skin cells with donated egg cells—and created an embryo with cells specific to the man. Scientists hope stem cells could replace damaged cells with reduced risk of rejection.
The first reported human cloning was in South Korea in 2004, the San Diego Union-Tribune reports; the work was eventually exposed as fraudulent, prompting the Californians—who achieved their breakthrough last May—to check research thoroughly before going public. The Boston Globe cautions that some top figures aren’t impressed; without a stem-cell line, one says, it’s “just not that big a leap.”