WASHINGTON — Stem cells made from human embryos can home in on damaged eyes, hearts and arteries of mice and rats, and appear to start repairs, a U.S. company said on Monday. Massachusetts-based Advanced Cell Technology said it had devised a straightforward way to make blood vessel precursor cells out of the stem cells and plans to test them in humans. ‘We figured out how to produce literally billions of so-called ‘hemangioblasts’ — the mythical cell in the embryo that gives rise to our entire blood and immune system as well as to the blood vessels in our body,’ Dr. Robert Lanza, vice president of research and scientific development at ACT, said in an e-mail. ‘We’ve also tested these cells in animals for the first time, and it turns out that they have incredible reparative potential.’ Embryonic stem cells are the ultimate master cell of the body, giving rise to all of the tissues and organs. The use of human embryonic stem cells is controversial because many people oppose destroying the embryo. The U.S. Congress has passed several bills that would expand federal funding of human embryonic stem cell research but President George W. Bush […]