Genetically engineered stem cells from bone marrow showed promise as a potential new way to deliver a cancer-killing protein to tumors, British researchers said on Tuesday. Experiments in cell cultures and in mice showed the adult stem cells — a type known as mesenchymal stem cells — could home in on cancer cells and deliver a lethal protein that attacked only the cancer while sparing normal healthy tissue. “We’ve developed cells which specifically target cancer through the body and deliver an anti-cancer protein to where it is needed in a seek-and-destroy approach,” said Dr. Michael Loebinger of University College London,...