The U.S. Senate is expected to approve a measure to broaden federally funded research on embryonic stem cells. But some government officials and scientists say the strict limits imposed by the Bush administration are only part of what's hindering stem-cell research. Another problem: several broad patents held by a University of Wisconsin foundation. When executives at Carlsbad, Calif.-based Invitrogen Corp. chose to locate their stem-cell research in Asia recently, they blamed the patents. And today, a California watchdog group, the Foundation for Taxpayer and Consumer Rights of Santa Monica, says it will ask the U.S. Patent and Trademark Office to overturn three patents awarded to James A. Thomson, the Wisconsin researcher who first isolated stem cells from human embryos in 1998.