One of the controversial issues in this year's presidential campaign is stem cell research. While both President George W. Bush and his Democratic challenger Sen. John Kerry favor research on adult stem cells, they have very different positions on embryonic stem cell research. In August of 2001, Bush decided to restrict public funding for research on embryonic stem cells to already existing cell lines. Kerry has said that, as president, he would reverse those restrictions. Embryonic stem cells are capable of becoming almost any type of cell or tissue in the body, which makes them valuable in the search for medical treatments. But the research also raises ethical questions, and many opponents say it destroys human life. The University of Minnesota's Stem Cell Research Institute is a leader in the field. Morning Edition host Cathy Wurzer spoke with Catherine Verfaillie, director of the Institute.