Science explores stem cell options.

Byline: Jeremy Manier and Ronald Kotulak

CHICAGO _ As the political fortunes of embryonic stem cell research hang in the balance, scientists increasingly are looking for alternatives in case federal funding for work on human embryos falls through.

The ethical dilemma of embryonic research grew in the last week when two groups revealed the first projects to create human embryos solely for their stem cells, using in vitro fertilization and cloning.

Those announcements came as President Bush, who has said he opposes using embryos for research, met with bioethicists for advice on whether to allow federal funding of embryonic stem cell experiments.

Opponents of such research argue that some alternatives are at least as promising as embryonic stem cells, which may be able to regenerate tissue to cure ailments such as diabetes and Parkinson's disease. The desperate search for other research options has led to possible stem cell sources in adult bone marrow, cells made by mimicking the process of cloning and even fat tissue.

Yet some of the alternatives, such as fat, almost certainly are dead ends, according to stem cell experts. Adult stem cells from bone marrow show more promise and have reached human trials for some diseases. Even so, experts say, such cells have lacked the power of embryonic stem cells to form virtually any type of tissue.…