Blood cells made from stem cells

Scientists at the University of Wisconsin medical school have for the first time turned human embryonic stem cells into blood cells. It's the first published report that the cells can be turned into other human tissues.

The discovery may one day lead to the development of treatments for leukemia, lymphoma and other blood disorders, but Dan Kaufman, a hematologist and the lead author of the study, said such goals remain a long way off.

"I don't want to give false hope to anybody that we're able to treat cancers or blood disorders now," Kaufman said. "I think it's something that we hope will come in the future, but there are a lot of hurdles to overcome in the meantime," Kaufman said.

Kaufman said the research would help scientists understand how blood and bone marrow cells develop, which could help them find new treatments.

Dr. Douglas Kerr, a stem cell researcher at the Department of Neurology at Johns Hopkins University in Baltimore calls it "the Holy Grail."

EXTRA INFORMATION Read more about the stem cell research in Proceedings of the National Academy of Sciences    RESOURCES In-Depth:The stem cell debate

"As is, undifferentiated, naive embryonic stem cells don't have a therapeutic use. They are too dangerous," Kerr said. "However, if we learn to appropriately shunt them down toward a particular cell lineage, then we have the potential to treat a wide variety of diseases, and that's really an important next step."

Stem cells are blank cells that can be turned into specialized cells such as heart cells, or any kind of tissue in the body, such as skin, muscle or the brain.

Scientists are just beginning to learn how to coax human embryonic stem cells into becoming various cell types in the laboratory. The hope is that by guiding this transformation in the laboratory, scientists can coax stem cells to make new cells that could be used to treat diabetes, Parkinson's disease, heart disease or other disorders.

The University of Wisconsin team exposed stem cells to bone marrow and other cells along with growth factors, which encouraged the cells to turn into blood cells.

Kaufman said the process worked in tissue cultures in a laboratory setting. It was too early, he said, to tell if the stem cells could actually grow in a person's, or animal's body.

"This is a way to start heading down that road, and it's a beginning stage, it's an early stage," Kaufman said. "We don't have cells yet that we're going to use to treat patients, but this shows that the potential is there one day."

The findings are published in the Proceedings of the National Academy of Sciences.

Stem cell research has been controversial because it requires destroying a days-old embryo that is not implanted in a woman's womb to harvest the cells.

President George W. Bush announced last month that he would allow federal funding for research on 60 lines of stem cells that were in existence on August 9, but would not fund future lines.