Scientists create first blood cells from stem cells

WASHINGTON -- For the first time, researchers have used embryonic stem cells to produce human blood cells, a step that could lead to a new source of cells for transfusion and other therapies.

Primitive human blood cells, known as hematopoietic precursor cells, were produced from human embryonic stem cells by researchers at the University of Wisconsin, led by James A. Thomson.

Similar work has been done in mice, but this is the first time human blood cells have been developed from embryonic stem cells, said Dan S. Kaufman, one of the authors of the study appearing in Tuesday's issue of Proceedings of the National Academy of Sciences.

Embryonic stem cells are the basic building blocks for the 260 or so cell types in the body. During development, stem cells transform into heart, muscle, brain, skin or other tissue.

Researchers hope that by guiding this transformation in the laboratory, they can coax stem cells to make new cells that could be used to treat diabetes, Parkinson's disease, heart disease or other disorders.

Not ready for humans

While development of these cells holds promise for the future, Kaufman stressed that it will take years before they can be developed to the point of use in people. "I don't want to raise any false hope," he said

In addition, embryonic stem cells have become the focus of debate because they are derived from blastocysts, one of the earliest stages of human embryos before they become implanted. Opponents of the research argue that it destroys a human life.

President Bush has ordered that federal funds be made available only for research on cell lines that were in existence on Aug. 9, restricting the establishment of new lines.

Thomson is a pioneer in the development of embryonic stem cells and his university holds five cell lines that are available for research under federal rules.