Stem cells turned into blood cells
2001-09-04 17:45
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.
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 George W. Bush has ordered that federal funds be made
available for research only on stem cell lines that were in
existence on August 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. Kaufman said this particular work was not done using federal funds.
Thomson's team grew the embryonic stem cells in a culture
containing mouse tissue that encouraged development of blood cells, a procedure used in attempting to develop stem cells in specific ways.
The result, they report, was cell colonies that "appear
identical to those produced from human bone marrow cells." Bone marrow produces blood cells.
The development of these early blood cells is important because
stem cells have the ability to continue reproducing themselves.
Scientists studying these early human blood cells have had to rely on such sources as bone marrow and umbilical cord blood.
While more work is needed to develop highly purified populations
of the cells, the team said the finding "could lead to a novel source of cells for transfusion and transplantation therapies."
Dr Ernest Beutler, chairman of the Department of Molecular and
Experimental Medicine at The Scripps Research Institute, cautioned that the cost of producing cells this way may make it impractical for transfusions.
"With respect to using such a system for the production of red cells or white cells for transfusion, the cost of producing such cells would be absolutely prohibitive," Beutler said.
"The possibilities of using such a system for (bone marrow)
transplantation are somewhat greater, but it is not at all clear
that such cells would not be rejected by the immune system," he said. "In short, these are high quality basic studies, but much remains to be done before it would be at all clear that embryonic stem cell-derived hematopoietic cells could play any practical role in the treatment of disease."
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