A functional immune system can be derived from embryonic stem cells, preliminary s...( (WASHINGTON February 12 2008) A new...),Health

(WASHINGTON, February 12, 2008) A new study demonstrates for the first time that embryonic stem cells can be used to create functional immune system blood cells, a finding which is an important step in the utilization of embryonic stem cells as an alternative source of cells for bone marrow transplantation. This hopeful news for patients with severe blood and immune disorders, who need these transplants for treatment, was prepublished online in Blood, the official journal of the American Society of Hematology.

Embryonic stem cells (ESCs) are being intensely investigated as a renewable source of primitive cells theoretically able to regenerate all tissues and organs. The use of ESC-derived blood-forming cells may have an important advantage over traditional transplants that use bone marrow, umbilical cord blood, and peripheral blood from donors. The antigens on the surface of donated cells must be compatible (determined by a method called HLA matching) with those of the patient to prevent rejection. The use of embryonic stem cells, which have low levels of these antigens and may therefore be less likely to provoke a defensive reaction by the patients body, may allow patients who cant find suitable HLA-matched donors to receive transplants.

Previous studies have shown that mouse ESCs can be coaxed to form blood-forming hematopoietic cells by introducing a protein called HOXB4, known for its unique ability to greatly enhance cell proliferation, into them. These cells could then be transplanted into mice whose own marrow had been destroyed by radiation, rescuing their marrow function and beginning to produce necessary blood cells. However, previous studies have not investigated whether ESC-derived bone marrow in these mice could regenerate normal immune function in particular, if they could allow the mice to respond to viruses or vaccines. Because fetuses have no need for a functional immune system as they are protected from the environm
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