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 patient's body, may allow patients who can't find suitable HLA-matched donors to receive transplants.