UCLA researchers find blood stem cells originate and are nurtured in th...(tists learn how to generate self-renewin...),Health

Currently, patients with certain types of leukemia have one shot at a cure a bone marrow transplant. However, there arent nearly enough bone marrow donors to provide patients with perfect matches. Use of a less than perfect donor match carries a risk of graft vs. host disease, in which the immune cells from the donated marrow attack the body of the transplant patient. Cord blood contains blood stem cells, but not in large enough quantities to transplant an adult patient, Mikkola said.

If researchers could grow blood stem cells, those cells could be transplanted into these patients. The blood stem cells would then differentiate into a new, and healthy, blood supply. And with the recent success in creating induced pluripotent stem cells (iPS) from human skin cells, a patients own skin cells could perhaps be used to create iPS cells. Those cells could then be transformed into blood stem cells, creating an immune-compatible source of blood supply that eliminates the risk of graft vs. host disease.

In her previous research, Mikkola and collaborators in Harvard and France had discovered that the placenta contained a large pool of blood stem cells, but it wasnt clear if they originated elsewhere and migrated to the placenta to self-renew. Using a unique mouse model, a mouse embryo without a heartbeat, Mikkola and her team were able to find the blood stem cells at the site of their origin because there was no circulation of blood through the body.

Using this model, we identified that the placenta has the potential to make hematopoietic (blood) stem cells with full differentiation ability to create all the major lineages of blood cells, Mikkola said. The placenta acts as a sort of kindergarten for these newly made blood stem cells, giving them the first education
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