The peripheral blood of the transplanted mice was examined every four weeks, and after 16-18 weeks the blood-forming organs (bone marrow, spleen, thymus, and lymph nodes) of the mice were dissected. Transplants using mouse AFKL cells were found to be successful; newly formed white blood cells of all lineages derived from AFKL cells appeared in most of the irradiated mice four weeks after the procedure. As expected, all of these blood cell types were detected in all of the control group mice who received fetal liver cell transplants. Scientists continued to find AFKL-derived cells in the irradiated mice four months later, demonstrating the long-term ability of the transplanted cells to produce new blood cells.
Bone marrow samples from the transplanted mice were also taken and injected in a second set of mice and the peripheral blood of this new group of irradiated mice was analyzed and their hematopoietic organs examined after 10-13 weeks. The secondary transplants with mouse AFKL cells were partially successful with some of the mice engrafting the donor cells. This finding shows that AFKL cells have the ability to self-renew, a key characteristic of stem cells.
Though the human AFKL cells failed to reconstitute the hematopoietic system in irradiated, immunodeficient mice, experiments are currently underway to overcome obstacles that may have led to this failure, such as using a low number of cells for the injection and conducting the transplant in adult mice (engraftment is easier to obtain in newborn mice).
As additional confirmation of the probability that AFKL cells are indeed stem cells, the researchers examined them for the expression of specific genes known to be involved in hematopoietic development. The ov
|Contact: Patrick C. Irelan|
American Society of Hematology