COMPARISON OF REPOPULATING ABILITY OF HEMATOPOIETIC PROGENITOR CELLS ISOLATED FROM HUMAN UMBILICAL-CORD BLOOD OR BONE-MARROW CELLS IN NOD SCID MICE/

The repopulating ability and homing potential of CD34(+) cells isolate d from either bone marrow (BM) or umbilical cord blood (UCB) was compa red in NOD/SCID mice. Mice were sublethally irradiated (3.5 Gy) and wi thin 24 h transplanted i.v. with 10(5)-10(6) CD34(+) cells. Four weeks post-transplantation blood was collected from the tail vein for detec tion of human cells and after 6-7 weeks the mice were sacrificed and b lood, BM, thymus, lymph nodes, spleen, liver, lung and kidney were har vested and single cells suspensions were made. Human cells were detect ed by flow cytometry, and staining was performed for CD34, CD45, and m arkers of the myeloid, and lymphoid lineages, CD34(+) cells from UCB s uccessfully engrafted into the NOD/SCID mice. Eighty-five percent of c ells in BM of the mice were of human origin, depending on the dose of cells injected. In all other organs these percentages were always lowe r, and maximally 63, 13, 3 and 2% in spleen, liver, lung and kidney, r espectively, Transplantation of CD34(+) cells isolated from human BM, on the other hand, resulted in a very low percentage of human cells af ter 6-7 weeks of transplantation, not exceeding 3% of the cell suspens ion. Whether this difference in repopulating ability can be explained by an intrinsic qualitative difference or by differences in quantity o f stem cells within the CD34(+) compartment from UCB or BM remains to be determined.