Quantity and quality of engrafting cells in cord blood and autologous mobilized peripheral blood

Cord blood (CB) and autologous mobilized peripheral blood stem/progenitor cells (PBSC) are now used widely for clinical transplantation. We characterized the short-term (8 weeks) engraftment in NOD/SCID mice resulting from transplanted CD34⁺ cells from these two sources. We also quantified the frequency of long-term engrafting cells, and the average proliferative capacity of individual engrafting cells by a competitive repopulation assay with binomial variance-covariance modeling. We found that 0.5 million CD34⁺ CB cells were able to generate sustained, high-level, multilineage human hematopoiesis, whereas a sixfold higher number of CD34⁺ PBSC (3 million) from cancer patients undergoing chemotherapy generated comparable short-term, but much lower sustained multilineage human hematopoiesis after transplantation. In comparison to CD34⁺ cells from PBSC from cancer patients, long-term engrafting cells were approximately eightfold enriched in CB CD34⁺ cells, and each CB long-term engrafting cell had an ∼15-fold higher multilineage proliferative capacity. Thus, the number and function of transplantable hematopoietic cells were remarkably different between these two sources of stem/progenitor cells.