CD26 Inhibition on CD34 + or Lineage − Human Umbilical Cord Blood Donor Hematopoietic Stem Cells/Hematopoietic Progenitor Cells Improves Long-Term Engraftment into NOD/SCID/Beta2 null Immunodeficient Mice

Given the tremendous need for and potential of umbilical cord blood (CB) to be utilized as a donor source for hematopoietic stem cell (HSC) transplantation in adults, there is a strong push to overcome the constraints created by the limited volumes and subsequent limited HSC and hematopoietic progenitor cell (HPC) numbers available for HSC transplantation from a single collection. We have previously described the use of CD26 inhibitor treatment of donor cells as a method to increase the transplant efficiency of mouse HSCs and HPCs into a mouse recipient. To study the use of CD26 inhibitors as a method of improving the transplantation of human CB HSCs and HPCs, we utilized the nonobese diabetic/severe combined immunodeficient/beta 2 microglobulin null (NOD/SCID/B2m^null) immunodeficient mouse model of HSC transplantation. We report here significant improvements in the engraftment of long-term repopulating cells following the treatment of either CD34⁺ or lineage negative (lin⁻) donor CB with the CD26 inhibitor, Diprotin A, prior to transplant. These results establish a basis on which to propose the use of CD26 inhibitor treatment of donor CB units prior to transplantation for the purpose of improving transplant efficiency and subsequently patient outcome.