NOD/SCID repopulating cells contribute only to short-term repopulation in the baboon.

We have previously compared the repopulation ability of gene-modified baboon CD34+ cells in an autologous transplantation versus a xenotransplant model in irradiated nonobese diabetic/severe combined immune deficiency (NOD/SCID) mice. Baboon CD34-selected marrow cells were transduced with a gammaretrovirus vector and infused into irradiated baboons and NOD/SCID mice. A limited integration-site analysis could only detect two common retrovirus integration sites in the NOD/SCID and monkey. Here, we performed locus-specific PCR on 30 clones recovered from NOD/SCID beta2-microglobulin mice reconstituted with transduced baboon CD34+ cells. We identified five common integrants in the baboon early after transplant (2-6 weeks) but none during the long-term follow-up (6 and 12 months). These results confirm that repopulating cells in the NOD/SCID mouse contribute only to short-term repopulation in a clinically relevant large animal model.