Year: 2009
Type: article
Abstract: In previous work, we fractionated CD34+ umbilical cord blood (UCB) progenitors to purify cells that express high levels of aldehyde dehydrogenase (ALDH). The ALDHbr CD34+ cells were enriched with progenitors that engraft NOD/SCID mice in both short-term (6–8 week) and long-term (>18 week) transplants. In contrast, ALDHneg CD34+ progenitors were not a significant source of NOD/SCID repopulating cells. These data strongly imply that transplantable human progenitors express ALDH; however, one shortcoming for that work remains that human hematopoietic development in NOD/SCID mice is limited to the myeloid and B-lymphoid lineages. Because the pace of T cell engraftment is a critical clinical concern, we have adopted the use of the NOD/SCID-IL2Rγnull mouse xenograft transplant model. In the current study, 20 mice were transplanted with lineage-depleted ALDHbr CD34+ progenitors at doses that ranged from 3,000 to 30,000 cells. In control studies, similar doses of ALDHneg CD34+ cells did not provide long-term engraftment. So that we might characterize the behavior of individual UCB, each transplant graft was derived from a single UCB. In addition, each UCB was assayed in multiple different mice. Twelve of 13 mice that survived until 21 weeks post-transplant demonstrated multiple-lineage human hematopoietic engraftment. Human T, B, NK and myeloid cells were detected in the bone marrow and spleen. In addition, in 9 mice human T cells were detected in the thymus. Furthermore, 7 mice had sufficient thymus tissue to measure T cell Receptor Excision Circles (TREC). By that assay, 3 of those mice demonstrated active human T cell rearrangements. As anticipated, the level of engraftment to all tissues was cell dose-dependent. One strength for this xenograft model was that engraftment could be monitored over time within the peripheral blood. Human B cells engrafted within 7 weeks post-transplant and were detected in 17 of 19 mice (≥ 5 B cells/μL). At 16 weeks post-transplant, 15 of 18 mice maintained detectable B cells. In contrast, human T cells emerged later, beginning at 13 weeks post-transplant. However, even by 16 weeks post-transplant, T cells were only detectable in the peripheral blood of 6 of 18 mice (≥ 5 T cells/μL). These studies provided evidence that ALDHbr CD34+ cells establish both short- and long-term hematopoiesis in NOD/SCID-IL2Rγnull mice. The emergence of T cells was the most stringent test for long-term engraftment.
Institution: Duke Medical Center
Language: English
Subfield: Hematology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,650
OpenAlex ID: W2161698985