文本框: LTC-IC AND NOD/SCID REPOPULATING CELLS IN NEONATAL BLOOD: A COMPARISON WITH CORD BLOOD
Zhang XB, Li K, Fok TF, Lam AC, Yau FW, Li CK, Yuen PMM
Hong Kong, China

Objective: Our prior research showed that neonatal blood contains early stem cells and progenitor cells and that the expansion capacity of NB is comparable to that of CB (Liu J, et al.: Bone Marrow Transplant 1999; 24:247-52). In this study we further compared the long-term culture initiating cells (LTC-IC) and NOD/SCID repopulating cells (SRC) in NB with CB.
Methods: LTC-IC were determined by limiting dilution assay. NB and CB CD34+ cells were enriched by MACS after thawing and ficoll density separation. 2-4X 104 CD34+ cells were injected into tails of sublethally irradiated NOD/SCID mice (300-325 cGy). Six weeks after transplant mice were sacrificed and bone marrow (BM) of 2 femurs, spleens (SP) and peripheral blood (PB) were collected for flow cytometry and DNA analysis
Results: Frequency of LTC-IC, in mononuclear cells of NB and CB was similar (1/ 4749 vs 1/ 3847, p=0.27 by t test), which suggested that within 72 hours after delivery, progenitor cells in PB did not obviously decreased. Bone marrow engraftment was defined by recipient animals containing measurable numbers of human CD45+ cells 6 weeks after transplantation. The proportion of CD45+ cells in recipient marrow was higher in animals receiving CB CD34+ cells (n=18) than in those receiving comparable numbers of NB CD34+ cells (n=26), percentages of CD45+ cells are 22.1% vs 12.2%, respectively (p=0.06, Mann-Whitney U test). Some subsets (CD33 and CD61) in huCD45+ cells of BM in mice transplanted with NB and CB had the similar proportion (CD33: 33.8% vs 24.0%; CD61: 1.64% vs 1.23%)  Interestingly, the percentage of CD14+ cells in mice engrafted with NB was significantly higher than those engrafted with CB (15.7% vs 9.19%, p=0.029), while percentage of CD19+ cells in the former was sign!
ificantly lower than that of the latter (28.0% vs 43.7%, p=0.027).
Conclusion: Our results demonstrated for the first time that NB collected within 72 hours after delivery of a baby has similar levels of LTC-IC cells and approximately half amount of NOD/SCID repopulating cells comparing with those of CB.
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