The number of CD34+CD133+ hematopoietic stem cells residing in umbilical cord blood (UCB) units is not correlated with the numbers of total nucleated cells and CD34+ cells: a possible new indicator for quality evaluation of UCB units
Umbilical cord blood transplantation (UCBT) is often associated with delayed neutrophil and platelet recovery. Engraftment failure is another major obstacle. Several factors influence these serious complications, including the numbers of total nucleated cells (TNCs) and CD34+ cells which have been used as reliable factors for selecting UCB units for transplantation. However, whether both factors are reliable indices of the hematopoietic stem cell (HSC) activity of UCB units remains unknown. To evaluate the quality of UCB units, we quantified the actual number of transplantable CD34+CD133+ HSCs (tHSCs) residing in UCB units. The number of tHSCs was not correlated with the numbers of TNCs or CD34+ cells. These results strongly suggest that neither factor reflects the numbers of tHSCs residing in UCB units. To validate the significance of the number of tHSCs, further analysis is required to determine whether the number of tHSCs residing in UCB units is useful as a new indicator for the quality assessment of UCB units.
KeywordsCD34+CD133+ HSCs UCBT Quality assurance UCB units
This work was supported by Health and Labour Sciences Research Grant from the Ministry of Health, Labour and Welfare of Japan. The authors are grateful to the Japanese Red Cross Kinki Cord Blood Bank for providing the CB samples used in this study. Drs. S. Nomura, S. Fujita, H. Ogawa, M. Inoue and H. Nakamae are acknowledged for their valuable contribution to this study.
YM, designed and performed a majority of the experiments, analyzed and interpreted the data; FN, KH, TF, contributed to the data analysis and interpretation; SO, TK, YF, designed and performed some of the experiments, analyzed and interpreted the data; HA, provided advice on the statistical analyses; YS, conceived of and designed the study, analyzed and interpreted the data, provided financial and administrative support, and wrote the paper.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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