Umbilical cord blood: the role of apoptosis in the control of CD34+ cell counts

BACKGROUND AND OBJECTIVE: Cord blood obtained at delivery can be used for hematopoietic precursor cells (HPC) transplantation. The major limit for its success is represented by the low cellular yield of the stem cell population. The objective of this study was to determine the role played by apoptosis in the numerical control of CD34+ cell counts. DESIGN AND METHODS: Umbilical cord blood samples were collected from 15 women at the time of the delivery and cord blood units processed. Cells, collected following 24 h and 48 It of incubation, were analysed by flow cytometry using the gating strategy. RESULTS: Remarkable levels of apoptosis were detected in the stem cell population and a significant difference between apoptosis mean values at 24 h and 48 h within CD34+ cells were found. The difference between the percentage of apoptosis in CD34+ cells and that in the remaining population was significant both at 24 h and at 48 h. CONCLUSIONS: CD34+ cells have a higher likelihood to undergo apoptosis in comparison to the remaining ones present in umbilical cord blood. This process of cellular death plays a major role in the control of CD34+ cell counts in placental blood and influence, for this reason, the possibility of success of a cord blood transplantation. (C) 2002 Elsevier Science Ltd. All rights reserved.