The Correlation between CD34+ Cell and Nucleated RBC Counts in Human Cord Blood

Lee, Seong Man; Kim, Kyu Chan; Kim, Sang Woo

Abstract

PURPOSE
Human umbilical cord blood as a potential source of hematopoietic stem cell for stem cell transplantation in children has recently been advocated. Clinical application of cord blood transplantation, however, requires adequate blood volume and number of stem cells. Currently, the number of stem cells in the cord blood is usually measured by flowcytometry, which requires strict quality control and high costs. Here, we postulate that the number of nucleated red blood cells(NRBC) which are relatively immature erythroid cells may correlate well with that of CD34-expressing(CD34+) cells which are considered lymphohematopoietic precursors. If so, CD34+ cell-rich cord blood can be selected and such cells enumerated by a simple and cost-effective blood smears.
METHODS
Correlation between CD34+ cell and nucleated RBC in human cord blood were checked. Sixty cord blood specimens(30 specimens for group A with NRBC>500/mul and 30 specimens for group B with NRBC<500/mul) from healthy newborns were collected in EDTA bottles and transported to our laboratory at room temperature. CD34+ cells were counted by flowcytometry(FACScanTM: Becton Dickinson) within 72 hours after collection, and NRBC by light microscopy. The results were as following.
RESULTS
1.The proportion of CD34+ cells in umbilical cord blood was, in the average, 0.85%(+/-1.1) of mononuclear cells. 2.There was a significant difference between the means of CD34+ cell counts in group A(NRBC<500/ul; 30+/-48(SD)) and in group B(NRBC>500/ul; 55+/-61(SD))(p<0.005). 3.Regression relationship among CD34+ cell, WBC, and NRBC counts was as following. ln(CD34+ cell) = -12.21 + 1.46xln(WBC)+ 0.25xln(NRBC) gamma2=30.07 p=0.0001 4.There was a significant correlation between CD34+ cell counts and NRBC counts(gamma=0.4334, p<0.005)
CONCLUSIONS
Our results suggest that there is a significant correlation between CD34+ cell counts and NRBC counts, and that CD34+ cell-rich cord blood specimens can be selected by a simple NRBC counting.