Nucleated red blood cells as a novel indicator of CD34+ cell content in umbilical cord blood

BACKGROUND: Umbilical cord blood (UCB) has become an important source of transplantable CD34(+) hematopoietic progenitor cells. Cord blood banks (CBBs) can increase their efficiency by minimizing the processing of UCB units with low CD34(+) content, which have a lower likelihood of transplant utilization. We sought to identify a readily available preprocessing metric that would correlate with CD34(+) cell counts, without the cost of additional analysis. STUDY DESIGN AND METHODS: Data were compiled for 131 UCB units processed at the regional CBB. Preprocessing hematologic metrics, including complete blood count and differential, were compared to postprocessing CD34(+) cell quantities. The data were divided into six groups of varying preprocessing metrics, then compared for significant differences in postprocessing CD34(+) cell quantities to develop a screening guidance. RESULTS: UCB units with nucleated RBC (nRBC) content of 15% or greater were found to have a significant increase in CD34(+) cell percentage (p < 0.00001) and total CD34(+) cell content (p < 0.0001). Units with preprocessing total nucleated cell count (TNC) of = 1.50 x 109 with nRBC content of 15% or greater, and for TNC = of 2.00 x 109 with nRBC content less than15%, had a significant increase in CD34(+) content (p < 0.05 and p < 0.001, respectively). Applied as a screening guideline, these units had an increase in mean CD34(+) content from 6.24 x 106 to 9.27 x 106. Units originally in the bottom and top quartiles of CD34(+) content constitute 5% and 53% of processed units meeting these TNC/nRBC criteria, respectively. CONCLUSION: These screening criteria utilizing nRBC provides a guideline that public CBBs may use to increase their efficiency by minimizing the processing of UCB units with lower CD34(+) cell content.