University of Washington Medical Center Seattle, Washington, United States
Background/Case Studies: Umbilical cord blood is a valuable source of CD34+ hematopoietic stem cells, widely used as an alternative to bone marrow or peripheral blood stem cells for transplantation for various diseases. Despite its clinical utility, the high cost of collection, processing, and storage as well as the variability in CD34+ cell yields underscore the need to optimize unit selection. While prior studies have reported a correlation between nucleated red blood cells (nRBCs) and CD34+ cell counts, independent observations within our internal cord blood data motivated deeper investigation. Recognizing the potential clinical implications, a systematic analysis of our inventory was conducted to evaluate nRBC percentage as a surrogate marker for stem cell content and predictor of transplant outcomes.
Study
Design/Methods: We conducted a retrospective analysis of all cord blood units (CBUs) processed at our cord blood bank since its establishment in 1998 through March 2025. Extracted data included complete blood count parameters including nRBC and total nucleated cell (TNC) counts, and CD34+ cell count. Transplant outcome data for 885 recipients of CBUs from our bank were obtained from the Center for International Blood and Marrow Transplant Research (CIBMTR). Recipients involving more than one CBU were excluded. Time to neutrophil recovery (absolute neutrophil count > 500/μL) and platelet recovery ( > 20,000/μL) were used as indicators of transplant outcomes. Pearson correlation coefficients assessed associations between variables, and multiple linear regression identified predictors of transplant outcomes. A p-value of < 0.05 was considered statistically significant.
Results/Findings: Of the 12,619 CBUs processed at our bank, 12,569 units (99.6%) were included in the analysis after excluding those with missing data. The percentage of nRBCs was moderately correlated with CD34+ cell count (Pearson’s r = 0.36, p < 0.001). Among 351 patients who received single-unit transplants, 197 (56.1%) had available data on time to neutrophil and/or platelet recovery. Correlation analysis demonstrated that nRBC percentage in the CBU was significantly correlated with faster platelet recovery (Table 1). Multiple linear regression evaluating relationships between nRBC percentage, TNC count, CD34+ cell count, and time to platelet recoverydemonstrated that nRBC percentage remained an independent predictor of platelet recovery time, even after adjusting for CD34+ cell count (β= -0.73, 95% CI [-1.38, -0.084], p = 0.027). Conclusions: Our findings reveal a significant association between nRBC percentage and CD34+ cell count in CBUs. Moreover, nRBC percentage independently predicts platelet recovery post-transplant, suggesting its potential utility in optimizing unit selection.
