Dominant unit CD34+ cell dose predicts engraftment after double-unit cord blood transplantation and is influenced by bank practice

Abstract

AbstractWe investigated the unit characteristics associated with engraftment after double-unit cord blood (CB) transplantation (dCBT) and whether these could be reliably identified during unit selection. Cumulative incidence of neutrophil engraftment in 129 myeloablative dCBT recipients was 95% (95% confidence interval: 90-98%). When precryopreservation characteristics were analyzed, the dominant unit CD34+ cell dose was the only characteristic independently associated with engraftment (hazard ratio, 1.43; P = .002). When postthaw characteristics were also included, only dominant unit infused viable CD34+ cell dose independently predicted engraftment (hazard ratio, 1.95; P < .001). We then examined the determinants of infused viable CD34+ cell dose (precryopreservation count, postthaw recovery, and postthaw viability) in 402 units thawed at our center. This revealed close correlation between precryopreservation and postthaw CD34+ cell counts (r2 = 0.73). Median CD34+ cell recovery was 101%, although it ranged from 12% to 1480%. Notably, units from non–Netcord Foundation for the Accreditation of Cellular Therapy (Netcord-FACT)–accredited banks were more likely to have low recovery (P < .001). Furthermore, although median postthaw CD34+ cell viability was 92%, 33 (8%) units had <75% viable CD34+ cells. Units from non–Netcord-FACT–accredited banks and units with cryovolumes other than 24.5 to 26.0 mL were more likely to have poor postthaw viability. Precryopreservation CD34+ cell dose and banking practices should be incorporated into CB unit selection.