title: Indiscernible Benefit of Double-Unit Umbilical Cord Blood Transplantation in Children: A Single-Center Experience From Hong Kong.
abstract: Double-unit umbilical cord blood (DU-UCB) may extend the use of UCB transplantation and improve clinical outcomes. Data in the literature show that single-unit dominance happened in a vast majority of recipients, and the mechanism is unknown. We examined the clinical relevance and engraftment kinetics of DU-UCB transplant in 65 consecutive children who underwent unrelated single-unit (n = 25) and double-unit (n = 40) UCB transplantation for various hematological malignancies (n = 45) and nonmalignant disorders (n = 20). Our result showed no discernible benefit to children receiving double-unit transplant over those receiving single-unit transplant when the total nucleated cell (TNC) doses are ≥2.5 × 10(7)/kg, in terms of the hastening of the engraftment of neutrophils and platelets, reduction of nonengraftment, disease recurrence, early mortality, and graft-versus-host disease, despite significantly higher numbers of TNCs in double units. Further analyses demonstrated that the phenomena were not associated with underlying disease, duration of UCB storage, postthaw viability, HLA disparity, ABO incompatibility, gender, or doses of TNCs, CD34(+) cells, CD3(+) cells, or colony-forming units. Engrafting units in DU-UCB transplants were notably associated with higher CD34(+) cell dose. Chimerism studies demonstrated that single-unit dominance started before neutrophil engraftment in DU-UCB transplants. Data from the study suggested no advantage of infusing double-unit UCB, if an adequately dosed single-unit UCB is available. Successful prediction of the dominant graft would optimize algorithms of UCB selection and maximize the long-term engraftment of chosen units.
authors.affiliation: Department of Pediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Kam Sze
authors.initials: KS
authors.lastname: Tsang
authors.forename: Alex Wing Kwan
authors.initials: AW
authors.lastname: Leung
authors.forename: Vincent
authors.initials: V
authors.lastname: Lee
authors.forename: Frankie Wai Tsoi
authors.initials: FW
authors.lastname: Cheng
authors.forename: Matthew Ming Kong
authors.initials: MM
authors.lastname: Shing
authors.forename: Henry Nga Hin
authors.initials: HN
authors.lastname: Pong
authors.forename: Ting Fan
authors.initials: TF
authors.lastname: Leung
authors.forename: Patrick Man Pan
authors.initials: PM
authors.lastname: Yuen
authors.forename: Chi Kong
authors.initials: CK
authors.lastname: Li
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D046528:Chimerism; D036101:Cord Blood Stem Cell Transplantation / Q000009:adverse effects / Q000401:mortality; D003710:Demography; D005260:Female; D006086:Graft vs Host Disease / Q000209:etiology / Q000401:mortality; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008297:Male; D012008:Recurrence; D016896:Treatment Outcome; D055815:Young Adult