Ethnic diversity and cord blood banking: satisfying the unmet need

In this study, the authors sought to assess whether cord blood units (CBUs) collected from donors of non-European ethnic backgrounds are utilized for umbilical cord blood transplantation (UCBT) at a different rate than those of European ethnic backgrounds. The authors also examined potential methods of enriching these under-represented ethnic backgrounds in cord blood bank (CBB) inventories without increasing financial overheads and without compromising total inventory utilization or post-transplant outcomes.

Data from N = 6506 searchable or shipped Anthony Nolan Cell Therapy Centre grafts were used in this study. Banked grafts were graded from A+ to D based on total nucleated cell and CD34+ cell content. Utilizations of each grade group were further stratified by graft ethnic background. The Mantel-Cox log-rank test was performed in conjunction with Kaplan-Meier survival analysis to compare utilization rates and post-transplant outcomes. For shipped grafts, levels of HLA matching at HLA-A, HLA-B and HLA-DR loci were also analyzed by graft ethnic background and grade using data from the Eurocord/EBMT registry.

Overall utilization of non-European grafts did not significantly differ from that of European grafts (2.5% versus 2.2%, P = 0.23). However, significant differences were found when stratifying utilization rates by cell content. The probability of non-European D grade grafts being utilized was 3-fold higher than that of European D grade grafts (1.1% versus 0.4%, P = 0.03) and comparable to that of European C grade grafts (1.1% versus 0.9%, P = 0.90). No significant differences were found between D and C grade grafts in terms of overall survival (OS) (P = 0.12), in part due to a disproportionate utilization of D grade grafts for pediatric UCBT (74% versus 39%, age difference P < 0.001). Furthermore, non-European graft shipments were 4-fold less likely to be a 6/6 HLA match to their recipients relative to European graft shipments (7% versus 29%).

The authors have identified a niche for CBUs of low cell content collected from donors of non-European ethnic backgrounds that has been overlooked by previous studies. Banking of these CBUs for pediatric UCBT instead of CBUs from European donors containing modestly higher cell content is an ethical approach to increasing the ethnic diversity of CBB inventory-and, consequently, the probability of non-European recipients finding a 6/6 HLA-matched graft-without compromising post-transplant OS or overall rate of inventory utilization.