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• Molecular profiling was used to optimize an ex vivo modulation protocol with dmPGE 2 for UCB transplantation.• Pulse treatment of UCB with dmPGE 2 is safe and may lead to accelerated UCB engraftment and preferential cord chimerism.Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells (HSCs) for use in allogeneic transplantation. Key advantages of UCB are rapid availability and less stringent requirements for HLA matching. However, UCB contains an inherently limited HSC count, which is associated with delayed time to engraftment, high graft failure rates, and early mortality. 16,16-Dimethyl prostaglandin E 2 (dmPGE 2 ) was previously identified to be a critical regulator of HSC homeostasis, and we hypothesized that brief ex vivo modulation with dmPGE 2 could improve patient outcomes by increasing the "effective dose" of HSCs. Molecular profiling approaches were used to determine the optimal ex vivo modulation conditions (temperature, time, concentration, and media) for use in the clinical setting. A phase 1 trial was performed to evaluate the safety and therapeutic potential of ex vivo modulation of a single UCB unit using dmPGE 2 before reduced-intensity, double UCB transplantation. Results from this study demonstrated clear safety with durable, multilineage engraftment of dmPGE 2 -treated UCB units. We observed encouraging trends in efficacy, with accelerated neutrophil recovery (17.5 vs 21 days, P 5 .045), coupled with preferential, long-term engraftment of the dmPGE 2 -treated UCB unit in 10 of 12 treated participants. This study was registered at www. clinicaltrials.gov as #NCT00890500. (Blood. 2013;122(17):3074-3081)

Double umbilical cord blood (DUCB) transplantation is an accepted transplantation strategy for patients without suitable human leukocyte antigen (HLA)-matched donors. However, DUCB transplantation is associated with increased morbidity and mortality due to slow recovery of immunity and a high risk of infection. To define the differences in immune reconstitution between DUCB transplantation and HLA-matched unrelated donor (MUD) transplantation, we performed a detailed, prospective analysis of immune reconstitution in 42 DUCB recipients and 102 filgrastim-mobilized unrelated peripheral blood stem cell recipients. Reconstitution of CD3 T cells was significantly delayed in the DUCB cohort compared with the MUD cohort for 1–6 months post-transplantation (p<0.001), including naive (CD45RO−) and memory (CD45RO+) CD4 T cells, regulatory (CD4CD25) T cells, and CD8 T cells. In contrast, CD19 B cells recovered more rapidly in the DUCB cohort and numbers remained significantly greater from 3–24 months after transplantation (p=0.001). CD56CD16 natural killer (NK) cells also recovered more rapidly in DUCB recipients and remained significantly greater from 1–24 months after transplantation. B cell activating factor (BAFF) levels were higher in the DUCB cohort at 1 month (p<0.001), were similar in both cohorts at 3 and 6 months, and were lower in the DUCB cohort at 12 months (p=0.002). BAFF/CD19 B cell ratios were lower in the DUCB cohort at 3 (p=0.045), 6 (p=0.02), and 12 months (p=0.002) after transplantation. DUCB recipients had more infections within the first 100 days after transplantation (p<0.001), and there was less chronic graft-versus-host disease (cGVHD) (p<0.001), but there were no differences in cumulative incidence of relapse, non-relapse death, progression-free survival or overall survival between the two groups. These results suggest that increased risk of infections is specifically associated with delayed reconstitution of all major T cell subsets, but the increased risk is limited to the first 3 months after DUCB transplantation. There is no increased risk of relapse suggesting that graft-versus-leukemia (GVL) activity is maintained. Early reconstitution of B cells and NK cells may, in part, account for these findings.

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The main limitations to umbilical cord blood (UCB) transplantation (UCBT) in adults are delayed engraftment, poor immunological reconstitution and high rates of non-relapse mortality (NRM). Double UCBT (DUCBT) has been used to circumvent the issue of low cell dose, but acute GVHD remains a significant problem. We describe our experience in 32 subjects, who underwent DUCBT after reduced-intensity conditioning with fludarabine/melphalan/ antithymocyte globulin and who received sirolimus and tacrolimus to prevent acute GVHD. Engraftment of neutrophils occurred in all patients at a median of 21 days, and platelet engraftment occurred at a median of 42 days. Three subjects had grade II-IV acute GVHD (9.4%) and chronic GVHD occurred in four subjects (cumulative incidence 12.5%). No deaths were caused by GVHD and NRM at 100 days was 12.5%. At 2 years, NRM, PFS and OS were 34.4, 31.2 and 53.1%, respectively. As expected, immunologic reconstitution was slow, but PFS and OS were associated with reconstitution of CD4 þ and CD8 þ lymphocyte subsets, suggesting that recovery of adaptive immunity is required for the prevention of infection and relapse after transplantation. In summary, sirolimus and tacrolimus provide excellent GVHD prophylaxis in DUCBT, and this regimen is associated with low NRM after DUCBT.

FlowPRA assays often detect anti-HLA class I not detected by conventional lymphocytotoxicity assays. These assays reveal anti-HLA class II in normal female donor plasma and in sera implicated in TRALI. Immunohistochemical studies failed to reveal endothelial or intravascular-WBC HLA class II antigen expression in lung tissue derived from TRALI cases or controls, but demonstrated HLA class II expression on pulmonary macrophages.

Double cord blood transplantation (DCBT) may overcome the slow hematopoietic recovery and engraftment failure associated with infusion of a single cord blood unit. In DCBT, only one unit typically contributes to long-term hematopoiesis, but little is known about factors affecting cord predominance. As results from a phase I trial suggested that order of infusion may affect cord predominance, we analyzed the effect of preinfusion variables on chimerism patterns of 38 patients enrolled in the initial study and a subsequent phase II trial. All patients were treated with a reduced-intensity conditioning (RIC) regimen of fludarabine, melphalan and thymoglobulin followed by DCBT. By day 100, 66% of patients had hematopoiesis derived from a single cord blood unit. Higher post-thaw total nucleated cell and CD34 þ cell dose were associated with cord predominance and in 68% of patients (P ¼ 0.03); the predominant cord blood unit was infused first. Only the post-thaw CD34 þ cell dose of the predominant unit predicted time to both neutrophil and platelet engraftment. Although based on a small number of patients, our results identify parameters that may affect cord predominance and engraftment in the setting of DCBT following RIC and suggest possible strategies for selecting infusion order for cord blood units.