Abstract Children with many inherited nonmalignant disorders can be cured or their condition alleviated by hematopoietic stem cell transplantation (HSCT). Umbilical cord blood (UCB) units are a rapidly available stem cell source and offer great flexibility in HLA matching, allowing nearly uniform access to HSCT. Although reduced-intensity conditioning (RIC) regimens promise decreased treatment-related morbidity and mortality, graft failure and infections have limited their use in chemotherapy-naive patients. We prospectively evaluated a novel RIC regimen of alemtuzumab, hydroxyurea, fludarabine, melphalan, and thiotepa with a single-unit UCB graft in 44 consecutive patients with inborn errors of metabolism, immunity, or hematopoiesis. In addition, 5% of the UCB graft was re-cryopreserved and reserved for cord donor leukocyte infusion (cDLI) posttransplant. All patients engrafted at a median of 15 days posttransplant, and chimerism was >90% donor in the majority of patients at 1-year posttransplant with only 1 secondary graft failure. The incidence of grade II to IV graft-versus-host disease (GVHD) was 27% (95% confidence interval [CI], 17-43) with no extensive chronic GVHD. Overall survival was 95% (95% CI, 83-99) and 85% (95% CI, 64-93) at 1 and 5 years posttransplant, respectively. No significant end-organ toxicities were observed. The use of cDLI did not affect GVHD and showed signals of efficacy for infection control or donor chimerism. This RIC transplant regimen using single-unit UCB graft resulted in outstanding survival and remarkably low rates of graft failure. Implementation of the protocol not requiring pharmacokinetic monitoring would be feasible and applicable worldwide for children with inherited disorders of metabolism, immunity, or hematopoiesis. This trial was registered at www.clinicaltrials.gov as #NCT01962415.

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Toxic levels of trace metals from human activities accumulate in natural environments, yet these metal mixtures are rarely characterized or quantified. Metal mixtures accumulate in historically industrial urban areas and change as economies shift. Previous research has often focused on the sources and fate of a specific element, which limits our understanding of metal contaminant interactions in our environment. Here, we reconstruct the history of metal contamination in a small pond downstream of an interstate highway and downwind of fossil fuel and metallurgical industries that have been active since the middle of the nineteenth century. Metal contamination histories were reconstructed from the sediment record using metal ratio mixing analysis to attribute the relative contributions of contamination sources. Cadmium, copper, and zinc concentrations in sediments accumulated since the construction of major road arteries in the 1930s and 40s are, respectively, 3.9, 2.4, and 6.6 times more concentrated than those during industry-dominated time periods. Shifts in elemental ratios suggest these changes in metal concentrations coincide with increased contributions from road and parking lot traffic, and to a lesser extent, from airborne sources. The metal mixture analysis demonstrates that in near-road environments, contributions from modern surface water pathways can obscure historical atmospheric industrial inputs.

The mechanism of immune tolerance after successful hematopoietic stem cell transplantation is not fully understood. Both central (clonal deletion) and peripheral (anergy, Treg, Tr1) mechanisms are conceivable and may even coexist. In this study, we set up serial experiments to test for the presence and relative contribution of these mechanisms after HLA-mismatched UCBT in the GvH direction. Nine patients (age 1m to 9y) were transplanted and enrolled on a clinical trial (NCT01852370). Five immunocompetent patients were off immunosuppression therapy (IST) with no GVHD, while 4 had either limited or recently resolved GvHD and were still on IST when studied. Donor T cell chimerism was a median 97%. Purified T cells responses to host APCs were measured by MLR (3HTdR) and CTL reaction (Europium assay), along with cytokine secretion profiling (Bioplex). Host-reactive T cell clones were tracked with TCRVβ repertoire by ImmunoSEQ® (Adaptive Biotech). In tolerant patients, there was no significant MLR or CTL response towards host APC. Similarly, cytokine profiles revealed non-responsiveness while T cells responded vigorously to 3rd party APC by all assays. Recipient-specific T cell clones that were identified from infused UCB stimulated by host APC pre-UCBT became undetectable. There was no indication of Treg or Tr1 cell involvement in sustaining tolerance as deletion by IL-2 immunotoxin or IL-10R blockade was unable to “break” tolerance. However, low dose IL-2 (5U/mL) was able to restore some proliferation (S.I.=19; p=0.05) and IL-13, IFNγ, TNFα secretion, but in lesser degree in comparison to 3rd party responses (S.I.=112). In summary, clonal deletion and anergy contribute to immune tolerance after UCBT with deletion being dominant.