BACKGROUND Hematopoietic stem cells (HSCs) are routinely obtained from marrow, mobilized peripheral blood, and umbilical cord blood. Mesenchymal stem cells (MSCs) are traditionally isolated from marrow. Bone marrow–derived MSCs (BM-MSCs) have previously demonstrated their ability to act as a feeder layer in support of ex vivo cord blood expansion. However, the use of BM-MSCs to support the growth, differentiation, and engraftment of cord blood may not be ideal for transplant purposes. Therefore, the potential of MSCs from a novel source, the Wharton’s jelly of umbilical cords, to act as stromal support for the long-term culture of cord blood HSC was evaluated. STUDY DESIGN AND METHODS Umbilical cord–derived MSCs (UC-MSCs) were cultured from the Wharton’s jelly of umbilical cord segments. The UC-MSCs were then profiled for expression of 12 cell surface receptors and tested for their ability to support cord blood HSCs in a long-term culture-initiating cell (LTC-IC) assay. RESULTS Upon culture, UC-MSCs express a defined set of cell surface markers (CD29, CD44, CD73, CD90, CD105, CD166, and HLA-A) and lack other markers (CD45, CD34, CD38, CD117, and HLA-DR) similar to BM-MSCs. Like BM-MSCs, UC-MSCs effectively support the growth of CD34+ cord blood cells in LTC-IC assays. CONCLUSION These data suggest the potential therapeutic application of Wharton’s jelly–derived UC-MSCs to provide stromal support structure for the long-term culture of cord blood HSCs as well as the possibility of cotransplantation of genetically identical, HLA-matched, or unmatched cord blood HSCs and UC-MSCs in the setting of HSC transplantation.

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All commercial influenza vaccines elicit antibody responses that protect against seasonal infection, but this approach is limited by the need for annual vaccine reformulation that precludes efficient responses against epidemic and pandemic disease. In this study we describe a novel vaccination approach in which a nanoparticulate, liposome-based agent containing short, highly conserved influenza-derived peptides is delivered to the respiratory tract to elicit potent innate and selective T cell-based adaptive immune responses. Prepared without virus-specific peptides, mucosal immunostimulatory therapeutic (MIT) provided robust, but short-lived, protection against multiple, highly lethal strains of influenza in mice of diverse genetic backgrounds. MIT prepared with three highly conserved epitopes that elicited virus-specific memory T-cell responses but not neutralizing antibodies, termed MITpep, provided equivalent, but more durable, protection relative to MIT. Alveolar macrophages were more important than dendritic cells in determining the protective efficacy of MIT, which induced both canonical and non-canonical antiviral immune pathways. Through activation of airway mucosal innate and highly specific T-cell responses, MIT and MITpep represent novel approaches to antiviral protection that offer the possibility of universal protection against epidemic and pandemic influenza.

Background Children of Hispanic ancestry have a higher incidence of acute lymphoblastic leukemia (ALL) than other ethnic groups, but the genetic basis for racial disparities remain incompletely understood. Genome-wide association studies (GWAS) of childhood ALL to date have focused on inherited genetic effects; however, maternal genetic effects (the role of maternal genotype on offspring phenotype development) may also play a role in ALL susceptibility. Methods We conducted a family-based exome-wide association study (EXWAS) of maternal genetic effects among Hispanics with childhood B-cell ALL (B-ALL) using the Illumina Human Exome BeadChip. We used a discovery cohort of 312 Guatemalan and Hispanic American families and an independent replication cohort of 152 Hispanic American families. Results Three maternal SNPs approached our threshold for significance, after correction for multiple testing (P<1.0×10−6): MTL5 rs12365708 (RR=2.62, 95% CI=1.61-4.27, P=1.8×10−5); ALKBH1 rs6494 (RR=3.77, 95% CI=1.84-7.74, P=3.7×10−5); NEUROG3 rs4536103 (RR=1.75, 95% CI=1.30-2.37, P=1.2×10−4). While effect sizes were similar, these SNPs were not nominally significant in our replication cohort. In a meta-analysis comprised of the discovery cohort and the replication cohort, these SNPs were still not statistically significant after correction for multiple comparisons (rs12365708: pooled RR=2.27, 95% CI=1.48-3.50, P=1.99×10−4; rs6494: pooled RR=2.31, 95% CI=1.38-3.85, P=0.001; rs4536103: pooled RR=1.67, 95% CI=1.29-2.16, P=9.23×10−5). Conclusions In the first family-based EXWAS to investigate maternal genotype effects associated with childhood ALL, our results did not implicate a strong role of maternal genotype on disease risk among Hispanics; however, we identified three maternal SNPs that may play a modest role in susceptibility.

We conducted an exome-wide association study of childhood acute lymphoblastic leukemia (ALL) among Hispanics to confirm and identify novel variants associated with disease risk in this population. We used a case-parent trio study design; unlike more commonly used case-control studies, this study design is ideal for avoiding issues with population stratification bias among this at-risk ethnic group. Using 710 individuals from 323 Guatemalan and US Hispanic families, two inherited SNPs in ARID5B reached genome-wide level significance: rs10821936, RR = 2.31, 95% CI = 1.70–3.14, p = 1.7×10−8 and rs7089424, RR = 2.22, 95% CI = 1.64–3.01, p = 5.2×10−8. Similar results were observed when restricting our analyses to those with the B-ALL subtype: ARID5B rs10821936 RR = 2.22, 95% CI = 1.63–3.02, p = 9.63×10−8 and ARID5B rs7089424 RR = 2.13, 95% CI = 1.57–2.88, p = 2.81×10−7. Notably, effect sizes observed for rs7089424 and rs10821936 in our study were >20% higher than those reported among non-Hispanic white populations in previous genetic association studies. Our results confirmed the role of ARID5B in childhood ALL susceptibility among Hispanics; however, our assessment did not reveal any strong novel inherited genetic risks for acute lymphoblastic leukemia among this ethnic group.

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Background Mutations or alteration in expression of the 5’ nucleotidase gene family can confer altered responses to treatment with nucleoside analogs. While investigating leukemia susceptibility genes, we discovered a very rare p.L254P NT5C1A missense variant in the substrate recognition motif. Given the paucity of cellular drug response data from NT5C1A germline variation, we characterized p.L254P and eight rare variants of NT5C1A from genomic databases. Methods Through lentiviral infection, we created HEK293 cell lines that stably overexpress wildtype NT5C1A, p.L254P, or eight NT5C1A variants reported in the NHLBI Exome Variant server (one truncating and seven missense). IC50 values were determined by cytotoxicity assays after exposure to chemotherapeutic nucleoside analogs (Cladribine, Gemcitabine, 5-Fluorouracil). In addition, we used structure-based homology modeling to generate a 3D model for the C-terminal region of NT5C1A. Results The p.R180X (truncating), p.A214T, and p.L254P missense changes were the only variants that significantly impaired protein function across all nucleotide analogs tested (>5-fold difference versus WT; p<.05). Several of the remaining variants individually displayed differential effects (both more and less resistant) across the analogs tested. The homology model provided a structural framework to understand the impact of NT5C1A mutants on catalysis and drug processing. The model predicted active site residues within NT5C1A motif III and we experimentally confirmed that p.K314 (not p.K320) is required for NT5C1A activity. Conclusion We characterized germline variation and predicted protein structures of NT5C1A. Individual missense changes showed substantial variation in response to the different nucleoside analogs tested, which may impact patients’ responses to treatment.