Cytomegalovirus-Specific Immunity Recovers More Slowly after Cord Blood Transplantation Compared with Matched Sibling Donor Allogeneic Transplantation.

BACKGROUND: Rapid quantitative recovery of NK cells but slower recovery of T-cell subsets along with frequent viral infections are reported after umbilical cord blood (UCB) compared with matched sibling donor (MSD) hematopoietic cell transplantation (HCT). However, it remains unclear whether increased propensity for viral infections is also a result of slower recovery of virus-specific immunity after UCB as compared to MSD HCT. OBJECTIVES: We examined the differences in the function of virus-specific peripheral blood mononuclear cells (PBMC) after UCB (N=17) vs. MSD (N=9) using previously collected patient blood samples at various time points after HCT. METHODS: Interferon-gamma (IFN-γ) enzyme-linked immune absorbent spot (ELISpot) assay was used to quantify the PBMC frequencies that secrete IFN-γ in response to 11 immunopeptides from 5 common viruses. We included the patients who received the same reduced intensity conditioning regimen without ATG, no systemic glucocorticoids and had no relapse or acute/chronic graft-versus-host disease within 1 year after HCT. RESULTS: The CMV-reactive PBMC frequencies were higher in CMV seropositive vs. seronegative patients after HCT. Among CMV seropositive patients, the frequency of CMV-reactive PBMC was lower after UCB compared to MSD throughout one year of HCT. We observed no differences in virus-specific PBMC responses towards HHV6, EBV, BK, and adenovirus antigens between UCB and MSD. CONCLUSION: Our data demonstrate that the reconstitution of CMV-specific immunity is slower in CMV seropositive recipients of UCB vs. MSD HCT in contrast to other viruses which had similar recoveries. These study findings support implementation of more potent prophylactic strategies for preventing CMV reactivation in CMV seropositive patients receiving UCB HCT.

Tubulogenesis of co-cultured human iPS-derived endothelial cells and human mesenchymal stem cells in fibrin and gelatin methacrylate gels.

Here, we investigate the tubulogenic potential of commercially-sourced iPS-ECs with and without supporting commercially-sourced hMSCs within 3D natural fibrin or semi-synthetic gelatin methacrylate (GelMA) hydrogels. We developed a selectable dual color third generation lentiviral reporter (hEF1α-H2B-mOrange2-IRES-EGFP PGK-Puro) to differentially label the nucleus and cytoplasm of iPS-ECs which allowed real-time tracking of key steps of vascular morphogenesis such as vacuole formation and coalescence to form shared multicellular lumens. We implement 3D quantification of the network character and validate that transduced and untransduced iPS-ECs can form tubules in fibrin with or without supporting hMSCs. In addition to natural fibrin gels, we also investigated tubulogenesis in GelMA, a semi-synthetic material that has received increased interest due to its ability to be photopatterned and 3D printed, and which may thus boost development of complex 3D models for regenerative medicine studies. We find that iPS-ECs alone have a muted tubulogenic response within GelMA, but that their tubulogenic response is enhanced when they are co-cultured with a small fraction of hMSCs (2% of total cells). Our work bolsters previous findings by validating established tubulogenic mechanisms with commercially available iPS-ECs, and we expect our findings will benefit biologic studies of vasculogenesis and will have applications in tissue engineering to pre-vascularize tissue constructs which are fabricated with advanced photopatterning and three-dimensional printing.

In Vitro Induction of Human Regulatory T Cells Using Conditions of Low Tryptophan Plus Kynurenines.

Thymic regulatory T cells (tTregs) and induced regulatory T cells (iTregs) suppress murine acute graft-versus-host disease (GVHD). Previously, we demonstrated that the plasmacytoid dendritic cell indoleamine 2,3-dioxygenase (IDO) fosters the in vitro development of human iTregs via tryptophan depletion and kynurenine (Kyn) metabolites. We now show that stimulation of naïve CD4+ T cells in low tryptophan (low Trp) plus Kyn supports human iTreg generation. In vitro, low Trp + Kyn iTregs and tTregs potently suppress T effector cell proliferation equivalently but are phenotypically distinct. Compared with tTregs or T effector cells, bioenergetics profiling reveals that low Trp + Kyn iTregs have increased basal glycolysis and oxidative phosphorylation and use glutaminolysis as an energy source. Low Trp + Kyn iTreg viability was reliant on interleukin (IL)-2 in vitro. Although in vivo IL-2 administration increased low Trp + Kyn iTreg persistence on adoptive transfer into immunodeficient mice given peripheral blood mononuclear cells to induce GVHD, IL-2-supported iTregs did not improve recipient survival. We conclude that low Trp + Kyn create suppressive iTregs that have high metabolic needs that will need to be addressed before clinical translation.

IL-15 super-agonist (ALT-803) enhances natural killer (NK) cell function against ovarian cancer.

OBJECTIVE: Natural killer (NK) cells represent a powerful immunotherapeutic target as they lyse tumors directly, do not require differentiation, and can elicit potent inflammatory responses. The objective of these studies was to use an IL-15 super-agonist complex, ALT-803 (Altor BioScience Corporation), to enhance the function of both normal and ovarian cancer patient derived NK cells by increasing cytotoxicity and cytokine production. METHODS: NK cell function from normal donor peripheral blood mononuclear cells (PBMCs) and ovarian cancer patient ascites was assessed using flow cytometry and chromium release assays ±ALT-803 stimulation. To evaluate the ability of ALT-803 to enhance NK cell function in vivo against ovarian cancer, we used a MA148-luc ovarian cancer NOD scid gamma (NSG) xenogeneic mouse model with transferred human NK cells. RESULTS: ALT-803 potently enhanced functionality of NK cells against all ovarian cancer cell lines with significant increases seen in CD107a, IFNγ and TNFα expression depending on target cell line. Function was also rescued in NK cells derived from ovarian cancer patient ascites. Finally, only animals treated with intraperitoneal ALT-803 displayed an NK dependent significant decrease in tumor. CONCLUSIONS: ALT-803 enhances NK cell cytotoxicity against ovarian cancer in vitro and in vivo and is able to rescue functionality of NK cells derived from ovarian cancer patient ascites. These findings suggest that ALT-803 has the potential to enhance NK cell-based immunotherapeutic approaches for the treatment of ovarian cancer.

Breast cancer risk and protracted low-to-moderate dose occupational radiation exposure in the US Radiologic Technologists Cohort, 1983-2008.

BACKGROUND: Although high-dose ionising radiation is associated with increased breast cancer risks, the association with protracted low-dose-rate exposures remains unclear. The US Radiologic Technologist study provides an opportunity to examine the association between low-to-moderate dose radiation and breast cancer incidence and mortality. METHODS: One thousand nine hundred and twenty-two self-reported first primary cancers were diagnosed during 1983-2005 among 66 915 female technologists, and 586 breast cancer deaths occurred during 1983-2008 among 83 538 female cohort members. Occupational breast dose estimates were based on work histories, historical data, and, after the mid-1970s, individual film badge measurements. Excess relative risks were estimated using Poisson regression with birth cohort stratification and adjustment for menopause, reproductive history, and other risk factors. RESULTS: Higher doses were associated with increased breast cancer incidence, with an excess relative risk at 100 mGy of 0.07 (95% confidence interval (CI): -0.005 to 0.19). Associations were strongest for technologists born before 1930 (excess relative risk at 100 mGy=0.16; 95% CI: 0.03-0.39) with similar patterns for mortality among technologists born before 1930. CONCLUSIONS: Occupational radiation to the breast was positively associated with breast cancer risk. The risk was more pronounced for women born before 1930 who began working before 1950 when mean annual doses (37 mGy) were considerably higher than in later years (1.3 mGy). However, because of the uncertainties and possible systematic errors in the occupational dose estimates before 1960, these findings should be treated with caution.

Advances in clinical NK cell studies: Donor selection, manufacturing and quality control.

Natural killer (NK) cells are increasingly used in clinical studies in order to treat patients with various malignancies. The following review summarizes platform lectures and 2013-2015 consortium meetings on manufacturing and clinical use of NK cells in Europe and United States. A broad overview of recent pre-clinical and clinical results in NK cell therapies is provided based on unstimulated, cytokine-activated, as well as genetically engineered NK cells using chimeric antigen receptors (CAR). Differences in donor selection, manufacturing and quality control of NK cells for cancer immunotherapies are described and basic recommendations are outlined for harmonization in future NK cell studies.

Lymphodepleting chemotherapy with donor lymphocyte infusion post-allogeneic HCT for hematological malignancies is associated with severe, but therapy-responsive aGvHD.

Donor lymphocyte infusion (DLI) is an option for relapsed hematologic malignancies or incomplete chimerism of non-malignant diseases following allogeneic hematopoietic cell transplantation (HCT). We analyzed the incidence of acute GvHD (aGvHD) in patients treated with DLI. From 1995 to 2013, 171 DLIs were given to 120 patients. The cumulative incidence of post-DLI grade II-IV aGvHD was 33% (CI 25-42%, n=40; 12 grade II), and of grade III-IV 24% (CI 16-32%, n=28). GvHD after DLI (n=46) involved the skin in 70% (n=32), lower gastrointestinal (GI) 65% (n=30), upper GI 43% (n=20) and liver 35% (n=16). Patients receiving chemotherapy accompanying the DLI (chemo-DLI) (n=37) had more frequent aGvHD and particularly lower GI GvHD. Risk factors for grade II-IV aGvHD included age >40, chemo-DLI, malignant disease and time from HCT to DLI <200 days. aGvHD response to treatment at 8 weeks was complete in 40% and complete/partial (CR/PR) in 52%. Chemo-DLI had higher response rates to aGVHD treatment in non-CML malignancies. We observed frequent, yet therapy-responsive aGvHD following DLI. GI GvHD in particular is a significant risk when giving chemotherapy prior to DLI. Improvements in DLI efficacy and GvHD management are still needed.

CD56dimCD57+NKG2C+ NK cell expansion is associated with reduced leukemia relapse after reduced intensity HCT.

We have recently described a specialized subset of human natural killer (NK) cells with a CD56(dim)CD57(+)NKG2C(+) phenotype that expand specifically in response to cytomegalovirus (CMV) reactivation in hematopoietic cell transplant (HCT) recipients and exhibit properties characteristic of adaptive immunity. We hypothesize that these cells mediate relapse protection and improve post-HCT outcomes. In 674 allogeneic HCT recipients, we found that those who reactivated CMV had lower leukemia relapse (26% (17-35%), P=0.05) and superior disease-free survival (DFS) (55% (45-65%) P=0.04) 1 year after reduced intensity conditioning (RIC) compared with CMV seronegative recipients who experienced higher relapse rates (35% (27-43%)) and lower DFS (46% (38-54%)). This protective effect was independent of age and graft-vs-host disease and was not observed in recipients who received myeloablative regimens. Analysis of the reconstituting NK cells demonstrated that CMV reactivation is associated with both higher frequencies and greater absolute numbers of CD56(dim)CD57(+)NKG2C(+) NK cells, particularly after RIC HCT. Furthermore, expansion of these cells at 6 months posttransplant independently trended toward a lower 2-year relapse risk. Together, our data suggest that the protective effect of CMV reactivation on posttransplant relapse is in part driven by adaptive NK cell responses.

Heterodimeric Bispecific Single Chain Variable Fragments (scFv) Killer Engagers (BiKEs) Enhance NK-cell Activity Against CD133+ Colorectal Cancer Cells.

BACKGROUND: Natural killer (NK) cells are potent cytotoxic lymphocytes that play a critical role in tumor immunosurveillance and control. Cancer stem cells (CSC) initiate and sustain tumor cell growth, mediate drug refractory cancer relapse, and express the well-known surface marker CD133. METHODS: DNA fragments from two fully humanized single chain fragment variable (scFv) antibodies recognizing CD16 on NK-cells and CD133 on CSC were genetically spliced forming a novel drug, 16 × 133 BiKE that simultaneously recognizes these antigens to facilitate an immunologic synapse. The anti-CD133 was created using a fusion protein prepared by fusing DNA fragments encoding the two extracellular domains of CD133. Immunization of mice with the resulting fusion protein generated a unique antibody that recognized the molecular framework and was species cross-reactive. RESULTS: In vitro chromium-51 ((51)Cr) release cytotoxicity assays at both high and low effector:target ratios demonstrated the ability of the heterodimeric biological drug to greatly enhance NK-cell killing of human Caco-2 colorectal carcinoma cells known to overexpress CD133. The tumor associated antigen specificity of the drug for CD133 even enhanced NK-cell cytotoxicity against the NK-resistant human Burkitt's lymphoma Daudi cell line, which has less than 5 % CD133 surface expression. Flow cytometry analysis revealed increases in NK-cell degranulation and Interferon-γ production upon co-culture with Caco-2 targets in the presence of the drug. CONCLUSION: These studies demonstrate that the innate immune system can be effectively recruited to kill CSC using bispecific antibodies targeting CD133 and that this anti-CD133 scFv may be useful in this bispecific platform or perhaps in the design of more complex trispecific molecules for carcinoma therapy.

Tissue vascularization through 3D printing: Will technology bring us flow?

BACKGROUND: Though in vivo models provide the most physiologically relevant environment for studying tissue function, in vitro studies provide researchers with explicit control over experimental conditions and the potential to develop high throughput testing methods. In recent years, advancements in developmental biology research and imaging techniques have significantly improved our understanding of the processes involved in vascular development. However, the task of recreating the complex, multi-scale vasculature seen in in vivo systems remains elusive. RESULTS: 3D bioprinting offers a potential method to generate controlled vascular networks with hierarchical structure approaching that of in vivo networks. Bioprinting is an interdisciplinary field that relies on advances in 3D printing technology along with advances in imaging and computational modeling, which allow researchers to monitor cellular function and to better understand cellular environment within the printed tissue. CONCLUSIONS: As bioprinting technologies improve with regards to resolution, printing speed, available materials, and automation, 3D printing could be used to generate highly controlled vascularized tissues in a high throughput manner for use in regenerative medicine and the development of in vitro tissue models for research in developmental biology and vascular diseases.