Bridging mechanisms of through-thickness reinforcement in dynamic mode I&II delamination

Z-pin through-thickness reinforcement is used to improve the impact resistance of composite structures; however, the effect of loading rate on Z-pin behaviour is not well understood. The dynamic response of Z-pins in mode I and II delamination of quasi-isotropic IM7/8552 laminates was characterized experimentally in this work. Z-pinned samples were loaded at both quasi-static and dynamic rates, up to a separation velocity of 12 m/s. The efficiency of Z-pins in mode I delamination decreased with loading rate, which was mainly due to the change in the pin misalignment, the failure surface morphology and to inertia. The Z-pins failed at small displacements in the mode II loading experiments, resulting in much lower energy dissipation in comparison with the mode I case. The total energy dissipation decreased with increasing loading rate, while enhanced interfacial friction due to failed pins may be largely responsible for the higher energy dissipation in quasi-static experiments

Bridging mechanisms of through-thickness reinforcement in dynamic mode I&II delamination

Z-pin through-thickness reinforcement is used to improve the impact resistance of composite structures; however, the effect of loading rate on Z-pin behaviour is not well understood. The dynamic response of Z-pins in mode I and II delamination of quasi-isotropic IM7/8552 laminates was characterized experimentally in this work. Z-pinned samples were loaded at both quasi-static and dynamic rates, up to a separation velocity of 12 m/s. The efficiency of Z-pins in mode I delamination decreased with loading rate, which was mainly due to the change in the pin misalignment, the failure surface morphology and to inertia. The Z-pins failed at small displacements in the mode II loading experiments, resulting in much lower energy dissipation in comparison with the mode I case. The total energy dissipation decreased with increasing loading rate, while enhanced interfacial friction due to failed pins may be largely responsible for the higher energy dissipation in quasi-static experiments

Treosulfan-fludarabine-thiotepa-based conditioning treatment before allogeneic hematopoietic stem cell transplantation for pediatric patients with hematological malignancies

Treosulfan-based conditioning prior to allogeneic transplantation has been shown to have myeloablative, immunosuppressive, and antineoplastic effects associated with reduced non-relapse mortality (NRM) in adults. Therefore, we prospectively evaluated the safety and efficacy of treosulfan-based conditioning in children with hematological malignancies in this phase II trial. Overall, 65 children with acute lymphoblastic leukemia (35.4%), acute myeloid leukemia (44.6%), myelodysplastic syndrome (15.4%), or juvenile myelomonocytic leukemia (4.6%) received treosulfan intravenously at a dose of 10 mg/m2/day (7.7%), 12 g/m2/day (35.4%), or 14 g/m2/day (56.9%) according to their individual body surface area in combination with fludarabine and thiotepa. The incidence of complete donor chimerism at day +28 was 98.4% with no primary and only one secondary graft failure. At 36 months, NRM was only 3.1%, while relapse incidence was 21.7%, and overall survival was 83.0%. The cumulative incidence of acute graft-vs.-host disease was 45.3% for grades I–IV and 26.6% for grades II–IV. At 36 months, 25.8% overall and 19.4% moderate/severe chronic graft-vs.-host disease were reported. These data confirm the safe and effective use of treosulfan-based conditioning in pediatric patients with hematological malignancies. Therefore, treosulfan/fludarabine/thiotepa can be recommended for myeloablative conditioning in children with hematological malignancies

Case report:: severe combined immunodeficiency with ligase 1 deficiency and Omenn-like manifestation

DNA ligase I deficiency is an extremely rare primary immunodeficiency with only 6 patients reported in the literature. Most common manifestations include radiosensitivity, macrocytic anemia, lymphopenia with an increased percentage of gamma-delta T cells, and hypogammaglobulinemia requiring replacement therapy. Two-month-old girl with delayed development, T-B-NK+ SCID, and macrocytic anemia presented features of Omenn syndrome. Whole exome sequencing revealed two novel, heterozygous variants (c.2312 G>A, p.Arg771Gly and c.776+5G>T, p.Pro260*) in the LIG1 gene (NM_000234.1). Hematopoietic stem cell transplantation from a fully matched unrelated donor was performed at the age of 4 months using GEFA03 protocol. Mixed donor-recipient chimerism was observed, with 60-70% chimerism in the mononucleated cell compartment and over 90% in T-lymphocyte compartment, but autologous myeloid recovery. Stable CD4+ and CD8+ T-cell counts above 200/mu L were achieved after 2 months, but the patient remained transfusion-dependent. Despite satisfactory immunological reconstitution, the second transplantation due to constitutional hemolytic defect has been considered. In light of possible re-transplantation, an issue of optimal conditioning protocol with sufficient myeloid engraftment is important. For the first time Omenn syndrome is described in a compound heterozygote carrying two the novel variants p.Arg771Gly and p.Pro260* in the LIG1 gene. Patients diagnosed with SCID and Omenn syndrome showing macrocytic anemia, should be screened for DNA ligase I deficiency.Transplantation and immunomodulatio

Epstein-Barr Virus-Related Post-Transplant Lymphoproliferative Disorder in Children Treated with Rituximab: The Impact of Viral Load and Non-Lymphoid Tissue Involvement

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Impact of in vivo lymphodepletion on outcome in children with nonmalignant disorders receiving peripheral blood stem cell transplantation

Peripheral blood stem cell transplantation (PBSCT) with in vivo lymphodepletion can provide faster neutrophil recovery with limited risk of severe graft-versus-host disease (GVHD) in children with nonmalignant disorders (NMDs). We aimed to provide an historical comparison of these 2 strategies regarding the prevalence of GVHD, viral reactivation, timing of immune reconstitution, and final outcomes. Data on 98 children undergoing PBSCT were collected from 5 European pediatric transplantation centers. Only patients with NMDs receiving treosulfan or myeloablative busulfan conditioning and 9-10/10 HLA-matched transplant were included. The patients were divided into 2 groups according to in vivo lymphodepletion with antithymocyte globulin (ATG) or with alemtuzumab. We compared rates of acute and chronic GVHD; Epstein-Barr virus, cytomegalovirus, and adenovirus reactivation; chimerism; lymphocyte recovery; overall survival (OS) and event-free survival (EFS) between the 2 groups. The rate of severe acute GVHD (grade III-IV) was significantly higher in patients receiving ATG (26% vs 10% in alemtuzumab recipients; P <.05), whereas viral reactivations occurred with a similar rate in the 2 groups (alemtuzumab, 56%; ATG, 57%). Alemtuzumab was the major risk factor for delayed T cell immune reconstitution in the first 3 months after transplantation (odds ratio [OR], 6.0; 95% confidence interval [CI], 1.8 to 19; P <.005). Extended chronic GVHD, ADV reactivation, slower CD3(+) cell recovery, and HLA-mismatch reduced the probability of survival. Infections were the main cause of mortality in our cohort, and delayed T cell recovery was significantly associated with mortality in multivariate analysis (OR, 12; 95% CI, 1.2 to 114; P <.05). Ultimately, no differences in OS and EFS survival were seen between the ATG and alemtuzumab groups. ATG and alemtuzumab showed similar impacts on outcomes of children undergoing PBSCT for NMDs. The 2 strategies of in vivo lymphodepletion showed specific drawbacks that were counterbalanced by benefits that ultimately led to a comparable survival rate. A patient-centered lymphodepletion strategy can be advised in children undergoing PBSCT for NMDs, by favoring T cell recovery in the presence of invasive infection or GVHD prevention in high-risk mismatched donor transplantation. (C) 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.Transplantation and immunomodulatio

Hematopoietic stem cell transplantation for Wiskott-Aldrich syndrome: an EBMT Inborn Errors Working Party analysis

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for patients affected by Wiskott-Aldrich syndrome (WAS). Reported HSCT outcomes have improved over time with respect to overall survival, but some studies have identified older age and HSCT from alternative donors as risk factors predicting poorer outcome. We analyzed 197 patients undergoing transplant at European Society for Blood and Marrow Transplantation centers between 2006 and 2017 who received conditioning as recommended by the Inborn Errors Working Party (IEWP): either busulfan (n = 103) or treosulfan (n = 94) combined with fludarabine 6 thiotepa. After a median follow-up post-HSCT of 44.9 months, 176 patients were alive, resulting in a 3-year overall survival of 88.7% and chronic graft-versus-host disease (GVHD)-free survival (events include death, graft failure, and severe chronic GVHD) of 81.7%. Overall survival and chronic GVHD-free survival were not significantly affected by conditioning regimen (busulfan-vs treosulfan-based), donor type (matched sibling donor/matched family donor vs matched unrelated donor/mismatched unrelated donor vs mismatched family donor), or period of HSCT (2006-2013 vs 2014-2017). Patients aged = 5 years remains a risk factor for overall survival.Transplantation and immunomodulatio

Hematopoietic stem cell transplantation for CD40 ligand deficiency: results from an EBMT/ESID-IEWP-SCETIDE-PIDTC Study

BACKGROUND: CD40 ligand (CD40L) deficiency, an X-linked primary immunodeficiency, causes recurrent sinopulmonary, Pneumocystis and Cryptosporidium infections. Long-term survival with supportive therapy is poor. Currently, the only curative treatment is hematopoietic stem cell transplantation (HSCT). OBJECTIVE: We performed an international collaborative study to improve patients' management, aiming to individualize risk factors and determine optimal HSCT characteristics. METHODS: We retrospectively collected data on 130 patients who underwent HSCT for CD40L deficiency between 1993-2015. We analyzed outcome and variables relevance with respect to survival and cure. RESULTS: Overall survival (OS), event-free survival (EFS) and disease-free survival (DFS) were 78.2%, 58.1% and 72.3% 5 years post-HSCT. Results were better in transplants performed ≥2000 and in children <10 years old at HSCT. Pre-existing organ damage negatively influenced outcome. Sclerosing cholangitis was the most important risk factor. After 2000, superior OS was achieved with matched donors. Use of myeloablative regimens and HSCT ≤2 years from diagnosis associated with higher OS and DFS. EFS was best with matched sibling donors, myeloablative conditioning (MAC) and bone marrow-derived stem cells. Most rejections occurred after reduced intensity or non-myeloablative conditioning, which associated with poor donor cell engraftment. Mortality occurred mainly early after HSCT, predominantly from infections. Among survivors who ceased immunoglobulin replacement, T-lymphocyte chimerism was ≥50% donor in 85.2%. CONCLUSION: HSCT is curative in CD40L deficiency, with improved outcome if performed before organ damage development. MAC is associated with better OS, EFS and DFS. Prospective studies are required to compare risks of HSCT with those of life-long supportive therapy

Population pharmacokinetics of treosulfan and development of a limited sampling strategy in children prior to hematopoietic stem cell transplantation

Purpose There is an increasing interest in use of treosulfan (TREO), a structural analogue of busulfan, as an agent in conditioning regimens prior to hematopoietic stem cell transplantation (HSCT), both in pediatric and adult populations. The aim of this study was to develop a population pharmacokinetic model and to establish limited sampling strategies (LSSs) enabling accurate estimation of exposure to this drug. Methods The study included 15 pediatric patients with malignant and non-malignant diseases, undergoing conditioning regimens prior to HSCT including TREO administered as a 1 h or 2 h infusion at daily doses of 10, 12, or 14 g/m2 . A population pharmacokinetic model was developed by means of non-linear mixed-effect modeling approach in Monolix® software. Multivariate regression analysis and Bayesian method were used to develop 2- and 3-point strategies for estimation of exposure to TREO. Results Pharmacokinetics of TREO was best described with a two-compartmental linear model with proportional residual error. Following sampling schedules allowed accurate estimation of exposure to TREO: 1 h and 6 h or 1 h, 2 h, and 6 h for a TREO dose 12 g/m2 in a 1 h infusion, or at 2 h and 6 h or 2 h, 4 h, and 8 h for a TREO dose of 12 g/m2 and 14 g/m2 in a 2 h infusion. Conclusions A two-compartmental population pharmacokinetic model of TREO was developed and successfully used to establish 2- and 3-point LSSs for accurate and precise estimation of TREO AUC0→∞