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Background: Acute graft-versus-host disease (aGVHD), which is mainly mediated by allogeneic T cells, is a decisive factor in the success of allogeneic hematopoietic stem cell transplantation (allo-HCT). Prophylaxis for aGVHD in clinical patients is unsatisfactory, and there is still a huge unmet need for novel approaches. Icariin (ICA) shows potent anti-inflammatory activity and suppresses T cell-mediated immune responses. Thus, ICA is a potential drug for the prevention of aGVHD. However, there is no data assessing the impact of ICA on aGVHD after allo-HCT., Purpose: This study aimed to investigate the protective effect of ICA against aGVHD and its mechanisms. Moreover, the impact of ICA on the graft-versus-leukemia (GVL) effect and engraftment of donor hematopoietic and immune cells were assessed., Methods: Different murine models of allo-HCT were developed to study the influence of the ICA on GVHD and GVL effect. Flow cytometry was used to analyze the growth of leukemia cells, alterations in different immune cells, and apoptosis. Cell proliferation was determined using a CCK-8 assay. RNA sequencing and quantitative proteomic analysis were performed to elucidate the underlying mechanisms, which were further verified by polymerase chain reaction or functional experiments., Results: Different concentrations of ICA exhibited opposite effects: low-concentration ICA promoted, while high concentrations suppressed the proliferation and function of T cells. A high dose of ICA administration during days +3 to +5 post-allo-HCT can alleviate murine aGVHD but does not affect the course of chronic GVHD (cGVHD), the GVL effect against both acute myeloid and lymphoblastic leukemia, or the recovery of donor hematological and immune cells. ICA extensively represses the expansion, function, and infiltration of donor alloreactive T cells, while preserving regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSC). Quantitative proteomic analysis showed that downregulation of integrin-linked kinase (ILK) and lymphocyte cytosolic protein 2 (LCP2) expression was possibly associated with ICA-mediated aGVHD protective effects. Furthermore, an inhibitor of ILK, which can alleviate murine aGVHD administered early after allo-HCT., Conclusion: These findings suggest that the bioactivities of ICA are associated with its concentration and that ICA can effectively mitigate aGVHD without losing GVL activity or engraftment of donor hematopoietic and immune cells. Thus, ICA may be a promising drug for preventing aGVHD in clinical settings., Competing Interests: Declaration of competing interest The authors have declared that no conflict of interest exists., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Graft failure and delayed hematopoietic recovery are the major limitations of cord-blood transplantation (CBT). Romiplostim, a thrombopoietin-receptor agonist, promotes megakaryopoiesis and multilineage hematopoiesis in aplastic anemia. The decreased number of hematopoietic stem cells in the early phase after CBT and aplastic anemia share certain characteristics. Therefore, we hypothesized that romiplostim administration immediately after CBT may promote multilineage hematopoietic recovery. We investigated the safety and preliminary efficacy of administering romiplostim a day after CBT. This phase 1 dose-escalation study included six adults with hematologic malignancies in remission. Romiplostim was administered subcutaneously within 7 days after single-unit CBT, initially at doses of 5 µg/kg or 10 µg/kg in three patients, then once a week for 14 weeks or until platelet recovery. The maximum dose was 20 µg/kg. The median number of romiplostim administrations was 6 (range, 3-15). Romiplostim-related adverse events included bone pain (3/6) and injection site reaction (1/6). Non-hematological grade ≥ 3 toxicities were observed in four patients; febrile neutropenia was the most common (4/6). All patients achieved neutrophil engraftment and the median time was 14 days (range, 12-32). Platelet counts ≥ 50 × 10 9 /L were recorded in all patients except for one who died on day 48; the median time was 34 days (range, 29-98). No relapse, thrombosis, or bone marrow fibrosis was observed during a median follow-up of 34 months. Romiplostim may be safely administered in the early phase of CBT. Further phase 2 trial is warranted for its efficacy evaluation. Trial registration number: UMIN000033799, August 18, 2018., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Following conventional i.v. hematopoietic stem cell transplantation (IV-HSCT), most of the hematopoietic stem cells get trapped in peripheral organs and do not reach the bone marrow niche. A promising approach to overcome this cell loss during the homing process seems to be the infusion of hematopoietic stem cells directly into the bone marrow cavity (intra-bone marrow [IBM]-HSCT). This study aimed to investigate the engraftment efficiency of IBM-HSCT compared with IV-HSCT following reduced-intensity conditioning in a canine HSCT model. Furthermore, the impact of 2 different graft infusion rates during IBM-HSCT on the engraftment was evaluated. Dogs received 4.5 Gy total body irradiation for conditioning at day -1 and 15 mg/kg cyclosporin A twice daily at days -1 to +35 as immunosuppression. The IV-HSCT group (n = 7) received unmodified bone marrow. The IBM-HSCT cohorts received buffy coat-enriched bone marrow that was applied into the humerus and femur simultaneously with an infusion time of either 10 minutes (IBM10; n = 8) or 60 minutes (IBM60; n = 7). Statistical analyses were performed using the Kruskal-Wallis test followed by the Mann-Whitney U test with Bonferroni correction for multiple comparisons. Statistical significance was declared at Bonferroni-adjusted P < .017. All dogs initially engrafted. One dog of the IBM10 cohort died at day +15 from infection. All 21 evaluable dogs developed a durable mixed donor chimerism over the course of 112 days. Engraftment kinetics did not differ significantly across the 3 groups. Leukocyte and platelet nadirs, as well as the durations of leukopenia and thrombocytopenia, were comparable in the 3 groups. Signs of toxicity for ingestion, body temperature, activity, and defecation did not show statistically significant differences among the 3 groups; only weight loss was greater in the IBM60 group compared with the IV group. IBM-HSCT following reduced-intensity conditioning resulted in an engraftment efficiency and hematopoietic recovery comparable to that seen with conventional IV-HSCT. In addition, modification of the graft infusion rate had no impact on engraftment and hematopoietic recovery in the canine IBM-HSCT model., (Copyright © 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Although intracellular Wnt signaling pathways need to be tightly regulated to promote hematopoietic stem cell self-renewal, the source and identity of important Wnt ligands in the bone marrow is still largely unknown. The noncanonical ligand Wnt4 is expressed in the bone marrow as well as in the stroma, and its overexpression in fetal liver cells facilitates thymic recovery; however, its impact on adult hematopoietic stem cell function remains unclear. Here, we report that the deletion of Wnt4 from hematopoietic cells in mice (Wnt4 Δ/Δ ) resulted in decreased lymphopoiesis at steady state. This was likely at least in part due to the increased proinflammatory environment present in the bone marrow of Wnt4 Δ/Δ mice. Wnt4 Δ/Δ hematopoietic stem cells displayed reduced reconstitution capacity in serial transplants, thus demonstrating defective self-renewal, and they expanded poorly in response to lipopolysaccharide stimulation. This appeared to be the result of the absence of Wnt4 in stem/progenitor cells, as myeloid-restricted Wnt4 deletion had no notable effect. Finally, we observed that Wnt4 Δ/Δ stem/progenitor cells were more quiescent, presenting enhanced levels of stress-associated JNK phosphorylation and p16 INK4a expression, likely contributing to the reduced expansion observed in transplants. In conclusion, our results identify a new, largely autocrine role for Wnt4 in hematopoietic stem cell self-renewal, suggesting that regulation of Wnt signaling in hematopoiesis may not need Wnt secretion and could be independent of morphogen gradients., (© 2021 AlphaMed Press.)

Allogeneic hematopoietic cell transplantation (allo-HCT) is potentially curative for certain hematologic malignancies and nonmalignant diseases. The field of allo-HCT has witnessed significant advances, including broadening indications for transplantation, availability of alternative donor sources, less toxic preparative regimens, new cell manipulation techniques, and novel GVHD prevention methods, all of which have expanded the applicability of the procedure. These advances have led to clinical practice conundrums when applying traditional definitions of hematopoietic recovery, graft rejection, graft failure, poor graft function, and donor chimerism, because these may vary based on donor type, cell source, cell dose, primary disease, graft-versus-host disease (GVHD) prophylaxis, and conditioning intensity, among other variables. To address these contemporary challenges, we surveyed a panel of allo-HCT experts in an attempt to standardize these definitions. We analyzed survey responses from adult and pediatric transplantation physicians separately. Consensus was achieved for definitions of neutrophil and platelet recovery, graft rejection, graft failure, poor graft function, and donor chimerism, but not for delayed engraftment. Here we highlight the complexities associated with the management of mixed donor chimerism in malignant and nonmalignant hematologic diseases, which remains an area for future research. We recognize that there are multiple other specific, and at times complex, clinical scenarios for which clinical management must be individualized., (Copyright © 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Background: Efficient and sustained hematopoietic recovery after hematopoietic stem cell or bone marrow transplantation is supported by paracrine signaling from specific subpopulations of mesenchymal stromal cells (MSCs). Here, we considered whether in vitro mechanopriming of human MSCs could be administered to predictively and significantly improve in vivo hematopoietic recovery after irradiation injury., Methods: First, we implemented regression modeling to identify eight MSC-secreted proteins that correlated strongly with improved rescue from radiation damage, including hematopoietic recovery, in a murine model of hematopoietic failure. Using these partial least squares regression (PLSR) model parameters, we then predicted recovery potential of MSC populations that were culture expanded on substrata of varying mechanical stiffness. Lastly, we experimentally validated these predictions using an in vitro co-culture model of hematopoiesis and using new in vivo experiments for the same irradiation injury model used to generate survival predictions., Results: MSCs grown on the least stiff (elastic moduli ~ 1 kPa) of these polydimethylsiloxane (PDMS) substrata secreted high concentrations of key proteins identified in regression modeling, at concentrations comparable to those secreted by minor subpopulations of MSCs shown previously to be effective in supporting such radiation rescue. We confirmed that these MSCs expanded on PDMS could promote hematopoiesis in an in vitro co-culture model with hematopoietic stem and progenitor cells (HSPCs). Further, MSCs cultured on PDMS of highest stiffness (elastic moduli ~ 100 kPa) promoted expression of CD123 + HSPCs, indicative of myeloid differentiation. Systemic administration of mechanoprimed MSCs resulted in improved mouse survival and weight recovery after bone marrow ablation, as compared with both standard MSC expansion on stiffer materials and with biophysically sorted MSC subpopulations. Additionally, we observed recovery of white blood cells, platelets, and red blood cells, indicative of complete recovery of all hematopoietic lineages., Conclusions: These results demonstrate that computational techniques to identify MSC biomarkers can be leveraged to predict and engineer therapeutically effective MSC phenotypes defined by mechanoprimed secreted factors, for translational applications including hematopoietic recovery.

It is unclear whether higher CD34 + cell doses infused for ASCT have any influence on survival or relapse in patients with lymphoma. We analyzed the correlation of infused CD34 + cell dose with relapse, survival, and hematopoietic recovery in 146 consecutive patients undergoing ASCT for lymphoma. Higher doses (>5 × 10 6 /kg) were significantly correlated with earlier hematopoietic recovery, fewer infectious episodes, lower transfusion needs. No differences were observed in lymphoma outcomes (4-year relapse incidence of 38% [95%CI: 29%-48%] in the lower dose group versus 51% [95%CI: 30%-69%] in the higher dose group, 10-year OS probabilities of 58% [95%CI: 48%-68%] versus 75% [95%CI: 59%-91%], 10-year DFS probabilities of 47% [95%CI: 37%-57%] versus 42% [95%CI: 23%-61%], p = NS for all outcomes). In this series, a higher infused CD34 + cell dose did not correlate with survival or relapse but correlated with earlier hematopoietic recovery and lower resource consumption.

This secondary analysis of a large, multicenter Blood and Marrow Transplant Clinical Trials Network randomized trial assessed whether patient-reported outcomes (PROs) and socioeconomic status (SES) before hematopoietic stem cell transplantation (HCT) are associated with each other and predictive of clinical outcomes, including time to hematopoietic recovery, acute graft-versus-host disease, hospitalization days, and overall survival (OS) among 646 allogeneic and autologous HCT recipients. Pretransplantation Cancer and Treatment Distress (CTXD), Pittsburgh Sleep Quality Index (PSQI), and mental and physical component scores of the Short-Form 36 were correlated with each other and with SES variables. PROs and SES variables were further evaluated as predictors of clinical outcomes, with the PSQI and CTXD evaluated as OS predictors (P < .01 considered significant given multiple testing). Lower attained education was associated with increased distress (P = .002), lower income was related to worse physical functioning (P = .005) and increased distress (P = .008), lack of employment before transplantation was associated with worse physical functioning (P < .01), and unmarried status was associated with worse sleep (P = .003). In this large heterogeneous cohort of HCT recipients, although PROs and SES variables were correlated at baseline, they were not associated with any clinical outcomes. Future research should focus on HCT recipients at greater psychosocial disadvantage., Competing Interests: Financial disclosure: Conflict of interest statement: There are no conflicts of interest to report., (Copyright © 2016 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

The outcome of umbilical cord blood transplantation for adult patients with hematologic malignancies now rivals that of matched unrelated donor transplantation. However, delayed hematopoietic and immunologic recovery remains a source of significant morbidity and mortality. Multiple strategies are now being studied to overcome these limitations. One strategy involves ex vivo expansion of the umbilical cord blood unit prior to transplantation. A second strategy involves exposure of the umbilical cord blood graft to compounds aimed at improving homing and engraftment following transplantation. Such a strategy may also address the problem of slow hematopoietic recovery as well as the increased risk of graft failure. Many of these strategies are now being tested in late phase multi-center clinical trials. If proven cost-effective and efficacious, they may alter the landscape of donor options for allogeneic stem cell transplantation.

The ABO incompatibility between donor and recipient is not considered a barrier to successful allogeneic HSCT. Nevertheless, conflicting data still exist about the influence of ABO incompatibility on transplant outcome in pediatric patients with thalassemia. Fifty-one children with beta-thalassemia major who underwent allogeneic HSCT were enrolled this study. Twenty-three of them (45%) received an ABO-incompatible transplant [minor ABO mismatch: six (26%), major ABO mismatch: fourteen (61%), and bidirectional mismatch: three (13%)]. In this study, ABO incompatibility did not significantly impair GVHD, VOD, neutrophil and platelet engraftment, TRM, OS and TFS. Particularly in major and bidirectional ABO-mismatched patients, a delayed erythroid recovery was recorded as compared to the group receiving an ABO-compatible graft (median time, 31 and 38 days vs. 19.5 days; p: 0.02 and p: 0.03). Median time to red cell transfusion independence was significantly longer in major ABO-incompatible patients (median time, 87 days vs. 32 days; p: 0.001). Therefore, whenever feasible, major ABO-mismatched donors should be avoided in HSCT recipients, to prevent delayed erythroid recovery with prolonged RBC transfusion needs and impaired quality of life., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Our previous in vitro studies proved a higher clonogenic potential of peripheral blood progenitor cells cryopreserved in 7.5% dimethyl sulfoxide (Me2SO) than in 10% Me2SO containing medium. Based on this findings 7.5% Me2SO cryopreservation medium was introduced to our protocol and both the hematopoietic recovery and infusion-related toxicity were compared with that obtained with standard 10% Me2SO containing solution. Two cohorts of consecutive patients treated with autologous hematopoietic stem cell transplantation were included in the analysis: 56 patients with PBPCs cryopreserved in 7.5% Me2SO solution and 52 patients who obtained cells cryopreserved in 10% Me2SO. Both study groups did not differ significantly with regard to age, diagnosis, and the number of transplanted CD34(+) cells. The time to leukocyte recovery was shorter for patients in the 7.5% Me2SO treated group than in the 10% one. Reconstitution of platelets and the frequency of adverse events did not differ in both groups. Reduction of Me2SO concentration from 10% to 7.5% in cryoprotective mixture has a beneficial impact on leukocyte recovery. These findings require verification in a prospective, randomized trial., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Preparative regimens before Hematopoietic Cell Transplantation (HCT) damage the bone marrow (BM) microenvironment, potentially leading to secondary morbidity and even mortality. The precise effects of cytotoxic preconditioning on bone and BM remodeling, regeneration, and subsequent hematopoietic recovery over time remain unclear. Moreover, the influence of recipient age and cytotoxic dose have not been fully described. In this study, we longitudinally investigated bone and BM remodeling after busulfan treatment with low intensity (LI) and high intensity (HI) regimens as a function of animal age. As expected, higher donor chimerism was observed in young mice in both LI and HI regimens compared to adult mice. Noticeably in adult mice, significant engraftment was only observed in the HI group. The integrity of the blood-bone marrow barrier in calvarial BM blood vessels was lost after busulfan treatment in the young mice and remained altered even 6 weeks after HCT. In adult mice, the severity of vascular leakage appeared to be dose-dependent, being more pronounced in HI compared to LI recipients. Interestingly, no noticeable change in blood flow velocity was observed following busulfan treatment. Ex vivo imaging of the long bones revealed a reduction in the frequency and an increase in the diameter and density of the blood vessels shortly after treatment, a phenomenon that largely recovered in young mice but persisted in older mice after 6 weeks. Furthermore, analysis of bone remodeling indicated a significant alteration in bone turnover at 6 weeks compared to earlier timepoints in both young and adult mice. Overall, our results reveal new aspects of bone and BM remodeling, as well as hematopoietic recovery, which is dependent on the cytotoxic dose and recipient age. [ABSTRACT FROM AUTHOR]

High-dose chemotherapy with autologous peripheral blood stem cell transplantation (PBSCT) includes the risk of infectious complications due to neutropenia and therapy-induced immune deviation. In order to understand early immune recovery in this situation, we analyzed the distribution of cell subsets by flow cytometry and we measured cytokine production in a whole blood assay stimulated with lipopolysaccharide (LPS) in order to induce monocyte (MO) activation in 43 patients with solid tumors or lymphoma treated with two cycles of high-dose chemotherapy and PBSCT. Blood was collected at the following time points: before start of mobilization chemotherapy, before and after high-dose chemotherapy, and 10 and 30 days after PBSCT. In the lymphocyte compartment, we found a depletion of B cells and naive T cells and a transitory reduction of natural killer (NK) cells, whereas MO and neutrophils recovered rapidly. However, during early recovery, HLA-DR expression on MO and the percentage of CD16+ MO was considerably reduced. Production of proinflammatory cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-alpha upon LPS stimulation was severely impaired directly after chemotherapy and unexpectedly remained low during early recovery of myeloid cells, whereas production of IL-1RA was enhanced, indicating a shift of immune competent cells to an anti-inflammatory or anergic state early after PBSCT. [ABSTRACT FROM AUTHOR]

Simple Summary: We have previously shown that high pre-conditioning levels of Interleukin-18 were associated with worse survival after allogeneic stem cell transplantation due to increased non-relapse mortality. While no correlations with acute graft-versus-host disease were observed, interleukin-18-related excess mortality was mainly driven by fatal infectious complications. In multiple studies, delayed hematopoietic recovery and poor graft function following allogeneic stem cell transplantation has been demonstrated as a powerful predictor of non-relapse mortality. The present study links high interleukin-18 to delayed platelet recovery in allografted patients. Given the functions of interleukin-18 in regulating the quiescence of hematopoietic stem/progenitor cells, our findings may be explained by Interferon gamma-independent inhibitory effects of interleukin-18 on stem cell proliferation and hematopoietic reconstitution in allografted patients. Importantly, considering recent successful interleukin-18-neutralizing approaches in autoimmune disorders, our results provide a rationale to explore modulation of interleukin-18 for improving hematopoietic recovery and outcomes in allogeneic stem cell transplantation recipients. Interleukin-18 (IL-18) is an immunoregulatory cytokine and a context-dependent regulator of hematopoietic stem/progenitor cell (HSPC) quiescence in murine models. In a previous study, high pre-conditioning levels of IL-18 were associated with increased non-relapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). To investigate the clinical impact of IL-18 status on hematopoietic function, the associations of pre-conditioning and day 0–3 cytokine levels with platelet and neutrophil recovery were analyzed in a training cohort of 714 allografted patients. In adjusted logistic regression analyses, both increasing pre-conditioning and day 0–3 IL-18 levels had a significantly higher adjusted odds ratio (aOR) of delayed platelet and neutrophil recovery on day +28 post-transplant (aOR per two-fold increase: 1.6–2.0). The adverse impact of high pre-conditioning IL-18 on day +28 platelet recovery was verified in an independent cohort of 673 allografted patients (aOR per two-fold increase: 1.8 and 1.7 for total and free IL-18, respectively). In both cohorts, a platelet count ≤20/nL on day +28 was associated with a significantly increased hazard of NRM (hazard ratio 2.13 and 2.94, respectively). Our findings support the hypothesis that elevated peritransplant IL-18 levels affect post-transplant HSPC function and may provide a rationale to explore modulation of IL-18 for improving alloSCT outcomes. [ABSTRACT FROM AUTHOR]