Clinical Bone Marrow Transplantation Research Articles

Hematopoietic stem cell heterogeneity and age-associated platelet bias are evolutionarily conserved.

Hematopoietic stem cells (HSCs) reconstitute multilineage human hematopoiesis after clinical bone marrow (BM) transplantation and are the cells of origin of some hematological malignancies. Although HSCs provide multilineage engraftment, individual murine HSCs are lineage biased and contribute unequally to blood cell lineages. Here, we performed high-throughput single-cell RNA sequencing in mice after xenograft with molecularly barcoded adult human BM HSCs. We demonstrated that human individual BM HSCs are also functionally and transcriptionally lineage biased. Specifically, we identified platelet-biased and multilineage human HSCs. Quantitative comparison of transcriptomes from single HSCs from young and aged BM showed that both the proportion of platelet-biased HSCs and their level of transcriptional platelet priming increase with age. Therefore, platelet-biased HSCs and their increased prevalence and transcriptional platelet priming during aging are conserved features of mammalian evolution.

Timing and regulation of hematopoietic stem cell colonization of the human fetal bone marrow by endothelial and CAR stromal cells during pregnancy

The bone marrow (BM) contains the major reservoir of immature and maturing hematopoietic and immune cells throughout adult life while also harboring most hematopoietic stem and progenitor cells (HSPCs). BM-retained hematopoietic stem cells (HSCs) are mostly maintained in a quiescent, non-motile mode. A small fraction of BM-retained HSPC daily proliferate, differentiate, and migrate to the circulation, to replenish the blood with new immature and maturing blood and (all) immune (both myeloid and lymphoid) cells with a finite life span.1 The anti-coagulation and anti-inflammatory receptor EPCR is also functionally expressed by primitive BM-retained HSCs which are endowed with the highest competitive long-term repopulation potential (LT-HSC). Only BM-retained, quiescent EPCR-positive LT-HSCs are protected from DNA damaging insults including clinical chemotherapy and radiation treatments. Primitive EPCR-positive LT-HSC chemotherapy resistance requires the CXCL12-CXCR4 axis that also regulates HSC quiescence, cell cycle, and directional migration as well as the aPC/EPCR/PAR1 axis.2,3 The chemokine CXCL12 is highly expressed by many BM endothelial and stromal cells types including HSC niche supporting osteoprogenitor cells termed CXCL12 abundant reticular cells (CAR cells), while primitive EPCR-positive fetal liver and adult BM HSC functionally express its major receptor CXCR4.4 Most functional HSC studies involve mice experimental preclinical models as well as results obtained from clinical BM transplantation protocols. During fetal development, HSCs migrate from the fetal liver to the fetal BM and spleen for their lodgment and repopulation. Stem cell homing to the BM during development and in functional experimental transplantation assays including with human HSC in transplanted immune deficient mice is CXCL12/CXCR4-dependent.5,6 The precise timepoint of HSC colonization of the human fetal BM and spleen during pregnancy, as well as the identity of BM stromal niche cells and ligand–receptor interactions which regulate human BM HSC lodgment during fetal development are poorly understood. The group of Zheng et al7 have recently reported on the emergence of HSC in the human fetal BM and spleen and their landscape microenvironment during pregnancy by single-cell RNAseq analysis. This work revealed that functional, human fetal LT-HSC as assayed in transplanted immune deficient mice do not emerge before week 12 post conception. By careful examination of various types of fetal BM stromal and endothelial cells during weeks 10–14 post conception and their transcriptome, this study revealed that fetal BM CAR-like cells endowed with the high levels of CXCL12 production together with fetal endothelial cells which also highly express CXCL12 are the major LT-HSC niche supporting cells. Interestingly, the human fetal spleen was not repopulated with functional human LT-HSC before week 14 post conception, revealing that fetal BM is superior in providing critical signals for LT-HSC homing and lodgment over the fetal spleen. Importantly, self-renewing human CD146 positive osteoprogenitor CAR-like cells were detected in adult human BM and were found to provide a niche for adult human LT-HSC as well as in a miniature human bone implanted in immune deficient mice.8 In conclusion, this study provides evidence for the first functional fetal BM LT-HSC as well as their BM supporting microenvironment and niches.

METABOLIC SYNDROME, GLUCOSE INTOLERANCE, AND PHYSICAL RESILIENCE

Abstract When confronted with a major physical stressor, some older adults are able to recover to baseline with minimal changes, while others undergo irreversible declines. The ability to adapt and recover well from physical stress is called physical resilience and may be impeded by altered glucose-insulin dynamics. Among 55 participants in the pilot phase of the Study of Physical Resilience IN Geriatrics(SPRING), we examined associations between metabolic syndrome and/or diabetes status to physical resiliency recovery parameters after the clinical stressors total knee replacement and bone marrow transplant. These parameters included health outcomes, functional recovery, and pain in the weeks after the intervention. Additionally, we hypothesized that less resilient individuals would have abnormal glucose and insulin responses to a 75-gram oral glucose tolerance test at 0, 30, 60, 120 minutes and tested this in a subset (n=40) without known diabetes. Exploratory analyses of this pilot study will be presented during this session.

An Old Researcher Challenges the Empirical Timing of Cy-Treatment in the Clinical Haplo-Identical Bone Marrow Transplantation Followed by High-Dose Cyclophosphamide

An Old Researcher Challenges the Empirical Timing of Cy-Treatment in the Clinical Haplo-Identical Bone Marrow Transplantation Followed by High-Dose Cyclophosphamide

Early Cytomegalovirus Reactivation after Allogenic Bone Marrow Transplantation Is Associated with the Loss of Recipient-Derived Humoral Immunity and Is Reduced By IL-6 Inhibition

Background:Interleukin-6 (IL-6) promotes the differentiation of pathogenic T cells and represents a dominant pathway of cytokine-dysregulation and graft-versus-host disease (GVHD). Cytomegalovirus (CMV) reactivation is a common and life-threatening infectious complication following allogenic bone marrow transplantation (BMT). The role of T cell immunity is long-established, and our group recently demonstrated that CMV strain-specific immunoglobulins (Ig) are critical in preventing CMV reactivation in preclinical models (Martins JP et al, Science 2019).Methods and Results:In a phase I/II clinical trial (Kennedy GA et al, Lancet Onc. 2014), we observed unexpectedly low rates of CMV reactivation following IL-6 receptor (IL-6R) blockade with tocilizumab (TCZ) compared to historical control (8/35 vs 20/43, P < 0.05). We used our preclinical models of murine CMV (MCMV) reactivation to pursue the mechanisms. We transplanted bone marrow (BM) and T cells from naïve B6 donors into CMV-latently infected B6D2F1 recipients and monitored MCMV reactivation. Ablation of IL-6R in donor T cells (using B6 CD4 cre x IL-6R fl/fl transgenic mice; IL-6R -/-) significantly reduced MCMV reactivation 5 weeks after BMT, as measured by plasma viremia and infectious viral loads in the liver (Fig 1A).Next, we examined the contribution of donor T and B cells to the suppression of MCMV reactivation by IL-6R inhibition. At 2 - 3 weeks after BMT and prior to MCMV reactivation, cytokine (IFNɣ/TNF) secretion from CD4 + T cells (in response to MCMV infected DC) was not detectable; MCMV m38 tetramer + CD8 T cells were present at very low frequencies (< 0.1% of CD8 T cells) which were not altered by IL-6R ablation. The frequency of CXCR-5 +PD-1 + T FH cells was comparable or lower in IL-6R -/- vs wild-type (WT) T cells after BMT. Transplant of BM from B6.μMT mice (unable to generate mature B cells and plasma cells) did not increase MCMV viremia (Fig 1B), excluding a role for donor B cells. Thus, early MCMV reactivation in the presence of IL-6 is independent of MCMV-specific T cells and donor B cells.To study the effects of IL-6 on recipient-derived humoral immunity we quantified MCMV-specific IgG in plasma after BMT and found that levels were significantly higher in recipients of IL-6R -/- T cells (Fig 1C). Furthermore, MCMV-IgG levels in plasma correlated with MCMV viremia (r = - 0.72, P < 0.0001) and viral loads in liver (r = - 0.68, P < 0.0001). MCMV-IgG2a, which can only be generated by B6D2F1 recipients, was significantly higher in recipients of IL-6R -/- T cells, confirming that differences in humoral responses were of recipient-origin. To define relevant mechanisms, we examined the kinetics of IgG after BMT by monitoring the loss of murine IgG (transferred on day 0) in plasma (Fig 1D). Recipients of IL-6R -/- T cells showed significantly slower loss of IgG than recipients of WT T cells, with or without GVHD prophylaxis with cyclosporine (CSA). Thus, ablation of IL-6 signaling in donor T cells is associated with reduced loss of recipient IgG and protection from MCMV reactivation, an outcome which seems independent of the effects of IL-6 on GVHD.We correlated our findings with data from a recent randomized, placebo-controlled, double-blind phase III clinical trial of TCZ administration on Day -1 of BMT (Kennedy GA et al, Blood 2021). TCZ reduced CMV reactivation in at risk seropositive BMT recipients of volunteer unrelated donor grafts regardless of acute GVHD (all at risk recipients, TCZ vs. control: 12/26 vs 21/28, P = 0.03; at risk without grade 2-4 GVHD, TCZ vs control: 6/18 vs 9/13, P = 0.03). TCZ did not alter the frequency of B cells or the frequency and function of HCMV-specific CD8 + T cells, quantified by HCMV-pMHC tetramer-staining and HCMV peptide-specific cytokine (IFNγ/TNF) secretion. In contrast, levels of HCMV-specific IgG at day +30 in HCMV-seropositive recipients were significantly higher in the TCZ versus control group (Fig 1E). Consistent with our preclinical studies, the level of HCMV-IgG significantly and inversely correlated with early HCMV reactivation (within 35 days) after transplant.Conclusion:These data confirm the importance of recipient-derived humoral immunity in controlling early CMV reactivation in clinical BMT recipients. Critically, we demonstrate the ability of IL-6R blockade to maintain protective humoral responses until effective donor-derived adaptive immunity can be generated. [Display omitted] DisclosuresBoeckh: Merck: Consultancy, Research Funding; SymBio Pharmaceuticals: Consultancy; Helocyte: Consultancy; Evrys Bio: Consultancy; Moderna: Consultancy; Gilead: Consultancy, Research Funding; AlloVir: Consultancy; GSK: Consultancy. Hill: Generon corporation: Consultancy; NapaJun Pharma: Consultancy; Compass Therapeutics: Research Funding; Syndax Pharmaceuticals: Research Funding; Applied Molecular Transport: Research Funding; iTeos Therapeutics: Consultancy, Research Funding; Roche: Research Funding; Neoleukin Therapeutics: Consultancy.

MM-299: Fibroblast Growth Factor 23 in Multiple Myeloma Patients with Renal Impairment

Context Intact fibroblast growth factor (iFGF23) is a 32 kDa factor containing 251 amino acids and belongs to the FGF family. iFGF23 is thought to increase the renal excretion of phosphates and decrease vitamin D levels. It is a novel factor introduced to the medical field, and the increased expression of iFGF23 has been reported in renal impairment and multiple myeloma. Objective To measure the level of serum iFGF23 in multiple myeloma patients with renal impairment and to investigate its possible predictive role in multiple myeloma patients with renal impairment. Design Cross-sectional comparative study. Setting Clinical Hematology and Bone Marrow Transplantation Unit, Ain Shams University Hospital, Cairo, Egypt. Patients and Method 80 subjects were classified into 4 groups. Group 1: 20 multiple myeloma patients with renal impairment (on dialysis and not on dialysis). Group 2: 20 multiple myeloma patients without renal impairment. Group 3: 30 healthy controls who were group-matched with patients for age and sex. Group 4: 10 non-multiple myeloma patients with renal impairment. Results Serum iFGF23 was higher in patients with multiple myeloma than in healthy controls (p Conclusion iFGF23 was observed to be associated with renal disease in multiple myeloma patients, so it may have predictive value as a biomarker, especially in multiple myeloma patients with renal impairment. Moreover, it could be used as a targetable marker for therapeutic intervention.

Daratumumab in T‐cell acute lymphoblastic leukaemia: A case report and review of the literature

Pediatric Blood & CancerVolume 68, Issue 5 e28829 LETTER TO THE EDITOR Daratumumab in T-cell acute lymphoblastic leukaemia: A case report and review of the literature Sandra D. Ruhayel, Corresponding Author sandra.ruhayel@gmail.com orcid.org/0000-0002-1559-2980 Department of Clinical Haematology, Oncology and Bone Marrow Transplantation, Perth Children's Hospital, Perth, Western Australia, Australia Correspondence Sandra D. Ruhayel, Department of Paediatric and Adolescent Haematology, Oncology, Blood and Marrow Transplantation, Perth Children's Hospital, 15 Hospital Ave, Perth, WA 6009, Australia. Email: sandra.ruhayel@gmail.comSearch for more papers by this authorSantosh Valvi, Department of Clinical Haematology, Oncology and Bone Marrow Transplantation, Perth Children's Hospital, Perth, Western Australia, AustraliaSearch for more papers by this author Sandra D. Ruhayel, Corresponding Author sandra.ruhayel@gmail.com orcid.org/0000-0002-1559-2980 Department of Clinical Haematology, Oncology and Bone Marrow Transplantation, Perth Children's Hospital, Perth, Western Australia, Australia Correspondence Sandra D. Ruhayel, Department of Paediatric and Adolescent Haematology, Oncology, Blood and Marrow Transplantation, Perth Children's Hospital, 15 Hospital Ave, Perth, WA 6009, Australia. Email: sandra.ruhayel@gmail.comSearch for more papers by this authorSantosh Valvi, Department of Clinical Haematology, Oncology and Bone Marrow Transplantation, Perth Children's Hospital, Perth, Western Australia, AustraliaSearch for more papers by this author First published: 27 November 2020 https://doi.org/10.1002/pbc.28829Citations: 3Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume68, Issue5May 2021e28829 RelatedInformation

MM-125: Assessment of Vitamin D Levels in Multiple Myeloma Patients Newly Diagnosed and After Treatment

Context: Vitamin D deficiency is extremely common in multiple myeloma (MM), with 40% of patients having vitamin D levels in the deficient range of levels less than 36 nmol/L, and it represents a surrogate feature for clinical multiple myeloma disease status. Objective: To compare vitamin D levels in newly diagnosed MM patients and those that received treatment. Design: Case-control study from July 2018 to July 2019. Setting: Clinical Hematology and Bone Marrow Transplantation Division of Internal Medicine Department, Ain Shams University, Cairo, Egypt. Patients and methods: A randomized sample of 60 participants enrolled, 20 are newly diagnosed multiple myeloma patients, 20 patients post-treatment and 20 age- and sex-matched apparently healthy volunteers as a control group. Serum 25-hydroxyvitamin D (25(OH) D) levels were measured by enzyme-linked immunoassay (ELISA) at diagnosis and after 12 weeks of treatment. Results: In the newly diagnosed group, 25% of subjects had vitamin D deficiency ( 30 ng/ml). In MM patients that received treatment, no patient had vitamin D deficiency, 65% had vitamin D insufficiency, and only 35% had sufficient levels. In control group; no vitamin D deficiency, 70% of subjects had vitamin D insufficiency, and 30% of subjects had sufficient levels, with statistically significant difference of vitamin D deficiency between newly diagnosed MM patients and those after treatment (p=0.024). Conclusion: Prevalence of vitamin D deficiency is higher amongst MM patients than that of controls. Moreover, it exhibits a relationship to disease status with lower values in newly diagnosed patients when compared to those that received treatment. This is suggesting the potential role of vitamin D in pathogenesis of MM.

AML-126: Prognostic Value of Serum CD 155 in Adult Acute Myeloid Leukemia Patients: Relation to Clinical Outcome

Context CD155 is called polio virus receptor (PVR) due to its function as the receptor for poliovirus; the role of CD 155 in hematological malignancies are limited. Objective The aim of the study is to measure CD 155 levels in serum of adult acute myeloid leukemia (AML) patients using (ELISA) and correlate the level with clinical outcome. Design Prospective study and follow-up for 6 months. Setting Clinical Hematology and Bone Marrow Transplantation Unit, Department of Internal Medicine, Faculty of Medicine, Ain Shams University, Cairo, Egypt. Patients The study conducted on 30 randomly selected, newly diagnosed adult AML patients and 15 healthy controls of matched age and sex. Intervention Measurement of CD 155 levels in serum of adult AML patients and healthy controls using ELISA. Main outcome measures Measurement of CD 155 levels in serum of adult AML patients in comparison to healthy controls and correlate its level with clinical outcome. Results Serum CD 155 was significantly higher in AML patients in comparison to controls (mean=66.067 ± 30.172 ng/L vs 11.067 ± 5.021 ng/L, P Conclusion Adult AML patients have elevated CD 155 levels, which were associated with an inferior OS, DFS, and poor prognosis.

Diagnosis of radiosensitive severe combined immunodeficiency disease (RS-SCID) by Comet Assay, management of bone marrow transplantation.

Severe combined immunodeficiency disease (SCID) is a rare inherited severe immunodeficiency, in which functions of T cells and B cells are impaired. SCID is inherited either in X-linked recessive, or autosomal recessive forms, and is either radiosensitive or radioresistant. Artemis (DCLRE1C gene), DNA ligase IV, DNA-PKC, and Cernunnos/XLF proteins are regarded as NHEJ (Non-Homologous End-Joining) proteins that are involved in the repair process of double-strand DNA breaks and their mutations would lead to cellular radiosensitivity. Diagnostic radiosensitivity assays are important for the management of clinical BMT (Bone Marrow Transplantation) conditions, such as what conditioning agents and doses should be used. In this study, five SCID patients and healthy controls were examined. Skin fibroblasts were cultured. After X-irradiation, cells either underwent clonogenic assay or incubated to allow DNA repair and examined by the alkaline comet assay. Finally, DCLRE1C, RAG-1, and RAG-2 genes sequenced. By clonogenic assay, three patients were detected as radiosensitive with possible mutations in NHEJ genes such as DCLRE1C gene. The percentage of DNA in the tail measured by comet assay, in all three patients, was significantly different from the two other patients and the control group (p-value < 0.05). By using Sanger sequencing, a mutation in DCLRE1C gene was detected in one of the radiosensitive patients and two mutations in RAG-1, and RAG-2 genes were detected in the two radioresistant patients. Our findings suggest that comet assay is a fast technique for the diagnosis of the radiosensitive form of SCID and is very suitable for the timely diagnosis of RS-SCID before BMT.

Bone Marrow Transplantation 1957-2019.

Clinical bone marrow transplantation started in 1957 at a time when remarkably little was known about hematopoietic stems cells, immune responses to transplants or the identity of transplant antigens. This review will delineate the substantial increase in knowledge about these three areas gained between then and 1992 when the Ceppellini School course on Bone Marrow Transplantation was held, along with the progress made in clinical application, as well as the stumbling blocks that remained to be overcome by further research to advance knowledge. It will outline the significant progress made between 1992 and the present year, 2019, and the remaining problems.

Monitoring the chronic myeloid leukemia patients between 2008 and 2018; the experience of the Hematology and Bone Marrow Transplantation Unit Târgu-Mureș

Chronic myeloid leukemia is a clonal myeloproliferative disorder characterized by the BCR-ABL gene rearrangement with translocation between chromosomes 9 and 22. The constitutively active BCR-ABL tyrosine kinase inhibitor became the standard frontline therapy. The molecular monitoring is essential. We studied the chronic myeloid leukemia patients at the Clinical Hematology and Bone Marrow Transplant Unit Tg-Mures between 2008 and 2018. We followed 59 patients, median age of 45 years, female:male ratio 1.5:1. 80% of the patients were in chronic phase. Sokal score was low in 61%, intermediate 27% and high in 12% of the patients. The median follow-up time was 5 years and 9 months. 59% of the patients reached molecular remission (average time 11 months). The cumulative overall survival was 80% at 5 years and 76% at 10 years. The overall survival according to disease phase was 98%, 85%, 20%; according to Sokal score it was 91%, 66%, 51%. The cumulative progression-free survival was 75% at 5 years and 50% at 10 years. Only 8% of the low risk patients are progressing opposite to 77% of the high risk patients. The cumulative probability to maintain the molecular remission for 5 years is 100%, for 10 years 91% and for 15 years 52%. A rising level of BCR-ABL is an early indication of the loss of response identifying the patients who need close monitoring and therapeutic change. Orv Hetil. 2019; 160(2): 67-72.

Recipient mucosal-associated invariant T cells control graft-versus-host-disease within the colon.

Abstract Mucosal-associated invariant T (MAIT) cells are a unique innate-like T-cell subset that responds to a wide array of bacteria and yeast through recognition of riboflavin metabolites presented by the MHC I-like molecule, MR1. Here we demonstrate using MR1 tetramers that recipient MAIT cells are present in small but definable numbers in graft-versus-host disease (GVHD) target organs and protect from acute GVHD in the colon following bone marrow transplantation (BMT). Consistent with their preferential juxtaposition to microbial signals in the colon, recipient MAIT cells generate large amounts of IL-17A, promote gastrointestinal tract integrity, and limit the donor alloantigen presentation that in turn drives donor Th1 and Th17 expansion specifically in the colon after BMT. Allogeneic BMT recipients deficient in IL-17A also develop accelerated GVHD, suggesting MAIT cells regulate GVHD, at least in part, by the generation of this cytokine. Indeed, analysis of stool microbiota and colon tissue from IL-17A−/− and MR1−/− mice identified analogous shifts in microbiome operational taxonomic units (OTU) and mediators of barrier integrity which represent pathways controlled by similar, IL-17A-dependent mechanisms. Thus, MAIT cells act to control intestinal microbiota and barrier function to attenuate pathogenic T-cell responses in the colon, and given their very high frequency in humans, likely represent an important population in clinical BMT.

Recipient mucosal-associated invariant T cells control GVHD within the colon.

Mucosal-associated invariant T (MAIT) cells are a unique innate-like T cell subset that responds to a wide array of bacteria and yeast through recognition of riboflavin metabolites presented by the MHC class I-like molecule MR1. Here, we demonstrate using MR1 tetramers that recipient MAIT cells are present in small but definable numbers in graft-versus-host disease (GVHD) target organs and protect from acute GVHD in the colon following bone marrow transplantation (BMT). Consistent with their preferential juxtaposition to microbial signals in the colon, recipient MAIT cells generate large amounts of IL-17A, promote gastrointestinal tract integrity, and limit the donor alloantigen presentation that in turn drives donor Th1 and Th17 expansion specifically in the colon after BMT. Allogeneic BMT recipients deficient in IL-17A also develop accelerated GVHD, suggesting MAIT cells likely regulate GVHD, at least in part, by the generation of this cytokine. Indeed, analysis of stool microbiota and colon tissue from IL-17A-/- and MR1-/- mice identified analogous shifts in microbiome operational taxonomic units (OTU) and mediators of barrier integrity that appear to represent pathways controlled by similar, IL-17A-dependent mechanisms. Thus, MAIT cells act to control barrier function to attenuate pathogenic T cell responses in the colon and, given their very high frequency in humans, likely represent an important population in clinical BMT.

Reduction in Bone Marrow Insulin-like Growth Factor-1 Levels Enhances Long-Term Hematopoietic Stem Cell Engraftment Following Bone Marrow Transplantation

Efficient donor hematopoietic stem cell (HSC) engraftment is critical for successful bone marrow transplantation (BMT) and requires interactions between donor HSC and host-derived HSC niche elements. Due to disruption of perivascular stem cell niches induced by myeloablative BMT conditioning, initial engraftment of HSC following BMT occurs in niches located near the endosteum. We have previously shown that myeloablative BMT conditioning with total body irradiation (TBI) induces expansion of endosteal niche osteolineage cells in a time course correlating with increases in bone marrow (BM) levels of insulin-like growth factor (IGF)-1. We also have shown that inhibition of IGF-1 Receptor (IGF1R) signaling blocks osteolineage cell expansion after TBI, resulting in poor engraftment of long-term (LT)-HSC after BMT and suggesting a critical role for IGF-1/IGF1R interactions in regulating engraftment after BMT. We now present data in which we have defined the cellular sources of BM IGF-1 following TBI and have surprisingly discovered that reduction in BM IGF-1 levels promotes LT-HSC retention at baseline and donor LT-HSC engraftment following BMT.Using mice with floxed IGF-1 alleles (IGF1L/L) and with tissue-specific expression of Cre-recombinase, we generated models with deletion of IGF-1 derived from mature osteolineage cells (Col1A1CreIGF1Exc), hematopoietic cells (CD45CreIGF1Exc), or liver (AlbCreIGF1Exc). We additionally generated a conditional IGF-1 deletion model (MX1CreIGF1Exc) in which polyI:polyC (pI:pC) treatment disrupts IGF-1 production from all 3 of the above sources.By qPCR analysis, CD45CreIGF1Exc BM showed marked reduction (>95%) in BM IGF-1 mRNA at baseline and following TBI, suggesting that hematopoietic cells produce most of the locally derived IGF-1 in BM. Unexpectedly however, neither deletion of osteoblast-derived (Col1A1CreIGF1Exc) nor hematopoietic cell-derived (CD45CreIGF1Exc) IGF-1 significantly reduced BM extracellular or intracellular IGF-1 protein levels at baseline, or extracellular BM IGF-1 levels following TBI. In contrast, elimination of liver-derived IGF-1 in AlbCreIGF1Exc mice not only reduced plasma IGF-1 levels by 80%, but surprisingly reduced BM extracellular IGF-1 protein levels by ≥80% both at baseline and 48 hours post-TBI, and reduced BM intracellular IGF-1 protein levels by >80% and >60% at baseline and post-TBI, respectively. These data suggest that most IGF-1 protein in BM during BMT is derived from liver. Conditional IGF-1 deletion in MX1CreIGF1Exc mice resulted in severe reduction of both BM IGF-1 mRNA and protein levels, combining effects seen in CD45CreIGF1Exc and AlbCreIGF1Exc mice. None of these models, however, showed deficits in TBI-induced endosteal cell expansion, suggesting that other ligands or perhaps only low levels of IGF-1 are required to induce IGFR1 signaling-dependent endosteal cell expansion.Unexpectedly, reduction of BM IGF-1 in ALBCreIGF1Exc and MX1CreIGF1Exc mice caused a 3-4 fold increase (% of total BM) in BM Lin-cKit+Sca1+CD48-CD150+ or Lin-cKit+Sca1+CD34-CD135- HSC. ALBCreIGF1Exc BM displayed enhanced multi-lineage long-term repopulating capacity in competitive transplant assays, proving that these cells are functional LT-HSC. Given this baseline LT-HSC enhancement, we asked if reduction in BM IGF-1 levels impacted capacity of ALBCreIGF1Exc BM niches to engraft donor HSC after BMT. Using competitive secondary transplantation assays to assess numbers of engrafted WT GFP+ LT-HSC 3 weeks after primary BMT into ALBCreIGF1Exc or control mice, we found that reduced IGF-1 in the ALBCreIGF1Exc BM microenvironment resulted in >2.5 fold enhancement of donor LT-HSC engraftment. In an initial search of downstream mediators of this effect, we discovered that reduction of IGF-1 levels in MX1CreIGF1Exc BM results in a 2.5-fold increase in post-TBI CXCL12 mRNA expression, suggesting that reducing BM IGF-1 may enhance donor LT-HSC engraftment by promoting LT-HSC homing and maintenance within HSC niches.Taken together our data define a critical role for IGF-1/IGF1R interactions in regulating the efficiency of donor HSC engraftment following BMT. Therapeutic strategies to reduce BM IGF-1 may prove to be a valuable approach to improving engraftment following clinical BMT. DisclosuresNo relevant conflicts of interest to declare.

Invasive fungal infections: managing the continuum of risk in HCT patients.

43rd Annual Meeting of the EBMT, 26-29 March 2017, Marseille, France The European Society for Blood and Marrow Transplantation (EBMT) was established in 1974 to enable scientists and physicians to share their experience and develop studies in clinical bone marrow transplantation. Despite advances in treatment, invasive fungal infections (IFI), especially those caused by moulds such as Aspergillus, remain a leading cause of morbidity and mortality in patients with hematological malignancies. There is a continuum of risk of IFI during induction and consolidation therapy, and after hematopoietic cell transplantation. New, evidence-based approaches to the prevention, diagnosis and treatment of IFI were, therefore, of major interest to the over 5000 delegates from 85 countries attending the 43rd EBMT Annual Meeting (EBMT 2017).

LB22 - Process validation of cryopreservation procedures of hematopoietic progenitor cells, apheresis (HPC-A) at a new processing facility for clinical bone marrow transplant program

LB22 - Process validation of cryopreservation procedures of hematopoietic progenitor cells, apheresis (HPC-A) at a new processing facility for clinical bone marrow transplant program

LOW SERUM VITAMIN D LEVELS IN EGYPTIAN ADULTS WITH CHRONIC PRIMARY IMMUNE THROMBOCYTOPENIA: A SINGLE CENTER STUDY.

30Mar 2017 LOW SERUM VITAMIN D LEVELS IN EGYPTIAN ADULTS WITH CHRONIC PRIMARY IMMUNE THROMBOCYTOPENIA: A SINGLE CENTER STUDY. Abdel Rahman A Soliman , M.D , Walaa A Elsalakawy M.D , Alia M Saeed M.D and Sana A Mohammed M.B. , B. CH. Clinical Hematology and Bone Marrow Transplant Unit, Internal medicine department , Faculty of Medicine ? Ain Shams University, Cairo, Egypt. Faculty of medicine- MisurataUniveristy, Misurata, Libya.

How to maintain hematopoietic stem cells

Hematopoiesis![Figure][1] Hematopoietic stem cell PHOTO: SPL / SCIENCE SOURCE Hematopoiesis provides the body with a continuous supply of blood cells (see the Perspective by Sommerkamp and Trumpp). Taya et al. report that amino acid content is important for hematopoietic stem cell (HSC) maintenance in vitro and in vivo. Dietary valine restriction seems to “empty” the mouse bone marrow niche. Ito et al. used single-cell approaches and cell transplantation to identify a subset of HSCs at the top of the HSC hierarchy. Self-renewal relied on the induction of mitophagy, a quality-control process linked to a cell's metabolic state. Both studies may be helpful in improving clinical bone marrow transplantation. Science , this issue p. [1103][2], p. [1152][3]; see also p. [1156][4] [1]: pending:yes [2]: /lookup/doi/10.1126/science.aal3466 [3]: /lookup/doi/10.1126/science.aag3145 [4]: /lookup/doi/10.1126/science.aaf5530

First UK trial of Xenex PX-UV, an automated ultraviolet room decontamination device in a clinical haematology and bone marrow transplantation unit

There is growing interest in the use of no-touch automated room decontamination devices within healthcare settings. Xenex PX-UV is an automated room disinfection device using pulsed ultraviolet (UV) C radiation with a short cycle time. To investigate the microbiological efficacy of this device when deployed for terminal decontamination of isolation rooms within a clinical haematology unit. The device was deployed in isolation rooms in a clinical haematology unit. Contact plates were applied to common touch points to determine aerobic total colony counts (TCCs) and samples collected using Polywipe™ sponges for detection of vancomycin-resistant enterococci (VRE). The device was easy to transport, easy to use, and it disinfected rooms rapidly. There was a 76% reduction in the TCCs following manual cleaning, with an additional 14% reduction following UV disinfection, resulting in an overall reduction of 90% in TCCs. There was a 38% reduction in the number of sites where VRE was detected, from 26 of 80 sites following manual cleaning to 16 of 80 sites with additional UV disinfection. The Xenex PX-UV device can offer a simple and rapid additional decontamination step for terminal disinfection of patient rooms. However, the microbiological efficacy against VRE was somewhat limited.