Detection of CD55- and CD59-Negative Immature Reticulocytes May Improves Sensitivity/Specificity to Identify a Minor Population of PNH-Type Cells in Patients with Myelodysplastic Syndrome/Aplastic Anemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4373-4373
Author(s):  
Naoshi Obara ◽  
Shoko Satoh ◽  
Yasushi Okoshi ◽  
Shigeru Chiba ◽  
Haruhiko Ninomiya
Keyword(s):  
Myelodysplastic Syndrome ◽  
Red Blood Cells ◽  
Aplastic Anemia ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Normal Subjects ◽  
Good Alternative ◽  
Minor Population

Abstract Abstract 4373 [Background] Paroxysmal nocturnal hemogloblinuria (PNH) is a hemolytic disease characterized by complement-sensitive red blood cells (RBC). Sometimes, a tiny amount of PNH-type, i.e., CD55- or CD59-negative, red blood cells as well as neutrophils can be detected in peripheral blood from patients with myelodysplastic syndrome (MDS)/ aplastic anemia (AA). It has been reported that the presence of PNH-type cells is correlated with a good response to immunosuppressive therapy foe these disease. However, the ratio of PNH-type RBCs to normal RBCs is always underestimated because PNH-type red blood cells have a shortened life span in the circulation, and there are some patients who have very low number of circulating granulocytes. [Metods] Peripheral blood was obtained from 37 patients with MDS or AA and 30 normal subjects. Mononuclear cells were then stained with antibodies against CD55, CD59, and CD71, and analyzed by a flowcytometer. Subsequently, CD55 and CD59-negative and CD71-positive reticulocytes, representing an immature fraction of reticulocytes, were identified. Sensitivity and specificity were compared for the detection of PNH-type immature reticulocytes with those evaluated by a PNH-type RBC- and granulocyte-detecting method. [Results and discussion] All 30 normal subjects were negative when the cut-off value for CD55 and CD59-negative and CD71-positive reticulocytes was set at 0.008%. With this cut-off value, PNH-type immature reticulocytes were detected in 18 out of 37 MSA/AA patients. When the cut-off values for PNH-type RBCs and granulocytes were set at 0.005% and 0.01%, respectively, in accordance with the original report by Sugimori, et al, 16 and 18 cases among 37 MDS/AA patients were positive for PNH-type RBCs and granulocytes, respectively. All the 16 cases positive for PNH-type RBCs were also positive for PNH-type granulocytes and immature reticulocytes, while 2 cases negative for PNH-type RBCs were evaluated to be positive for both PNH-type granulocytes and immature reticulocytes. All the cases positive for granulocytes were also positive for immature reticulocytes, and vice versa. These observations indicate that the method to detect minor population of PNH-type immature reticulocytes is feasible and comparable with that to detect PNH-type granulocytes, and could be superior to the PNH-type RBC-detection method in terms of sensitivity, without reducing specificity. If the evaluation of PNH-type granulocytes is difficult, PNH-type immature reticulocytes may be a good alternative to be evaluated. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Human erythroid burst-promoting activity produced by phytohemagglutinin- stimulated, radioresistant peripheral blood mononuclear cells

Blood ◽  
1979 ◽  
Vol 54 (5) ◽  
pp. 1050-1057 ◽  
Author(s):  
D Meytes ◽  
JA Ma Ortega ◽  
NA Shore ◽  
PP Dukes
Keyword(s):  
T Cell ◽  
Red Blood Cells ◽  
Peripheral Blood Mononuclear Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells

Abstract The regulation of erythroid burst-colony formation was studied in cultures of human peripheral blood mononuclear cells. Numbers of erythropoietin-stimulated colonies obtainable from the cells in response to various treatments were compared. One-day preincubation of the cells with phytohemagglutinin (PHA) doubled the yield of colonies. Irradiation of the cells with 3000 rad eliminated their ability to form erythroid bursts, but did not impair the ability of PHA-treated cells to enhance burst formation when added to a fresh batch of cells. This was due to a humoral factor, since media conditioned by PHA-treated washed cells were as effective as the cells themselves. When cells were separated into subpopulations by an adherence procedure and according to their ability to form rosettes with sheep red blood cells, it was found that the PHA-dependent burst-promoting activity released into the medium originated in a nonadherent, nonrosetting (T-cell depleted) cell population.

scholarly journals MNC-RED A Chemically-Defined Method to Produce Enucleated Red Blood Cells from Adult Peripheral Blood Mononuclear Cells

2019 ◽  
Author(s):  
Shouping Zhang ◽  
Emmanuel N Olivier ◽  
Zi Yan ◽  
Sandra Suzuka ◽  
Karl Roberts ◽  
...  
Keyword(s):  
Cell Culture ◽  
Red Blood Cells ◽  
Peripheral Blood Mononuclear Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Mononuclear Cells ◽  
Iron Chelator ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells ◽  
The Many

AbstractMany methods have been developed to produce red blood cellsin vitrobut translational applications have been hampered by the high cost of production. We have developed R6, a chemically-defined, albumin-free, low-transferrin culture medium, and MNC-RED, a protocol to differentiate peripheral blood mononuclear cells into enucleated erythroid cells that does not require any albumin or any animal components. Erythropoiesis requires large amounts of iron for hemoglobin synthesis. In all existing protocols, these large iron needs are met by increasing the concentration of holo-transferrin. This is necessary because transferrin recycling does not take place in existing erythroid culture conditions. In the R6 medium, iron is provided to the differentiating erythroblasts by small amounts of recombinant transferrin supplemented with FeIII-EDTA, an iron chelator that allows transferrin recycling to take place in cell culture. As a result of the absence of albumin and the use of low amounts of transferrin, the production of cultured red blood cells using the MNC-RED protocol is much less expensive than with existing protocols. The MNC-RED protocol should therefore help make the many translational applications of cultured RBCs economically more feasible.HighlightsWe have developed R6, a chemically-defined, albumin-free low-transferrin culture medium, and MNC-RED, a protocol to differentiate peripheral blood mononuclear cells into enucleated erythroid ER6 is suitable for red blood cell culture despite the low transferrin amounts because of the presence of FeIII-EDTA, an iron chelator that allows transferrin recycling to take place in cell culture.The MNC-RED protocol should help make the many translational applications of cultured RBCs more economically feasible.

scholarly journals Large Scale Culture and Differentiation of Erythroblasts from PBMC and iPSC

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2319-2319
Author(s):  
Maria Claessen ◽  
Eszter Varga ◽  
Steven Heshusius ◽  
Esther Heideveld ◽  
Martin Hansen ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Group ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Large Scale ◽  
Mononuclear Cells ◽  
Blood Group Antigens ◽  
Erythroid Cells ◽  
Expression Of Genes ◽  
Blood Mononuclear Cells

Abstract Transfusion of donor-derived red blood cells to aleviate anemia is the most common form of cellular therapy. In addition, red blood cells hold great promise as delivery agents of e.g. specific drugs or enzymes. However, the source depends on donor availability and carries a potential risk of alloimmunization and blood borne diseases. More than 30 bloodgroup systems encode >300 bloodgroup antigens and bloodgroup matching becomes increasingly challenging in a multiethnic society. Particularly the chronically transfused patients are at risk for alloimmunisation. In vitro cultured, customizable red blood cells (cRBC) would negate these concerns and introduce precision medicine both in transfusion medicine as well as in drug delivery applications. We aim to produce human cRBC at large-scale and cost effective, for which we need to optimize culture conditions and reduce cost-drivers. We adapted our protocols to GMP culture requirements, which reproducibly provided pure human erythroid cultures within 25 days with a 3.4x107 times expansion from peripheral blood mononuclear cells without prior CD34+ isolation. This expansion depended on the serum free medium we produce, which is supplemented with erythropoietin (Epo, 1 U/ml), stem cell factor (SCF) and glucocorticoids. Expanded erythroblasts CD71 highCD235low/- were differentiated for 10 days in medium supplemented with 5% human plasma, heparin and a higher concentration of Epo (10U/ml) yielding CD71dimCD235a+CD44+CD117-DRAQ5- cRBC. More than 90% of the cells enucleated and expressed adult hemoglobin as well as the correct blood group antigens. Passaging cRBC through a leukodepletion filter yielded 100% enucleated, stable cRBC. Deformability was measured by an Automated Rheoscope and Cell Analyser (ARCA), and oxygen equilibrium curves were measured with a Hemox analyzer. Both parameters were similar in cRBC and freshly isolated reticulocytes. RNA sequencing was performed daily during differentiation and revealed expression dynamics of important erythroid processes, e.g. increased expression of genes involved in blood group expression, globin regulation, and erythroid specific metabolic enzymes, concommittant with loss of expression of genes involved in the formation of organelles, and cell proliferation. The culture process is compatible with upscaling using 5L G-Rex bioreactors., Currently we are preparing a clinical study using biotinylated cRBC. Ultimately, however, large scale production requires an immortal source, for which we aim to use human induced pluripotent stem cells (iPSC) established from rare donors that lack most blood group antigens. Using single cell passaging of iPSC and differentiation in colonies, we generate at average 2x105 cRBC per single iPSC. However, the cRBC cultured from iPSC were less stable following enucleation, and expressed embryonic type globins. Comparison of transcriptome data from iPSC-derived erythroid cells at distinct differentiation stages with erythroid cells at similar stages that were cultured from adult- or cord blood mononuclear cells, or from fetal liver confirmed that most iPSC-derived erythroid cells largely express an embryonic RNA profile. In conclusion, our current protocols enable us to test cRBC cultured from adult peripheral blood for their stability after transfusion. Concurrently, we develop novel bioreactors to upscale the production, and we optimise the protocol to generate cRBC from immortal iPSC lines with near 'universal donor' genotypes. Disclosures No relevant conflicts of interest to declare.

scholarly journals Human erythroid burst-promoting activity produced by phytohemagglutinin- stimulated, radioresistant peripheral blood mononuclear cells

Blood ◽  
1979 ◽  
Vol 54 (5) ◽  
pp. 1050-1057
Author(s):  
D Meytes ◽  
JA Ma Ortega ◽  
NA Shore ◽  
PP Dukes
Keyword(s):  
T Cell ◽  
Red Blood Cells ◽  
Peripheral Blood Mononuclear Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells

The regulation of erythroid burst-colony formation was studied in cultures of human peripheral blood mononuclear cells. Numbers of erythropoietin-stimulated colonies obtainable from the cells in response to various treatments were compared. One-day preincubation of the cells with phytohemagglutinin (PHA) doubled the yield of colonies. Irradiation of the cells with 3000 rad eliminated their ability to form erythroid bursts, but did not impair the ability of PHA-treated cells to enhance burst formation when added to a fresh batch of cells. This was due to a humoral factor, since media conditioned by PHA-treated washed cells were as effective as the cells themselves. When cells were separated into subpopulations by an adherence procedure and according to their ability to form rosettes with sheep red blood cells, it was found that the PHA-dependent burst-promoting activity released into the medium originated in a nonadherent, nonrosetting (T-cell depleted) cell population.

scholarly journals Large-scalein-vitroproduction of red blood cells from human peripheral blood mononuclear cells

2019 ◽  
Author(s):  
Steven Heshusius ◽  
Esther Heideveld ◽  
Patrick Burger ◽  
Marijke Thiel-Valkhof ◽  
Erica Sellink ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Peripheral Blood Mononuclear Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Mononuclear Cells ◽  
Cellular Therapy ◽  
Small Scale ◽  
Blood Group Antigens ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells

AbstractTransfusion of donor-derived red blood cells is the most common form of cellular therapy. Donor availability and the potential risk of alloimmunization and other transfusion-related complications may, however, limit the availability of transfusion units especially for chronically transfused patients.In-vitrocultured, customizable red blood cells would negate these concerns and introduce precision medicine. Large-scale, cost effective production depends on optimization of culture conditions. We developed a defined medium and adapted our protocols to GMP culture requirements, which reproducibly provided pure erythroid cultures from peripheral blood mononuclear cells without prior CD34+isolation, and a 3×107-fold increase in erythroblasts in 25 days. Expanded erythroblast cultures could be differentiated to CD71dimCD235a+CD44+CD117−DRAQ5−red blood cells in 12 days. More than 90% of the cells enucleated and expressed adult hemoglobin as well as the correct blood group antigens. Deformability and oxygen binding capacity of cultured red blood cells was comparable toin-vivoreticulocytes. Daily RNA sampling during differentiation followed by RNA-seq provided a high-resolution map/resource of changes occurring during terminal erythropoiesis. The culture process was compatible with upscaling using a G-Rex bioreactor with a capacity of 1L per reactor, allowing transition towards clinical studies and small-scale applications.

Rapid and Sensitive Single Tube Screen for Paroxysmal Nocturnal Hemoglobinuria (PNH) Clones in Aplastic Anemia, Myelodysplastic Syndrome and Bone Marrow Failure Syndromes by Multiparameter Flow Cytometry.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3680-3680
Author(s):  
Mayur K. Movalia ◽  
Andrea Illingworth
Keyword(s):  
Flow Cytometry ◽  
Myelodysplastic Syndrome ◽  
Red Blood Cells ◽  
Aplastic Anemia ◽  
Blood Cells ◽  
Response To Therapy ◽  
Detection Sensitivity ◽  
Multiparameter Flow Cytometry ◽  
Single Tube ◽  
Depth Analysis

Abstract Several studies have shown that the presence of glycosylphosphatidylinositol (GPI) anchored protein-deficient PNH-type cells in patients with aplastic anemia and myelodysplastic syndrome may indicate favorable response to therapy and an overall favorable prognosis. Multiparameter flow cytometry is a powerful tool in the detection of even minimal populations of these cells. Evaluation for PNH-type clones has typically required in-depth analysis of red blood cells, granulocytes and monocytes using three tubes looking for the loss of multiple GPI-anchored proteins. Our laboratory has used this method in over 2,100 patients with known aplastic anemia and myelodysplastic syndrome. Accurate PNH-type clone evaluation requires careful backgating, strict gating strategies and a certain level of experience as immature cells, including blasts, may mimic PNH-type clones. The aim of this study was to develop a single tube five-color assay that could be used as a rapid and sensitive screen for the presence of PNH-type cells. We prospectively analyzed the granulocytes in the peripheral blood of 27 patients with known aplastic anemia and myelodysplastic syndrome using a single tube 5-color assay with FLAER-Alexa488 / CD24-PE / CD14-ECD / CD15-PC5 / CD45-PC7. This one-tube approach allows lineage specific gating on granulocytes looking for CD24 and FLAER deficiency. Also, to a more limited extent, the monocytes can be evaluated for CD14 and FLAER deficiency. The results were compared to a more in-depth three tube analysis for PNH-type cells analyzing the red blood cells (GPA-FITC/CD59-PE), granulocytes (CD66b-FITC/ CD24-PE/ CD45-ECD/ CD15-PC5/ CD16) and monocytes (CD64-FITC/ CD55-PE/ CD45-ECD/ CD33-PC5/ CD14). The results are summarized in Table 1. Using a detection sensitivity of 0.05% among the granulocytes showing loss of CD24 and FLAER, the screening assay was able to detect all six patients with PNH-type clones (range 0.4% – 79.1%), which was confirmed by the multiple tube panel. Of the 21 negative samples, all were below the 0.05% limit of detection. Four samples did show a population of CD24-negative, FLAER-negative granulocytes ranging from 0.01%–0.02%. The overall sensitivity and specificity of the single tube screen was 100%. This single tube five-color approach allows for a rapid and simple approach to screening patients for PNH-type clones with a detection sensitivity of 0.05%. Although an extended multiple tube analysis may still be required on positive screening samples to evaluate for the type of red blood cell PNH clone, the single tube screen optimizes the testing approach for PNH-type cells. Single tube screen versus multiple tube analysis for PNH-type Clones Multiple tube Multiple tube Positive Negative Total Positive = greater than or equal to 0.05% PNH-type cells detected Single tube Positive 6 (22%) 0 (0%) 6 Single tube Negative 0 (0%) 21 (78%) 21 Total 6 21

Clinicopathological Features and Mutational Analysis of Patients with Aplastic Anemia and Hypoplastic Myelodysplastic Syndrome

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1993-1993
Author(s):  
Xiaohui Zhang ◽  
Alan F List ◽  
Jeffrey E. Lancet ◽  
Song Jinming ◽  
Lynn C. Moscinski ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Myelodysplastic Syndrome ◽  
Aplastic Anemia ◽  
Peripheral Blood ◽  
Mutational Analysis ◽  
Conflicts Of Interest ◽  
Gene Mutations ◽  
Cancer Center ◽  
Bone Marrow Aplasia ◽  
Allele Burden

Abstract Background: Pancytopenia and bone marrow aplasia/hypoplasia are caused by a heterogeneous group of disorders, most commonly aplastic anemia (AA), hypoplastic myelodysplastic syndrome (MDS), paroxysmal nocturnal hemoglobinuria (PNH), and T-cell large granular lymphocytosis (T-LGL). Clinical and morphological distinction among these entities is often challenging, particularly between AA and hypoplastic MDS. This study is to examine the clinicopathological and genetic features of a group of AA and hypoplastic MDS patients, with or without concurrent T-LGL and/or PNH, in order to better understand and differentiate the two entities. Methods and Materials: We retrieved 45 cases with cytopenias and hypoplastic bone marrow at Moffitt Cancer Center. Peripheral blood complete blood counts, bone marrow morphological findings, flow cytometric analyses for LGL and PNH, and cytogenetics data were extracted from electronic medical records. Targeted next-generation sequencing (54 myeloid neoplasm related genes) was performed on the bone marrow. Results: The 45 patients showed peripheral blood cytopenias and bone marrow aplasia or marked hypocellularity. There were 26 cases diagnosed with AA with no morphologic evidence of dysplasia or increased blasts in the bone marrow, and 19 cases diagnosed with hypoplastic MDS based on morphological and cytogenetic criteria. In the meantime, distinct T-LGL population was identified in 2 of 11 cases with AA (18.2%) and 3 of 11 cases with hypoplastic MDS (27.3%); PNH clones were identified in 8 of 17 cases with AA (47%) and 3 of 11 cases with hypoplastic MDS (27.3%). Clonal cytogenetic abnormalities were found in 2 of 25 cases with AA (8%) and 11 of 18 cases with hypoplastic MDS (61.1%). Twelve of 26 cases of AA (46%) showed one or more gene mutations with allele burden ranging from 7% to 52%, and most of these cases (9 of 12; 75%) involved only one gene. In contrast, 15 of 19 cases of hypoplastic MDS (78.9%) had one or more gene mutations with allele burden ranging from 19% to 53%. Seven of the 15 cases (46.7%) had two or more gene mutations. The most common mutated genes in the two groups in this study were ASXL1 and TET2. Conclusion: Although there are overlapping clinical and morphological features between AA and hypoplastic MDS, differences are present between the two entities including presence of PNH clones, cytogenetic changes, and gene mutation frequencies. These features may help to make differential diagnosis and identify the cases with more progression potential. Clinical outcomes with different treatment and larger scale studies are needed to better characterize and define the two different entities. Disclosures No relevant conflicts of interest to declare.

scholarly journals Effect of Contaminating Red Blood Cells on OKT3-Mediated Polyclonal Activation of Peripheral Blood Mononuclear Cells

2002 ◽  
Vol 9 (3) ◽  
pp. 708-712 ◽  
Author(s):  
Samuel Song ◽  
Joseph Goodwin ◽  
Jenny Zhang ◽  
Bruce Babbitt ◽  
Janet L. Lathey
Keyword(s):  
Red Blood Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Mononuclear Cells ◽  
Dependent Manner ◽  
Peripheral Blood Mononuclear ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Dose Dependent ◽  
Necrosis Factor

ABSTRACT Erythrocytes are typically present as impurities in the majority of peripheral blood mononuclear cell (PBMC) preparations. This study was undertaken to investigate the effects of contaminating red blood cells (RBC) on the ability of OKT3 to activate CD4+ and CD8+ T cells. Surprisingly, the levels of gamma interferon, tumor necrosis factor alpha, and interleukin-1β (IL-1β) produced by PBMC upon stimulation by OKT3 were increased (P < 0.05) in a dose-dependent manner when increasing amounts of autologous RBC (RBC-to-PBMC ratios of 2:1, 10:1, and 50:1) were spiked into PBMC preparations. The OKT3-driven induction of the IL-2 receptor (CD25) and the proliferation of T lymphocytes in response to phorbol myristate acetate were not affected by the addition of RBC.

scholarly journals Bone Marrow Contains High Levels of Microparticles

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5145-5145
Author(s):  
Andreas Rank ◽  
Rienk Nieuwland ◽  
Anton Koehler ◽  
Hans Jochem Kolb ◽  
Bettina Toth
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Red Blood Cells ◽  
Progenitor Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Conflicts Of Interest ◽  
White Blood Cells ◽  
Cell Source ◽  
Bone Marrow Blood

Abstract Background: Microparticles (MP) are shed in humans from a broad variety of cells and play an important role in activation of coagulation, cell to cell interaction and transport of membrane components. Alternations in plasma levels have been found in a variety of diseases, mostly associated with thrombosis and inflammation. However, little is known about tissue levels of MP. The aim of this pilot study was to investigate the bone marrow compartment as a possible source of circulating MP. Material and Methods: MP were analysed in bone marrow blood and peripheral blood in 12 healthy stem cell donors. MPs were isolated and measured by flow-cytometric double-staining (FACScalibur, BD) with Anexin V and cell-specific antibodies for hematopoietic cells, platelets, white blood cells, red blood cells and endothelial cells. Statistical analysis was performed with SPSS for Windows 20.0. Results: Total MP levels differed between bone marrow and peripheral blood: 14.8 x109/l [8.5–19.3] vs. 9.2 x109/l [3.8–14.8] (median value [25-75 percentile]), p=0.060. Pattern of MP´s origin varied likewise: in bone marrow blood (bmb), main cell source of MP were CD235a positive red blood cells/erythropoetic cells (6.4x109/l [3.7–13.7], 43.2% of total bmb MP), CD61 positive platelets/megacaryocytes (4.1x109/l [1.7–10.1], 27.7% of total bmb MP), CD45 positive leucocytes/myeloic and lymphatic progenitor cells (3.8x109/l [2.7-4.9], 25.7% of total bmb MP) and CD62e positive endothelial cells (0.3x109/l [0.1-1.0], 2.0% of total bmb MP). In contrast, MP in peripheral blood (pb) mainly derived from CD61 positive platelets/megacaryocytes (8.5x109/l [2.4–14.4], 92.0% of total pb MP), CD45 positive leucocytes/myeloic and lymphatic progenitor cells (0.5x109/l [0.2–1.1], 4.5% of total pb MP), CD235a positive red blood cells/erythropoetic cells (0.2x109/l [0.1–0.6], 1.8% of total pb MP), and CD62e positive endothelial cells (0.1x109/l [0.0–0.1], 0.9% of total pb MP). Mean levels of tissue factor bearing MP were low in bone marrow blood as well as in peripheral blood (0.19 x109/l [0.16 – 0.29] and 0.08 x109/l [0.05 – 0.12], respectively, p=0.004). Conclusion: Within our study we were able to detect MP in bone marrow blood. When comparing MP from bone marrow and peripheral blood, major differences with regard to cell source and concentration was present. Our data suggest that the blood – bone marrow barrier is not only existentant for cells, but also for circulating MP. Disclosures No relevant conflicts of interest to declare.

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