scholarly journals Acquired amegakaryocytic thrombocytopenia: Three case reports and a literature review

2004 ◽  
Vol 57 (5-6) ◽  
pp. 292-297 ◽  
Author(s):  
Nebojsa Antonijevic ◽  
Tatjana Terzic ◽  
Vesna Jovanovic ◽  
Nada Suvajdzic-Vukovic ◽  
Rajko Milosevic ◽  
...  
Keyword(s):  
Myelodysplastic Syndrome ◽  
Rare Disease ◽  
Case Reports ◽  
Selective Reduction ◽  
Lithium Carbonate ◽  
Therapeutic Effects ◽  
Severe Thrombocytopenia ◽  
Hematopoietic Stem ◽  
Acquired Amegakaryocytic Thrombocytopenia

Introduction Acquired amegakaryocytic thrombocytopenia (AAT) is a rare disease characterized by thrombocytopenia due to selective reduction/absence of bone marrow (BM) megakaryocytes. In the BM culture isolated reduction of colony-forming units-megakaryocyte (CFU-Mk) may occur. Material and methods BM aspirates and trephine biopsies were obtained from all patients and processed by routine methods. In vitro BM culture and cytogenetic analysis was performed in one patient. Results This article presents three patients with manifested signs of hemorrhagic syndrome due to severe thrombocytopenia caused by an absence/significant reduction of BM megakaryocytes. Eexistence of systemic or any other disease was excluded in all patients. BM culture of the second patient showed reduction of all hematopoietic progenitors. In the subsequent course of the disease in this patient, signs of dysplastic erythrocytic series and megakaryocytes were also noted, although there were no positive proofs of evolution into myelodysplastic syndrome. Discussion AAT is a disease of hematopoietic stem cells manifesting in a certain period as amegakaryocytic thrombocytopenia which subsequently may progress into aplastic anemia or myelodysplastic syndrome. Patients were treated with corticosteroids, lithium carbonate, androgens, vincristine, immunoglobulins, folic acid, platelet and erythrocyte transfusions along with plasma substitution. The first patient reacted positively to the therapy. In two other patients a minimal, short-term therapeutic effect was achieved, followed by improvement of hemorrhagic syndrome and an insignificant increase in platelet count. In one patient the treatment was stopped after 4 months and the other died of bleeding after 4 months. Conclusion AAT is a rare disease with unpredictable course. This is a case report of three patients with AAT and different therapeutic effects.

scholarly journals “Almost Bleeding to Death”: The Conundrum of Acquired Amegakaryocytic Thrombocytopenia

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Gabrielle Elena Brown ◽  
Hani M. Babiker ◽  
Carlos L. Cantu ◽  
Andrew M. Yeager ◽  
Ravitharan Krishnadasan
Keyword(s):  
Antithymocyte Globulin ◽  
Case Reports ◽  
Immunosuppressive Treatment ◽  
Severe Bleeding ◽  
Severe Thrombocytopenia ◽  
Disease Entity ◽  
Excessive Bleeding ◽  
Substantial Risk ◽  
Acquired Amegakaryocytic Thrombocytopenia

Acquired amegakaryocytic thrombocytopenia (AAT) is a rare hematological disorder causing severe thrombocytopenia and bleeding. Previous in vitro studies postulated both cell-mediated suppression of megakaryocytopoiesis in early megakaryocytic progenitor cells and humoral-mediated suppression by anti-thrombopoietin antibodies as possible etiologies of AAT. Patients with AAT usually present with severe bleeding and thrombocytopenia that is unresponsive to steroids and intravenous immunoglobulin (IVIG). Although standard guidelines have not been established for management of AAT, a few case reports have indicated a response to immunosuppressive treatment. The prompt recognition of this disease entity is essential in view of the substantial risk of morbidity and mortality from excessive bleeding. We report a case of AAT successfully treated with equine antithymocyte globulin (ATG) and cyclosporine (CSP).

Abstract P019: Exosomes from Human CD34+ Cells: Critical Mediators of Proangiogenic Paracrine Effect of EPCs

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Susmita Sahoo ◽  
Sol Misener ◽  
Tina Thorne ◽  
Meredith Millay ◽  
Kathryn M Schultz ◽  
...  
Keyword(s):  
Cell Transplantation ◽  
Human Peripheral Blood ◽  
Limb Ischemia ◽  
Therapeutic Effects ◽  
Dependent Manner ◽  
Hematopoietic Stem ◽  
Paracrine Effect ◽  
Human Cd34 ◽  
Cd34 Cells

Local transplantation of human CD34+ hematopoietic stem cells has been shown to promote neovascularization in pre-clinical studies in models of myocardial and limb ischemia. In early phase clinical trials, transplantation of CD34+ cells has been associated with reduced angina, improved exercise time and reduced amputation rates. Several studies have suggested that paracrine effects by these pro-angiogenic cells mediate the effects induced by cell transplantation. We hypothesized that CD34+ cells secrete exosomes (Exo), which mediate at least a part of the therapeutic function of the cells. Methods and Results: We isolated Exo from the conditioned media of adult human peripheral blood (PB) CD34+ cells. The angiogenic and therapeutic potency of CD34+ Exo was compared with the intact CD34+ cells and also with PB mononuclear cell (MNC) Exo. Exo from both CD34+ cells and MNC are 50–90nm in size, have cup shaped morphology, and carry known Exo-marker proteins such as CD63, TSG101 and Annexin V as shown by electron microscopy, Western blot and flow cytometry. Compared to CD34+ cells or MNC Exo, CD34+ Exo significantly induces in vitro angiogenic activities such as viability, proliferation and tube formation of HUVECs on matrigel- in a dose dependent manner. In vivo, CD34+ Exo stimulated significant neovascularization in mouse corneal angiogenesis assay (14±4 mm v MNC Exo, 4±1 mm, p<0.01) and incorporation of endothelial (CD31+) cells in mouse matrigel-plug assay (6±1.7% v CD34+ cells, 2±0.8%, p<0.01). Finally, in a mouse model of hind limb ischemia (HLI), CD34+ Exo significantly improved perfusion (ratio: 1.01±0.04 v 0.57±0.1, P<0.05), increased capillary density (1.8±0.3/HPF v 0.9±0.1/HPF, p<0.001) and prevented ischemic leg amputation (16% v 100%), as compared with MNC Exo. Conclusions: These data demonstrate that CD34+ Exo induce angiogenic activity and ischemic tissue repair in the absence of CD34+ cells, and suggest that Exo represent important mediators of the therapeutic effects associated with CD34+ cell therapy. We speculate that Exo derived from CD34+ cells may represent a significant component of the paracrine effect of progenitor-cell transplantation for therapeutic angiogenesis.

A Case of Acquired Amegakaryocytic Thrombocytopenia with Anti-c-mpl Autoantibody: Comparison with Idiopathic Thrombocytopenic Purpura

2019 ◽  
Vol 142 (4) ◽  
pp. 239-243
Author(s):  
Bora Son ◽  
Hee sue Park ◽  
Hye Sook Han ◽  
Hee Kyung Kim ◽  
Seung Woo Baek ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Platelet Count ◽  
Rare Disease ◽  
Idiopathic Thrombocytopenic Purpura ◽  
Immunosuppressive Treatment ◽  
Severe Bleeding ◽  
Severe Thrombocytopenia ◽  
Thrombocytopenic Purpura ◽  
Acquired Amegakaryocytic Thrombocytopenia

Acquired amegakaryocytic thrombocytopenia (AAMT) is a rare disease that causes severe bleeding. The pathogenesis and treatment of AAMT have not yet been defined. We report the case of a 60-year-old woman diagnosed with AAMT, who presented with severe thrombocytopenia, gastroin­testinal bleeding, and significantly reduced bone marrow megakaryocytes. The patient was treated with methylprednisolone, cyclosporin, and intravenous immunoglobulin. After 2 weeks of treatment, her platelet count started to increase, and her bone marrow megakaryocyte count had normalized 3 months after diagnosis. At the time of diagnosis, the patient was seropositive for anti-c-mpl antibody but was seen to be seronegative once the platelet count recovered. In contrast, anti-c-mpl antibodies were not detected in the serum of 3 patients with idiopathic thrombocytopenic purpura. This case study suggests that anti-c-mpl antibody plays an important role in the development of AAMT, and that intensive immunosuppressive treatment is required for autoantibody clearance and recovery of megakaryocyte count.

scholarly journals A Patient with Supraclavicular Lymphadenopathy and Anterior Mediastinal Mass Presenting as a Rare Case of Composite Lymphoma: A Case Report and Literature Review

2016 ◽  
Vol 9 (3) ◽  
pp. 854-860 ◽  
Author(s):  
Alex Raufi ◽  
James Jerkins ◽  
Yung Lyou ◽  
Deepa Jeyakumar
Keyword(s):  
T Cell ◽  
B Cell ◽  
Rare Disease ◽  
Case Reports ◽  
Mediastinal Lymphadenopathy ◽  
Anterior Mediastinal Mass ◽  
Cell Transplant ◽  
Single Patient ◽  
Composite Lymphoma ◽  
Hematopoietic Stem

Composite lymphoma (CL) is a rare disease with 2 distinct lymphomas concurrently arising in a single patient with an estimated incidence of 1–4.7% of newly diagnosed lymphomas per year. CL most commonly involves 2 B-cell non-Hodgkin lymphomas (NHL) or a B-cell NHL with a Hodgkin lymphoma. Our case is unique in that it was a bilineage CL with both a T-cell and B-cell NHL, which has only been reported in a few case reports. A 49-year-old woman presented with several months of progressive cough, weight loss, dyspnea, and supraclavicular lymphadenopathy. Computed tomographic imaging done upon admission to the hospital found that she had extensive anterior and middle mediastinal lymphadenopathy as well as bilateral supraclavicular lymphadenopathy. The patient underwent an excisional biopsy on the supraclavicular lymph node and was found to have a composite lymphoma involving both a T-cell and B-cell NHL. Her final pathological diagnosis was peripheral T-cell lymphoma and lymphoplasmacytic lymphoma. The patient was found to have stage IIIB disease. Her HIV, hepatitis panel, and tuberculosis tests were all negative. She then underwent chemotherapy with dose-adjusted EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab). The patient showed a complete response and was then referred to a bone marrow transplant center for an autologous hematopoietic stem cell transplant. CL is a rare disease composed of at least 2 distinct lymphomas concurrently arising in a single patient. Due to the complexity in having to treat multiple types of lymphoma simultaneously CL presents challenges with treatment and assessing prognosis.

The Biological Characteristics of Osteoblasts Derived from Myelodysplastic Syndrome Patients.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4101-4101
Author(s):  
Wen-ming Chen ◽  
Zi-xing Chen ◽  
Jian-nong Cen ◽  
Jun He ◽  
Xiao-li Jiao ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Myelodysplastic Syndrome ◽  
Biological Characteristics ◽  
Bone Marrow Mononuclear Cell ◽  
Feeder Layer ◽  
Rt Pcr ◽  
Osteoblastic Cell Line ◽  
Hematopoietic Stem ◽  
Gm Csf

Abstract It was hypothesized that osteoblasts play a central role in hematopoiesis, and it has been shown that osteoblasts produce many factors essential for the survival, renewal, and maturation of hematopoietic stem cells (HSCs). By using human fetal osteoblastic cell line hFOB1.19 as a model of control, we investigated the biological characteristics of osteoblasts derived from patients with myelodysplastic syndrome (MDS) and their hematopoietic supportive function in vitro. MSCs isolated from bone marrow of MDS patients and normal donors were cultured and checked for their morphology, immunophenotype, CFU-F forming capacity and the expression of hematopoietic cytokines. A feeder layer was prepared by osteoblasts induced from 3rd generation of cultured MSCs and treated with mitomycin C. Ficoll-isolated bone marrow mononuclear cell from normal donors were then seeded on the feeder layer to co-culture in vitro without exogenous cytokines. FCM revealed that both MSCs and hFOB cells were positive for CD44, CD73(SH3), CD105(SH2) and CD90 (Thy1), but negative for CD34, CD45, HLA-DR. RT-PCR found that hFOB cells expressed mRNA of SCF, IL-6, IL-11, SDF-1, GM-CSF and G-CSF. MSCs obtained from MDS patients and normal donors were displaying fibroblastoid morphology. Their growth pattern, immunophenotype and CFU-F forming capacity were similar (P >0.05). Without exogenous cytokines, the osteoblasts derived from MDS could sustain GM-CFC survival for at least 3 weeks. The CFU-GM yield from cells in upper layer of co-culture was not different from those of control in hematopoiesis supportive experiments in vitro (P>0.05). RT-PCR clearly demonstrated that the cultured BM-MSCs from normal donor expressed mRNA of SCF, SDF-1, IL-6, and IL-11. As the MSCs differentiated toward osteoblasts, the expression of G-CSF could be detected, whereas GM-CSF remained undetectable. The same expression profile of above cytokines were also seen in osteoblasts induced from BM-MSCs of MDS patients. In conclusion, osteoblasts may play a pivotal role in hematopoiesis. The biological characteristics of osteoblasts from bone marrow of MDS patients were generally not different from those of osteoblasts in bone marrow of normal controls. Both of them could support survival of GM-CFC hematopoietic progenitor cells in vitro, according to their expression of multiple cytokines. These findings suggested that the osteoblasts derived from MDS patients may not be involved in the malignant process.

Eltrombopag Can Stimulate Trilineage Hematopoiesis In Patients with Refractory Severe Aplastic Anemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4427-4427
Author(s):  
Matthew J. Olnes ◽  
Yong Tang ◽  
Susan Soto ◽  
Elaine M Sloand ◽  
Philip Scheinberg ◽  
...  
Keyword(s):  
Stem Cell ◽  
Platelet Count ◽  
Aplastic Anemia ◽  
Severe Aplastic Anemia ◽  
Successful Outcome ◽  
Severe Thrombocytopenia ◽  
Hematopoietic Stem ◽  
Platelet Counts ◽  
Transfusion Independence

Abstract Abstract 4427 Severe aplastic anemia (SAA) is characterized by trilineage marrow hypoplasia and a paucity of hematopoietic stem cell progenitors. SAA is treated with immunosuppression or allogeneic stem cell transplantation (SCT), with a successful outcome in a majority. However, 20–40% of patients without a suitable donor for SCT do not respond to immunosuppression and may have persistent severe thrombocytopenia. Thrombopoietin (TPO) is the principal regulator of platelet production, and it exerts its effects through binding the megakaryocyte progenitor TPO receptor mpl, which stimulates production of mature megakaryocytes and platelets. Eltrombopag, a small molecule TPO mimetic that binds to mpl, increases platelet counts in healthy subjects, and in patients with chronic immune thrombocytopenic purpura. Both TPO and eltrombopag stimulate more primitive multilineage progenitors and stem cells in vitro. Patients with SAA and thrombocytopenia have very elevated TPO levels; nevertheless, we asked whether pharmacologic doses of eltrombopag could stimulate hematopoiesis in these patients without other options. We are conducting a pilot phase II study of eltrombopag in SAA patients with severe thrombocytopenia refractory to immunosuppressive therapy. Consecutive eligible adult patients were treated with oral eltrombopag at an initial dose of 50 mg daily, with escalation to a maximum dose 150 mg daily, with the goal of maintaining a platelet count of >20,000/uL above baseline. Treatment response was measured after three months and was defined as platelet count increases to 20,000/uL above baseline, or stable platelet counts with transfusion-independence for a minimum of 8 weeks. Nine patients have been enrolled and six are evaluable for response to date. Two patients did not respond to treatment. Three patients achieved platelet responses by 12 weeks of treatment, and all have sustained their responses (median follow up 10 months). Four patients exhibited improved hemoglobin levels 12 weeks after starting treatment (median hemoglobin increase of 2.1 g/dL) and two patients who were previously dependent on packed red blood cell transfusions have achieved transfusion-independence. Three neutropenic patients exhibited increased neutrophil counts after treatment with eltrombopag (median increase 0.46K cells/uL). These results provide evidence that eltrombopag can improve platelet counts in patients with severe refractory thrombocytopenia, and perhaps more surprisingly, have a clinically relevant impact on erythropoiesis and myelopoiesis. Updated data will be presented at the Society's meeting. Disclosures: Off Label Use: Eltrombopag for thrombocytopenia in refractory severe aplastic anemia patients.

The Role of Nucleophosmin In Hematopoietic Stem Cells and the Pathogenesis of Myelodysplastic Syndrome

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 95-95 ◽  
Author(s):  
Keisuke Ito ◽  
Paolo Sportoletti ◽  
John G Clohessy ◽  
Grisendi Silvia ◽  
Pier Paolo Pandolfi
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Myelodysplastic Syndrome ◽  
Cell Biology ◽  
De Novo ◽  
Stem Cell Biology ◽  
Hematopoietic Stem

Abstract Abstract 95 Myelodysplastic syndrome (MDS) is an incurable stem cell disorder characterized by ineffective hematopoiesis and an increased risk of leukemia transformation. Nucleophosmin (NPM) is directly implicated in primitive hematopoiesis, the pathogenesis of hematopoietic malignancies and more recently of MDS. However, little is known regarding the molecular role and function of NPM in MDS pathogenesis and in stem cell biology. Here we present data demonstrating that NPM plays a critical role in the maintenance of hematopoietic stem cells (HSCs) and the transformation of MDS into leukemia. NPM is located on chromosome 5q and is frequently lost in therapy-related and de novo MDS. We have previously shown that Npm1 acts as a haploinsufficient tumor suppressor in the hematopoietic compartment and Npm1+/− mice develop a hematologic syndrome with features of human MDS, including increased susceptibility to leukemogenesis. As HSCs have been demonstrated to be the target of the primary neoplastic event in MDS, a functional analysis of the HSC compartment is essential to understand the molecular mechanisms in MDS pathogenesis. However, the role of NPM in adult hematopoiesis remains largely unknown as Npm1-deficiency leads to embryonic lethality. To investigate NPM function in adult hematopoiesis, we have generated conditional knockout mice of Npm1, using the Cre-loxP system. Analysis of Npm1 conditional mutants crossed with Mx1-Cre transgenic mice reveals that Npm1 plays a crucial role in adult hematopoiesis and ablation of Npm1 in adult HSCs leads to aberrant cycling and followed by apoptosis. Analysis of cell cycle status revealed that HSCs are impaired in their ability to maintain quiescence after Npm1-deletion and are rapidly depleted in vivo as well as in vitro. Competitive reconstitution assay revealed that Npm1 acts cell-autonomously to maintain HSCs. Conditional inactivation of Npm1 leads to an MDS phenotype including a profoundly impaired ability to differentiate into cells of the erythroid lineage, megakaryocyte dyspoiesis and centrosome amplification. Furthermore, Npm1 loss evokes a p53-dependent response and Npm1-deleted HSCs undergo apoptosis in vivo and in vitro. Strikingly, transfer of the Npm1 mutation into a p53-null background rescued the apoptosis of Npm1-ablated HSCs and resulted in accelerated transformation to an aggressive and lethal form of acute myeloid leukemia. Our findings highlight the crucial role of NPM in stem cell biology and identify a new mechanism by which MDS can progress to leukemia. This has important therapeutic implications for de novo MDS as well as therapy-related MDS, which is known to rapidly evolve to leukemia with frequent loss or mutation of TRP53. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Bone Marrow-Derived Mesenchymal Stem Cells Modified with Akt1 Ameliorates Acute Liver GVHD

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Lukun Zhou ◽  
Shuang Liu ◽  
Zhao Wang ◽  
Jianfeng Yao ◽  
Wenbin Cao ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Liver Injury ◽  
Therapeutic Effects ◽  
Hematopoietic Stem ◽  
Ifn Γ ◽  
Immunomodulatory Function

Abstract Background Liver injury associated with acute graft-versus-host disease (aGVHD) is a frequent and severe complication of hematopoietic stem cell transplantation and remains a major cause of transplant-related mortality. Bone marrow-derived mesenchymal stem cells (BM-MSCs) has been proposed as a potential therapeutic approach for aGVHD. However, the therapeutic effects are not always achieved. In this study, we genetically engineered C57BL/6 mouse BM-MSCs with AKT1 gene and tested whether AKT1-MSCs was superior to control MSCs (Null-MSCs) for cell therapy of liver aGVHD. Results In vitro apoptosis analyses showed that, under both routine culture condition and high concentration interferon-γ (IFN-γ) (100ng/mL) stimulation condition, AKT1-MSCs had a survival (anti-apoptotic) advantage compared to Null-MSCs. In vivo imaging showed that AKT1-MSCs had better homing capacity and longer persistence in injured liver compared to Null-MSCs. Most importantly, AKT1-MSCs demonstrated an enhanced immunomodulatory function by releasing more immunosuppressive cytokines, such as IL-10. Adoptive transfer of AKT1-MSCs mitigated the histopathological abnormalities of concanavalin A(ConA)-induced liver injury along with significantly lowered serum levels of ALT and AST. The attenuation of liver injury correlated with the decrease of TNF-α and IFN-γ both in liver tissue and in the serum. Conclusions In summary, BM-MSCs genetically modified with AKT1 has a survival advantage and an enhanced immunomodulatory function both in vitro and in vivo and thus demonstrates the therapeutic potential for prevention and amelioration of liver GVHD and other immunity-associated liver injuries.

scholarly journals Monocyte-Derived Macrophages Are Impaired in Myelodysplastic Syndrome

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yu Han ◽  
Huaquan Wang ◽  
Zonghong Shao
Keyword(s):  
Myelodysplastic Syndrome ◽  
Ex Vivo ◽  
Regulatory Protein ◽  
Control Group ◽  
Phagocytic Capacity ◽  
Hematopoietic Stem ◽  
Gm Csf ◽  
Increased Risk ◽  
Macrophage Colony

Background. The myelodysplastic syndrome (MDS) comprises a group of clonal hematopoietic stem cell diseases characterized by cytopenia, dysplasia in one or more of the major myeloid lineages, ineffective hematopoiesis, and increased risk of development of acute myeloid leukemia (AML). Macrophages are innate immune cells that ingest and degrade abnormal cells, debris, and foreign material and orchestrate inflammatory processes. We analyzed the role of macrophages from MDS patients in vitro. Methods. Macrophages were induced from peripheral blood of patients with MDS via granulocyte macrophage colony-stimulating factor (GM-CSF). Phagocytic capacity of macrophages was measured with carboxyfluorescein succinimidyl ester and fluorescent microspheres. CD206 and signal regulatory protein alpha (SIRPα) on macrophages were detected by flow cytometry. Inducible nitric oxide synthase (iNOS) was measured by ELISA method. Results. Compared with normal control group, the number of monocytes increased in MDS patients. However, the monocytes showed impaired ability to induce macrophages and the number of macrophages induced from MDS samples was lower. Further, we demonstrated that the ex vivo phagocytic function of macrophages from MDS patients was impaired and levels of reorganization receptors CD206 and SIRPα were lower. Levels of iNOS secreted by macrophages in MDS were increased. Conclusions. Monocyte-derived macrophages are impaired in myelodysplastic syndromes.

Lenalidomide Selectively Inhibits In Vitro Growth of the Malignant Clone in Myelodysplastic Syndrome (MDS) Patients with 5q Deletion.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3438-3438 ◽  
Author(s):  
Martin Jädersten ◽  
Andrea Pellagatti ◽  
Ann-Mari Forsblom ◽  
Emma K. Emanuelsson ◽  
Mats Merup ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Myelodysplastic Syndrome ◽  
Fold Increase ◽  
Healthy Controls ◽  
In Vitro Growth ◽  
Normal Cells ◽  
Hematopoietic Stem ◽  
5Q Deletion

Abstract The immunomodulatory drug lenalidomide induces 82% complete cytogenetic remissions in patients with myelodysplastic syndrome (MDS) and 5q31 deletion. Lenalidomide has multiple effects, but the causal mechanisms of action are unknown. In this study we assessed the direct effect of lenalidomide on hematopoietic cells from eight MDS patients with del(5)(q31) and from five healthy controls. Lenalidomide titrated up to 500 μM caused no growth inhibition of mononuclear cells from healthy controls. Selected CD34+ hematopoietic stem cells were then cultured with or without 10 μM of lenalidomide in a 14-day model for pure erythroblast differentiation in a medium containing IL-3, IL-6, and SCF, and with addition of Epo during the second week. Cell count and viability was monitored regularly, and FISH and FACS analyses were performed at day 0, 7, and 14. The median proportion of 5q- cells by FISH at day 7 was 98% (range 86–99), dropping to 88% (range 35–98) at day 14 due to a variable outgrowth of cytogenetically normal cells. Day 7 cells, the majority still being 5q-, were used for gene expression analyses. In erythroblast cultures with cells from healthy controls, lenalidomide had no inhibitory effect on fold increase of cell counts (P=0.92). However, in cultures with cells from 5q- patients, the clone with 5q deletion showed significant inhibition of fold increase at day 14 (P=0.009), while the cytogenetically normal progenitors were not inhibited (P=0.83). Gene expression profiling was performed using Affymetrix Human Genome U133 Plus 2.0 Arrays. A group of genes was found whose expression was affected by the addition of lenalidomide to the cultures of both normal erythroblasts and 5q- erythroblasts. Furthermore, lenalidomide decreased the proportion of cells expressing late erythroid markers on FACS analysis at day 14. We conclude that lenalidomide selectively inhibits in vitro growth of 5q- hematopoietic stem cells, while not affecting growth of cytogenetically normal cells from MDS patients with 5q deletion or from healthy controls. In addition, we see that lenalidomide affects cell differentiation and induces changes in gene expression.

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