Acute megakaryoblastic leukemia (AMKL) is a relatively common type of acute myeloid leukemia in children. We describe two unusual cases of AMKL that by flow cytometry (FC) lacked expression of any commonly evaluated myeloid antigens. One case presented as a periorbital myeloid sarcoma and clinically was thought to be a solid tumor. In both cases, the leukemic blasts were variably positive for the megakaryocytic marker CD61. Cytogenetics confirmed the presence of the t(1;22) in one case. Cytogenetics and inclusion of megakaryocytic markers in FC panels when evaluating pediatric specimens is critical for appropriate diagnosis for myeloid antigen negative AMKL.

Pure erythroid leukemia (PEL) is a rare form of acute myeloid leukemia characterized by the neoplastic proliferation of erythroblasts. PEL is associated with inferior survival outcomes, particularly among patients harboring complex karyotype abnormalities. In this case, we present a 21-year-old Sudanese man who presented to our ER with a two-week history of fever, shortness of breath, fatigue, and exercise intolerance. He had no significant personal medical history or family history of malignancy. A bone marrow biopsy revealed hypercellularity and infiltration by cells with an immature appearance. A flow cytometry (FC) analysis of the bone marrow aspirate revealed that approximately 21% of the total nucleated cells were negative for CD45 and positive for CD71, glycophorin A, and CD36 but negative for myeloperoxidase (MPO), CD33, CD13, CD61, CD41, and other lymphoid and myeloid markers. Consistent with the microscopic analysis, <1% of the total cells were identified as CD34/CD13/CD117-positive myeloblasts. Notably, all stains (CD45, MPO, CD34, CD163, CD61, glycophorin A) were negative except E-cadherin, which positively stained >80% of the cells. Our findings suggested a differential diagnosis that included erythroid leukemia and myelodysplastic syndrome (MDS). The morphological, FC, immunohistochemistry, and cytogenetic findings strongly supported a diagnosis of PEL.

Keywords: aml-m6; e-cadherin; glycophorin a; pure erythroid leukemia.

Natural killer (NK) cell neoplasms are a group of rare but highly malignant tumors. We report here one case of NK cell leukemia. A 54-yr-old woman presented with a 2-month history of progressive left neck mass. Based on the positive result of tissue PCR for Mycobacterium tuberculosis, she was at first diagnosed with tuberculous lymphadenopathy. After two weeks, she developed generalized lymphadenopathy, hepatosplenomegaly, fever and anemia. Subsequent evaluation was performed including bone marrow aspiration and biopsy. Peripheral blood smear showed leukoerythroblastic features with 31% blasts. Bone marrow was packed with agranular blastoid cells, which were periodic acid-Schiff (PAS) positive and myeloperoxidase (MPO) negative. Immunophenotyping showed that these cells were positive for CD45 and HLA-DR, whereas negative for CD3, CD5, CD7, CD10, CD13, CD14, CD19, CD20, CD22, CD33, CD34, and CD61. Because of the absence of the markers of T-cell, B-cell, and myeloid lineage-specific antigens, we added CD16/56 for the immunophenotyping and the blasts were positive (94%). The tumor cells of biopsied lymph node were only positive for CD56, consistent with NK cell lymphoma. Epstein-Barr virus (EBV) was not detected by RNA in situ hybridization. Culture for M. tuberculosis was negative. Thus this patient was diagnosed with blastic NK cell lymphoma/leukemia involving bone marrow and lymph node.

Myeloblastomas (granulocytic sarcomas) occurring within the central nervous system (CNS) are extremely rare lesions that may develop in patients with acute or chronic myeloproliferative disorders. The majority of such lesions involve brain or spinal cord by contiguous spread from meningeal or bony sites, rather than originating within the CNS parenchyma. We describe a patient with acute myelogenous leukemia in remission, who developed a purely intraparenchymal cerebellar myeloblastoma with megakaryocytic differentiation. The neoplastic cells expressed the megakaryocytic markers factor VIII-related antigen and platelet glycoprotein-IIIa (CD61), and showed ultrastructural features that were indicative of megakaryocytic differentiation. Clinically, myeloblastomas of the CNS invoke a broad differential diagnosis that includes abscess, hemorrhage, and metastatic neoplasms because of their intraparenchymal location and radiologic features. Although they are rare, myeloblastomas should be included in the histopathologic differential diagnosis of a poorly differentiated neoplasm occurring within the CNS, particularly in a patient with a history of myeloproliferative or myelodysplastic disease.

The risk of sepsis through bacterial transmission is one of the most serious problems in platelet transfusion. In processing platelet concentrates (PCs), several methods have been put into practice to minimize the risk of bacterial transmission, such as stringent monitoring by cultivation assays and inactivation treatment by photoirradiation with or without chemical agents. As another potential option, we applied a light-emitting diode (LED) with a peak emission wavelength of 265 nm, which has been shown to be effective for water, to disinfect PCs. In a bench-scale UV-LED exposure setup, a 10-min irradiation, corresponding to an average fluence of 9.2 mJ/cm2, resulted in >2.0 log, 1.0 log, and 0.6 log inactivation (mean, n = 6) of Escherichia coli, Staphylococcus aureus, and Bacillus cereus, respectively, in non-diluted plasma PCs. After a 30-min exposure, platelet counts decreased slightly (18 ± 7%: mean ± SD, n = 7); however, platelet surface expressions of CD42b, CD61, CD62P, and PAC-1 binding did not change significantly (P>0.005), and agonist-induced aggregation and adhesion/aggregation under flow conditions were well maintained. Our findings indicated that the 265 nm UV-LED has high potential as a novel disinfection method to ensure the microbial safety of platelet transfusion.

Activation of innate receptors in megakaryocytes (MKs) may affect the ability to produce functional platelets. Low platelet count is one of the clinical manifestations of dengue virus (DENV) infection. In MKs, the effect of innate receptors during DENV-infection is not well studied. Here we used MEG-01 cells to investigate DENV serotype 2 induced innate receptors in these cells. DENV RNA was estimated by qRT-PCR in the culture supernatant. The expression of innate receptors was determined by western blot and qPCR. DENV infection led to increased expression of RIG-I at 24 hrs post-infection (hpi) and MDA-5 at 48 and 72 hpi (p<0.05). However, no change in the expression of TLR3 at protein level was observed. Activation of MDA-5 resulted in increased expression of IFN-β and ISG-15 in DENV infected MEG-01 cells, which was further confirmed by MDA-5 siRNA treatment. Apart from inducing innate receptors, DENV significantly decreases the expression of CD61, an activation marker of megakaryocyteson MEG-01 cells as observed by flow cytometry analysis (p<0.01). Results from this study confirm that DENV infection activates the type-I interferon in megakaryocytes and may play a significant role in maturation and development.

Keywords: Dengue virus; MDA-5 and IFN-β; Megakaryocytes; RIG-I; TLR3.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most highly consumed drugs worldwide and the main triggers of drug hypersensitivity reactions. The most frequent reaction, named cross-reactive NSAID-hypersensitivity, is due to the pharmacological activity of these drugs by blocking the cyclooxygenase-1 enzyme. Such inhibition leads to cysteinyl-leukotriene synthesis, mainly LTE4, which are responsible for the reaction. Although the complete molecular picture of the underlying mechanisms remains elusive, the participation of platelet-adherent leukocytes (CD61⁺) and integrins have been described for NSAID-exacerbated respiratory disease (NERD). However, there is a lack of information concerning NSAID-induced urticaria/angioedema (NIUA), by far the most frequent clinical phenotype. Here we have evaluated the potential role of CD61⁺ leukocytes and integrins (CD18, CD11a, CD11b, and CD11c) in patients with NIUA, and included the other two phenotypes with cutaneous involvement, NSAID-exacerbated cutaneous disease (NECD) and blended reactions (simultaneous skin and airways involvement). A group NSAID-tolerant individuals was also included. During the acute phase of the reaction, the three clinical phenotypes showed increased frequencies of CD61⁺ neutrophils, eosinophils, and monocytes compared to controls, which correlated with urinary LTE4 levels. However, no correlation was found between these variables at basal state. Furthermore, increased expressions of CD18 and CD11a were found in the three CD61⁺ leukocytes subsets in NIUA, NECD and blended reactions during the acute phase when compared with CD61^-leukocyte subpopulations. During the acute phase, CD61⁺ neutrophils, eosinophils and monocytes showed increased CD18 and CD11a expression when compared with CD61⁺ leukocytes at basal state. No differences were found when comparing controls and CD61⁺ leukocytes at basal state. Our results support the participation of platelet-adherent leukocytes and integrins in cutaneous cross-hypersensitivity to NSAIDs and provide a link between these cells and arachidonic acid metabolism. Our findings also suggest that these reactions do not involve a systemic imbalance in the frequency of CD61⁺ cells/integrin expression or levels of LTE4, which represents a substantial difference to NERD. Although further studies are needed, our results shed light on the molecular basis of cutaneous cross-reactive NSAID-hypersensitivity, providing potential targets for therapy through the inhibition of platelet-leukocyte interactions.

Keywords: cysteinyl-leukotrienes; integrins; nonsteroidal anti-inflammatory drugs-hypersensitivity; platelet-adherent leukocytes; transcellular metabolism.

Background/aim: Glanzmann thrombasthenia (GT) is a rare autosomal recessively inherited bleeding disorder characterized by the quantitative (type 1 and type 2) or qualitative (type 3) deficiency in platelet membrane glycoprotein (GP) IIb/IIIa (CD41a/CD61) fibrinogen receptors. In type 1, 2 and 3, CD41a/CD61 expression is 5%, 5-20% and above 20%, respectively. In this study, diagnosis of GT was confirmed and subgroups were identified in 32 Turkish patients by flow cytometry analysis.

Methods: CD41a/CD61 expression levels in platelet-rich plasma (PRP) obtained from peripheral venous EDTA blood samples were analyzed with a BD FACSCanto II flow cytometer (Becton Dickinson, Franklin Lakes, NJ, USA). GT subgroup analysis was performed by counting 50000 events in the BD FACSDiva Software v6.1.3 program of the instrument.

Results: In the present study, in blood samples of 32 patients from 23 family with GT and 22 healthy controls, co-expression levels of CD41a and CD61 in PRP was analyzed. 12 out of 23 families were consistent with type 1 GT (52.2%), 4 were consistent with type 2 GT (17.4%) and 7 were consistent with type 3 GT (30.4%).

Conclusions: Especially due to consanguineous marriages, GT with various glycoprotein levels may be detected. As a result of the flow-cytometry analysis of the present study with the highest GT patient population in Turkey, type 1 GT patients were the most common subgroup. In the determination of the GT subgroups; especially in the detection of type 3 GT, flow cytometry is the most sensitive glycoprotein analysis method. In addition to light transmission aggregometry, CD41a/CD61 study by flow-cytometer confirms diagnosis when mutation analysis cannot be performed.

Keywords: CD41a/CD61; Glanzmann Thrombasthenia; flow cytometry; platelet-rich plasma.

Background: Inhibitors of vascular endothelial growth factor (VEGF)-VEGF receptor 2 (VEGFR2) signaling, such as bevacizumab (Bmab), are used for the treatment of various advanced cancers. However, these inhibitors induce renal thrombotic microangiopathy (TMA). Recently, two European cohort studies showed a distinctive histopathological pseudothrombotic pattern different from TMA in Bmab-treated patients.

Methods: We analyzed 9 renal biopsies from proteinuric cancer patients treated with VEGF-VEGFR2 inhibitors in our Japanese cohort. Clinical and laboratory features were also assessed in these patients.

Results: All 9 patients had moderate to heavy proteinuria with normal or slightly elevated serum creatinine levels. On light microscopy, a patchy pattern of hemispherical/spherical lesions along glomerular capillary walls was a characteristic finding. On immunofluorescence microscopy, staining for immunoglobulins (IgM dominant) at varying intensities was observed mainly along glomerular capillary walls. Especially, hemispherical/spherical positive staining for immunoglobulins was a characteristic pattern. Immunohistochemical studies showed positive staining for immunoglobulins and negative staining for CD61-positive platelets in capillary hemispherical/spherical lesions and positive VEGF staining in podocytes. On electron microscopy, variably electron-dense material in dilated glomerular capillaries and partial effacement of podocyte foot processes were observed. After the withdrawal of VEGF-VEGFR2 inhibitors, proteinuria improved without any specific treatment in 8 patients.

Conclusions: Histopathological findings in our patients treated with VEGF-VEGFR2 inhibitors were consistent with those observed in the recently described new form of Bmab-associated hyaline occlusive glomerular microangiopathy. This form should be considered in proteinuric cancer patients treated with VEGF-VEGFR2 inhibitors. Discontinuing VEGF-VEGFR2 inhibitors may lead to improvement of glomerular microangiopathy induced by these drugs.

Keywords: Bevacizumab; Hyaline occlusive glomerular microangiopathy; Nephrotic syndrome; Onconephrology; Ramucirumab; Vascular endothelial growth factor.

Ten mAbs of preliminary clusters PC13 and PC27 with specificity for bovine platelets were studied by immunohistochemistry. Cryostat sections of bovine lymph node, spleen, thymus, small intestine, liver, kidney and smears of bone marrow cells were used. Five mAbs (CAPP2, IVA30, IVA125, IL-A164 and IL-A166) assigned to cluster PC13 (CD41/CD61) stained platelets and non-lymphocytic cells of various tissues. Our data confirm the presence of two specificities in PC27: three mAbs (IVA120, IVA197 and IVA198) specific for fibrinogen strongly reacted with the endothelial and reticular tissues whereas the other two mAbs Co-3D1D4 and Buf13 (WC13) were negative.

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is well known for its cardiovascular co-morbidities. Increased platelet-monocyte interaction is found in COPD and may reflect altered platelet function and a potential role for anti-platelet therapy.

OBJECTIVE

The objectives were to investigate platelet-monocyte interaction, platelet activation and reactivity and plasmatic coagulation in stable COPD.

METHODS

Platelet-monocyte interaction and platelet activation were determined by flow cytometry in 30 stable COPD patients and 25 controls. Platelet activation was measured by binding of fibrinogen to the activated fibrinogen receptor and platelet P-selectin expression at baseline and after platelet stimulation with platelet agonists. Plasmatic coagulation was measured by D-dimer and thrombin generation.

RESULTS

Platelet-monocyte interaction was increased in stable COPD (median fluorescence intensity of platelet CD61 was 19.8 [IQR 14.0-33.2] vs. 10.0 [IQR 8.7-16.7], p = 0.002). In contrast, platelet activation and reactivity, reflected by fibrinogen binding and P-selectin expression, were the same in both groups. Plasma P-selectin and interleukin-6 were increased in COPD (p = 0.01 and p = 0.02, respectively), whereas soluble fibrinogen, D-dimer and thrombin generation were similar.

CONCLUSIONS

Increased platelet-monocyte interaction was found in the absence of platelet hyper-reactivity and activation of plasmatic coagulation in stable COPD. Future clinical evaluation of the effects of different anti-platelet drugs in COPD is warranted, as anti-platelet therapy may interfere with platelet-monocyte interaction.

We report an extraordinary case of primary myelofibrosis with transformation to leukemia cutis. A 64-year-old Caucasian man with a history of JAK2-positive primary myelofibrosis presented with erythematous papulonodules on his right lower extremity. A punch biopsy revealed a normal epidermis with an underlying diffuse dermal infiltrate composed of medium-to-large-sized myeloid cells and leukocytes. Neoplastic cells were immunoreactive for LCA, CD34, CD61, CD117, and CD68 and negative for lysozyme, CD20, CD3, myeloperoxidase, and TdT. These findings were consistent with a diagnosis of leukemia cutis. A concurrent bone marrow biopsy demonstrated a markedly fibrotic, hypercellular marrow without a significant increase in blasts. With no morphologic evidence of bone marrow involvement by acute myeloid leukemia, our case suggests that the patient's primary myelofibrosis transformed to leukemia cutis. Our patient died 2 months after the onset of his skin nodules. Our case demonstrates that leukemia cutis should be included in the differential diagnosis for cutaneous nodular lesions in patients with a history of an advanced-stage hematological malignancy.

Glanzmann thrombasthenia (GT) is a rare autosomal recessive disorder of fibrinogen-mediated platelet aggregation due to a quantitative or qualitative deficit of the α_IIbβ₃ integrin at the platelet surface membrane resulting from mutation(s) in ITGA2B and/or ITGB3. Patients tend to present in early childhood with easy bruising and mucocutaneous bleeding. The diagnostic process requires consideration of more common disorders of haemostasis and coagulation prior to confirming the disorder with platelet light transmission aggregation, flow cytometry of CD41 and CD61 expression, and/or exon sequencing of ITGA2B and ITGB3. Antifibrinolytic therapy, recombinant activated factor VII, and platelet transfusions are the mainstay of therapy, although the latter may trigger formation of anti-platelet antibodies in GT patients and inadvertent platelet-refractory disease. The management of these patients therefore remains complex, particularly in the context of trauma, labour and delivery, and perioperative care. Bone marrow transplantation remains the sole curative option, although the venue of gene therapy is being increasingly explored as a future alternative for definitive treatment of GT.

Keywords: ITGA2B; ITGB3; bleeding disorders; inherited platelet defects; platelet aggregation; αIIbβ3.

Alzheimer's disease (AD) is the most common form of dementia, characterized by the accumulation of β-amyloid plaques and the formation of neurofibrillary tangles. Extracellular vesicles (EVs) are small vesicles surrounded by a lipid bilayer membrane, which may be involved in the progression of AD. Glycans are essential building blocks of EVs, and we hypothesized that EV glycans may reflect pathological conditions of various diseases. Here, we performed glycan profiling of EVs prepared from sera of three AD patients (APs) compared to three healthy donors (HDs) using lectin microarray. Distinct glycan profiles were observed. Mannose-binding lectins exhibited significantly higher signals for AP-derived EVs than HD-derived EVs. Lectin blotting using mannose-binding lectin (rPALa) showed a single protein band at approximately 80 kDa exclusively in AP-derived EVs. LC-MS/MS analysis identified a protein band precipitated by rPALa as CD61, a marker of platelet-derived exosomes (P-Exo). Sandwich assays using Tim4 with specificity for phosphatidylserine on EVs and antibodies against P-Exo markers (CD61, CD41, CD63, and CD9) revealed that P-Exo is significantly elevated in sera of APs (n = 16) relative to age- and sex-matched HDs (n = 16). Tim4-αCD63 showed the highest value for the area under the curve (AUC: 0.957) for discriminating APs from HDs, which should lead to a better understanding of AD pathology and may facilitate the development of a novel diagnostic method for AD.

Keywords: Alzheimer’s disease; Tim4; extracellular vesicles; lectin microarray; platelet; sandwich assay.

Human platelet lysates (HPLs) made from clinical-grade platelet concentrates are currently evaluated in the preclinical models of Parkinson's disease, Alzheimer's disease, traumatic brain injury, and others, as a new polyvalent neuroprotective biotherapy of the central nervous system. However, the presence and content of extracellular vesicles (EVs) in HPLs and their potential contribution to the neuroprotective and neurorestorative activities of HPLs are still unknown. We, therefore, characterized the EVs present in four different HPL preparations and after purification by size-exclusion chromatography. We then tested the effect of the isolated EVs on neuronal cell repair. We identified that all four HPLs contained a high and similar amount of EVs (10¹¹ to 10¹²/mL) with a mean size ranging from ca. 50 to 300 nm and a negative zeta potential as determined by nanoparticle tracking analysis and dynamic light scattering. Western blot analysis revealed that the EVs present in HPLs expressed the clusters of differentiation 41 (CD41) and 61 (CD61) characteristic of platelets. These EVs were efficiently isolated from HPL proteins by Sepharose CL-2B size-exclusion column chromatography as confirmed by total protein determination and protein profile by sodium dodecyl sulfate polyacrylamide gel electrophoresis, with 73-85% recovery and maintenance of their size, negative zeta potential, and CD41 and CD61 expression. Interestingly, the EVs purified from the four HPLs exhibited a differential capacity to promote cell growth and migration in a wound-healing assay using SH-SY5Y neuronal cells, and one EV preparation stimulated network formation in primary neuronal cultures. These data indicated that the EVs present in HPLs have different neuroregenerative capacities and that some EV preparations may have interesting applications as a stand-alone therapy for usage in neuroregenerative medicine.

Keywords: extracellular vesicles; human platelet lysate; isolation; neuroprotection; size-exclusion chromatography.

Background: Platelet transfusion therapy is widely used to prevent hemorrhage in patients with thrombocytopenia and platelet disorders. The platelet concentrate (PC) quality is affected by increased storage time, as reflected in the decreased number of platelets, morphological changes, and impaired functions. This study aimed to analyze the impact of 5 days storage on platelets count and the expression of CD63, and Annexin V as activation markers during PC storage.

Methods: Fifty PCs collected from single donors were tested for platelet count on days 0, 3, and 5 using a Sysmex blood counter. CD61, CD63, and Annexin V expression was analyzed by a multicolor Navios flow cytometer.

Results: There was a significant decrease in platelet count during 5 days of storage. There was a direct relationship between storage time and degree of platelet activation. CD63 had almost double increased expression on day 5 than day 3. Annexin V showed significantly increased expression on day 3 with minor differences between days 3 and 5.

Conclusion: According to standard blood bank conditions, PC stored for 5 days showed a degree of in vitro activation as evidenced by CD63 and Annexin V expression, may lead to reduced therapeutic efficacy. Flow cytometry monitoring platelet activation in PC offers a better understanding of the changes during PC storage and may help improve platelet products.

Keywords: Annexin V; CD63; Platelet transfusion.

Patients with ischemic stroke (IS) are at increased risk of mortality and recurrent cerebro- or cardiovascular events. Determining prognosis after IS remains challenging but blood-based biomarkers might provide additional prognostic information. As platelets are crucially involved in the pathophysiology of vascular diseases, platelet surface proteins (PSP) are promising candidates as prognostic markers in the hyperacute stage. In this pilot study, feasibility of PSP analysis by flow cytometry (HMGB1, CD84, CXCR4, CXCR7, CD62p with and without ADP-stimulation, CD41, CD61, CD40, GPVI) was investigated in 99 (median 66 years, 67.5% male) acute IS patients admitted to Stroke Unit within a substudy of the Stroke-Induced Cardiac FAILure in mice and men (SICFAIL) cohort study. Association between PSP expression and unfavorable one-year outcome (cerebro- or cardiovascular event, all-cause mortality and care dependency defined as Barthel Index <60) was explored. PSP measurements were feasible. Several process- (e.g. temperatures, processing times) and patient-related factors (e.g. prestroke ischemic events, surgery, blood pressure, antiplatelet therapy) were identified to be potentially associated with PSP expression. Elevated CD40 levels above study population's median were associated with unfavorable outcome. Standardized conditions during blood draw and processing within the hyperacute stroke unit setting are required and patient-related characteristics must be considered for valid measurements of PSP.Trial registration: German Clinical Trials Register (DRKS00011615).

Keywords: Biomarker; flow cytometry; platelets; prognosis; stroke; surface markers.

The present study proposes to legitimize in sepsis a characteristic found in platelets that suffer storage lesions in blood banks, which is the increased expression of miRNA miR-320a in relation to miR-127. Under physiologically normal conditions, an inverse relationship is observed. The aim of this study was to verify whether the analysis of miR-320a and miR-127 expression in platelets could detect a decrease in their viability and function due to the presence of pathogens in the blood of patients hospitalized in the Intensive Care Unit. We also investigated the expression of membrane antigens sensitive to platelet activation. Of the 200 patients analyzed, only those who developed sepsis (140) were found to have a higher relative quantity of miR-320a than that of miR-127. This characteristic and the increased expression of membrane antigens P2Y12, CD62P, CD41, and CD61 showed a significant association (p < 0.01) with all types of sepsis evaluated in this study. Additionally, 40% of patients hospitalized for sepsis had negative results for the first cultures. We conclude that analysis of miR-127 and miR-320a expression combined with membrane antigens evaluation, in association with the available clinical and diagnostic parameters, are important tools to detect the onset of sepsis.

Keywords: membrane antigens; microRNA; platelets; sepsis.

Wiskott-Aldrich Syndrome, WAS/WAVE, is a rare, X-linked immune-deficiency disease caused by mutations in the WAS gene, which together with its homolog, N-WASP, regulates actin cytoskeleton remodeling and cell motility. WAS patients suffer from microthrombocytopenia, characterized by a diminished number and size of platelets, though the underlying mechanism is not fully understood. Here, we identified FLI1 as a direct transcriptional regulator of WAS and its binding partner WIP. Depletion of either WAS or WIP in human erythroleukemic cells accelerated cell proliferation, suggesting tumor suppressor function of both genes in leukemia. Depletion of WAS/WIP also led to a significant reduction in the percentage of CD41 and CD61 positive cells, which mark committed megakaryocytes. RNAseq analysis revealed common changes in megakaryocytic gene expression following FLI1 or WASP knockdown. However, in contrast to FLI1, WASP depletion did not alter expression of late-stage platelet-inducing genes. N-WASP was not regulated by FLI1, yet its silencing also reduced the percentage of CD41+ and CD61+ megakaryocytes. Moreover, combined knockdown of WASP and N-WASP further suppressed megakaryocyte differentiation, indicating a major cooperation of these related genes in controlling megakaryocytic cell fate. However, unlike WASP/WIP, N-WASP loss suppressed leukemic cell proliferation. WASP, WIP and N-WASP depletion led to induction of FLI1 expression, mediated by GATA1, and this may mitigate the severity of platelet deficiency in WAS patients. Together, these results uncover a crucial role for FLI1 in megakaryocyte differentiation, implicating this transcription factor in regulating microthrombocytopenia associated with Wiskott-Aldrich syndrome.

Keywords: FLI1; N-WASP; WASP; WIP; Wiskott–Aldrich Syndrome; immunodeficiency; megakaryopoiesis; microthrombocytopenia.

BCR-ABL-fusion-negative myeloproliferative neoplasms (MPNs) with myelofibrosis (MF) include primary MF, post-polycythemia vera MF and post-essential thrombocythemia MF. Clonal extramedullary hematopoiesis (EMH) can occur during MPN pathogenesis. Although histopathological bone-marrow (BM) features during clonal EMH have been investigated, those of the spleen have been poorly described. We analyzed splenectomy samples from 28 patients with MF and BM samples from 20 of them. Slides were stained with hematoxylin and eosin, reticulin, and trichrome, with immunohistochemical labeling of glycophorin A, myeloperoxidase, CD61, CD34, and CD117. We also subjected splenectomy and BM samples from six patients and spleen samples from seven patients to next-generation sequencing (NGS). Megakaryocyte-rich spleen nodules (MRSNs), seen in seven of the 28 patients, were significantly associated with megakaryocyte proliferation in the spleen (p = 0.04). We devised a grading system for spleen fibrosis (SF) and found that SF was increased in 20 of 28 patients. Notably, patients with SF were more likely to have MRSNs, suggesting that megakaryocytes might participate in SF, as previously described in BM. Comparisons of spleen and BM NGS findings of six patients' specimens revealed identical mutational status in the two organs for half of the patients. We observed additional mutations in the spleen of two patients. However, the meaning of this finding remains unknown since there was a long interval between BM and spleen samplings (68 and 82 months, respectively).

Keywords: Immunohistochemistry; Molecular biology; Myelofibrosis; Spleen pathology; Splenectomy.

Rationale: Multiple myeloma (MM) is a multifocal malignancy of bone marrow plasma cells, characterized by vicious cycles of remission and relapse that eventually culminate in death. The disease remains mostly incurable largely due to the complex interactions between the bone microenvironment (BME) and MM cells (MMC). In the "vicious cycle" of bone disease, abnormal activation of osteoclasts (OCs) by MMC causes severe osteolysis, promotes immune evasion, and stimulates the growth of MMC. Disrupting these cancer-stroma interactions would enhance treatment response. Methods: To disrupt this cycle, we orthogonally targeted nanomicelles (NM) loaded with non-therapeutic doses of a photosensitizer, titanocene (TC), to VLA-4 (α4ß1, CD49d/CD29) expressing MMC (MM1.S) and αvß3 (CD51/CD61) expressing OC. Concurrently, a non-lethal dose of a radiopharmaceutical, ¹⁸F-fluorodeoxyglucose ([¹⁸F]FDG) administered systemically interacted with TC (radionuclide stimulated therapy, RaST) to generate cytotoxic reactive oxygen species (ROS). The in vitro and in vivo effects of RaST were characterized in MM1.S cell line, as well as in xenograft and isograft MM animal models. Results: Our data revealed that RaST induced non-enzymatic hydroperoxidation of cellular lipids culminating in mitochondrial dysfunction, DNA fragmentation, and caspase-dependent apoptosis of MMC using VLA-4 avid TC-NMs. RaST upregulated the expression of BAX, Bcl-2, and p53, highlighting the induction of apoptosis via the BAK-independent pathway. The enhancement of multicopper oxidase enzyme F5 expression, which inhibits lipid hydroperoxidation and Fenton reaction, was not sufficient to overcome RaST-induced increase in the accumulation of irreversible function-perturbing α,ß-aldehydes that exerted significant and long-lasting damage to both DNA and proteins. In vivo, either VLA-4-TC-NM or αvß3-TC-NMs RaST induced a significant therapeutic effect on immunocompromised but not immunocompetent MM-bearing mouse models. Combined treatment with both VLA-4-TC-NM and αvß3-TC-NMs synergistically inhibited osteolysis, reduced tumor burden, and prevented rapid relapse in both in vivo models of MM. Conclusions: By targeting MM and bone cells simultaneously, combination RaST suppressed MM disease progression through a multi-prong action on the vicious cycle of bone cancer. Instead of using the standard multidrug approach, our work reveals a unique photophysical treatment paradigm that uses nontoxic doses of a single light-sensitive drug directed orthogonally to cancer and bone cells, followed by radionuclide-stimulated generation of ROS to inhibit tumor progression and minimize osteolysis in both immunocompetent murine and immunocompromised human MM models.

Keywords: Cerenkov radiation; bone marrow; multiple myeloma; nanomicelles; orthogonal drug delivery; photosensitizer; tumor microenvironment.

Objective: To investigate the effect of vitamin D3 to platelet activation by tumor cell culture medium.

Methods: The peripheral blood platelets of BALB/c mice were isolated. The platelets were activated in 4T1 culture fluid for 24 h. The platelets were divided into 7 groups: control group, activation group, 1 nmol/L vitamin D3 group, 10 nmol/L vitamin D3 group, 50 nmol/L vitamin D3 group, 100 nmol/L vitamin D3 group, and positive drug (0.1 μmol/L eptifibatide) group. CCK-8 assay was used to detect the platelet proliferation at 24, 48 and 72 h. Flow cytometry was used to detect the expression of CD61 and CD62p and receptor for advanced glycation end products (RAGE) at 24, 48 and 72 h. ELISA was used to detect the level of platelet-endothelial cell adhesion molecule-1 (PECAM-1) at 24, 48 and 72 h.

Results: The CD41⁺/CD61⁺ and CD41⁺/CD62p⁺ ratio, PECAM-1 content and RAGE expression of platelets in activated group were all significantly increased as compared with those in control group (P<0.05). Compared with the activated group, the platelet proliferation, proportion of CD41⁺/CD61⁺ and CD41⁺/CD62p⁺, content of PECAM-1 and RAGE expression in vitamin D3 groups were all decreased (P<0.05).

Conclusion: Vitamin D3 shows antiplatelet effect and can inhibit platelet proliferation and activation.

题目: 维生素D3对肿瘤细胞培养液介导血小板活化的影响.

目的: 探讨维生素D3对肿瘤细胞培养液介导血小板活化的影响.

方法: 原代分离BALB/c小鼠外周血血小板，采用小鼠乳腺癌细胞4T1培养液培养血小板24 h进行活化。将血小板分为7组：对照组、活化组、1 nmol/L维生素D3组、10 nmol/L维生素D3组、50 nmol/L维生素D3组、100 nmol/L维生素D3组、阳性药物（0.1 μmol/L依替巴肽）组。CCK-8法检测24、48、72 h血小板增殖能力；流式细胞术检测24、48、72 h血小板活化标志物CD61和CD62p及晚期糖基化终末产物受体（RAGE）的表达水平；ELISA检测24、48、72 h血小板内皮细胞粘附分子1（PECAM-1）的水平.

结果: 与对照组比较，活化组血小板CD41⁺/CD61⁺及CD41⁺/CD62p⁺比例、PECAM-1含量、RAGE表达均明显升高（P<0.05）。与活化组比较，维生素D3组血小板增殖、CD41⁺/CD61⁺及CD41⁺/CD62p⁺比例、PECAM-1含量及RAGE表达均明显降低（P<0.05）.

结论: 维生素D3可抑制血小板增殖与活化，具有抗血小板作用.

Background & aims: Circulating microvesicles (cMV) are both effectors and biomarkers of cardiovascular disease (CVD), and the effects of omega 3 polyunsaturated fatty acids (n3 PUFA) in MV shedding are not yet well known. Therefore, we aimed to investigate the effects of long-term n3 PUFA supplementation on cMV release from cells of the vascular compartment in elderly subjects at very high risk of CVD.

Methods: We included 156 elderly patients 2-8 weeks after suffering an acute myocardial infarction from the OMEMI cohort. Subjects were randomly allocated to receive 930 mg EPA + 660 mg DHA (n3 PUFA intervention) or corn oil (56% linoleic acid, 32% oleic acid, 10% palmitic acid) used as placebo daily for two years. At inclusion and after one-year follow-up, prothrombotic [annexin V (AV)⁺] cMV derived from blood and vascular cells were phenotyped by flow cytometry.

Results: No differences were observed in the levels of cMV between the randomized groups at inclusion in the study. After one-year follow-up, total AV⁺, platelet-derived CD61⁺/AV⁺, and endothelial-derived CD31⁺/AV⁺ and CD31⁺/CD42b^-/AV⁺ cMV increased significantly in both groups. In the n3 PUFA supplemented group, platelet-derived CD62P⁺/AV⁺, CD42b⁺/AV⁺ and CD31⁺/CD42b⁺/AV⁺; leukocyte-derived CD62L⁺/AV⁺, CD45⁺/AV⁺, and CD11b⁺/AV⁺, as well as endothelial derived CD146⁺/AV⁺, CD62E⁺/AV⁺, and CD309⁺/AV⁺ cMV also increased significantly. No significant differences were however, observed in the changes of cMV levels between groups.

Conclusion: In elderly Norwegians who have suffered a recent acute myocardial infarction and treated as per guidelines, long-term supplementation with 1.8 g/day n3 PUFA does not modulate prothrombotic MV release from blood and vascular cells.

Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01841944.

Keywords: DHA; EPA; Elderly; Microvesicles; Omega 3 fatty acids; Thrombosis.

The objective of this study was to elucidate the molecular characteristics of a Chinese family with Glanzmann's thrombasthenia (GT). The proband was diagnosed with GT based on clinical manifestations, platelet aggregation, and the expression of CD41 and CD61 in platelets. Whole-exome and Sanger sequencing were used to detect genetic defects related to GT in the proband and the family of the pedigree. Whole-exome sequencing showed a c.1784-1802delinsGTCACA, p. S595Cfs*70 homozygous mutation in exon 11 of the ITGB3 gene in the proband. Heterozygous mutations were found in the proband's parents, grandmother, uncle, aunt, and younger brother. This novel p. S595Cfs*70 ITGB3 gene mutation is not present in the 1000 Genomes and ExAC databases.

Keywords: Family studies; Glanzmann’s thrombasthenia; ITGB3; Integrin αIIbβ3; Mutation.