Publications (296) View all
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Article: OP9 Bone Marrow Stroma Cells Differentiate into Megakaryocytes and Platelets.
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ABSTRACT: Platelets are essential for hemostatic plug formation and thrombosis. The mechanisms of megakaryocyte (MK) differentiation and subsequent platelet production from stem cells remain only partially understood. The manufacture of megakaryocytes (MKs) and platelets from cell sources including hematopoietic stem cells and pluripotent stem cells have been highlighted for studying the platelet production mechanisms as well as for the development of new strategies for platelet transfusion. The mouse bone marrow stroma cell line OP9 has been widely used as feeder cells for the differentiation of stem cells into MK lineages. OP9 cells are reported to be pre-adipocytes. We previously reported that 3T3-L1 pre-adipocytes differentiated into MKs and platelets. In the present study, we examined whether OP9 cells differentiate into MKs and platelets using MK lineage induction (MKLI) medium previously established to generate MKs and platelets from hematopoietic stem cells, embryonic stem cells, and pre-adipocytes. OP9 cells cultured in MKLI medium had megakaryocytic features, i.e., positivity for surface markers CD41 and CD42b, polyploidy, and distinct morphology. The OP9-derived platelets had functional characteristics, providing the first evidence for the differentiation of OP9 cells into MKs and platelets. We then analyzed gene expressions of critical factors that regulate megakaryopoiesis and thrombopoiesis. The gene expressions of p45NF-E2, FOG, Fli1, GATA2, RUNX1, thrombopoietin, and c-mpl were observed during the MK differentiation. Among the observed transcription factors of MK lineages, p45NF-E2 expression was increased during differentiation. We further studied MK and platelet generation using p45NF-E2-overexpressing OP9 cells. OP9 cells transfected with p45NF-E2 had enhanced production of MKs and platelets. Our findings revealed that OP9 cells differentiated into MKs and platelets . OP9 cells have critical factors for megakaryopoiesis and thrombopoiesis, which might be involved in a mechanism of this differentiation. p45NF-E2 might also play important roles in the differentiation of OP9 cells into MK lineages cells.PLoS ONE 01/2013; 8(3):e58123. · 4.09 Impact Factor -
Article: Ability of fibrinogen γ-derived dodecapeptides with different sequences to bind to rat platelets.
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ABSTRACT: A dodecapeptide (γ400-411) derived from a fibrinogen γ-chain carboxyl-terminal sequence recognizes specifically the active form of GPIIb/IIIa on the surface of activated platelets. For the purpose of efficient hemostasis, we previously developed ADP-encapsulated liposomes modified with human-dodecapeptide (HHLGGAKQAGDV, human-H12). On the other hand, the amino-acid sequence of H12 from rats is HHMGGSKQVGDM, having only 67% homology to that from humans. Here, we investigated the ability of rat-H12 in comparison with human-H12 to bind to platelets. Firstly, rat platelets were activated with phorbol-12-myristate-13-acetate (PMA), and the activation was confirmed by flow cytometry. Next, we evaluated the dissociation constant (K(d)) of human-H12 and rat-H12 for dissociation from rat platelets by using FACS. As a result, the K(d) of human-H12 and rat-H12 with respect to rat platelets was 2.78±0.21 and 2.91±0.22μM, respectively. Furthermore, H12 from both species inhibited quite similarly the aggregation of rat platelets in platelet-rich plasma (PRP). These results suggest that H12 from different species with different amino acid sequences interacts similarly with GPIIb/IIIa on platelets.International journal of pharmaceutics 09/2012; 438(1-2):296-301. · 2.96 Impact Factor -
Article: Post-transplant consolidation therapy using thalidomide alone for the patients with multiple myeloma: a feasibility study in Japanese population.
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ABSTRACT: In order to test for improved survival following autologous transplantation (ASCT), we conducted a prospective clinical trial of post-ASCT thalidomide therapy in Japanese patients with multiple myeloma (MM). Twenty-five newly diagnosed patients received double or single ASCT with high-dose melphalan (200 mg/m(2)). Two months after stem cell infusion, if the patients failed to achieve a near-complete response, thalidomide was administered at 200 mg/day until disease progression or occurrence of intolerable adverse events. Seventeen patients were in partial response or minimal response after ASCT and received thalidomide alone. Their median progression-free survival (PFS) from ASCT was 17.4 months, and the median overall survival (OS) was 42.9 months. Some patients with normal karyotype experienced durable disease stabilization for over 5 years. Five patients who exhibited high-risk chromosomal changes such as t(4;14) or deletion of chromosome 13 or 17 showed very short PFS and OS compared with those who did not. Observed grade 3 or 4 toxicities included infection in three patients, hematological toxicities in three, and gastrointestinal toxicities in two, but there was no grade 3 or higher peripheral neuropathy, probably due to appropriate dose modifications. This long-term prospective study is the first to demonstrate the feasibility of post-ASCT thalidomide therapy in Japanese patients with MM.International journal of hematology 09/2012; 96(4):477-84. · 1.17 Impact Factor -
Article: Direct reprogramming of terminally differentiated B cells into erythroid lineage.
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ABSTRACT: Hematopoietic progenitors have been shown to retain plasticity and switch lineages by appropriate stimuli. However, mature blood cells hardly showed such differentiation plasticity. In this paper, we tried to reprogram mature B cells into erythroid lineage by expressing various hematopoietic transcription factors. Among various factors, GATA-1, SCL together with CCAAT/enhancer binding protein (C/EBP) α turned out to be a minimal set of factors that efficiently reprogrammed terminally differentiated mature B cells into erythroid lineage, as evidenced by colony forming assays and erythroid-specific gene expressions. This study sets an avenue to generate autologous erythrocytes from peripheral B cells.FEBS letters 08/2012; 586(20):3645-52. · 3.54 Impact Factor -
Article: Induction of functional platelets from mouse and human fibroblasts by p45NF-E2/Maf.
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ABSTRACT: Determinant factors leading from stem cells to megakaryocytes (MKs) and subsequently platelets have yet to be identified. We now report that a combination of p45NF-E2, Maf G, and Maf K can convert mouse fibroblast 3T3 cells and adult human dermal fibroblasts (HDFs) into MKs. To screen MK-inducing factors, gene expressions were compared between 3T3 cells that do not differentiate into MKs and 3T3-L1 cells known to differentiate into MKs. 3T3 cells transfected with candidate factors were cultured in a defined MK lineage induction (MKLI) medium. Among the tested factors, transfection with p45NF-E2/MafG/MafK lead to the highest frequency of CD41-positive cells. Adult HDFs transfected with these genes were cultured in MKLI medium. Cultured cells had megakaryocytic features, including surface markers, ploidy, and morphology. More than 90% of MK-sized cells expressed CD41, designated induced MK (iMK). Infusion of these iMK cells into immunodeficient mice led to a time-dependent appearance of CD41-positive, platelet-sized particles. Blood samples from iMK-infused into thrombocytopenic immunodeficient mice were perfused on collagen-coated chip, and human CD41-positive platelets were incorporated into thrombi on the chip demonstrating their functionality. These findings demonstrate that a combination of p45NF-E2, Maf G, and Maf K is a key determinant of both megakaryopoiesis and thrombopoiesis.Blood 07/2012; · 9.90 Impact Factor
