Kentaro Yamamura

Pleiotropic role of histone deacetylases in the regulation of human adult erythropoiesis

Histone acetylation and deacetylation play fundamental roles in transcriptional regulation. We investigated the role of histone deacetylases (HDACs) in human adult haematopoiesis, using the structurally distinct HDAC inhibitors FK228 (depsipeptide) and Trichostatin A. When CD34+ cells were cultured with interleukin (IL)‐3 or stem cell factor (SCF) + IL‐3, FK228 (0·5 ng/ml) specifically enhanced the generation of immature erythroid cells with a CD36+ glycophorin A (GPA)low phenotype. In semisolid cultures, FK228 promoted the formation of erythroid colonies by CD34+ cells with IL‐3 and SCF + IL‐3. Furthermore, upon exposure to FK228, CD34+ cell‐derived CD36+GPA− cells were induced to form erythroid colonies with IL‐3 alone. Conversely, FK228 inhibited the generation of CD36+GPAhigh relatively mature erythroid cells from CD34+ cells in the presence of erythropoietin (EPO) and SCF + EPO. FK228 suppressed the EPO‐mediated survival of CD36+GPAlow/‐and CD36+GPAhigh cells and induced their apoptosis. Similar effects were observed for trichostatin A in the generation of erythroid cells in IL‐3‐ and EPO‐containing cultures. These data suggest that HDACs negatively regulate the IL‐3‐mediated growth of early erythroid precursors by suppressing their responsiveness to IL‐3, while playing an important role in EPO‐mediated differentiation and survival of erythroid precursors. Our data revealed that HDACs have diverse functions in human adult erythropoiesis.

A potential activity of valproic acid in the stimulation of interleukin-3 mediated megakaryopoiesis and erythropoiesis

OBJECTIVE Although the anticancer activities of histone deacetylase (HDAC) inhibitors have been studied, a role for HDAC in normal hematopoiesis has not been clearly defined. Previous studies have shown that the potent HDAC inhibitor FK228 stimulates interleukin (IL)-3-mediated erythropoiesis. Here, we examined whether the widely used valproic acid (VPA) affects megakaryopoiesis as well as erythropoiesis. MATERIALS AND METHODS CD34(+) cells were incubated in serum-free or serum-containing cultures with cytokines, with or without VPA. RESULTS In the serum-free cultures containing IL-3+stem cell factor (SCF), VPA significantly increased generation of CD61(+)GPA(-) megakaryocytic and a CD61(+)GPA(+) mixture of megakaryocytic and erythroid precursors from CD34(+) hematopoietic precursors at a pharmacological concentration (100 microg/mL). The increase in generation of megakaryocytic and erythroid precursors by VPA was confirmed by replating cultured cells with thrombopoietin+SCF and erythropoietin+SCF, respectively. VPA was as potent as FK228. In cultures with granulocyte-macrophage colony-stimulating factor+SCF, where CD61(-)GPA(+) erythroid precursors were mostly developed, VPA mainly enhanced the generation of CD61(-)GPA(+) erythroid precursors. In serum-containing cultures, only low numbers of CD61(+) or GPA(+) cells were developed with IL-3+SCF. Nevertheless, a substantial number of these cells were generated with VPA. Furthermore, these stimulating effects of VPA were observed by incubating CD34(+) cells from patients with myelodysplastic syndrome. Quantitative reverse transcription polymerase chain reaction showed that VPA enhanced GATA-2, but not GATA-1, messenger RNA expression with IL-3+SCF. CONCLUSIONS These results indicate a novel role for VPA in enhancing the potential of IL-3 to stimulate megakaryopoiesis as well as erythropoiesis and suggest a new therapeutic approach of epigenetic therapy for hematological disease.

Notch ligand Delta-1 differentially modulates the effects of gp130 activation on interleukin-6 receptor α-positive and -negative human hematopoietic progenitors

Interleukin (IL)‐6 plays pleiotropic roles in human hematopoiesis and immune responses by acting on not only the IL‐6 receptor‐α subunit (IL‐6Rα)+ but also IL‐6Rα− hematopoietic progenitors via soluble IL‐6R. The Notch ligand Delta‐1 has been identified as an important modulator of the differentiation and proliferation of human hematopoietic progenitors. Here, it was investigated whether these actions of IL‐6 are influenced by Delta‐1. When CD34+CD38− hematopoietic progenitors were cultured with stem cell factor, flt3 ligand, thrombopoietin and IL‐3, Delta‐1, in combination with the IL‐6R/IL‐6 fusion protein FP6, increased the generation of glycophorin A+ erythroid cells but counteracted the effects of IL‐6 and FP6 on the generation of CD14+ monocytic and CD15+ granulocytic cells. Although freshly isolated CD34+CD38− cells expressed no or only low levels of IL‐6Rα, its expression was increased in myeloid progenitors after culture but remained negative in erythroid progenitors. It was found that Delta‐1 acted in synergy with FP6 to enhance the generation of erythroid cells from the IL‐6Rα− erythroid progenitors. In contrast, Delta‐1 antagonized the effects of IL‐6 and FP6 on the development of monocytic and granulocytic cells, as well as CD14−CD1a+ dendritic cells, from the IL‐6Rα+ myeloid progenitors. These results indicate that Delta‐1 interacts differentially with gp130 activation in IL‐6Rα− erythroid and IL‐6Rα+ myeloid progenitors. The present data suggest a divergent interaction between Delta‐1 and gp130 activation in human hematopoiesis. (Cancer Sci 2007; 98: 1597–1603)

Ex Vivo Culture of Human Cord Blood Hematopoietic Stem/Progenitor Cells Adversely Influences Their Distribution to Other Bone Marrow Compartments After Intra-Bone Marrow Transplantation

Intra‐bone marrow injection is a novel strategy for hematopoietic stem cell transplantation. Here, we investigated whether ex vivo culture of cord blood hematopoietic stem/progenitor cells influences their reconstitution in bone marrow after intra‐bone marrow transplantation. Freshly isolated AC133+ cells or cells derived from AC133+ cells cultured with cytokines (stem cell factor, flt‐3 ligand, and thrombopoietin) for 5 days were injected into the bone marrow of the left tibia in irradiated NOD/SCID mice. In the bone marrow of the injected left tibia, the engraftment levels of human CD45+ cells at 6 weeks after transplantation did not differ considerably between transplantation of noncultured and cytokine‐cultured cells. However, the migration and distribution of transplanted cells to the bone marrow of other, noninjected bones were extremely reduced for cytokine‐treated cells compared with noncultured cells. Similar findings were observed for engraftment of CD34+ cells. Administration of granulocyte colony‐stimulating factor to mice after transplantation induced the migration of cytokine‐cultured cells to the bone marrow of previously aspirated bone but not to other intact bones. These data suggest that ex vivo manipulation of hematopoietic progenitor/stem cells significantly affects their migration properties to other bone marrow compartments after intra‐bone marrow transplantation. Our data raise a caution for future clinical applications of the intra‐bone marrow transplantation method using ex vivo‐manipulated hematopoietic stem cells.

Central venous catheter-related thrombosis after replacement therapy for intracranial bleeding in a patient with afibrinogenaemia

T. MATSUMOTO,* H. WADA, S. TAMARU, § Y. SUGIMOTO,* A. FUJIEDA,* K. YAMAMURA,* T. KOBAYASHI,* T. KANEKO, – M. YAMAGUCHI,* T. NOBORI and N. KATAYAMA* *Department of Haematology and Oncology, Mie University Graduate School of Medicine; Haemophilia and Thrombophilia Centre, Mie University Hospital; Clinical Laboratory Medicine, Mie University Graduate School of Medicine; §Institute of Human Reseach Promotion and Drug Development, Mie University Graduate School of Medicine; and –Patient Safety Division, Mie University Hospital, Mie, Japan

Development of Mixed-Type Autoimmune Hemolytic Anemia and Evans’ Syndrome following Chicken Pox Infection in a Case of Low-Titer Cold Agglutinin Disease

We describe a patient with low-titer cold agglutinin disease (CAD) who developed mixed-type autoimmune hemolytic anemia (AIHA) and idiopathic thrombocytopenia following chicken pox infection. At least 1 year before admission to hospital, the patient had mild hemolytic anemia associated with low-titer cold agglutinins. A severe hemolytic crisis and thrombocytopenia (Evans’ syndrome) occurred several days after infection with chicken pox, and the patient was referred to our hospital. Serological findings revealed the presence of both cold agglutinins and warm-reactive autoantibodies against erythrocytes, and the diagnosis was mixed-type AIHA. Following steroid therapy, the hemoglobin (Hb) level and platelet count improved. The patient was closely followed over a 10-year period with recurrent documented hemolysis after viral or bacterial infections. Warm-reactive autoantibodies have not been detected in the last 2 years, and only the immunoglobulin M anti-I cold agglutinins with a low titer and wide thermal amplitude have remained unchanged. Therefore, the patient has received at least 10 mg prednisolone daily to maintain a Hb level of 10 g/dL. To the best of our knowledge, no adult case of low-titer CAD that has evolved into mixed-type AIHA and Evans’ syndrome after chicken pox infection has been previously reported in the literature.

Deletion of chromosome arm 15q in a case of minimally differentiated hypoplastic AML-M0.

Deletion of the long arm of chromosome 15 is known as a rare but recurrent chromosomal abnormality in myeloid malignancies. We report a novel case of minimally differentiated hypoplastic acute myeloid leukemia (AML M0) in a patient who initially had a normal karyotype, but clonal interstitial deletion of chromosome 15, del(15)(q11.2q22), coincided with increment of leukemic cells a year later. We also summarize 18 published cases with myeloid malignancies and this chromosomal abnormality.