Search

Osteoblasts and their progenitors play an important role in the support of hematopoiesis within the bone marrow (BM) microenvironment. We have previously reported that parathyroid hormone receptor (PTH1R) signaling in osteoprogenitors is required for normal B cell precursor differentiation, and for trafficking of maturing B cells out of the BM. Cells of the osteoblast lineage have been implicated in the regulation of several other hematopoietic cell populations, but the effects of PTH1R signaling in osteoprogenitors on other maturing hematopoietic populations have not been investigated. Here we report that numbers of maturing myeloid, T cell, and erythroid populations were increased in the BM of mice lacking PTH1R in Osx-expressing osteoprogenitors (PTH1R-OsxKO mice; knockout [KO]). This increase in maturing hematopoietic populations was not associated with an increase in progenitor populations or proliferation. The spleens of PTH1R-OsxKO mice were small with decreased numbers of all hematopoietic populations, suggesting that trafficking of mature hematopoietic populations between BM and spleen is impaired in the absence of PTH1R in osteoprogenitors. RNA sequencing (RNAseq) of osteoprogenitors and their descendants in bone and BM revealed increased expression of vascular cell adhesion protein 1 (VCAM-1) and C-X-C motif chemokine ligand 12 (CXCL12), factors that are involved in trafficking of several hematopoietic populations. © 2022 American Society for Bone and Mineral Research (ASBMR).

Haematopoietic stem cells (HSCs) are a rare cell type that reconstitute the entire blood and immune systems after transplantation and can be used as a curative cell therapy for a variety of haematological diseases1,2. However, the low number of HSCs in the body makes both biological analyses and clinical application difficult, and the limited extent to which human HSCs can be expanded ex vivo remains a substantial barrier to the wider and safer therapeutic use of HSC transplantation3. Although various reagents have been tested in attempts to stimulate the expansion of human HSCs, cytokines have long been thought to be essential for supporting HSCs ex vivo4. Here we report the establishment of a culture system that allows the long-term ex vivo expansion of human HSCs, achieved through the complete replacement of exogenous cytokines and albumin with chemical agonists and a caprolactam-based polymer. A phosphoinositide 3-kinase activator, in combination with a thrombopoietin-receptor agonist and the pyrimidoindole derivative UM171, were sufficient to stimulate the expansion of umbilical cord blood HSCs that are capable of serial engraftment in xenotransplantation assays. Ex vivo HSC expansion was further supported by split-clone transplantation assays and single-cell RNA-sequencing analysis. Our chemically defined expansion culture system will help to advance clinical HSC therapies.

Hematopoietic stem cells (HSC) have self-renewal as well as multilineage differentiation capacity and maintain hematopoiesis throughout life. HSC transplantation (HSCT) is performed as a curative therapy for hematopoietic malignancies and nonmalignant hematopoietic disorders. Furthermore, bone marrow, mobilized peripheral blood, and cord blood are available sources for HSCT. HLA compatibility is the most critical factor for a successful HSCT. The HSC number in a graft is also invaluable for engraftment. Moreover, it is challenging to obtain an abundant number of HSC for patients with obesity, particularly, in cord blood. HSC ex vivo expansion is an appropriate solution for this problem. Extrinsic factors to expand and maintain HSCs, such as cytokines are identified from analysis of HSCs and their niche. Thus, HSC ex vivo expansion is improved by adding them in culture medium; however, it is still difficult for therapeutic applications. Recently, several small molecular compounds have been reported to facilitate ex vivo expansion of HSC. Clinical trials that transplant ex vivo expanded cord blood have been already expanded, and some trials demonstrate reduction of time to hematopoietic recovery. Thus, we anticipate that ex vivo expanded cord blood transplantation will be applied widely in the future.

Hematopoiesis is extrinsically controlled by cells of the bone marrow microenvironment, including skeletal lineage cells. The identification and subsequent studies of distinct subpopulations of maturing skeletal cells is currently limited because of a lack of methods to isolate these cells. We found that murine Lin–CD31–Sca-1–CD51+ cells can be divided into 4 subpopulations by using flow cytometry based on their expression of the platelet-derived growth factor receptors ⍺ and β (PDGFR⍺ and PDGFRβ). The use of different skeletal lineage reporters confirmed the skeletal origin of the 4 populations. Multiplex immunohistochemistry studies revealed that all 4 populations were localized near the growth plate and trabecular bone and were rarely found near cortical bone regions or in central bone marrow. Functional studies revealed differences in their abundance, colony-forming unit–fibroblast capacity, and potential to differentiate into mineralized osteoblasts or adipocytes in vitro. Furthermore, the 4 populations had distinct gene expression profiles and differential cell surface expression of leptin receptor (LEPR) and vascular cell adhesion molecule 1 (VCAM-1). Interestingly, we discovered that 1 of these 4 different skeletal populations showed the highest expression of genes involved in the extrinsic regulation of B lymphopoiesis. This cell population varied in abundance between distinct hematopoietically active skeletal sites, and significant differences in the proportions of B-lymphocyte precursors were also observed in these distinct skeletal sites. This cell population also supported pre-B lymphopoiesis in culture. Our method of isolating 4 distinct maturing skeletal populations will help elucidate the roles of distinct skeletal niche cells in regulating hematopoiesis and bone.

Gene editing using engineered nucleases frequently produces on- and off-target indels in hematopoietic stem cells (HSCs). Gene-edited HSC cultures thus contain genetically heterogenous populations, the majority of which either do not carry the desired edit or harbor unwanted mutations. In consequence, transplanting edited HSCs carries the risks of suboptimal efficiency and of unwanted mutations in the graft. Here, we present an approach for expanding gene-edited HSCs at clonal density, allowing for genetic profiling of individual clones before transplantation. We achieved this by developing a defined, polymer-based expansion system and identifying long-term expanding clones within the CD201+CD150+CD48-c-Kit+Sca-1+Lin- population of pre-cultured HSCs. Using the Prkdcscid immunodeficiency model, we demonstrate that we can expand and profile edited HSC clones to check for desired and unintended modifications. Transplantation of Prkdc-corrected HSCs rescued the immunodeficient phenotype. Our ex vivo-manipulation platform establishes a novel paradigm to control genetic heterogeneity in HSC gene editing and therapy.

Advanced breast cancer is frequently associated with skeletal metastases and accelerated bone loss. Recombinant parathyroid hormone [teriparatide, PTH(1-34)] is the first anabolic agent approved in the US for treatment of osteoporosis. While signaling through the PTH receptor in the osteoblast lineage regulates bone marrow hematopoietic niches, the effects of anabolic PTH on the skeletal metastatic niche are unknown. Here, we demonstrate, using orthotopic and intratibial models of 4T1 murine and MDA-MB-231 human breast cancer tumors, that anabolic PTH decreases both tumor engraftment and the incidence of spontaneous skeletal metastasis in mice. Microcomputed tomography and histomorphometric analyses revealed that PTH increases bone volume and reduces tumor engraftment and volume. Transwell migration assays with murine and human breast cancer cells revealed that PTH alters the gene expression profile of the metastatic niche, in particular VCAM-1, to inhibit recruitment of cancer cells. While PTH did not affect growth or migration of the primary tumor, it elicited several changes in the tumor gene expression profile resulting in a less metastatic phenotype. In conclusion, PTH treatment in mice alters the bone microenvironment, resulting in decreased cancer cell engraftment, reduced incidence of metastases, preservation of bone microarchitecture and prolonged survival.

Appropriate and abundant sources of bone-forming osteoblasts are essential for bone tissue engineering. Pluripotent stem cells can self-renew and thereby offer a potentially unlimited supply of osteoblasts, a significant advantage over other cell sources. We generated mouse embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) from transgenic mice expressing rat 2.3 kb type I collagen promoter-driven green fluorescent protein (Col2.3GFP), a reporter of the osteoblast lineage. We demonstrated that Col2.3GFP ESCs and iPSCs can be successfully differentiated to osteoblast lineage cells that express Col2.3GFP in vitro. We harvested GFP+ osteoblasts differentiated from ESCs. Genome wide gene expression profiles validated that ESC- and iPSC-derived osteoblasts resemble calvarial osteoblasts, and that Col2.3GFP expression serves as a marker for mature osteoblasts. Our results confirm the cell identity of ESC- and iPSC-derived osteoblasts and highlight the potential of pluripotent stem cells as a source of osteoblasts for regenerative medicine.

Foxp3+ regulatory T cells (Treg cells) modulate the immune system and maintain self-tolerance, but whether they affect haematopoiesis or haematopoietic stem cell (HSC)-mediated reconstitution after transplantation is unclear. Here we show that B-cell lymphopoiesis is impaired in Treg-depleted mice, yet this reduced B-cell lymphopoiesis is rescued by adoptive transfer of affected HSCs or bone marrow cells into Treg-competent recipients. B-cell reconstitution is abrogated in both syngeneic and allogeneic transplantation using Treg-depleted mice as recipients. Treg cells can control physiological IL-7 production that is indispensable for normal B-cell lymphopoiesis and is mainly sustained by a subpopulation of ICAM1+ perivascular stromal cells. Our study demonstrates that Treg cells are important for B-cell differentiation from HSCs by maintaining immunological homoeostasis in the bone marrow microenvironment, both in physiological conditions and after bone marrow transplantation.

Bone-forming osteoblasts play critical roles in supporting bone marrow hematopoiesis. Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs) and induced PSCs (iPSC), are capable of differentiating into osteoblasts. To determine the capacity of stem cells needed to rescue aberrant skeletal development and bone marrow hematopoiesis in vivo, we used a skeletal complementation model. Mice deficient in Runx2, a master transcription factor for osteoblastogenesis, fail to form a mineralized skeleton and bone marrow. Wild-type (WT) green fluorescent protein (GFP)+ ESCs and yellow fluorescent protein (YFP)+ iPSCs were introduced into Runx2-null blastocyst-stage embryos. We assessed GFP/YFP+ cell contribution by whole-mount fluorescence and histological analysis and found that the proportion of PSCs in the resulting chimeric embryos is directly correlated with the degree of mineralization in the skull. Moreover, PSC contribution to long bones successfully restored bone marrow hematopoiesis. We validated this finding in a separate model with diphtheria toxin A-mediated ablation of hypertrophic chondrocytes and osteoblasts. Remarkably, chimeric embryos harboring as little as 37.5% WT PSCs revealed grossly normal skeletal morphology, suggesting a near-complete rescue of skeletogenesis. In summary, we demonstrate that fractional contribution of PSCs in vivo is sufficient to complement and reconstitute an osteoblast-deficient skeleton and hematopoietic marrow. Further investigation using genetically modified PSCs with conditional loss of gene function in osteoblasts will enable us to address the specific roles of signaling mediators to regulate bone formation and hematopoietic niches in vivo.

Foxp3+ regulatory T cells (Treg cells) modulate the immune system and maintain self-tolerance, but whether they affect haematopoiesis or haematopoietic stem cell (HSC)-mediated reconstitution after transplantation is unclear. Here we show that B-cell lymphopoiesis is impaired in Treg-depleted mice, yet this reduced B-cell lymphopoiesis is rescued by adoptive transfer of affected HSCs or bone marrow cells into Treg-competent recipients. B-cell reconstitution is abrogated in both syngeneic and allogeneic transplantation using Treg-depleted mice as recipients. Treg cells can control physiological IL-7 production that is indispensable for normal B-cell lymphopoiesis and is mainly sustained by a subpopulation of ICAM1+ perivascular stromal cells. Our study demonstrates that Treg cells are important for B-cell differentiation from HSCs by maintaining immunological homoeostasis in the bone marrow microenvironment, both in physiological conditions and after bone marrow transplantation., Treg cells suppress peripheral immune responses, but their function in haematopoiesis is unclear. Here the authors show they modulate the bone marrow microenvironment to sustain haematopoietic stem cell-driven generation of mature B cells.

A 70-year-old male was admitted because of back pain due to peri-vertebral tumors. The histologic picture of a needle-biopsied tumor specimen showed pleomorphic large cell infiltration into the collagen fibers. On immunohistochemistry, these abnormal cells were positive for CD68, CD163 and lysozyme but negative for CD1a, 21, 30, and S100. Flow cytometric analysis also demonstrated that these cells were positive for CD13, 14, 38, 45, 56, and HLA-DR. A bone marrow aspirate showed the marked infiltration of abnormal large cells with the same surface antigens as described above. A diagnosis of HS was made. He showed monocytosis in the peripheral blood of more than 1.0 x 10(9)/L from presentation. The karyotype of bone marrow cells was 46,XY,+8. Fluorescent in situ hybridization (FISH) analysis with a probe for chromosome no. 8 showed that all these monocytes carried +8, indicating that he had another disorder of chronic myelomonocytic leukemia (CMML). FISH analysis with a probe for chromosome no. 12 demonstrated that the abnormal large cells in the bone marrow were all tetraploid, while analysis with the chromosome no. 8 probe showed more than 8 signals per cell, indicating that HS cells carried octasomy to decasomy of chromosome no. 8. These findings strongly suggest that HS in the present patient originated from underlying CMML.

A 32-year-old male with chronic hepatitis B was admitted to a hospital with cellulitis in the right leg in September 2006. Pancytopenia, hepatosplenomegaly, and systemic superficial lymph node swelling were noted, and he was referred to our hospital. He developed fever and liver dysfunction in June 2007 and underwent a splenectomy. His pancytopenia subsequently improved. A pathologic diagnosis of hepatosplenic alphabeta T cell lymphoma was made by examining spleen tissue and biopsy specimens of the liver and mesenteric lymph node. He had stage IVB disease because neoplastic T cells were noted in the bone marrow. The response of the lymphoma to conventional chemotherapy including the CHOP (cyclophosphamide, adriamycin, vincristine, prednisolone) and DeVIC (dexamethasone, etoposide, ifoshamide, carboplatin) regimens was poor and transient. A partial remission was obtained with an ESHAP (etoposide, cisplatin, cytarabine, methylprednisolone) regimen. Therefore, we planned a bone marrow transplantation (BMT) from an HLA-haploidentical sibling donor. He was moved to the Department of Hematology, Hyogo Medical College, to receive this BMT as part of a clinical trial. During the conditioning procedure for the transplantation, however, he died of septicemia. Since hepatosplenic alphabeta T cell lymphoma is very rare with only 23 reported cases to date, herein we report this case and discuss the therapeutic strategy.

A 55-year-old woman was diagnosed with POEMS syndrome; however, we could not perform high-dose chemotherapy with autologous peripheral blood stem cell transplantation (auto-PBSCT) because of rapidly progressive congestive heart failure. Thus, we treated the patient with thalidomide plus dexamethasone, which brought about a marked improvement of systolic dysfunction, POEMS syndrome-related symptoms and the serum concentrations of vascular endothelial growth factor. Subsequently, we safely performed high-dose chemotherapy with auto-PBCST. This report strongly suggests that thalidomide is effective for POEMS syndrome, even if complicated by congestive heart failure which is considered to be related to POEMS syndrome.

A 30-year-old woman developed severe liver dysfunction 1 year after bone marrow transplantation (BMT) from an HLA-identical sibling donor for B lymphoblastic leukemia (B-ALL) during the tapering of cyclosporin A. The histologic picture resembled autoimmune hepatitis (AIH), although neither autoantibody nor hypergammaglobulinemia was detected. She entered hepatic coma, and underwent living donor liver transplantation from the same donor on day 421 after BMT. She is well 18 months after the procedure, showing normal liver function and hematopoiesis. AIH-like hepatic graft-versus-host disease (GVHD) has not been documented. This patient is the second case of living donor liver transplantation for hepatic GVHD from the same donor.

Myeloid sarcoma (MS), which usually develops concurrently with acute myeloid leukemia (AML), is an extramedullary tumor that consists of immature myeloid cells. Clinically, the incidence of MS in AML is 3–5% [1, 2], and the association of MS is linked to a poor prognosis [3]. De novo MS is characterized by leukemic tumor formation without the involvement of bone marrow and peripheral blood. Patients receiving radiotherapy or incorrect chemotherapy develop AML at a median time of 7 and 12 months, respectively, and show an extremely poor prognosis after leukemic transformation [4]. Thus, systemic chemotherapy effective against AML, which lowers the rate of leukemic transformation from 71 to 41%, is essential for the treatment of de novo MS [5]. A 17-year-old male was referred to our hospital in April 2007, because of small tumors in the left neck and supraclavicular fossa. A CT scan showed several separated tumors in the neck and mediastinum, one being 4 9 2 cm in the superior mediastinum and the others around 1.5 cm. The histologic picture of a biopsied left supraclavicular lymph node demonstrated that the normal architecture had been destroyed and completely replaced by middle-sized immature myeloid cells (Fig. 1), which expressed T-cell markers including CD2 and CD7 in addition to CD13, CD33, CD38, CD43, cytoplasmic myeloperoxidase, and HLA-DR on flow cytometry. Chromosomal analysis of the specimen revealed an abnormal karyotype of 46,XY,i(17)(q10) in 5 of 7 dividing cells. Blood and marrow cells did not contain abnormal cells as evaluated by flow cytometry and G-banding. A diagnosis of de novo MS was made. After 2 courses of intensive chemotherapy effective against AML, a complete remission (CR) of MS was achieved as evaluated by CT scan. Two months after the initial therapy, however, we detected a small population of myeloblasts (0.05% of all nucleated cells), which aberrantly expressed CD2 and CD7 in the bone marrow on flow cytometry, regardless of the disappearance of MS tumors. Thus, we regarded CD2/CD13 myeloblasts as MRD in the bone marrow. Subsequently, 3 courses of consolidation therapy including high-dose cytarabine were performed; however, MRD in the bone marrow persisted (0.05– 0.20%). Although we planned allogeneic HSCT, overt AML rapidly developed during the recovery phase after the third consolidation chemotherapy. The leukemia was highly refractory to any treatment including the regimens for acute lymphoblastic leukemia after December 2007. Chromosomal analysis of the bone marrow cells showed an abnormal karyotype of 46,XY,t(1;11)(p10;q10),add(4) (q21),i(17)(q10) in 8 of 20 dividing cells in addition to that D. Inoue (&) Y. Nagai T. Kimura S. Shimoji M. Mori K. Togami S. Tabata M. Kurata A. Matsushita K. Nagai T. Takahashi Department of Hematology and Clinical Immunology, Kobe City Medical Center General Hospital, 4-6 Minatojima nakamachi, Chuo-ku, Kobe 650-0046, Japan e-mail: daichi@kcgh.gr.jp

Parathyroid hormone (PTH) is an important regulator of osteoblast function and is the only anabolic therapy currently approved for treatment of osteoporosis. The PTH receptor (PTH1R) is a G protein-coupled receptor that signals via multiple G proteins including Gsα. Mice expressing a constitutively active mutant PTH1R exhibited a dramatic increase in trabecular bone that was dependent upon expression of Gsα in the osteoblast lineage. Postnatal removal of Gsα in the osteoblast lineage (P-Gsα(OsxKO) mice) yielded markedly reduced trabecular and cortical bone mass. Treatment with anabolic PTH(1-34) (80 μg/kg/day) for 4 weeks failed to increase trabecular bone volume or cortical thickness in male and female P-Gsα(OsxKO) mice. Surprisingly, in both male and female mice, PTH administration significantly increased osteoblast numbers and bone formation rate in both control and P-Gsα(OsxKO) mice. In mice that express a mutated PTH1R that activates adenylyl cyclase and protein kinase A (PKA) via Gsα but not phospholipase C via Gq/11 (D/D mice), PTH significantly enhanced bone formation, indicating that phospholipase C activation is not required for increased bone turnover in response to PTH. Therefore, although the anabolic effect of intermittent PTH treatment on trabecular bone volume is blunted by deletion of Gsα in osteoblasts, PTH can stimulate osteoblast differentiation and bone formation. Together these findings suggest that alternative signaling pathways beyond Gsα and Gq/11 act downstream of PTH on osteoblast differentiation.

We demonstrated previously that membrane depolarization and excitatory receptor agonists such as noradrenaline induce Ca2+-dependent Rho activation in VSM (vascular smooth muscle), resulting in MP (myosin phosphatase) inhibition through the mechanisms involving Rho kinase-mediated phosphorylation of its regulatory subunit MYPT1. In the present study, we show in de-endothelialized VSM strips that the PI3K (phosphoinositide 3-kinase) inhibitors LY294002 and wortmannin inhibited KCl membrane depolarization- and noradrenaline-induced Rho activation and MYPT1 phosphorylation, with concomitant inhibition of MLC (20-kDa myosin light chain) phosphorylation and contraction. LY294002 also augmented de-phosphorylation of MLC and resultantly relaxation in KCl-contracted VSM, whereas LY294002 was much less effective or ineffective under the conditions in which MP was inhibited by either a phosphatase inhibitor or a phorbol ester in Rho-independent manners. VSM express at least four PI3K isoforms, including the class I enzymes p110alpha and p110beta and the class II enzymes PI3K-C2alpha and -C2beta. The dose-response relationships of PI3K-inhibitor-induced inhibition of Rho, MLC phosphorylation and contraction were similar to that of PI3K-C2alpha inhibition, but not to that of the class I PI3K inhibition. Moreover, KCl and noradrenaline induced stimulation of PI3K-C2alpha in a Ca2+-dependent manner, but not of p110alpha or p110beta. Down-regulation of PI3K-C2alpha expression by siRNA (small interfering RNA) inhibited contraction and phosphorylation of MYPT1 and MLC in VSM cells. Finally, intravenous wortmannin infusion induced sustained hypotension in rats, with inhibition of PI3K-C2alpha activity, GTP-loading of Rho and MYPT1 phosphorylation in the artery. These results indicate the novel role of PI3K-C2alpha in Ca2+-dependent Rho-mediated negative control of MP and thus VSM contraction.

The entire genome of a thermophilic unicellular cyanobacterium, Thermosynechococcus elongatus BP-1, was sequenced. The genome consisted of a circular chromosome 2,593,857 bp long, and no plasmid was detected. A total of 2475 potential protein-encoding genes, one set of rRNA genes, 42 tRNA genes representing 42 tRNA species and 4 genes for small structural RNAs were assigned to the chromosome by similarity search and computer prediction. The translated products of 56% of the potential protein-encoding genes showed sequence similarity to experimentally identified and predicted proteins of known function, and the products of 34% of these genes showed sequence similarity to the translated products of hypothetical genes. The remaining 10% lacked significant similarity to genes for predicted proteins in the public DNA databases. Sixty-three percent of the T. elongatus genes showed significant sequence similarity to those of both Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120, while 22% of the genes were unique to this species, indicating a high degree of divergence of the gene information among cyanobacterial strains. The lack of genes for typical fatty acid desaturases and the presence of more genes for heat-shock proteins in comparison with other mesophilic cyanobacteria may be genomic features of thermophilic strains. A remarkable feature of the genome is the presence of 28 copies of group II introns, 8 of which contained a presumptive gene for maturase/reverse transcriptase. A trace of genome rearrangement mediated by the group II introns was also observed.

The complete nucleotide sequence of the genome of a symbiotic bacterium Mesorhizobium loti strain MAFF303099 was determined. The genome of M. loti consisted of a single chromosome (7,036,071 bp) and two plasmids, designated as pMLa (351,911 bp) and pMLb (208, 315 bp). The chromosome comprises 6752 potential protein-coding genes, two sets of rRNA genes and 50 tRNA genes representing 47 tRNA species. Fifty-four percent of the potential protein genes showed sequence similarity to genes of known function, 21% to hypothetical genes, and the remaining 25% had no apparent similarity to reported genes. A 611-kb DNA segment, a highly probable candidate of a symbiotic island, was identified, and 30 genes for nitrogen fixation and 24 genes for nodulation were assigned in this region. Codon usage analysis suggested that the symbiotic island as well as the plasmids originated and were transmitted from other genetic systems. The genomes of two plasmids, pMLa and pMLb, contained 320 and 209 potential protein-coding genes, respectively, for a variety of biological functions. These include genes for the ABC-transporter system, phosphate assimilation, two-component system, DNA replication and conjugation, but only one gene for nodulation was identified.

The sequence determination of the entire genome of the Synechocystis sp. strain PCC6803 was completed. The total length of the genome finally confirmed was 3,573,470 bp, including the previously reported sequence of 1,003,450 bp from map position 64% to 92% of the genome. The entire sequence was assembled from the sequences of the physical map-based contigs of cosmid clones and of lambda clones and long PCR products which were used for gap-filling. The accuracy of the sequence was guaranteed by analysis of both strands of DNA through the entire genome. The authenticity of the assembled sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA using the assembled sequence data. To predict the potential protein-coding regions, analysis of open reading frames (ORFs), analysis by the GeneMark program and similarity search to databases were performed. As a result, a total of 3,168 potential protein genes were assigned on the genome, in which 145 (4.6%) were identical to reported genes and 1,257 (39.6%) and 340 (10.8%) showed similarity to reported and hypothetical genes, respectively. The remaining 1,426 (45.0%) had no apparent similarity to any genes in databases. Among the potential protein genes assigned, 128 were related to the genes participating in photosynthetic reactions. The sum of the sequences coding for potential protein genes occupies 87% of the genome length. By adding rRNA and tRNA genes, therefore, the genome has a very compact arrangement of protein- and RNA-coding regions. A notable feature on the gene organization of the genome was that 99 ORFs, which showed similarity to transposase genes and could be classified into 6 groups, were found spread all over the genome, and at least 26 of them appeared to remain intact. The result implies that rearrangement of the genome occurred frequently during and after establishment of this species.

Background: Foxp3+regulatory T cells (Treg) are a subpopulation of T cells, which regulate the immune system, maintain self-tolerance and enhance immune tolerance after transplantation. It was also reported that recipient derived Treg could provide immune privilege niche to allogeneic hematopoietic stem cells (HSC) after transplantation. However, the precise role of Treg in hematopoiesis has not been fully elucidated. Methods: We used Foxp3-DTR mice (B6, CD45.2) for in vivo depletion of Treg through diphtheria toxin (DT) injection and investigated whether Treg depletion would affect hematopoiesis derived from HSC. To investigate whether Treg depletion affects the function of the bone marrow microenvironment, we transplanted wild type bone marrow cells into lethally irradiated Foxp3-DTR mice after Treg depletion. Results: We found 1) a significant defect on B cell progenitors including mature B cells (IgM+B220+, P Conclusions: These data demonstrate that Treg play a key role in B cell differentiation from HSCs by maintaining the immunological homeostasis in the bone marrow microenvironment. These data provide new insights into Treg biology and function in normal and stress hematopoiesis. Disclosures Negrin: Stanford University: Patents & Royalties.

A 73-year-old woman with Sjögren's syndrome and autoimmune neutropenia (AIN) associated with large granular lymphocytosis of the polyclonal T cell type, demonstrated autoimmune thrombocytopenia (AIT) at diagnosis of sigmoid colon cancer. Ten months later, both AIN and AIT had exacerbated to agranulocytosis and severe thrombocytopenia below 10×10(9)/L, respectively. There were no dysplastic features of bone marrow hematopoietic cells. Furthermore, an in vitro assay of hematopoietic progenitors showed normal granuloid and erythroid colony formation. Although we serially treated her with prednisolone (oral), filgrastim, intravenous high-dose immunoglobulin infusion, cyclophosphamide (oral), danazol, cyclosporine A (oral), and rituximab, number of neutrophils and platelets elevated only temporarily. During the course of agranulocytosis and severe thrombocytopenia, the patient also developed autoimmune hemolytic anemia (AIHA). She died of pneumonia 5 months after the onset of agranulocytosis. This case is very unique and novel in terms of autoimmune phenomena simultaneously directed to granulocytes, platelets, and red blood cells under the background of Sjögren's syndrome.

A 19-year-old girl with T-lymphoblastic lymphoma (T-LBL) was referred to our hospital because of refractory disease. After complete remission was achieved by the JALSG ALL-97 protocol, she received a bone marrow transplantation (BMT) from an unrelated, HLA-matched donor with myeloablative conditioning. Four months after BMT, T-LBL relapsed and donor lymphocyte infusion was ineffective. After partial remission was achieved with l-asparaginase therapy, she received 2 antigen-mismatched cord blood transplantation with non-myeloablative conditioning; however, sustained engraftment of cord blood stem cells has failed. This was associated with the reappearance of the blood cells from the first donor and the disappearance of leukemic cells from both the peripheral blood and bone marrow. Computed tomography showed no enlarged lymph nodes. The patient and the cord blood donor shared two minor histocompatibility antigens (mHAgs), while these mHAgs were not detected in the blood cells of the first donor. TCR analysis disclosed expanded oligoclonal Vbeta2T cells in the peripheral blood at relapse, and these cells secreted IFN-gamma in response to stimulation by the patient's leukemic cells. Moreover, these cells exhibited cytotoxicity against both leukemic cells and cord blood mononuclear cells. These results strongly suggest that Vbeta2T cells, derived from the first donor, may have been cytotoxic lymphocytes against both leukemic cells and cord blood stem cells.

The prognosis of angioimmunoblastic T cell lymphoma (AITL) is poor because of chemotherapy-resistance and the short duration of remission. In recent years, cyclosporin A (CyA) has been employed as a alternative treatment for AITL in some patients with the rationale that CyA inhibits the activity and proliferation of neoplastic T cells. We herein report 4 chemotherapy-resistant AITL patients who were treated with oral CyA. The dosage of CyA was individually determined in each patient in order to achieve a blood CyA concentration of around 200 ng/ml at the trough level. A patient in whom AITL had relapsed 3 months after high dose chemotherapy with autologous hematopoietic stem cell transplantation (HSCT) achieved a sustained complete remission (CR) with CyA and underwent allogeneic HSCT. In 2 patients who had failed to respond to conventional chemotherapies, the circulating lymphoma cells rapidly disappeared after the initiation of CyA, and one of these patients demonstrated a durable CR. The other patient showed a good response to CyA, but the agent was discontinued because of infection. The remaining one patient with advanced AITL did not respond to CyA and died of disease progression. To our knowledge, the efficacy of CyA for chemotherapy-resistant AITL, even in a leukemic state, has not previously been reported.

Bacillus cereus is a growing concern as a cause of life-threatening infections in patients with hematologic malignancies. However, the risk factors for patients with unfavorable outcomes have not been fully elucidated. At our institution, we observed the growth of B. cereus in blood culture in 68 patients with (23) or without (45) hematologic malignancies treated from September 2002 to November 2009. We defined a case as having sepsis when more than two blood culture sets were positive for B. cereus or only a single set was positive in the absence of other microorganisms in patients who had definite infectious lesions. We determined 12 of 23 patients with hematologic malignancies as having sepsis, as well as 10 of 45 patients without hematologic malignancies (p = 0.012). Of the 12 patients with hematologic malignancies, four patients with acute leukemia died of B. cereus sepsis within a few days. In our cohort, risk factor analysis demonstrated that a neutrophil count of 0/mm(3), central venous (CV) catheter insertion, and the presence of central nervous system (CNS) symptoms were significantly associated with a fatal prognosis (p = 0.010, 0.010, and 0.010, respectively). Analysis of data from our cohort in conjunction with those from 46 previously reported patients with B. cereus sepsis identified similar risk factors, that is, acute leukemia, extremely low neutrophil count, and CNS symptoms (p = 0.044, 0.004, and 0.002, respectively). These results indicate that appropriate prophylaxis and early therapeutic intervention against possible B. cereus sepsis are crucially important in the treatment of hematologic malignancies.

A 21-year-old man who was diagnosed with Diamond-Blackfan anemia at 2 years of age came to our hospital with the hope of undergoing bone marrow transplantation (BMT). He had been red cell transfusion-dependent for about 8 years; at presentation he had transfusion-induced hemochromatosis, a subsequent low left ventricular ejection fraction (LVEF) of 43%, and diabetes mellitus requiring insulin therapy. He received unrelated BMT with reduced intensity conditioning and sufficient GVHD prophylaxis. Regardless of the cardiac dysfunction, he had an uneventful course during pre- and post-grafting periods, and is currently doing well with an improved LVEF (55%), although he is still insulin dependent.

A 50-year-old woman was emergently admitted because of rapidly progressive unconsciousness, renal failure, hepatic dysfunction, hemolytic anemia, thrombocytopenia, and high-grade fever in July, 2008. Based on clinical and laboratory findings, we made a tentative diagnosis of thrombotic thrombocytopenic purpura (TTP) and immediately initiated the plasma exchange (PE). Despite the PE, she developed panperitonitis due to multiple intestinal perforation and massive splenic infarction within a week after the admission. Thrombosis of arterioles at perforated portion in the resected small and large intestines was histologically confirmed. Therefore, we made a definite diagnosis of catastrophic antiphospholipid syndrome (CAPS) based on the presence of antiphosphatidylserine-prothrombin complex antibodies (aPS/PT) throughout the course and lupus anticoagulant that was revealed positive on one occasion, and multiple thrombotic lesions. The underlying disease of CAPS appeared to be lupus erythematosus because of her clinical history and laboratory findings such as persistent leukopenia. Although it has been reported that CAPS causes systemic thrombosis at microvessels mostly within a week from the onset and the mortality rate in this disorder is as high as 50%, we successfully treated her in combination with high-dose corticosteroid, anticoagulation, concentrated human IgG, surgical procedures, and hemodialysis in addition to PE. Early diagnosis of CAPS and immediate start of PE may have contributed to the successful treatment.

A 64-year-old woman suffering from progressive amyloid A (AA) amyloidosis of the gastrointestinal (GI) tract, associated with active rheumatoid arthritis, was transferred to our hospital due to hypovolemic shock. Although intensive care, including treatment with prednisolone and methotrexate, improved the hypovolemic shock, paralytic ileus became dominant instead of the marked diarrhea, suggesting the terminal stage of AA amyloidosis of the GI tract. Thus, we administered tocilizumab, a humanized anti-interleukin 6 receptor antibody (8 mg/kg, repeated every 4 weeks). Two weeks after the first injection of tocilizumab, serum AA rapidly returned to their normal ranges in accordance with the amelioration of paralytic ileus and systemic joint pain. Surprisingly, after three courses of tocilizumab treatment, colon biopsy revealed no amyloid deposition. Tocilizumab is a promising agent to treat secondary AA amyloidosis by strongly suppressing serum AA levels.

A 30-year-old woman developed severe liver dysfunction 1 year after bone marrow transplantation (BMT) from an HLA-identical sibling donor for B lymphoblastic leukemia (B-ALL) during the tapering of cyclosporin A. The histologic picture resembled autoimmune hepatitis (AIH), although neither autoantibody nor hypergammaglobulinemia was detected. She entered hepatic coma, and underwent living donor liver transplantation from the same donor on day 421 after BMT. She is well 18 months after the procedure, showing normal liver function and hematopoiesis. AIH-like hepatic graft-versus-host disease (GVHD) has not been documented. This patient is the second case of living donor liver transplantation for hepatic GVHD from the same donor.

A 62-year-old man was diagnosed with human immunodeficiency virus (HIV) infection while suffering from recurrent herpes zoster infection. Laboratory examination revealed CD4(+) lymphocyte count 16 cells/mul and HIV loading 150,000 copies/ml at presentation. In addition, he had multiple lymph node swelling. Histologic diagnosis of a biopsied lymph node was diffuse, large, B cell-type malignant lymphoma. The karyotype of the lymphoma cells was t(8;14)(q24;q32), which was confirmed by G-banding and fluorescent in situ hybridization. Positron emission tomography (PET)-combined CT scanning revealed systemic extranodal tumors involving the gastrointestinal tract, pancreas, and bone marrow. The clinical stage of the lymphoma was IVB and the international prognosis index was categorized as high. Complete remission (CR) of the lymphoma was obtained after 2 courses of CHOP (cyclophosphamide, adriamycin, vincristine, prednisolone) chemotherapy and 4 subsequent courses of rituximab-combined CHOP (R-CHOP). Highly active antiretroviral therapy (HAART) was started at the initiation of CHOP. Because of the poor prognosis of AIDS-related lymphoma, he received autologous peripheral blood stem cell transplantation with the MEAM protocol (ranimustine, etoposide, cytarabine, melphalan) as a conditioning procedure without a severe infectious episode. He remains in CR 24 months after the transplantation.

A 32-year-old male with chronic hepatitis B was admitted to a hospital with cellulitis in the right leg in September 2006. Pancytopenia, hepatosplenomegaly, and systemic superficial lymph node swelling were noted, and he was referred to our hospital. He developed fever and liver dysfunction in June 2007 and underwent a splenectomy. His pancytopenia subsequently improved. A pathologic diagnosis of hepatosplenic alphabeta T cell lymphoma was made by examining spleen tissue and biopsy specimens of the liver and mesenteric lymph node. He had stage IVB disease because neoplastic T cells were noted in the bone marrow. The response of the lymphoma to conventional chemotherapy including the CHOP (cyclophosphamide, adriamycin, vincristine, prednisolone) and DeVIC (dexamethasone, etoposide, ifoshamide, carboplatin) regimens was poor and transient. A partial remission was obtained with an ESHAP (etoposide, cisplatin, cytarabine, methylprednisolone) regimen. Therefore, we planned a bone marrow transplantation (BMT) from an HLA-haploidentical sibling donor. He was moved to the Department of Hematology, Hyogo Medical College, to receive this BMT as part of a clinical trial. During the conditioning procedure for the transplantation, however, he died of septicemia. Since hepatosplenic alphabeta T cell lymphoma is very rare with only 23 reported cases to date, herein we report this case and discuss the therapeutic strategy.

Pulmonary alveolar proteinosis (PAP) is a rare disorder characterized by the abnormal accumulation of alveolar surfactant protein in alveolar spaces. We report herein a rare case of myelodysplastic syndrome (MDS-RAEB) complicated by severe PAP, and successful allogeneic bone marrow transplantation (BMT) for both disorders. An unrelated BMT was planned for a 48-year-old male with advanced MDS-RAEB. Just before the initiation of the conditioning regimen for unrelated BMT in March 2007, he developed dyspnea. A diagnosis of PAP was made based on findings of chest X-ray, CT scanning, and the fluid obtained by bronchoalveolar lavage. To improve his dyspnea and improve BMT safety, whole lung lavage (WLL) was performed twice, with the partial improvement of PAP. Unrelated allogeneic BMT was performed in September 2007. We had to perform a third WLL because of the worsening of PAP on day 26 after BMT. Despite many infectious complications after BMT, GVHD was relatively mild. PAP had almost disappeared 6 months after BMT. He was well with favorable hematopoiesis 20 months after the BMT without any specific treatment. There has been no report of an MDS patient with PAP in whom 3 WLL procedures were performed before and after allogeneic BMT.

A 73-year-old man was hospitalized with fever, erythema, generalized superficial lymphadenopathy and marked neutropenia in July 2007. Hematologic examination demonstrated a white blood cell count of 1,400/microl with 0% neutrophils, and 18% abnormal lymphocytes. A bone marrow aspirate showed marked myeloid hypoplasia. A diagnosis of drug-induced agranulocytosis was made. Although neutrophil counts immediately returned to normal levels in response to filgrastim, fever, skin rash and systemic lymphadenopathy were all persistent. He also developed autoimmune hemolytic anemia and a second episode of agranulocytosis. The causative agent of the both episodes of agranulocytosis appeared to be acetaminophen. The histologic picture of a biopsied lymph node showed diffuse infiltration of polymorphous lymphoid cells with clear cytoplasm and proliferation of arborizing capillary vessels. Based on the histologic findings, PCR, and immunohistologic analyses, he was diagnosed with angioimmunoblastic T cell lymphoma (AILT) in leukemic state. The response of the lymphoma to conventional chemotherapy (CHOP and ESHAP) was poor. We next performed an immunomodulatory therapy using cyclosporine A to suppress cytokine production by neoplastic T cells. The treatment resulted in a partial remission of AILT including disappearance of circulating lymphoma cells. To our knowledge, this is the first published report of AILT complicated by drug-induced agranulocytosis.

Waardenburg syndrome type 2 (WS2) Is an autosomal dominant disorder characterized by a combination of pigmentary and auditory abnormalities. Approximately 20% of WS2 cases are associated with mutations In the gene encoding microphthalmia-associated transcription factor (MITF). MITF plays a critical role in the development of both neural-crest-derived melanocytes and optic cup-derived retinal pigmented epithelium (RPE); the loss of a functional Mitf in mice results in complete absence of all pigment cells, which in turn induces microphthalmia and inner ear deafness. The black-eyed white Mitf mi-bw homozygous mouse normally has a pigmented RPE but lacks melanocytes essential for the pigmentation of the body and hearing. We show here that Mitf mi-bw is caused by an insertion into intron 3 of a 7.2 kb novel L1 element, L1 bw , which belongs to an actively retrotransposing T F subfamily. The L1 bw insertion reduces the amount of mRNAs for two Mitf isoforms, Mitf-A and Mitf-H, by affecting their overall expression levels and pre-mRNA splicing patterns, while it abolishes mRNA expression of another isoform, Mitf-M, which is specifically expressed in neural-crest-derived melanocytes. The consequence of the L1 insertion in the black-eyed white Mitf mi-bw mouse is that the developmental programme for RPE cells proceeds normally, most likely because of the presence of residual, full-length Mitf-A and Mitf-H proteins, whereas the lack of Mitf-M results in loss of the melanocyte population. The results suggest that melanocyte development depends critically on a single Mitf isoform, Mitf-M, and raise the possibility that specific mutations affecting MITF-M, the human equivalent of Mitf-M, may be responsible for a subset of WS2 conditions.

Fas is a cell-surface receptor molecule that relays apoptotic (cell death) signals into cells. When Fas is activated by binding of its ligand, the proteolytic protein caspase-8 is recruited to a signalling complex known as DISC by binding to a Fas-associated adapter protein. A large new protein, FLASH, has now been identified by cloning of its complementary DNA. This protein contains a motif with oligomerizing activity whose sequence is similar to that of the Caenorhabditis elegans protein CED-4, and another domain (DRD domain) that interacts with a death-effector domain in caspase-8 or in the adapter protein. Stimulated Fas binds FLASH, so FLASH is probably a component of the DISC signalling complex. Transient expression of FLASH activates caspase-8, whereas overexpression of a truncated form of FLASH containing only one of its DRD or CED-4-like domains does not allow activation of caspase-8 and Fas-mediated apoptosis to occur. Overexpression of full-length FLASH blocks the anti-apoptotic effect of the adenovirus protein E1B19K. FLASH is therefore necessary for the activation of caspase-8 in Fas-mediated apoptosis.

We do not consider that our inferences about FLASH function are misleading because they were deduced from functional analyses1. We originally identified the death-effector domain (DED)-binding activity of the DED-recruiting domain (DRD) of FLASH before analysing the structural homology between the DED and DRD domains. Moreover, we deduced the self-association activity of FLASH through its central region from functional analysis of several deletion mutants of mouse FLASH. We note that self-association activity of CED-4-homologous proteins is required for the activation of caspases2.

The nucleotide sequence of the entire genome of a filamentous cyanobacterium, Anabaena sp. strain PCC 7120, was determined. The genome of Anabaena consisted of a single chromosome (6,413,771 bp) and six plasmids, designated pCC7120alpha (408,101 bp), pCC7120beta (186,614 bp), pCC7120gamma (101,965 bp), pCC7120delta (55,414 bp), pCC7120epsilon (40,340 bp), and pCC7120zeta (5,584 bp). The chromosome bears 5368 potential protein-encoding genes, four sets of rRNA genes, 48 tRNA genes representing 42 tRNA species, and 4 genes for small structural RNAs. The predicted products of 45% of the potential protein-encoding genes showed sequence similarity to known and predicted proteins of known function, and 27% to translated products of hypothetical genes. The remaining 28% lacked significant similarity to genes for known and predicted proteins in the public DNA databases. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome based on their similarity to the reported genes. One hundred and ninety-five genes coding for components of two-component signal transduction systems, nearly 2.5 times as many as those in Synechocystis sp. PCC 6803, were identified on the chromosome. Only 37% of the Anabaena genes showed significant sequence similarity to those of Synechocystis, indicating a high degree of divergence of the gene information between the two cyanobacterial strains.