Yumiko Ishii

The University of Tokyo, Edo, Tōkyō, Japan

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Publications (8)24.5 Total impact

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    ABSTRACT: While the role of p75(NTR) signaling in the regulation of nerve-related cell growth and survival has been well documented, its actions in osteoblasts are poorly understood. In this study, we examined the effects of p75(NTR) on osteoblast proliferation and differentiation using the MC3T3-E1 pre-osteoblast cell line. Proliferation and osteogenic differentiation were significantly enhanced in p75(NTR)-overexpressing MC3T3-E1 cells (p75GFP-E1). In addition, expression of osteoblast-specific osteocalcin (OCN), bone sialoprotein (BSP), and osterix mRNA, ALP activity, and mineralization capacity were dramatically enhanced in p75GFP-E1 cells, compared to wild MC3T3-E1 cells (GFP-E1). To determine the binding partner of p75(NTR) in p75GFP-E1 cells during osteogenic differentiation, we examined the expression of trkA, trkB, and trkC that are known binding partners of p75(NTR), as well as NgR. Pharmacological inhibition of trk tyrosine kinase with the K252a inhibitor resulted in marked reduction in the level of ALPase under osteogenic conditions. The deletion of the GDI binding domain in the p75(NTR)-GFP construct had no effect on mineralization. Taken together, our studies demonstrated that p75(NTR) signaling through the trk tyrosine kinase pathway affects osteoblast functions by targeting osteoblast proliferation and differentiation.
    Differentiation 08/2012; · 2.86 Impact Factor
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    ABSTRACT: We describe a novel role for CD271 in the differentiation of mesenchymal stem cells (MSCs), including deciduous dental pulp stem cells (DDPSCs) and murine multipotent MSCs (C3H10T1/2 cells). The CD271(+) subpopulation of deciduous dental pulp cells (CD271(+)/DDPSCs) and the forced expression of CD271 in C3H10T1/2 (10T271) were analyzed by fluorescence-activated cell sorting. CD271 expression was detected in DDPSCs that expressed both CD44 and CD90, simultaneously, and the clonogenic capacity of the CD271(+)/DDPSCs was higher than that of the CD271(-)/DDPSCs that expressed both CD44 and CD90. Further, the differentiation of CD271(+)/DDPSCs into osteoblasts and adipocytes was inhibited although CD271(-)/DDPSCs were capable of differentiating into osteoblasts and adipocytes. CD271 was overexpressed in C3H10T1/2 cells, which have the potential to differentiate into osteoblasts, adipocytes, chondrocytes, and myocytes. CD271 inhibited the differentiation of C3H10T1/2 cells into any of these lineages. These results indicate a role for CD271 in inhibiting the differentiation of MSCs.
    Stem cells and development 01/2011; 20(5):901-13. · 4.15 Impact Factor
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    ABSTRACT: Recent studies have demonstrated that human dental pulp contains adult stem cells. A pulse of the thymidine analog BrdU given to young animals at the optimal time could clarify where slow-cycling long-term label-retaining cells (LRCs), putative adult stem cells, reside in the pulp tissue. This study focuses on the mapping of LRCs in growing teeth and their regenerative capacity after tooth injuries. Two to seven peritoneal injections of BrdU into pregnant Wistar rats revealed slow-cycling long-term dense LRCs in the mature tissues of born animals. Numerous dense LRCs were postnatally decreased in number and reached a plateau at 4 weeks after birth when they mainly resided in the center of the dental pulp, associating with blood vessels. Mature dental pulp cells were stained with Hoechst 33342 and sorted into (<0.76%) side population cells using FACS, which included dense LRCs. Some dense LRCs co-expressed mesenchymal stem cell markers such as STRO-1 or CD146. Tooth injuries caused degeneration of the odontoblast layer, and newly differentiated odontoblast-like cells contained LRCs. Thus, dense LRCs in mature pulp tissues were supposed to be dental pulp stem cells possessing regenerative capacity for forming newly differentiated odontoblast-like cells. The present study proposes the new hypothesis that both granular and dense LRCs are equipped in the dental pulp and that the dense LRCs with proliferative capacity play crucial roles in the pulpal healing process following exogenous stimuli in cooperation with the granular LRCs.
    Histochemie 09/2010; 134(3):227-41. · 2.61 Impact Factor
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    ABSTRACT: Although there are numerous reports describing the in vivo bone forming capability of recombinant human bone morphogenetic proteins-2 (rhBMP-2), studies have reported limited effects on human mesenchymal stem cells (hMSCs). However, the reasons for these discrepancies are not well understood. The aim of this study was to investigate the responsiveness of hMSCs to osteoinductive signals, focusing on rhBMP-2 and the effect of serum on that responsiveness. Human MSCs from six donors were analysed. When those cells were treated with osteoinduction medium including dexamethasone (Dex), alkaline phosphatase (ALP) activities increased in all cell lines. On the other hand, rhBMP-2-containing medium failed to increase ALP activity. When five different sera were used for cultivation and induction with rhBMP-2, ALP activities increased in two of them, but not in the others. The expression of BMP-2 antagonist noggin was induced in almost all combinations regardless of the responsiveness to rhBMP-2. On the other hand, the expression of follistatin showed significant variations depending on the serum and cell line. However, the expression did not correlate with the responsiveness to rhBMP-2. The results from this study showed limited but heterogeneous osteogenic response of hMSCs to rhBMP-2 and that the results are affected by the choice of serum. This fact should be concerned for the successful and effective clinical application of rhBMP-2.
    Growth factors (Chur, Switzerland) 10/2009; 28(1):34-43. · 2.47 Impact Factor
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    ABSTRACT: Although human bone marrow stromal cells (BMSCs) have the ability to form bone when transplanted, the responsible factors for in vivo osteogenic abilities are poorly understood. Here we report conditions that are required for human BMSCs to demonstrate their in vivo osteogenic abilities. BMSCs were obtained from healthy donors and their in vivo osteogenic abilities were analyzed. Transplantation analyses revealed that the passage number and length of osteogenic induction significantly affected ectopic bone formation. Although 2-week induction increased the percentage of success in bone formation compared with the 1-week induction, BMSCs completely lost their in vivo osteogenic ability after passage 4 regardless of the length of osteogenic induction. Despite their in vivo osteogenic ability, no significant difference was observed in alkaline phosphatase activity or gene expression of osteogenic markers between BMSCs at passages 1 and 3. Differences were only observed in in vitro mineralizing abilities. Application of basic fibroblast growth factor helped to maintain the BMSCs in vivo osteogenic ability; basic fibroblast growth factor altered cell growth and expression of HLA-DR. The results strongly suggest that there are several required conditions for human BMSCs to demonstrate their bone-forming capabilities, which should be further investigated and considered when designing a protocol for clinical bone tissue engineering.
    Tissue Engineering Part A 09/2009; 16(2):663-73. · 4.64 Impact Factor
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    ABSTRACT: Current standard techniques for bone tissue engineering utilize ex vivo expanded osteogenic cells. However, ex vivo expansion requires serum, which may hinder clinical applications. Here, we report the feasibility and efficacy of bone tissue engineering with human bone marrow stromal cells (BMSCs) expanded in serum-free conditions. Bone marrow was aspirated from 4 healthy donors and adherent cells were cultured in either serum-free medium (STEMPRO((R)) MSC SFM) or conventional serum-containing medium (alpha-MEM supplemented with 10% serum). Efficacy of expansion was greater in serum-free medium. Phenotypically, serum-free expanded BMSCs were smaller in cell-size and showed expression of CD105(++) and CD146(dim). After osteogenic induction, serum-free expanded BMSCs showed lower alkaline phosphatase activity. However, they showed higher responsiveness to induction. In vivo bone-forming ability was also confirmed. In conclusion, bone tissue engineering with serum-free expanded BMSCs is feasible and as efficient as that obtained with BMSCs expanded in conventional serum-containing medium.
    Biochemical and Biophysical Research Communications 06/2009; 382(2):353-8. · 2.28 Impact Factor
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    ABSTRACT: That generation of allele-specific anti-human leukocyte antigen (HLA) monoclonal antibodies (ASHmAb) is very difficult is well known. This is thought to be due to the unique epitope structure, an assemblage of amino acid residues that lie separately in the amino acid sequence of human HLA, and to its low antigenicity compared with that of common epitopes recognized as xenogeneic determinants by mice. Here we report a rapid and efficient strategy to generate ASHmAb. Different from usual immunization methods is that we suppressed the production of non-allele-specific anti-HLA antibodies against xenogeneic determinants of HLA molecules by immunizing human HLA-B51 transgenic mice against non-HLA-B51 HLA tetramers. In addition, HLA-coated beads enabled rapid and efficient screening for ASHmAb. ASHmAb generated by this strategy will be useful for HLA typing and for clinical diagnosis, such as flow cytometry-based chimerism analysis for early detection of graft failure and relapse of leukemia after HLA-mismatched hematopoietic stem cell transplantation.
    Journal of immunological methods 02/2009; 343(1):56-60. · 2.35 Impact Factor
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    ABSTRACT: Although umbilical cord blood has been increasingly used as an alternative donor source to treat hematologic malignancies, cord blood transplantation (CBT) is frequently complicated by graft failure and relapse of primary diseases. Because persistence or increase of recipient-derived hematopoietic or malignant cells has pathogenic import under these conditions, analysis of recipient-derived cells should be useful to understand the pathogenesis of graft failure and relapse of primary disease. Because most CBT involves human leukocyte antigen (HLA)-mismatched transplantation, we developed a 9-color fluorescence activated cell sorter (FACS)-based method of mixed chimerism (MC) analysis using anti-HLA antibodies to detect mismatched antigens (HLA-Flow method). Among CD4(+) T cells, CD8(+) T cells, B cells, NK cells, monocytes, and granulocytes, donor- and recipient-derived cells alike could be individually analyzed simultaneously in a rapid, quantitative and highly sensitive manner, making the HLA-Flow method very valuable in monitoring the engraftment process. In addition, this method was also useful in monitoring recipient-derived cells with leukemia-specific phenotypes, both as minimal residual disease (MRD) and as early harbingers of relapse. Leukemia relapse can be definitively diagnosed by cytogenetic or PCR studies using recipient-derived cells sorted for leukemia markers. Multicolor HLA-fFlow analysis and cell sorting in early diagnosis of graft failure and relapse was confirmed as valuable in 14 patients who had received HLA-mismatched CBT.
    Biology of blood and marrow transplantation: journal of the American Society for Blood and Marrow Transplantation 07/2008; 14(6):693-701. · 3.15 Impact Factor