研究活動情報

• Alteration of long and short-term hematopoietic stem cell ratio causes myeloid-biased hematopoiesis

  Katsuyuki Nishi, Taro Sakamaki, Akiomi Nagasaka, Kevin S Kao, Kay Sadaoka, Masahide Asano, Nobuyuki Yamamoto, Akifumi Takaori-Kondo, Masanori Miyanishi

  Abstract Myeloid-biased hematopoiesis is a well-known age-related alteration. Several possibilities, including myeloid-biased hematopoietic stem cell (HSC) clones, may explain this. However, the precise mechanisms remain controversial. Utilizing the Hoxb5 reporter system to prospectively isolate long-term HSCs (LT-HSCs) and short-term HSCs (ST-HSCs), we found that young and aged LT-HSCs co-transplanted into the same recipients demonstrated nearly equivalent myeloid lineage output, contrary to the theory of myeloid-biased HSC clones. Transcriptomics indicated no significant myeloid gene enrichment in aged LT-HSCs compared to their young counterparts. Instead, transplanting reconstituted young HSCs with the ratio of LT/ST-HSCs seen in aged mice can significantly skew the lineage output to myeloid cells. In addition, while the niche environment in the bone marrow minimally affects myeloid-biased hematopoiesis, aged thymi and spleens substantially hinder lymphoid hematopoiesis, resulting in further myeloid-domination. Thus, we demonstrate that myeloid-biased hematopoiesis in aged organisms originates due to alteration of the ratio between LT-HSCs and ST-HSCs rather than in heterogeneous HSC clones with various cell fates.

  eLife Sciences Publications, Ltd, 2025年06月


• Isolation Method for Long-Term and Short-Term Hematopoietic Stem Cells.

  Katsuyuki Nishi, Akiomi Nagasaka, Taro Sakamaki, Kay Sadaoka, Masanori Miyanishi

  Self-renewal capacity and multi-lineage differentiation potential are generally regarded as the defining characteristics of hematopoietic stem cells (HSCs). However, numerous studies have suggested that functional heterogeneity exists in the HSC compartment. Recent single-cell analyses have reported HSC clones with different cell fates within the HSC compartment, which are referred to as biased HSC clones. The mechanisms underlying heterogeneous or poorly reproducible results are little understood, especially regarding the length of self-renewal when purified HSC fractions are transplanted by conventional immunostaining. Therefore, establishing a reproducible isolation method for long-term HSCs (LT-HSCs) and short-term HSCs (ST-HSCs), defined by the length of their self-renewal, is crucial for overcoming this issue. Using unbiased multi-step screening, we identified a transcription factor, Hoxb5, which may be an exclusive marker of LT-HSCs in the mouse hematopoietic system. Based on this finding, we established a Hoxb5 reporter mouse line and successfully isolated LT-HSCs and ST-HSCs. Here we describe a detailed protocol for the isolation of LT-HSCs and ST-HSCs using the Hoxb5 reporter system. This isolation method will help researchers better understand the mechanisms of self-renewal and the biological basis for such heterogeneity in the HSC compartment.

  2023年05月, Journal of visualized experiments : JoVE, (195) (195), 英語, 国際誌

  研究論文（学術雑誌）


• Identification of the minimum requirements for successful haematopoietic stem cell transplantation.

  Katsuyuki Nishi, Taro Sakamaki, Kay Sadaoka, Momo Fujii, Akifumi Takaori-Kondo, James Y Chen, Masanori Miyanishi

  Historically, defining haematopoietic subsets, including self-renewal, differentiation and lineage restriction, has been elucidated by transplanting a small number of candidate cells with many supporting bone marrow (BM) cells. While this approach has been invaluable in characterising numerous distinct subsets in haematopoiesis, this approach is arguably flawed. The haematopoietic stem cell (HSC) has been proposed as the critical haematopoietic subset necessary for transplantation. However, due to the presence of supporting cells, the HSC has never demonstrated sufficiency. Utilising the homeobox B5 (Hoxb5)-reporter system, we found that neither long-term (LT) HSCs nor short-term (ST) HSCs alone were sufficient for long-term haematopoietic reconstitution. Critically, reconstitution can be rescued by transplanting combined LT- and ST-HSCs, without supporting cells; a fraction we term the 'Minimum Subset for Transplantation' (MST). The MST accounts for only 0·005% of nucleated cells within mouse BM, and this MST can be cultured, expanded and genetically modified while preserving its rapid haematopoietic engraftment potential. These results support the consideration of an MST approach for clinical translation, especially for gene therapy approaches that require HSC compartment modification.

  2022年02月, British journal of haematology, 196(3) (3), 711 - 723, 英語, 国際誌

  研究論文（学術雑誌）


• Hoxb5 defines the heterogeneity of self-renewal capacity in the hematopoietic stem cell compartment.

  Taro Sakamaki, Kevin S Kao, Katsuyuki Nishi, James Y Chen, Kay Sadaoka, Momo Fujii, Akifumi Takaori-Kondo, Irving L Weissman, Masanori Miyanishi

  Self-renewal and multipotency are essential functions of hematopoietic stem cells (HSCs). To maintain homeostatic hematopoiesis, functionally uniform HSCs have been thought to be an ideal cell-of-origin. Recent technological advances in the field have allowed us to analyze HSCs with single cell resolution and implicate that functional heterogeneity may exist even within the highly purified HSC compartment. However, due in part to the technical limitations of analyzing extremely rare populations and our incomplete understanding of HSC biology, neither the biological meaning of why heterogeneity exists nor the precise mechanism of how heterogeneity is determined within the HSC compartment is entirely known. Here we show the first evidence that self-renewal capacity varies with the degree of replication stress dose and results in heterogeneity within the HSC compartment. Using the Hoxb5-reporter mouse line which enables us to distinguish between long-term (LT)-HSCs and short-term (ST)-HSCs, we have found that ST-HSCs quickly lose self-renewal capacity under high stress environments but can maintain self-renewal under low stress environments for long periods of time. Critically, exogeneous Hoxb5 expression confers protection against loss of self-renewal to Hoxb5-negative HSCs and can partially alter the cell fate of ST-HSCs to that of LT-HSCs. Our results demonstrate that Hoxb5 imparts functional heterogeneity in the HSC compartment by regulating self-renewal capacity. Additionally, Hoxb5-positive HSCs may exist as fail-safe system to protect from the exhaustion of HSCs throughout an organism's lifespan.

  2021年02月, Biochemical and biophysical research communications, 539, 34 - 41, 英語, 国際誌

  研究論文（学術雑誌）


• [Significance and purification of long-term hematopoietic stem cells in the hematopoietic system].

  Taro Sakamaki, Masanori Miyanishi

  The hematopoietic stem cells, defined as blood stem cells with self-replication ability and multipotency, are key to successful hematopoietic stem cell transplantation. With the history of transplantation in the past 60 years and advances in stem cell technologies, our understanding of the hematopoietic system has deepened. However, the molecular mechanisms of self-renewal and pluripotency, which are the essence of the hematopoietic stem cells, remain poorly understood. One reason is that the identification/purification methods of the hematopoietic stem cells, particularly the long-term hematopoietic stem cells capable of lifelong self-renewal, is technically difficult owing to their scarcity in the bone marrow and has not been established to this date. Considering that a long-lasting blood production after hematopoietic stem cell transplantation is crucial, it is essential to understand the biology of the long-term hematopoietic stem cells not only scientifically but also clinically. This review describes the scientific and clinical significance of the long-term hematopoietic stem cells by showing the results of the latest researches in the introduction of hematopoietic stem cell identification/purification history.

  2019年, [Rinsho ketsueki] The Japanese journal of clinical hematology, 60(9) (9), 1056 - 1062, 日本語, 国内誌

  研究論文（学術雑誌）


• Successful Treatment of TAFRO Syndrome, a Variant of Multicentric Castleman's Disease, with Cyclosporine A: Possible Pathogenetic Contribution of Interleukin-2.

  Yoshinobu Konishi, Satoshi Takahashi, Katsuyuki Nishi, Taro Sakamaki, Sachiko Mitani, Hitomi Kaneko, Chisato Mizutani, Naoya Ukyo, Hirokazu Hirata, Mitsuru Tsudo

  Multicentric Castleman's disease is a systemic inflammatory disorder characterized by lymphadenopathy and excessive interleukin-6 production. A unique clinicopathologic variant of multicentric Castleman's disease, TAFRO (i.e., thrombocytopenia, anasarca, fever, renal failure or reticulin fibrosis, and organomegaly) syndrome, was recently proposed in Japan. Despite the successful use of anti-interleukin-6 therapy in some patients with TAFRO syndrome, not all patients achieve remission. The pathophysiological etiology of and suitable therapeutic strategies for this variant have not been established. Here, we present our experience of a unique case of TAFRO syndrome in a 78-year-old woman whose symptoms responded differently to several therapies. Tocilizumab, an anti-interleukin-6 receptor antibody, successfully induced remission of fever and lymphadenopathy. However, severe thrombocytopenia persisted and she developed anasarca, ascites, and pleural effusion shortly thereafter. Rituximab, an anti-CD20 antibody, and glucocorticoid therapy provided no symptom relief. In contrast, cyclosporine A, an immunosuppressive agent that blocks T cell function by inhibiting interleukin-2, yielded immediate improvements in systemic fluid retention and a gradual increase in platelet count, with complete resolution of disease symptoms. Excessive serum interleukin-2, when used as an anti-cancer agent, has been reported to cause side effects such as fluid retention, thrombocytopenia, and renal failure. Our case was unique because the anti-interleukin-2 therapy successfully improved symptoms that were not relieved with anti-interleukin-6 therapy. The present report therefore provides insight into the possible role of interleukin-2, in addition to interleukin-6, in TAFRO syndrome. This report will certainly help to clarify the pathogenesis of and optimal treatment strategies for TAFRO syndrome.

  2015年08月, The Tohoku journal of experimental medicine, 236(4) (4), 289 - 95, 英語, 国内誌

  研究論文（学術雑誌）

• 免疫不全マウスモデルにおけるLineage特異的なin vivo細胞分化法に関する基礎的検討

  長坂明臣, 酒巻太郎, 宮西正憲

  2025年, 日本再生医療学会総会(Web), 24th


• 10色超マルチカラーフローサイトメトリー法を用いたヒト骨髄由来間葉系幹細胞分画の不均一性の可視化

  田中秀弥, 宮西正憲, 西克幸, 酒巻太郎, 長坂昭臣, 美舩泰, 林申也, 松本知之, 黒田良祐

  2024年, 日本整形外科学会雑誌(CD-ROM), 98(8) (8)


• 多層性解析によるヒト造血幹細胞単離法の最適化

  宮西正憲, 宮西正憲, 長坂明臣, 酒巻太郎, 西克幸, 塚本成幸, 定岡恵, 山本暢之, 井上翔太郎, MY An Le

  2024年, 日本再生医療学会総会(Web), 23rd


• HSCの細胞運命は造血ストレスにより柔軟に制御される

  酒巻太郎, 西克幸, 西克幸, 定岡恵, 藤井桃, 宮西正憲

  2021年, 日本血液学会学術集会抄録(Web), 83rd


• 短期/長期造血幹細胞比の変化は系統バイアス造血を引き起こす

  西克幸, 西克幸, 酒巻太郎, 酒巻太郎, KAO Kevin, 定岡恵, 藤井桃, 高折晃史, 宮西正憲

  2021年, 日本血液学会学術集会抄録(Web), 83rd

• 自己複製能制御遺伝子を用いた造血幹細胞の新規体外培養法確立

  酒巻 太郎

  日本学術振興会, 科学研究費助成事業, 若手研究, 神戸大学, 2024年04月01日 - 2026年03月31日


• 高精度造血幹細胞分離技術に基づくストレス造血制御機構の解明

  酒巻 太郎

  日本学術振興会, 科学研究費助成事業, 若手研究, 国立研究開発法人理化学研究所, 2022年04月01日 - 2024年03月31日


• 高純度長期造血幹細胞単離技術を用いた自己複製能制御遺伝子の同定

  酒巻 太郎

  日本学術振興会, 科学研究費助成事業, 研究活動スタート支援, 国立研究開発法人理化学研究所, 2021年08月30日 - 2023年03月31日

  造血幹細胞は、造血系階層の頂点に位置する細胞で、自己複製能と多分化能を有し、血液細胞を供給し続ける。しかし、造血幹細胞がどのようにその機構を維持しているかは、ほとんど明らかとなっていない。その理由として、実験に供する造血幹細胞分画には、技術的限界のため生涯に渡り自己複製能を有する長期造血幹細胞と一過性にしか有さない短期造血幹細胞が混在しており、正確な解析が困難であったことが考えられる。私達の研究グループは、これまで長期造血幹細胞特異的に発現する遺伝子Hoxb5を初めて同定した。さらに、Hoxb5発現を識別可能なレポーターマウスを作製することで、長期造血幹細胞と短期造血幹細胞を高純度に分離することに成功している。 長期・短期造血幹細胞に関しては、自己複製能以外の細胞機能は同じであることから、両造血幹細胞を単離し比較することで自己複製能に強く関与する細胞情報を抽出できる可能性が高い。また、Hoxb5以外のホメオボックス遺伝子の中には、造血に関与するものが複数報告されているが、長期造血幹細胞における機能は、あまり検証されていない。 そこで、本研究では、長期造血幹細胞で特異的に発現している遺伝子群やホメオボックス遺伝子群を対象として造血幹細胞における機能解析を行うことで、自己複製能を制御する遺伝子を同定することを目標としている。本年度は、マイクロアレイやRNAシークエンス法によるオミクス解析の結果から、短期造血幹細胞に比し長期造血幹細胞で高く発現している遺伝子群を抽出してきた。さらに、令和４年度に骨髄移植実験を行い造血幹細胞における候補遺伝子の機能を確認するため、前段階スクリーニングとしてin vitroで候補遺伝子の機能を解析してきた。その結果、自己複製能に関与する可能性の高い候補遺伝子を複数同定してきた。