同種骨髄移植後の新規免疫モニタリングシステムと免疫寛容メカニズムの解明

科学研究費助成事業 研究成果報告書：基盤研究(C)2015-2017課題番号 : 15K0949

Metalloproteinase regulation improves in vitro generation of efficacious platelets from mouse embryonic stem cells

Embryonic stem cells (ESCs) could potentially compensate for the lack of blood platelets available for use in transfusions. Here, we describe a new method for generating mouse ESC-derived platelets (ESPs) that can contribute to hemostasis in vivo. Flow cytometric sorting of cells from embryoid bodies on day 6 demonstrated that c-Kit+ integrin αIIb (αIIb)+ cells, but not CD31+ cells or vascular endothelial cadherin+ cells, are capable of megakaryopoiesis and the release of platelet-like structures by day 12. αIIbβ3-expressing ESPs exhibited ectodomain shedding of glycoprotein (GP)Ibα, GPV, and GPVI, but not αIIbβ3 or GPIbβ. ESPs showed impaired αIIbβ3 activation and integrin-mediated actin reorganization, critical events for normal platelet function. However, the administration of metalloproteinase inhibitors GM6001 or TAPI-1 during differentiation increased the expression of GPIbα, improving both thrombogenesis in vitro and posttransfusion recovery in vivo. Thus, the regulation of metalloproteinases in culture could be useful for obtaining high-quality, efficacious ESPs as an alternative platelet source for transfusions

SINC-seq: correlation of transient gene expressions between nucleus and cytoplasm reflects single-cell physiology

We report a microfluidic system that physically separates nuclear RNA (nucRNA) and cytoplasmic RNA (cytRNA) from a single cell and enables single-cell integrated nucRNA and cytRNA-sequencing (SINC-seq). SINC-seq constructs two individual RNA-seq libraries, nucRNA and cytRNA, per cell, quantifies gene expression in the subcellular compartments, and combines them to create novel single-cell RNA-seq data. Leveraging SINC-seq, we discover distinct natures of correlation among cytRNA and nucRNA that reflect the transient physiological state of single cells. These data provide unique insights into the regulatory network of messenger RNA from the nucleus toward the cytoplasm at the single-cell level

The Road Map for Megakaryopoietic Lineage from Hematopoietic Stem/Progenitor Cells

Megakaryocytes (Mgks) are terminally differentiated blood cells specified to produce platelets, whereas hematopoietic stem cells (HSCs) are the most undifferentiated blood cells that retain multipotency to produce all kinds of blood cells. As such, these two cell types reside at the bottom and the top of the hematopoietic hierarchy, respectively. In spite of this distance, they share several important cell surface molecules as well as transcription factors.In the conventional step-wise differentiation model, HSCs gradually lose their self-renewal capacity and differentiate into multipotent progenitors (MPPs), which is the first branch point of myeloid and lymphoid lineage. In this model, common myeloid progenitors can differentiate into bipotent Mgk/erythroid progenitors (MEPs), and MEPs eventually differentiate into unipotent mature Mgks. However, it has been recently reported that a subpopulation within the HSC and MPP compartments demonstrates an Mgk-biased differentiation potential. These reports imply that revisions to the HSC-to-Mgk differentiation pathway should be discussed. In this review, we summarize recent findings about Mgk differentiation from HSCs and discuss future directions in this research field. Stem Cells Translational Medicine 2017;6:1661–166

Compte rendu de « Desrosières, Alain (2014), Prouver et gouverner. Une analyse politique des statistiques publiques »

Prouver et gouverner étudie le rôle des institutions, des conventions et des enjeux normatifs dans la construction d’indicateurs quantitatifs. Desrosières pense qu’on ne peut étudier le développement scientifique des statistiques sans prendre en compte le développement institutionnel – en particulier le rôle de l’État – dans la constitution de cette discipline

Risk factors for CAR-T cell manufacturing failure among DLBCL patients: A nationwide survey in Japan

CAR-T細胞製造を成功させるためのレシピ --アフェレーシス前の下ごしらえでの工夫--. 京都大学プレスリリース. 2023-04-27.For successful chimeric antigen receptor T (CAR-T) cell therapy, CAR-T cells must be manufactured without failure caused by suboptimal expansion. In order to determine risk factors for CAR-T cell manufacturing failure, we performed a nationwide cohort study in Japan and analysed patients with diffuse large B-cell lymphoma (DLBCL) who underwent tisagenlecleucel production. We compared clinical factors between 30 cases that failed (7.4%) with those that succeeded (n = 378). Among the failures, the proportion of patients previously treated with bendamustine (43.3% vs. 14.8%; p < 0.001) was significantly higher, and their platelet counts (12.0 vs. 17.0 × 10⁴/μL; p = 0.01) and CD4/CD8 T-cell ratio (0.30 vs. 0.56; p < 0.01) in peripheral blood at apheresis were significantly lower than in the successful group. Multivariate analysis revealed that repeated bendamustine use with short washout periods prior to apheresis (odds ratio [OR], 5.52; p = 0.013 for ≥6 cycles with washout period of 3–24 months; OR, 57.09; p = 0.005 for ≥3 cycles with washout period of <3 months), low platelet counts (OR, 0.495 per 105/μL; p = 0.022) or low CD4/CD8 ratios (<one third) (OR, 3.249; p = 0.011) in peripheral blood at apheresis increased the risk of manufacturing failure. Manufacturing failure remains an obstacle to CAR-T cell therapy for DLBCL patients. Avoiding risk factors, such as repeated bendamustine administration without sufficient washout, and risk-adapted strategies may help to optimize CAR-T cell therapy for DLBCL patients

Clinical significance of disease-specific MYD88 mutations in circulating DNA in primary central nervous system lymphoma

Recent sequencing studies demonstrated the MYD88 L265P mutation in more than 70% of primary central nervous system lymphomas (PCNSL), and the clinical significance of this mutation has been proposed as diagnostic and prognostic markers in PCNSL. In contrast, mutational analyses using cell-free DNAs have been reported in a variety of systemic lymphomas. To investigate how sensitively the MYD88 L265P mutation can be identified in cell-free DNA from PCNSL patients, we carried out droplet digital PCR (ddPCR) and targeted deep sequencing (TDS) in 14 consecutive PCNSL patients from whom paired tumor-derived DNA and cell-free DNA was available at diagnosis. The MYD88 L265P mutation was found in tumor-derived DNA from all 14 patients (14/14, 100%). In contrast, among 14 cell-free DNAs evaluated by ddPCR (14/14) and TDS (13/14), the MYD88 L265P mutation was detected in eight out of 14 (ddPCR) and in 0 out of 13 (TDS) samples, implying dependence on the detection method. After chemotherapy, the MYD88 L265P mutation in cell-free DNAs was traced in five patients; unexpectedly, the mutations disappeared after chemotherapy was given, and they remained undetectable in all patients. These observations suggest that ddPCR can sensitively detect the MYD88 L265P mutation in cell-free DNA and could be used as non-invasive diagnostics, but may not be applicable for monitoring minimal residual diseases in PCNSL

Foxp3+ regulatory T cells maintain the bone marrow microenvironment for B cell lymphopoiesis

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

High efficacy of eculizumab treatment for fulminant hemolytic anemia in primary cold agglutinin disease

Letter to the Edito