Successful bone marrow (BM) transplantation requires the homing of the transplanted hematopoietic stem/progenitor cells (HSPCs) to their bone marrow niche, where they undergo differentiation to form mature cells that are eventually released into the peripheral blood. However, the survival rate of patients receiving BM transplants is poor since many of the transplanted HSPCs do not make it to their BM niches in the recipient’s body. Since the availability of HSPCs from traditional sources is limited, transplanting more number of HSPCs is not a solution to this problem. This study aims to characterize the adhesion molecules mediating cell migration in order to better understand the adhesion mechanisms of HSCs with the bone marrow endothelium. This will aid in developing future tools to improve the clinical transplantation of HSPCs. This study also aims to understand the factors that influence HSPC proliferation in the bone marrow niche. E-selectin plays an important role in the process of homing; however, its ligands on HSPCs are not well characterized. We used western blotting and immunoprecipitation to show that endomucin is expressed on HSPCs and plays a role in the binding of HSPCs to E-selectin. We also studied the effect of recombinant E-selectin on the expression of a newly characterized E-selectin ligand in our lab, CD34, in HSPCs. This will provide us insight into novel roles for endomucin and E-selectin and help us to understand the factors influencing HSPC migration to BM endothelium.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21992号 / 医博第4506号 / 新制||医||1037(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 川口 義弥, 教授 坂井 義治, 教授 濵﨑 洋子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Type 1 diabetes mellitus is a metabolic disorder characterized by an autoimmune attack against the insulin producing Beta-cells of the pancreas. Also known as insulin-dependent diabetes, patients must receive exogenous injections of insulin in order to maintain glycemic homeostasis. The necessity of monitoring one’s own blood glucose levels and self-administering insulin is a tedious routine for type 1 diabetics, and this standard treatment option fails to treat any of the underlying causes of the disease. According to van Belle et al, the prevalence of diabetes is rising worldwide amongst all age-groups, from 2.8% in 2000 to an estimated 4.4% by 2030, thus the need to find a more curative treatment approach is eminent. In the emerging field of regenerative medicine, mesenchymal stem cells have been identified as a possible therapeutic tool to replace damaged parenchymal tissue. Along with their ability to modulate the local microenvironment, the introduction of properly differentiated mesenchymal stem cells into patients with Type 1 diabetes may provide a treatment option that helps supplement the lost islet cells without provoking an immune response. Preliminary clinical trials have shown that stem cell therapy decreases the amount of exogenous insulin required daily, decreases fasting glucose levels, decreases amount of glycated hemoglobin and increases C-peptide levels. These four indicators of diabetic control suggest that mesenchymal stem cells are an effective means of helping manage Type 1 diabetes. Still, much research needs to be done to fully understand the biomechanics behind the cells’ actions in order to expand human clinical trials. Although complete insulin independence is rarely achieved in patients receiving mesenchymal stem cell treatment, the promising results shown so far suggest more studies be undertaken in hopes of finding a corrective approach to treat Type 1 diabetes.

Background. Relapsed acute promyleocytic leukemia (APL) is treated with re-induction chemotherapy, commonly arsenic trioxide, and stem cell transplantation (SCT). The effect of arsenic trioxide on autologous peripheral blood stem cell collection is unknown. Procedure. Five pediatric patients with relapsed APL had PML-RARA negative peripheral blood stem cells mobilized (four after arsenic trioxide) and underwent autologous SCT after cyclophosphamide (60 mg/kg x 2) and total body irradiation (TBI-fractionated 1,200 cGy) conditioning. Results. All five patients remain in molecular remission a median of 20 months post-transplant. Conclusion. Autologous SCT performed during molecular remission is a treatment option for pediatric patients with relapsed APL and may provide durable leukemia-free survival without the complications of allogeneic transplantation.

京都大学 / マギル大学 / 新制・課程博士 / 博士(ゲノム医学) / 甲第24204号 / 医博JD第2号 / 新制||医||JD1(附属図書館) / 京都大学大学院医学研究科京都大学マギル大学ゲノム医学国際連携専攻 / (主査)准教授 Wilson Michael (トロント大学), 教授 竹内 理, 准教授 Bailey Swneke (マギル大学), 教授 伊藤 貴浩, 教授 Shoubridge Eric (マギル大学) / 学位規則第4条第1項該当 / Doctor of Philosophy in Human Genetics / Kyoto University / McGill University / DFAM

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Indiana University-Purdue University Indianapolis (IUPUI) / Hematopoietic stem and progenitor cells (HSCs/HPCs) transplantation is a curative treatment for a variety of hematologic and non-hematologic diseases. Successful HSC transplantation requires infusing patients with a sufficient number of long-term engrafting HSCs. As a result, research efforts have focused on optimizing the collection process. Previous work established that harvesting mouse bone marrow HSCs under low oxygen tension similar to that reported for the bone marrow niche in situ (physioxia), results in enhanced HSC recovery and function. However, collecting bone marrow cells under physioxia is not a clinically viable approach. Here, I demonstrated that the collection and processing of peripheral blood mobilized with G-CSF alone or G-CSF and Plerixafor under physioxia resulted in a greater number of phenotypically defined long-term engrafting HSCs. Using high-resolution single cell sequencing to explore the molecular programs governing HSCs under physioxia, I identified increased expression of genes involved in HSC self-renewal and maintenance. In contrast, HSCs under ambient air upregulated genes implicated in HSC differentiation, apoptosis, and inflammatory pathways. Furthermore, wild-type HSCs under physioxia revealed a significant reduction in gene expression and activity of the epigenetic modifier Tet2. Consequently, I evaluated the phenotyping, engraftment potential and gene expression of preleukemic Tet2-/- bone marrow cells under physioxia and ambient air. Unlike wild-type HSCs, Tet2-/- HSCs/HPCs were unresponsive to changes in oxygen tension. Notably, we observed similar phenotypes, functions, and self-renewal and quiescence gene expression in wild-type HSCs under physioxia and Tet2- /- HSCs under physioxia or ambient air. These findings imply that the preserved stemness and enhanced engraftment of HSCs under physioxia may in part be a result of Tet2 downregulation. Understanding the mechanisms regulating wild-type and preleukemic HSCs under physioxia will have therapeutic implications for optimizing HSC transplantation and mitigating the growth advantage of preleukemic stem cells. / 2022-12-15

Indiana University-Purdue University Indianapolis (IUPUI) / The aldehyde dehydrogenase (ALDH) superfamily comprises a group of NAD(P)+-dependent enzymes that catalyze the conversion of aldehydes to their corresponding carboxylic acids. Of the nineteen human ALDH enzymes, members of the ALDH1A subfamily consisting of ALDH1A1, ALDH1A2, and ALDH1A3 have attracted interest as markers of cancer stem cells (CSCs) in several cancer types including lung, breast, and ovarian. CSCs represent a distinct subpopulation of highly tumorigenic cells that promote metastasis, recurrence, and resistance to conventional cancer therapies. The increased expression and activity of ALDH1A in CSCs is well-documented, as is the correlation between ALDH1A and a more aggressive cancer phenotype with poorer treatment outcomes. However, the actual functional role of ALDH1A in the context of CSCs has yet to be clearly defined. Elucidating this role will lead to a greater understanding of CSC biology and evaluate ALDH1A as a potential anti-CSC therapeutic target. In this study, previously developed and characterized selective small-molecule inhibitors of ALDH1A were used in conjunction with global transcriptomic, proteomic, and metabolomic analyses to identify pathways that could potentially establish a link between ALDH1A activity and early events in CSC formation in a triple-negative breast cancer (TNBC) model. These approaches revealed that ALDH1A inhibition is associated with mitochondrial and metabolic dysfunction and perturbation of the electron transport chain. ALDH1A inhibition also resulted in an increase in markers of endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR), specifically mediated through the Protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway. These effects appear to occur independently of both the canonical function of ALDH1A in detoxifying reactive aldehydes as well as its potential metabolic contribution through the generation of NADH. Together, these results suggest a separate role for ALDH1A in TNBC CSCs in protecting against ER stress that warrants further study. / 2024-10-03

Rapidly progressive diffuse systemic sclerosis (dSSc) is a life-threatening condition characterized by increased mortality with few effective therapies, typically only helpful in stabilizing disease. Autologous hematopoietic stem cell transplantation (AHSCT) is the only treatment that has demonstrated improved survival. Despite promising results from three randomized controlled trials (RCTs), best practice use of AHSCT in the real-world setting is not well established. The primary objective of this thesis was to summarize the clinical efficacy, limitations and utilization of AHSCT in the management of rapidly progressive dSSc. Specifically, we conducted (1) a systematic review to describe the efficacy of AHSCT in dSSc as well as practice variation in patient selection and treatment regimens; and (2) a multicenter retrospective cohort study to compare outcomes for subjects who received AHSCT in France compared to those who received conventional care in Canada. There was important variability in the criteria for patient selection and treatment protocols. While AHSCT is associated with improved overall survival, skin fibrosis and lung function, further studies are needed to understand its potential for expanded eligibility and effects on other disease manifestations.

Owing to the presence of muscle stem cells (MuSC), adult skeletal muscle is capable of regenerating after injury. Quiescent muscle stem cells become activated and proliferate into myoblasts which undergo myogenic differentiation to repair damaged tissue. The transcription factor (TF) Six1 is a known regulator of muscle stem cells which potentially plays a role in the early stages of MuSC activation. When bound to the appropriate cofactor, Six family transcription factors are capable of activating or repressing transcription. Previous work suggests that Six1 establishes the accessibility landscape required for the myogenic regulatory factor (MRF) MyoD to bind to DNA. It was hypothesized that Six1 recruits p300 to acetylate Histone H3 lysine 122 which then renders DNA more accessible and facilitates gene transcription. The objective of this research was to investigate the role of Six1 in regulating the epigenetic and accessibility state of DNA in myoblasts. It was found that Six1 and the histone acetyltransferase p300 coincide at many gene enhancers. In addition, Six1 knock-down is associated with reduced DNA accessibility at a large number of loci in C2C12 myoblasts and with gene downregulation. In this research, we determined that recruitment of p300 by Six1 alters chromatin accessibility and gene expression in proliferating myoblasts, providing evidence of Six1 pioneer factor activity.