Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative treatment for hematologic malignancies. However, graft-versus-host disease (GVHD) and disease relapse negatively impact prognosis. Chronic GVHD significantly affects both prognosis and quality of life, making its prevention crucial. The current standard GVHD prophylaxis, using calcineurin inhibitors (CNIs) and methotrexate (MTX), is effective against acute GVHD but its effect on chronic GVHD is limited. The mechanism by which CNIs fail to prevent chronic GVHD has long been unclear. Recently, we conducted single-cell RNA sequencing of donor T cells after mouse HCT and found that CNIs inhibit donor T-cell exhaustion while inducing effector-like exhausted T cells. These cells contribute to the development of chronic GVHD after allo-HCT and play a role in enhancing graft-versus-leukemia (GVL) effects after post-HCT PD-1 blockade. We are currently accumulating and analyzing patient samples to validate our findings from the mouse HCT models.

Cord blood, which is rich in hematopoietic stem/progenitor cells, is now an important cell source for allogeneic hematopoietic cell transplantation (HCT). Although cord blood transplantation (CBT) was initially only performed in pediatric patients due to the limited number of cells, it now accounts for around 30% of allogeneic HCT for adults in Japan. It has overcome the shortage of donors caused by the declining birthrate and aging population. Although the greatest disadvantage of CBT is the high incidence of Engraftment failure, it has been shown that even in HLA-incompatible recipients, graft-versus-host disease (GVHD) is less frequent and less severe in CBT, whereas the graft-versus-leukemia (GVL) effect is stronger. CBT in Japan differs from that in other countries in that a single-unit is used in adult patients, and CBT is actively performed in elderly patients and patients with advanced hematopoietic disease. Based on the Japanese analysis, the usefulness of intensified conditioning regimen, the survival-improving effect on mild acute or chronic GVHD, and the strong GVL effect are all characteristic of CBT, which is an important source of cells for allogeneic HCT.

Non-clinical pharmacological safety studies are conducted using cells and animals to ensure the safety of pharmaceuticals in humans. Following these studies, drug candidates are administered to humans during clinical trials. Safety must be sufficiently confirmed in non-clinical studies to ensure that test participants suffer no adverse health effects. However, due to species differences, low ability to extrapolate from in vitro to in vivo evaluation methods, and other problems, health hazards may unfortunately still occur. Therefore, sophisticated in vitro evaluation systems using human cells are actively being pursued. The main challenge remains the lack of a reliable methodology for extrapolating in vitro results to in vivo settings. We have attempted to extract parameters that can be predictably translated from in vitro [contractile evaluation in three-dimensional (3D) heart tissue] to in vivo (guinea pig echocardiography) conditions, using cardiac contractile dysfunction induced by anticancer drugs as an example. In this review, we introduce the in vitro methods developed to date to evaluate this cardiac contractile dysfunction, analyze the factors enabling highly accurate prediction of torsades de pointes in humans based on past proarrhythmic risk prediction methods using human induced pluripotent stem cell-derived cardiomyocytes, and apply them to evaluate cardiac contractile dysfunction caused by anticancer drugs using three-dimensional heart tissue. We also introduce the proposed strategy for this evaluation method in this section.

To increase success rates of clinical studies, preclinical evaluation systems have been expected to improve human predictability. In addition, future preclinical studies need to become more sophisticated and efficient on the back ground of the adoption of FDA Modernization Act 2.0 and the 3R principle promotion of animal tests. In this review, we will discuss about the efficiency of in vivo imaging in preclinical studies taking 'an attempt to establishment of in vitro in vivo extraporation (IVIVE) model for seizure risk assessment using microphysiological system (MPS) and magnetic resonance imaging (MRI)', and 'an attempt to predict drug delivery to the alveoli' as examples. In the seizure risk assessment of new drugs so far, primary cultures of rodent neurons and in vivo behavioral observation have been mainly used, however, since the human induced pluripotent stem cell (iPSC) technology was reported, the need for IVIVE model is more and more increasing to improve human predictability. As an MPS, we here introduce microelectrode array (MEA) system recording of primary culture of rodent neurons, while as in vivo experiments, we here introduce the measurement of cerebrospinal fluid (CSF) concentrations and MRI imaging of forebrains of the rats i.p. injected with seizurogenic compounds. In case of inhalation drugs, it has been difficult to confirm whether or not the drugs surely reach alveoli. We visualized two-dimensional spatial localization of inhaled ciclesonide (CIC) in rat lungs after administration of a single dose of a CIC aerosol using by desorption electrospray ionization-time of flight mass spectrometry imaging (DESI-MSI).

The development of new in vitro cell culture systems, the microphysiological systems(MPSs), is progressing rapidly around the world. MPS is a biomimetic cell culture system that recapitulate tissue biology(patho)physiologically using clinically derived specimens, organoids, or differentiated cells from stem cells on a culture device with circulation and detection devices. New disease model systems are being constructed using MPS and are used as proof-of-concept and drug evaluation systems, and are attracting attention as an approach to addressing unmet medical needs. In conventional anti-cancer drug research, in vitro culture systems are mainly used to evaluate the growth inhibitory potential of cancer cell line monocultures. On the other hand, MPS has made it possible to monitor cancer pathology, malignant traits, and pharmacological activity, such as reproduction of the cancer niche, interactions between cancer cells and various stroma in the tumor microenvironment, cancer cell movement, and immune cell accumulation in cancer tissue. MPS is also used to evaluate safety and adverse effects and pharmacokinetics, which are essential for anticancer drug development. Various MPSs have been developed and reported for these purposes also in Japan, MPS technology is being developed, including for use in the regulatory process for non-clinical studies. Through these efforts, it is expected to lead to innovation in drug discovery in the field of oncology.

Paroxysmal nocturnal hemoglobinuria (PNH) is a hematopoietic stem cell disease that results from clonal expansion of hematopoietic stem cells with gene mutations. Patients with PNH are known to have an increased risk of developing myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). We report a case of a 42-year-old woman diagnosed with AML 13 years after a diagnosis of PNH. Gene mutations associated with MDS were detected. She did not achieve complete remission (CR) after induction therapy with idarubicin and cytarabine. Unrelated bone marrow transplantation was performed with a myeloablative conditioning regimen with cyclophosphamide (120 mg/kg) and total body irradiation (12 Gy). Ravulizumab was administered until 47 days after transplantation. She achieved CR after transplantation with complete donor engraftment. The transplantation was successful without severe complications such as graft-versus-host disease or sinusoidal obstruction syndrome. Further accumulation of cases is necessary to determine the efficacy and safety of anti-complement inhibitors in allogeneic hematopoietic stem cell transplantation.

A 46-year-old woman developed chronic skin graft-versus-host disease (GVHD) with bilateral axillary lymph node (LN) swelling 7 months after cord blood transplantation for acute myeloid leukemia. Histological examination of the LNs revealed dermatopathic lymphadenopathy (DL). After treatment with topical steroids, GVHD improved and lymphadenopathy subsided.DL typically occurs associated with chronic dermatologic disorders, and its pathology is characterized by paracortical LN hyperplasia by Langerhans cells and interdigitating cell infiltration. LN swelling rarely occurs with GVHD, and the clinical course in this patient suggests that her DL was caused by chronic skin GVHD. Interestingly, chimerism analysis of the Langerhans cells indicated donor origin.

A 41-year-old woman with myelodysplastic syndrome underwent unrelated bone marrow transplantation following conditioning with fludarabine, busulfan, total body irradiation, and anti-thymocyte globulin. She received tacrolimus and short-term methotrexate for graft-versus-host disease (GVHD) prophylaxis. After engraftment, she developed acute GVHD involving the skin, gut, and liver. Even after treatment with glucocorticoids, human mesenchymal stem cells, and ruxolitinib, skin GVHD progressed and caused extensive epidermolysis and erosions with persistent bleeding. The patient was started on a daily skin care regimen, which included washing, application of dimethyl isopropylazulene and betamethasone ointment, and topical trafermin and hydrogel wound dressing for bleeding sites. A multi-disciplinary team consisting of hematologists, plastic surgeons, and nurses, and physical therapists, psychiatrists/clinical psychologists, and palliative care providers for physical, mental, and pain supportive care managed the patient's care. After 4 months of treatment under this team, complete epithelial regeneration was achieved. This case demonstrates the efficacy of local skin care and multi-disciplinary collaboration in acute GHVD causing extensive skin damage.

Based on the perspectives of the environment, food, and health, this review reflects on previous research examining stem cells for the early detection of chemical hazards and the development of preventive health tools. The risks posed by endocrine-disrupting chemicals in the environment are investigated, including studies on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), phthalate esters, and bisphenol A. Building on the findings of these studies, this review identifies emerging challenges in the field of endocrine-disrupting chemical research. Moreover, this paper explores innovative testing methods aimed at accurately evaluating the impact of chemicals on human health. The key topics covered include the implementation of developmental neurotoxicity testing methods, the species-specific effects of methylmercury, nanomaterials and the application of human pluripotent cells to assess the effects of low-dose radiation. Additionally, this review highlights transformative approaches in chemical health impact assessment that integrate cell science and artificial intelligence, and addresses challenges related to the application of multi-omics technologies in environmental health and toxicology.

Primary bone marrow lymphoma (PBML) is a malignant lymphoma characterized by proliferation of lymphoma cells exclusively in the bone marrow without lymphadenopathy. Despite the dismal prognosis of PBML, it is a very rare lymphoma with limited evidence concerning its pathophysiology, making accumulation of cases important. We herein report three cases of PBML at our institution. The first patient was an 80-year-old man who presented with hemophagocytic syndrome and pancytopenia at admission, and died of septic shock during initial chemotherapy. The second patient was a 64-year-old man who achieved complete remission with intensive chemotherapies, but relapsed shortly after completing the final chemotherapy course. The third patient was a 66-year-old woman who underwent chemotherapies and allogeneic hematopoietic stem cell transplantation, only to relapse shortly after transplantation. Although early intervention with chemotherapy is essential for PBML treatment, diagnosis of PBML is very challenging due to the absence of lymph node involvement. Moreover, treatment outcomes of existing chemotherapy and transplantation therapies for PBML are still poor. Further accumulation of cases and development of new treatment strategies are desirable.

Chronic obstructive pulmonary disease (COPD) is characterized by chronic bronchitis and emphysema, and current drug treatments is limited to symptomatic therapy. Thus, there is an urgent need for development of new treatments to repair alveolar destruction. To regenerate the destroyed alveoli, we focused on the differentiation of alveolar epithelial progenitor cells into type I or type II alveolar epithelial cells that constitute the alveoli. Our concept of alveolar regeneration therapy is based on developing a drug delivery system (DDS) and dry powder inhalation that can efficiently deliver new alveolar regeneration drugs, which were discovered using human alveolar epithelial progenitor cells, to stem cells present on the surface of the alveoli of COPD patients, thereby inducing alveolar regeneration. This review article summarizes our data on the discovery of the synthetic retinoid Am80 as a candidate drug for alveolar regeneration, the construction of a DDS that utilizes a biological mechanism that enhances its effect on alveolar regeneration, and the formulation design of a dry powder inhalation.

Currently, a variety of anticancer agents are used in the treatment of cancer. Since anticancer agents are used continuously over a long time, they carry the risk of side effects. One of the major side effects is cardiac dysfunction. For example, doxorubicin, an anthracycline-type anticancer agent, is clinically restricted because of its dose-dependent cardiotoxicity. Cardiotoxicity includes decreased ejection fraction, arrhythmias, and congestive heart failure, all of which are associated with high mortality rates. Therefore, it is important to assess the risk of cardiotoxicity of anticancer agents in advance. Cardiomyocytes require energy to beat and retain an abundance of mitochondria. We established quantitative measurements of mitochondrial length and respiratory activities using cardiomyocytes. We found that exposure of human iPS cell-derived cardiomyocytes (hiPSC-CMs) to anticancer agents with reported cardiotoxicity enhanced mitochondrial hyperfission and the oxygen consumption rate was significantly reduced. Knockdown of dynamin-related protein 1 (Drp1), mitochondrial fission-accelerating GTP-binding protein, suppressed mitochondrial hyperfission in hiPSC-CMs. This indicates that visualizing mitochondrial functions in hiPSC-CMs will be helpful in assessing the risk of cardiotoxicity caused by anticancer agents and that maintaining mitochondrial quality will become a new strategy to reduce anticancer agents-induced cardiotoxicity. In this review, we present the evaluation of cardiotoxicity targeting mitochondrial quality in anticancer agents, using osimertinib, a non-small cell lung cancer drug, as an example.

The delay and loss of drugs are serious problems in Japan. To overcome this issue, it is important to strengthen drug development capabilities. For drug development, the establishment and advancement of non-clinical testing methods are necessary for safe and effective clinical trials. Recently, the movement toward alternatives to animal testing has accelerated internationally. New Approach Methodologies (NAMs), such as human inducible pluripotent stem cell (hiPSC) technology and in silico modeling & simulation, are considered valuable for drug development. It has been demonstrated that hiPSC-derived cardiomyocytes (hiPSC-CMs) are useful tools to assess drug-induced cardiotoxicity, including arrhythmia and cardiac contractile dysfunction, leading to the use of hiPSC-CMs in the drug review process. Advancing hiPSC technologies have enabled the generation of mature hiPSC-CMs and engineered heart tissues, which are expected to provide novel information in drug safety and efficacy evaluation. Furthermore, it would be possible to establish the non-clinical evaluation that takes into account individual differences by developing hiPSCs bearing characteristics specific to certain populations, such as pediatrics or rare disease patients. Here, we present the recent findings and future perspectives on non-clinical evaluation using hiPSC technology.

Human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) can recapitulate the properties of human cardiomyocyte and exhibit disease phenotypes in vitro, attributable to their healthy- or patient-specific genetic backgrounds. Therefore, hiPSC-CMs are a crucial tool for developing therapeutic agents for cardiovascular diseases, and regenerative medicine using hiPSC-CMs is expected to be an alternative therapy to heart transplantation. Moreover, the development of organoid models has been advanced to replicate the complex structure of heart tissue in vitro, thereby effectively facilitating drug discovery. On the other hand, current methods for advancing drug discovery using hiPSC-CMs face limitations, including the difficulty of quantifying characteristics such as cell structure and predicting the risk and efficacy of candidate drug in clinical practice. In the field of regenerative medicine, challenges include quality control and the verification of safety of transplanted cells in human. In silico model, including artificial intelligence (AI) and simulation, have been developed in the field of drug discovery using hiPSC-CMs. These advancements encompass phenotype scoring via AI and risk prediction through simulations. This review outlines the current status and challenges of drug discovery using hiPSC-CMs and in silico model, based on the published reports.

Tacrolimus is widely recognized as an anti-rejection agent due to its immunosuppressive characteristics. It binds to the immunophilin FK506-binding protein (FKBP) and thus to calcineurin, and inhibits its activity. Tacrolimus' therapeutic concentration range in blood is narrow, and its pharmacokinetics are highly variable among individuals. First, because tacrolimus primarily distributes to red blood cells (RBCs), anemia and blood transfusions can cause fluctuations in tacrolimus blood concentrations. Variations in blood tacrolimus concentration significantly correlated with variations in RBC count, hemoglobin level, and hematocrit value, but not with variations in white blood cell or platelet counts. Interestingly, FKBP played an important role in tacrolimus distribution to RBCs. The effects of intracellular and extracellular FKBP levels on RBC distribution of tacrolimus in circulating blood were substantial. Secondly, proteins affecting pharmacokinetics can differ at the genetic level in their expression and functional potency. Genetic polymorphisms that influence tacrolimus pharmacokinetics have been reported. A polymorphism in the gene encoding the metabolic enzyme cytochrome P450 (CYP) 3A5 is a particularly influential factor affecting tacrolimus pharmacokinetics in Japanese patients. CYP3A5 polymorphisms correlated with individual differences in tacrolimus blood concentration changes after starting continuous infusion in allogeneic hematopoietic stem cell transplantation (HSCT) recipients. In addition, CYP3A5*3 polymorphism also correlated with differences in the frequency of acute graft-versus-host disease (GVHD) development in allogeneic HSCT recipients.

Advanced cell culture systems including human induced pluripotent stem (iPS) cells and organoids enable the generation of intricate structural and functional organ models in vitro. Application of these advanced cell culture systems to research on a wide range of diseases including infectious diseases is underway. Due to the impact of the coronavirus disease 2019 (COVID-19) pandemic, advanced cell culture systems in the virus research field are rapidly becoming popular. Respiratory models generated using human iPS cells and organoid technology are useful for analyzing respiratory cell responses caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, there is still room for the development of an apical-out model, which is essential for simple virus infection experiments, and a model that can analyze host responses in the alveoli and airways. In this study, we developed human iPS cell-derived alveolar and airway models with an apical-out structure by using a micropatterning plate. In the alveolar model, we confirmed that this model contains abundant type II alveolar epithelial (AT2) cells, which are the target cells of SARS-CoV-2 in the alveoli. In the airway model, we confirmed that this model contains abundant ciliated cells, which are the target cells of SARS-CoV-2 in the airway. Using our alveolar and airway models, we can analyze the differences in infection efficiency and host response of each SARS-CoV-2 variant. We hope that the human iPS cell-derived alveolar and airway models generated using a micropatterning plate will be used to analyze not only SARS-CoV-2 but also a wide range of respiratory viruses.

Bone marrow (BM) failure is a condition characterized by peripheral pancytopenia resulting from decreased hematopoiesis in the BM. It includes congenital disorders such as Fanconi anemia (FA), as well as acquired conditions such as acquired aplastic anemia (AA), myelodysplastic syndrome (MDS), and paroxysmal nocturnal hemoglobinuria (PNH). AA presents with pancytopenia and BM hypoplasia, primarily triggered by an autoimmune mechanism involving T cells that damage hematopoietic stem cells (HSCs). Genomic investigations utilizing next-generation sequencing or SNP arrays have revealed that clonal hematopoiesis by HSCs with genetic aberrations, including PIGA, DNMT3A, ASXL1, BCOR/BCORL1, copy-number neutral LOH of chromosome 6p (6pLOH), and somatic mutations in HLA class I alleles are prevalent in AA patients. Recent studies have identified somatic mutations in genes associated with the JAK-STAT and MAPK pathways in T cells of AA patients. Genomic abnormalities in AA differ from those observed in MDS and age-related clonal hematopoiesis. Notably, the presence of PNH-type cells and HLA class I allele-lacking cells represent two major instances of escape hematopoiesis, which indicate the presence of HSCs evading autoimmune T cell attacks. These findings provide crucial insights into the immune pathophysiology of BM failure.

Mitochondrial metabolic dependencies characteristic of acute myeloid leukemia (AML) have recently been identified, demonstrating that metabolic enzymes regulate AML gene expression and control cell differentiation and stemness. These mitochondrial metabolic adaptations occur independently of underlying genomic abnormalities and contribute to chemotherapy resistance and relapse. Mitochondrial alterations also lead to metabolic vulnerability of AML cells, whose metabolism is characterized by dependence on oxidative phosphorylation, fatty acid oxidation, reactive oxygen species (ROS) production, and mitochondrial dynamics. Currently, mitochondrial properties of AML cells and leukemia stem cells are being investigated, focusing on metabolism, signal transduction, mitochondrial respiration, ROS generation, and mitophagy. In addition, mitochondria-targeted agents have shown promising results in clinical trials. This paper outlines recent findings from preclinical and clinical trials on the utility of agents targeting mitochondria-related molecules and metabolic pathways and their efficacy in combination with existing chemotherapies.

EVI1 is a zinc finger transcription factor encoded by the MECOM locus and is essential for the development and maintenance of hematopoietic stem cells. However, overexpression of EVI1 in various myeloid malignancies is associated with aggressive clinical behavior and poor outcome. The locus encodes multiple isoforms that are differentially acting and independently regulated. EVI1 interacts with a variety of transcription and epigenetic factors via different domains. It also regulates cell survival, differentiation, and proliferation through a variety of mechanisms, including transcriptional activation and repression, regulation of other transcription factors' activity, and chromatin remodeling. While the mechanism by which 3q26 translocation leads to high EVI1 expression through enhancer hijacking of genes active in myeloid development is now better understood, regulation of EVI1 expression in the absence of chromosomal translocations and in normal hematopoiesis remains unclear. Recent studies have provided insight into the regulatory mechanisms of EVI1 expression and action, which may lead to development of targeted therapies in the near future.

Sustaining lifelong hematopoiesis requires maintenance, proliferation, and differentiation of hematopoietic stem cells. Thrombopoietin is a cytokine essential for regulation of hematopoietic stem cells as well as differentiation and maturation of megakaryocytes required for platelet production. Due to these properties, thrombopoietin agonists have been used to treat bone marrow failure syndromes such as aplastic anemia. Through analysis of thrombopoietin gene-deficient mice, my colleagues and I have demonstrated the mechanism of action of thrombopoietin receptor agonists in hematopoietic stem cell maintenance and differentiation. This review focuses on governance of homeostasis in the hematopoietic system by thrombopoietin signaling.