Understanding Normal and Malignant Human Hematopoiesis Using Next-Generation Humanized Mice.

Rodent models for human diseases contribute significantly to understanding human physiology and pathophysiology. However, given the accelerating pace of drug development, there is a crucial need for in vivo preclinical models of human biology and pathology. The humanized mouse is one tool to bridge the gap between traditional animal models and the clinic. The development of immunodeficient mouse strains with high-level engraftment of normal and diseased human immune/hematopoietic cells has made in vivo functional characterization possible. As a patient-derived xenograft (PDX) model, humanized mice functionally correlate putative mechanisms with in vivo behavior and help to reveal pathogenic mechanisms. Combined with single-cell genomics, humanized mice can facilitate functional precision medicine such as risk stratification and individually optimized therapeutic approaches.

[Performing integrative transcriptomic and chemical screening to identify patient-specific vulnerabilities in poor-prognosis acute myeloid leukemia].

Genetic complexity and heterogeneity have made drug discovery difficult in human malignancies. In the past few years, we aimed to find vulnerabilities in therapy-resistant and refractory acute myeloid leukemia (AML) through integrative analyses of genomic data, clinical information, and results from in vivo/in vitro cell biological assays. Through analyses, we found that the cells of patients with AML show distinct sensitivity/resistance to small inhibiting molecules for anti-apoptosis and cell cycle/division. In particular, AML cells harboring the IDH1/2 mutations were highly sensitive to BCL-2 inhibition, while inhibition of IAP proteins resulted in efficient elimination of AML cells with varied FLT3, NRAS, and CBL mutations. Linking AML-initiating events with appropriate therapeutic strategies through cellular and genomic analyses might be further translated into nonmyeloid malignancies and solid tumors in the future.

Deregulated Mucosal Immune Surveillance through Gut-Associated Regulatory T Cells and PD-1+ T Cells in Human Colorectal Cancer.

Disturbed balance between immune surveillance and tolerance may lead to poor clinical outcomes in some malignancies. In paired analyses of adenocarcinoma and normal mucosa from 142 patients, we found a significant increase of the CD4/CD8 ratio and accumulation of regulatory T cells (Tregs) within the adenocarcinoma. The increased frequency of Tregs correlated with the local infiltration and extension of the tumor. There was concurrent maturation arrest, upregulation of programmed death-1 expression, and functional impairment in CD8+ T cells (CTLs) isolated from the adenocarcinoma. Adenocarcinoma-associated Tregs directly inhibit the function of normal human CTLs in vitro. With histopathological analysis, Foxp3+ Tregs were preferentially located in stroma. Concurrent transcriptome analysis of epithelial cells, stromal cells, and T cell subsets obtained from carcinomatous and normal intestinal samples from patients revealed a distinct gene expression signature in colorectal adenocarcinoma-associated Tregs, with overexpression of CCR1, CCR8, and TNFRSF9, whereas their ligands CCL4 and TNFSF9 were found upregulated in cancerous epithelium. Overexpression of WNT2 and CADM1, associated with carcinogenesis and metastasis, in cancer-associated stromal cells suggests that both cancer cells and stromal cells play important roles in the development and progression of colorectal cancer through the formation of a tumor microenvironment. The identification of CTL anergy by Tregs and the unique gene expression signature of human Tregs and stromal cells in colorectal cancer patients may facilitate the development of new therapeutics against malignancies.

Induction of WT1-specific human CD8+ T cells from human HSCs in HLA class I Tg NOD/SCID/IL2rgKO mice.

Induction of specific immune response against therapy-resistant tumor cells can potentially improve clinical outcomes in malignancies. To optimize immunotherapy in the clinic, we aimed to create an in vivo model enabling us to analyze human cytotoxic T-lymphocyte (CTL) responses against human malignancies. To this end, we developed NOD/SCID/IL2rgKO (NSG) mice expressing the HLA class I molecules HLA-A*0201 and A*2402. In the bone marrow (BM) and spleen of HLA class I transgenic (Tg) NSG mice transplanted with cord blood hematopoietic stem cells (HSCs), we found human memory CD8(+) T cells and antigen-presenting cells. To evaluate antigen-specific human CTL responses, we immunized HLA class I Tg NSG mice using polyinosinic:polycytidylic acid mixed Wilms tumor 1 (WT1) peptides, with or without WT1 peptide-loaded autologous dendritic cells. After immunization, the frequencies of HLA-restricted WT1-specific CTLs increased significantly in the spleen. Next, we transplanted the WT1-specific T-cell receptor (WT1-TCR) gene-transduced human HSCs into HLA class I Tg NSG newborn mice. WT1 tetramer-positive CD8(+) T cells differentiated from WT1-TCR-transduced HSCs in the recipients' BM, spleen, and thymus. Upon stimulation with WT1 peptide in vitro, these CTLs produced interferon-γ and showed lytic activity against leukemia cells in an antigen-specific, HLA-restricted manner. HLA class I Tg NSG xenografts may serve as a preclinical model to develop effective immunotherapy against human malignancies.

Humanized mice in translational biomedical research.

The culmination of decades of research on humanized mice is leading to advances in our understanding of human haematopoiesis, innate and adaptive immunity, autoimmunity, infectious diseases, cancer biology and regenerative medicine. In this Review, we discuss the development of these new generations of humanized mice, how they will facilitate translational research in several biomedical disciplines and approaches to overcome the remaining limitations of these models.

Identification of CD34+ and CD34- leukemia-initiating cells in MLL-rearranged human acute lymphoblastic leukemia.

Translocation of the mixed-lineage leukemia (MLL) gene with AF4, AF9, or ENL results in acute leukemia with both lymphoid and myeloid involvement. We characterized leukemia-initiating cells (LICs) in primary infant MLL-rearranged leukemia using a xenotransplantation model. In MLL-AF4 patients, CD34(+)CD38(+)CD19(+) and CD34(-)CD19(+) cells initiated leukemia, and in MLL-AF9 patients, CD34(-)CD19(+) cells were LICs. In MLL-ENL patients, either CD34(+) or CD34(-) cells were LICs, depending on the pattern of CD34 expression. In contrast, in patients with these MLL translocations, CD34(+)CD38(-)CD19(-)CD33(-) cells were enriched for normal hematopoietic stem cells (HSCs) with in vivo long-term multilineage hematopoietic repopulation capacity. Although LICs developed leukemic cells with clonal immunoglobulin heavy-chain (IGH) rearrangement in vivo, CD34(+)CD38(-)CD19(-)CD33(-) cells repopulated recipient bone marrow and spleen with B cells, showing broad polyclonal IGH rearrangement and recipient thymus with CD4(+) single positive (SP), CD8(+) SP, and CD4(+)CD8(+) double-positive (DP) T cells. Global gene expression profiling revealed that CD9, CD32, and CD24 were over-represented in MLL-AF4, MLL-AF9, and MLL-ENL LICs compared with normal HSCs. In patient samples, these molecules were expressed in CD34(+)CD38(+) and CD34(-) LICs but not in CD34(+)CD38(-)CD19(-)CD33(-) HSCs. Identification of LICs and LIC-specific molecules in primary human MLL-rearranged acute lymphoblastic leukemia may lead to improved therapeutic strategies for MLL-rearranged leukemia.

[A Case of Perforative Peritonitis Due to Intestinal Metastasis from Lung Cancer].

We here describe a case of an acute peritonitis due to perforation of a small intestine tumor metastasized from a lung cancer. A 66-year-old man who had undergone a bladder cancer procedure 2 years ago and was hospitalized for the second operation, complained sudden abdominal pain. An enhanced abdominal CTrevealed a small amount of free gas and ascites in the abdominal cavity. On the same day, emergency exploratory surgery was performed with the diagnosis of perforative peritonitis. A laparotomy revealed a jejunal tumor with perforation 40 cm distal from the Treitz ligament. After surgery, the patient confessed that he had got a notice of the recurrence of lung cancer which had been treated 9 years ago. The pathological result indicated the lesion was metastasis from lung cancer. Although small intestinal metastatic tumor from lung cancer is rare, it should be considered when acute abdomen is observed.

[Repeated Insertion of Self-Expandable Metallic Stents as a Palliative Therapy for Unresectable Colorectal Cancer].

A 62-year-old man was admitted to our hospital for malignant rectal stricture due to metastatic rectal cancer. He underwent placement of a self-expandable metallic stent (SEMS). After the administration of 5 courses of FOLFOX4 with bevacizumab, chemotherapy-induced tumor shrinkage led to migration of the SEMS, which was removed immediately without complication. After 10 courses of chemotherapy, he had to discontinue the treatment due to liver failure resulting from tumor progression. Another SEMS was successfully inserted for the progression of rectal stenosis. The patient's QOL was maintained to the end with the SEMS. This case suggests that although it is essential to pay attention to possible complications, SEMS insertion is a very useful procedure for palliative therapy.

[Conversion Therapy of Initially Unresectable Rectal Cancer with Perforation via FOLFOX4 Chemotherapy].

We describe a case of perforated rectal cancer that became curatively resectable after FOLFOX4 chemotherapy. An 81- year-old woman was transferred to our hospital with a diagnosis of bowel perforation. She underwent emergency transverse colostomy, peritoneal lavage, and the insertion of indwelling drainage tubes, because the perforated rectal cancer was considered unresectable. After recuperation, she received chemotherapy consisting of FOLFOX4 and bevacizumab. Owing to a good response to the treatment after 4 months, rectal resection was achieved curatively. Wound dehiscence occurred as a postoperative complication. The patient chose not to receive adjuvant chemotherapy. Currently, she has been alive for more than 1 year 3 months after resection without recurrence.

Membrane-bound human SCF/KL promotes in vivo human hematopoietic engraftment and myeloid differentiation.

In recent years, advances in the humanized mouse system have led to significantly increased levels of human hematopoietic stem cell (HSC) engraftment. The remaining limitations in human HSC engraftment and function include lymphoid-skewed differentiation and inefficient myeloid development in the recipients. Limited human HSC function may partially be attributed to the inability of the host mouse microenvironment to provide sufficient support to human hematopoiesis. To address this problem, we created membrane-bound human stem cell factor (SCF)/KIT ligand (KL)-expressing NOD/SCID/IL2rgKO (hSCF Tg NSG) mice. hSCF Tg NSG recipients of human HSCs showed higher levels of both human CD45(+) cell engraftment and human CD45(+)CD33(+) myeloid development compared with NSG recipients. Expression of hSCF/hKL accelerated the differentiation of the human granulocyte lineage cells in the recipient bone marrow. Human mast cells were identified in bone marrow, spleen, and gastrointestinal tissues of the hSCF Tg NSG recipients. This novel in vivo humanized mouse model demonstrates the essential role of membrane-bound hSCF in human myeloid development. Moreover, the hSCF Tg NSG humanized recipients may facilitate investigation of in vivo differentiation, migration, function, and pathology of human mast cells.

Development of mature and functional human myeloid subsets in hematopoietic stem cell-engrafted NOD/SCID/IL2rγKO mice.

Although physiological development of human lymphoid subsets has become well documented in humanized mice, in vivo development of human myeloid subsets in a xenotransplantation setting has remained unevaluated. Therefore, we investigated in vivo differentiation and function of human myeloid subsets in NOD/SCID/IL2rγ(null) (NSG) mouse recipients transplanted with purified lineage(-)CD34(+)CD38(-) cord blood hematopoietic stem cells. At 4-6 mo posttransplantation, we identified the development of human neutrophils, basophils, mast cells, monocytes, and conventional and plasmacytoid dendritic cells in the recipient hematopoietic organs. The tissue distribution and morphology of these human myeloid cells were similar to those identified in humans. After cytokine stimulation in vitro, phosphorylation of STAT molecules was observed in neutrophils and monocytes. In vivo administration of human G-CSF resulted in the recruitment of human myeloid cells into the recipient circulation. Flow cytometry and confocal imaging demonstrated that human bone marrow monocytes and alveolar macrophages in the recipients displayed intact phagocytic function. Human bone marrow-derived monocytes/macrophages were further confirmed to exhibit phagocytosis and killing of Salmonella typhimurium upon IFN-γ stimulation. These findings demonstrate the development of mature and functionally intact human myeloid subsets in vivo in the NSG recipients. In vivo human myelopoiesis established in the NSG humanized mouse system may facilitate the investigation of human myeloid cell biology including in vivo analyses of infectious diseases and therapeutic interventions.

[Long-term control of stage IV breast and gastric cancer with combination therapy of S-1 and paclitaxel].

We here describe a case of Stage IV breast and gastric cancer in which S-1/paclitaxel therapy was effective in maintaining the patient's QOL. A 50-year-old woman visited our hospital with complaints of her right breast tumor and right brachialgia. She was diagnosed with breast cancer with multiple bone metastases including cervical vertebrae. Accordingly, local radiation therapy and tamoxifen(TAM)administration was started immediately. Gastrointestinal endoscopy revealed gastric cancer, but laparotomy disclosed the gastric cancer was unresectable. At that time, the complaints of pain, nausea, and fatigue had increased and S-1/paclitaxel therapy was started immediately. The treatment reduced the size of the lesions in the breast and stomach and improved the QOL without serious adverse events. We have been maintaining partial response(PR)in this patient for 28 months.

[Three cases of endoscopic gastroduodenal stenting for gastric outlet obstruction caused by unresectable gastric cancer].

Gastroduodenal stenting for gastric outlet obstruction (GOO) caused by malignant disease has been covered by health insurance in Japan since April 2010. We have inserted WallFlex™ duodenal stents (WDS) in 3 patients with GOO caused by unresectable advanced gastric cancer. WDS placement was successful with no complications in all cases. Mean treatment time was 44.7 (35-50) minutes, and mean survival time after WDS placement was 34.7 (19-51) days. Oral food intake was improved in all patients but 1. Enteroparalysis due to peritoneal metastasis supposedly voided WDS placement in 1 patient. WDS placement for GOO caused by advanced gastric cancer is expected to be a safe and effective palliative treatment but sometimes yields no benefit in the patient with peritoneal metastasis.

[Four cases of operations for malignant disease in elderly patients].

The management of elderly patients with malignant disease is determined by their condition, complications, and living environment. Sometimes it is difficult to judge surgical indications for elderly patients. We report 4 cases of patients, 80 years or older, who underwent an operation for malignancy. In the first case we performed a bile duct excision for bile duct cancer, and in the second case we performed distal pancreatectomy for pancreatic cancer. Both operations were non-curative, and the patients were alive and maintained quality of life for 12 months after the operation. In the third non-curative operation, we performed total gastrectomy for remnant gastric cancer. The patient died of cancer 4 months after the surgery. In the fourth case we performed pancreaticoduodenectomy for bile duct cancer; it was a curative operation. The patient was in very good condition 4 months post-operation, but died suddenly due to acute myocardial infarction. In operations treating malignancy in elderly patients, it is important for the patients and their families to fully understand the significance of the operations.

Generation of functional human T-cell subsets with HLA-restricted immune responses in HLA class I expressing NOD/SCID/IL2r gamma(null) humanized mice.

Whereas humanized mouse models have contributed significantly to human immunology research, human T cells developing in mouse thymic environment fail to demonstrate HLA-restricted function. To achieve HLA-restricted human immune response, we created an immune-compromised non-obese diabetic/SCID/IL2rg(null) strain (NSG) with homozygous expression of HLA class I heavy chain and light chain (NSG-HLA-A2/HHD). Transplantation of purified Lin-CD34+CD38- human hematopoietic stem cells into NSG-HLA-A2/HHD newborns resulted in the development of human CD4+ and CD8+ TCR alphabeta+ T cells and CD4-CD8- and CD8+ TCR gammadelta+ cells in recipient bone marrow and spleen. Human cytotoxic T lymphocytes (CTLs) become functionally mature, as evidenced by the production of granzyme corresponding to phenotypic transition from naïve to effector memory CTLs. In these recipients, human Th17 cells developed along with Th1 and Th2 cells. Epstein-Barr virus (EBV) infection in the humanized NSG-HLA-A2/HHD recipients resulted in the formation of lymphoproliferative lesions consisting mainly of human B cells with scattered human T cells. Human CTLs developing in the recipients recognized EBV-derived peptides in an HLA-restricted manner and exerted HLA-restricted cytotoxicity against EBV-infected human B cells. The HLA-expressing humanized mouse with functional HLA-restricted T cells and consistent representation of rare T-cell subsets overcomes a major constraint in human immunology, and serves as a useful model for investigation of human immune responses against pathogens and for the development of therapeutic strategies against human diseases.

Humanized mouse models for immuno-oncology research.

Immunotherapy has emerged as a promising treatment paradigm for many malignancies and is transforming the drug development landscape. Although immunotherapeutic agents have demonstrated clinical efficacy, they are associated with variable clinical responses, and substantial gaps remain in our understanding of their mechanisms of action and specific biomarkers of response. Currently, the number of preclinical models that faithfully recapitulate interactions between the human immune system and tumours and enable evaluation of human-specific immunotherapies in vivo is limited. Humanized mice, a term that refers to immunodeficient mice co-engrafted with human tumours and immune components, provide several advantages for immuno-oncology research. In this Review, we discuss the benefits and challenges of the currently available humanized mice, including specific interactions between engrafted human tumours and immune components, the development and survival of human innate immune populations in these mice, and approaches to study mice engrafted with matched patient tumours and immune cells. We highlight the latest advances in the generation of humanized mouse models, with the aim of providing a guide for their application to immuno-oncology studies with potential for clinical translation.

Myeloid/natural killer (NK) cell precursor acute leukemia as a distinct leukemia type.

Myeloid/natural killer (NK) cell precursor acute leukemia (MNKPL) has been described on the basis of its unique immunophenotype and clinical phenotype. However, there is no consensus on the characteristics for identifying this disease type because of its rarity and lack of defined distinctive molecular characteristics. In this study, multiomics analysis revealed that MNKPL is distinct from acute myeloid leukemia, T cell acute lymphoblastic leukemia, and mixed-phenotype acute leukemia (MPAL), and NOTCH1 and RUNX3 activation and BCL11B down-regulation are hallmarks of MNKPL. Although NK cells have been classically considered to be lymphoid lineage-derived, the results of our single-cell analysis using MNKPL cells suggest that NK cells and myeloid cells share common progenitor cells. Treatment outcomes for MNKPL are unsatisfactory, even when hematopoietic cell transplantation is performed. Multiomics analysis and in vitro drug sensitivity assays revealed increased sensitivity to l-asparaginase and reduced levels of asparagine synthetase (ASNS), supporting the clinically observed effectiveness of l-asparaginase.

Circulating CD34+ cells of primary myelofibrosis patients contribute to myeloid-dominant hematopoiesis and bone marrow fibrosis in immunodeficient mice.

INTRODUCTION: Primary myelofibrosis (PMF) is a clonal stem cell disorder characterized by myeloid dominant hematopoiesis and dysregulated proliferation of fibroblasts in the bone marrow. However, how these aberrant myeloid cells and fibroblasts are produced remains unclear. AIM AND METHODS: In this study, we examined in vivo engraftment kinetics of PMF patient-derived CD34+ cells in immunecompromised NOD/SCID/IL2rgKO (NSG) mice. Engrafted human cells were analyzed with flow cytometry, and proliferation of fibroblastic cells and bone marrow fibrosis were assessed with the histo-pathological examination. RESULTS: Transplantation of PMF patient-derived circulating CD34+ fractions into NSG newborns recapitulates clinical features of human PMF. Engraftment of human CD45+ leukocytes resulted in anemia and myeloid hyperplasia accompanied by bone marrow fibrosis by six months post-transplantation. Fibrotic bone marrow contained CD45-vimentin+ cells of both human and mouse origin, suggesting that circulating malignant CD34+ subsets contribute to myelofibrotic changes in PMF through direct and indirect mechanisms. CONCLUSION: A patient-derived xenotransplantation (PDX) model of PMF allows in vivo examination of disease onset and propagation originating from immature CD34+ cells and will support the investigation of pathogenesis and development of therapeutic modalities for the disorder.

Multi-omics analysis defines highly refractory RAS burdened immature subgroup of infant acute lymphoblastic leukemia.

KMT2A-rearranged infant acute lymphoblastic leukemia (ALL) represents the most refractory type of childhood leukemia. To uncover the molecular heterogeneity of this disease, we perform RNA sequencing, methylation array analysis, whole exome and targeted deep sequencing on 84 infants with KMT2A-rearranged leukemia. Our multi-omics clustering followed by single-sample and single-cell inference of hematopoietic differentiation establishes five robust integrative clusters (ICs) with different master transcription factors, fusion partners and corresponding stages of B-lymphopoietic and early hemato-endothelial development: IRX-type differentiated (IC1), IRX-type undifferentiated (IC2), HOXA-type MLLT1 (IC3), HOXA-type MLLT3 (IC4), and HOXA-type AFF1 (IC5). Importantly, our deep mutational analysis reveals that the number of RAS pathway mutations predicts prognosis and that the most refractory subgroup of IC2 possesses 100% frequency and the heaviest burden of RAS pathway mutations. Our findings highlight the previously under-appreciated intra- and inter-patient heterogeneity of KMT2A-rearranged infant ALL and provide a rationale for the future development of genomics-guided risk stratification and individualized therapy.

Spred-1 negatively regulates allergen-induced airway eosinophilia and hyperresponsiveness.

T helper 2 cytokines, including interleukin (IL)-4, IL-5, and IL-13, play a critical role in allergic asthma. These cytokines transmit signals through the Janus kinase/signal transducer and activator of transcription (STAT) and the Ras-extracellular signal-regulated kinase (ERK) signaling pathways. Although the suppressor of cytokine signaling (SOCS) family proteins have been shown to regulate the STAT pathway, the mechanism regulating the ERK pathway has not been clarified. The Sprouty-related Ena/VASP homology 1-domain-containing protein (Spred)-1 has recently been identified as a negative regulator of growth factor-mediated, Ras-dependent ERK activation. Here, using Spred-1-deficient mice, we demonstrated that Spred-1 negatively regulates allergen-induced airway eosinophilia and hyperresponsiveness, without affecting helper T cell differentiation. Biochemical assays indicate that Spred-1 suppresses IL-5-dependent cell proliferation and ERK activation. These data indicate that Spred-1 negatively controls eosinophil numbers and functions by modulating IL-5 signaling in allergic asthma.