Chemically defined cytokine-free expansion of human haematopoietic stem cells.

Haematopoietic stem cells (HSCs) are a rare cell type that reconstitute the entire blood and immune systems after transplantation and can be used as a curative cell therapy for a variety of haematological diseases1,2. However, the low number of HSCs in the body makes both biological analyses and clinical application difficult, and the limited extent to which human HSCs can be expanded ex vivo remains a substantial barrier to the wider and safer therapeutic use of HSC transplantation3. Although various reagents have been tested in attempts to stimulate the expansion of human HSCs, cytokines have long been thought to be essential for supporting HSCs ex vivo4. Here we report the establishment of a culture system that allows the long-term ex vivo expansion of human HSCs, achieved through the complete replacement of exogenous cytokines and albumin with chemical agonists and a caprolactam-based polymer. A phosphoinositide 3-kinase activator, in combination with a thrombopoietin-receptor agonist and the pyrimidoindole derivative UM171, were sufficient to stimulate the expansion of umbilical cord blood HSCs that are capable of serial engraftment in xenotransplantation assays. Ex vivo HSC expansion was further supported by split-clone transplantation assays and single-cell RNA-sequencing analysis. Our chemically defined expansion culture system will help to advance clinical HSC therapies.

Ex vivo expansion of human hematopoietic stem cells and clinical applications.

Hematopoietic stem cells (HSCs) are a rare population of cells found in the bone marrow that play a critical role in lifelong hematopoiesis and the reconstitution of the hematopoietic system after hematopoietic stem cell transplantation. Hematopoietic stem cell transplantation remains the only curative treatment for patients with refractory hematologic disorders, and umbilical cord blood (CB) serves as an alternative stem cell source due to its several advantageous characteristics, including human leukocyte antigen flexibility and reduced donor burden. However, CB also has the disadvantage of containing a small number of cells, resulting in limited donor selection and a longer time for engraftment. Therefore, the development of techniques to expand HSCs ex vivo, particularly umbilical CB, is a goal in hematology. While various combinations of cytokines were once the mainstream approach, these protocols had limited expansion rates and did not lead to clinical application. However, in recent years, the development of a technique in which small molecules are added to cytokines has enabled the stable, long-term ex vivo expansion of human HSCs. Clinical trials of expanded umbilical CB using these techniques have been undertaken and have confirmed their efficacy and safety. In addition, we have successfully developed a recombinant-cytokine-free and albumin-free culture system for the long-term expansion of human HSCs. This approach could offer the potential for more selective expansion of human HSCs compared to previous protocols. This review discusses ex vivo culture protocols for expanding human HSCs and presents the results of clinical trials using these techniques, along with future perspectives.

[Philadelphia chromosome-positive acute lymphoblastic leukemia complicated by bone marrow necrosis during consolidation chemotherapy].

A 46-year-old man who had previously undergone open surgery for renal cell carcinoma (RCC) developed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-ALL). After the induction therapy, he achieved complete molecular remission. However, fever and bilateral buttock pain continued during the consolidation therapy. 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) showed FDG accumulation in both iliac bones and in the sacrum; however, no causative diseases, including relapse of Ph-ALL and RCC, were detected. Iliac bone marrow biopsy revealed bone marrow necrosis (BMN), the etiology of which was presumed to be the leukemia itself and the therapeutic response to chemotherapy. Fever resolution and buttock pain alleviation were observed over the next months. We observed diffuse fibrosis in the bone marrow at day 162 and day 364 after cord blood transplantation. Moreover, the FDG accumulation was significantly reduced on PET-CT. BMN is not widely recognized despite its potential association with hematologic malignancies. Additional cases of BMN should be reviewed to clarify BMN etiology and clinical features.

[Fatal exacerbations of chronic active Epstein-Barr virus infection subsequent to cytotoxic chemotherapy].

Chronic active Epstein-Barr virus infection (CAEBV) is critical owing to lethal complications such as hemophagocytic lymphohistiocytosis (HLH), multiple organ failure, and malignant lymphoma. Here we present two cases of CAEBV who developed rapid and life-threatening disease progression after cytotoxic chemotherapy. Case 1: In a 34-year-old male, CAEBV recurred after 4-month remission obtained by initial therapy with etoposide, cyclosporine, and prednisolone. Accordingly, cord blood transplantation was planned. A day after administering high-dose melphalan as the conditioning, he developed respiratory failure, pancytopenia, and hyperferritinemia. He died 3 days later. Case 2: A 53-year-old female attained remission after initial therapy for CAEBV. After 1 month, she relapsed, and high-dose cytarabine (HDAC) was administered. A day after HDAC administration, she suddenly developed respiratory failure, which was followed by multiple organ failure. She died 3 days later. Thus, planned strategy for prompt allogeneic hematopoietic stem cell transplantation is necessary to prevent disease progression and control cytokinemia before cytotoxic chemotherapy for CAEBV.

Purging myeloma cell contaminants and simultaneous expansion of peripheral blood-mobilized stem cells.

Human hematopoietic stem cells (HSCs) are widely used as a cellular source for hematopoietic stem cell transplantation (HSCT) in the clinical treatment of hematological malignancies. After transplantation therapy, delays in hematopoietic recovery due to insufficient donor-derived HSCs can lead to increased risks of life-threatening infections and bleeding. Our previous studies developed an efficient ex vivo expansion culture medium (3a medium) for umbilical cord blood-derived HSCs (CBSCs), offering a potential solution to this problem. Nevertheless, the broader applicability of our culture method to alternative cell sources and, of greater significance, its efficacy in eliminating potentially disease-associated contaminated tumor cells, especially in autologous transplantation, raise critical clinical questions. In this study, we modified the 3a medium by incorporating UM729 to replace UM171, adding FMS-like tyrosine kinase 3 (Flt3) ligand, and adjusting the concentrations of butyzamide, 740Y-P, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG, Soluplus) to create the modified-3a medium. This sophistication allowed the efficient expansion of not only CBSCs but also peripheral blood-mobilized HSCs (PBSCs). Additionally, we successfully removed contaminated myeloma cells by adding bortezomib and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) at appropriate concentrations, although we maintained HSCs through the addition of lenalidomide. Our research findings present the potential for widespread clinical application of the modified-3a medium and suggest a safe ex vivo culture technique for expanding human HSCs within peripheral blood-derived donor grafts used for autologous HSCT.

Female and preserved platelet count subgroups of myelodysplastic syndrome patients benefit from standard-dose azacitidine.

BACKGROUND: Hypomethylating agents, including azacytidine (AZA), are standard therapeutics for patients with high-risk myelodysplastic syndromes (MDS), a group of myeloid neoplasms. However, treatment schedules are not unified in real-world practice; in addition to the standard 7-day (standard-dose) schedule, shortened (reduced-dose) schedules are also used. AIMS: The aim of this study was to discover the patient group(s) which show differential efficacy between standard-and reduced-dose AZA to MDS. METHODS AND RESULTS: The outcome of different AZA doses in a cohort of 151 MDS patients were retrospectively analyzed. Overall survival (OS) was not significantly different between standard- and reduced-dose AZA groups by multivariate analysis. However, an interaction was found between either the sex (female vs. male), the platelet counts (< 40 × 103 /µl vs. ≥ 40 × 103 /µl), or the karyotype risk (< poor vs. ≥ poor) and standard-dose AZA for longer OS. Subgroup analyses revealed better OS with standard- over reduced-dose AZA in female patients (HR, 0.27 [95% CI, 0.090-0.79]; p = 0.011), and those with platelet counts ≥ 40 × 103 /µl (HR, 0.51 [95% CI, 0.26-0.99]; p = 0.041). The union of female and preserved platelet count subgroups also benefited from standard-dose AZA. With this as a test cohort, we next analyzed patients registered in the JALSG MDS212 study, for whom 7-day and 5-day AZA treatment strategies were prospectively compared, as a validation cohort (N = 172). That cohort showed the same tendency as the retrospective results. CONCLUSION: We identified the union of female and preserved platelet count subgroups which benefited from standard-dose AZA, imparting crucial information to physicians planning treatment regimens in MDS patients.

[The MD-PhD program at Fukushima Medical University].

Fukushima Medical University launched an MD-PhD program in July, 2011, to foster a research-oriented mindset among medical students. This program consists of a first phase that proceeds in parallel with the regular medical school curriculum, and a second postgraduate phase. Upon completion of the first phase, the second phase is expected to take only 3 years, rather than the usual 4 required for a PhD. Moreover, students can obtain financial support from the university. Because of such attractive benefits, 19 medical students enrolled in 2011, much more than we had expected. Here we outline our program and report on a questionnaire survey taken 8 months after the program started.

Administration of brentuximab vedotin to a Hodgkin lymphoma patient with liver dysfunction due to vanishing bile duct syndrome resulting in a partial response without any severe adverse events.

Vanishing bile duct syndrome (VBDS) is a rare hepatic disorder which leads to liver failure as a result of progressive destruction of the intrahepatic bile ducts. There are no treatment modalities for VBDS itself and severe hepatic dysfunction restricts the treatment of underlying diseases. We safely treated a case of classic Hodgkin lymphoma (HL) with VBDS using brentuximab vedotin (BV). The patient was treated with 5 cycles of reduced BV and a partial metabolic response was obtained. Moreover, a standard dose of BV for another 5 cycles was accomplished with minimal adverse events. Our experience indicates that BV could be a treatment option for classic HL with VBDS.

Dasatinib Is an Effective Treatment for Angioimmunoblastic T-cell Lymphoma.

Recurrent hotspot (p.Gly17Val) mutations in RHOA encoding a small GTPase, together with loss-of-function mutations in TET2 encoding an epigenetic regulator, are genetic hallmarks of angioimmunoblastic T-cell lymphoma (AITL). Mice expressing the p.Gly17Val RHOA mutant on a Tet2-null background succumbed to AITL-like T-cell lymphomas due to deregulated T-cell receptor (TCR) signaling. Using these mice to investigate therapeutics for AITL, we found that dasatinib, a multikinase inhibitor prolonged their survival through inhibition of hyperactivated TCR signaling. A phase I clinical trial study of dasatinib monotherapy in 5 patients with relapsed/refractory AITL was performed. Dasatinib was started at a dose of 100 mg/body once a day and continued until days 10-78 (median day 58). All the evaluable patients achieved partial responses. Our findings suggest that AITL is highly dependent on TCR signaling and that dasatinib could be a promising candidate drug for AITL treatment. SIGNIFICANCE: Deregulated T-cell receptor signaling is a critical molecular event in angioimmunoblastic T-cell lymphoma and can be targeted with dasatinib.