Luminescent Radicals.

Organic radicals are attracting increasing interest as a new class of molecular emitters. They demonstrate electronic excitation and relaxation dynamics based on their doublet or higher multiplet spin states, which are different from those based on singlet-triplet manifolds of conventional closed-shell molecules. Recent studies have disclosed luminescence properties and excited state dynamics unique to radicals, such as highly efficient electron-photon conversion in OLEDs, NIR emission, magnetoluminescence, an absence of heavy atom effect, and spin-dependent and spin-selective dynamics. These are difficult or sometimes impossible to achieve with closed-shell luminophores. This review focuses on luminescent organic radicals as an emerging photofunctional molecular system, and introduces the material developments, fundamental properties including luminescence, and photofunctions. Materials covered in this review range from monoradicals, radical oligomers, and radical polymers to metal complexes with radical ligands demonstrating radical-involved emission. In addition to stable radicals, transiently formed radicals generated in situ by external stimuli are introduced. This review shows that luminescent organic radicals have great potential to expand the chemical and spin spaces of luminescent molecular materials and thus broaden their applicability to photofunctional systems.

Spin-Correlated Luminescence of a Carbazole-Containing Diradical Emitter: Single-Molecule Magnetoluminescence and Thermally Activated Emission.

Luminescent radicals have been intensively studied as a new class of materials exhibiting novel photofunctions unique to open-shell systems. When luminescent radicals are assembled, intriguing spin-correlated luminescence phenomena emerge, including excimer-like emission and magnetic-field effects on luminescence (i.e., magnetoluminescence, MagLum). However, the underlying mechanisms of these phenomena arising from spin multiplicity and spin-dependent excited-state dynamics are poorly understood due to the limited number of luminescent polyradical systems available for study. In particular, the correlation between stronger intramolecular exchange interactions (|2J/kB| > ∼10 K, where J and kB are the intramolecular exchange coupling constant and the Boltzmann constant, respectively) and luminescence properties has not been fully explained. In this study, a novel carbazole-containing diradical emitter (1) and the corresponding monoradical (2) were prepared for the in-depth study of spin-correlated luminescence properties, with luminescence measurements under magnetic fields of up to 18 T. Diradical 1 has a negative 2J/kB value of several tens of kelvin and exhibits a single-molecule MagLum and thermally activated luminescence, whereas 2 does not. Detailed quantitative analyses revealed that both the spin-correlated luminescence properties of 1 are strongly dominated by ground-state spin statistics based on the Boltzmann distribution (i.e., 2J/kB values). Furthermore, diradical 1 exhibits external heavy-atom effects in heavy-atom-containing solvents such as iodobenzene, whereas monoradical 2 does not. This is the first experimental verification of external heavy-atom effects in polyradical emitters. This work demonstrates that polyradical emitters can be designed based on spin degrees of freedom in both ground and excited states.

[Durable remission of T-cell prolymphocytic leukemia with CLEC16A::IL2 after allogeneic hematopoietic stem cell transplantation].

A 64-year-old woman presented with fine motor impairment in both hands. MRI revealed a contrast-enhanced lesion in the medulla oblongata. Lymphoid cells with abnormal blebs were observed and a CD4+/CD8+ double positive (DP) T cell population was detected by flow cytometry (FCM) in the bone marrow (BM) and the peripheral blood (PB). CLEC16A::IL2 fusion gene was identified by whole exome sequencing with DNA prepared from DP T cells. Clonal rearrangement of the T-cell receptor gene and expression of TCL1A protein were detected. This led to a diagnosis of T-cell prolymphocytic leukemia (T-PLL) with central nervous system (CNS) infiltration. Abnormal cells in BM and PB became undetectable on microscopy and FCM, and the CNS lesion disappeared on MRI after second-line therapy with alemtuzumab. Meanwhile, the CLEC16A::IL2 fusion mRNA remained detectable in PB. Allogeneic hematopoietic stem-cell transplantation was performed, and the fusion mRNA has now been undetectable for more than 5 years since transplantation. This is the first report of a T-PLL case with a CLEC16A::IL2 fusion gene.

Single-Molecule Magnetoluminescence from a Spatially Confined Persistent Diradical Emitter.

Luminescent radicals are an emerging class of materials that exhibit unique photofunctions not found in closed-shell molecules due to their open-shell electronic structure. Particularly promising are photofunctions in which radical's spin and luminescence are correlated; for example, when a magnetic field can affect luminescence (i.e., magnetoluminescence, ML). These photofunctions could be useful in the new science of spin photonics. However, previous observations of ML in radicals have been limited to systems in which radicals are randomly doped in host crystals or polymerized through metal complexation. This study shows that a covalently linked luminescent radical dimer (diradical) can exhibit ML as a single-molecular property. This facilitates detailed elucidation of the requirements for and mechanisms of ML in radicals and can aid the rational design of ML-active radicals based on synthetic chemistry.

Safety of romiplostim administered immediately after cord-blood transplantation: a phase 1 trial.

Graft failure and delayed hematopoietic recovery are the major limitations of cord-blood transplantation (CBT). Romiplostim, a thrombopoietin-receptor agonist, promotes megakaryopoiesis and multilineage hematopoiesis in aplastic anemia. The decreased number of hematopoietic stem cells in the early phase after CBT and aplastic anemia share certain characteristics. Therefore, we hypothesized that romiplostim administration immediately after CBT may promote multilineage hematopoietic recovery. We investigated the safety and preliminary efficacy of administering romiplostim a day after CBT. This phase 1 dose-escalation study included six adults with hematologic malignancies in remission. Romiplostim was administered subcutaneously within 7 days after single-unit CBT, initially at doses of 5 µg/kg or 10 µg/kg in three patients, then once a week for 14 weeks or until platelet recovery. The maximum dose was 20 µg/kg. The median number of romiplostim administrations was 6 (range, 3-15). Romiplostim-related adverse events included bone pain (3/6) and injection site reaction (1/6). Non-hematological grade ≥ 3 toxicities were observed in four patients; febrile neutropenia was the most common (4/6). All patients achieved neutrophil engraftment and the median time was 14 days (range, 12-32). Platelet counts ≥ 50 × 109 /L were recorded in all patients except for one who died on day 48; the median time was 34 days (range, 29-98). No relapse, thrombosis, or bone marrow fibrosis was observed during a median follow-up of 34 months. Romiplostim may be safely administered in the early phase of CBT. Further phase 2 trial is warranted for its efficacy evaluation. Trial registration number: UMIN000033799, August 18, 2018.

Historical and current perspectives on blood endothelial cell heterogeneity in the brain.

Dynamic brain activity requires timely communications between the brain parenchyma and circulating blood. Brain-blood communication is facilitated by intricate networks of brain vasculature, which display striking heterogeneity in structure and function. This vascular cell heterogeneity in the brain is fundamental to mediating diverse brain functions and has long been recognized. However, the molecular basis of this biological phenomenon has only recently begun to be elucidated. Over the past century, various animal species and in vitro systems have contributed to the accumulation of our fundamental and phylogenetic knowledge about brain vasculature, collectively advancing this research field. Historically, dye tracer and microscopic observations have provided valuable insights into the anatomical and functional properties of vasculature across the brain, and these techniques remain an important approach. Additionally, recent advances in molecular genetics and omics technologies have revealed significant molecular heterogeneity within brain endothelial and perivascular cell types. The combination of these conventional and modern approaches has enabled us to identify phenotypic differences between healthy and abnormal conditions at the single-cell level. Accordingly, our understanding of brain vascular cell states during physiological, pathological, and aging processes has rapidly expanded. In this review, we summarize major historical advances and current knowledge on blood endothelial cell heterogeneity in the brain, and discuss important unsolved questions in the field.

[Waldenström macroglobulinemia complicated by peripheral neuropathy due to neural infiltration].

A 51-year-old man with the chief complaint of glove- and stocking-type dysesthesia for >3 years was diagnosed with Waldenström's macroglobulinemia (WM) based on IgM-type M-proteinemia, bone marrow infiltration of plasmacytoid B cells, multiple lymphadenopathies, and splenomegaly. A nerve conduction examination suggested demyelinating neuropathy. Serum anti-myelin-associated glycoprotein antibody was negative. Sural nerve biopsy showed myelin thinning, suggesting demyelination. Axonal damage and tumor cell infiltration in the intrafascicular epineurium were also observed. After chemotherapies with rituximab and bendamustine, M-proteinemia and lymphadenopathies disappeared. However, abnormalities in the nerve conduction examination and dysesthesia were only slightly alleviated. As articles describing patients with WM with peripheral nerve infiltration are limited, we report this case with a literature review.

[Hematopoietic recovery by ASXL1-mutated clones after immune suppressive therapy in a patient with severe aplastic anemia].

Sequencing technology has identified aplastic anemia (AA) not only as an autoimmune bone marrow failure syndrome, but also as a clonal hematopoietic disease. Here, we present a case in which an ASXL1-mutated clone was predominantly expanded during the treatment of AA. A 58-year-old man with chronic glomerulonephritis on maintenance hemodialysis presented with pancytopenia. The findings of bone marrow biopsy indicated a hypoplastic bone marrow. Magnetic resonant imaging showed fatty changes in the bone marrow. The patient was eventually diagnosed with severe AA. He was treated with anti-human thymocyte globulin, cyclosporine, granulocyte colony-stimulating factor, and the thrombopoietin receptor agonist (TPO-RA) eltrombopag. After switching to another TPO-RA, romiplostim, the neutrophil, reticulocyte, and platelet counts gradually improved, and blood transfusion was not needed 1 year after treatment. Mutational analyses revealed that reconstituted hematopoietic cells originated from the ASXL1-mutated clone. Nevertheless, the patient's blood cell counts remained normal 2 years after treatment.

[Lymphoplasmacytic lymphoma accompanied by severe myelofibrosis].

A 61-year-old female was referred to our hospital because of pancytopenia and febrile neutropenia. On admission, computed tomography showed mild hepatosplenomegaly and intra-abdominal abscess formation in the right pelvic region; however, no lymphadenopathy was found. Bone marrow (BM) examination showed severe fibrosis by silver staining. Several small- to medium-sized lymphocytes with a constriction in the nuclei were observed, exhibiting CD3 (-), CD10 (-), CD20 (+), BCL-2 (+-), and CD138 (+-). Genetic testing revealed that BM cells were positive for MYD88 mutation and positive for IgH rearrangement, whereas neither JAK2 nor CALR mutation was positive. A diagnosis of BM infiltration of lymphoplasmacytic lymphoma (LPL) was made. Rituximab monotherapy was administered once a week for four times. BM examination 4 weeks after the end of treatment showed that lymphoma cells had disappeared and that myelofibrosis had been almost gone. The MYD88 mutation of BM turned out to be negative at that moment.

Disruption of the pancreatic vasculature in zebrafish affects islet architecture and function.

A dense local vascular network is crucial for pancreatic endocrine cells to sense metabolites and secrete hormones, and understanding the interactions between the vasculature and the islets may allow for therapeutic modulation in disease conditions. Using live imaging in two models of vascular disruption in zebrafish, we identified two distinct roles for the pancreatic vasculature. At larval stages, expression of a dominant negative version of Vegfaa (dnVegfaa) in ß-cells led to vascular and endocrine cell disruption with a minor impairment in ß-cell function. In contrast, expression of a soluble isoform of Vegf receptor 1 (sFlt1) in ß-cells blocked the formation of the pancreatic vasculature and drastically stunted glucose response, although islet architecture was not affected. Notably, these effects of dnVegfaa or sFlt1 were not observed in animals lacking vegfaa, vegfab, kdrl, kdr or flt1 function, indicating that they interfere with multiple ligands and/or receptors. In adults, disrupted islet architecture persisted in dnVegfaa-expressing animals, whereas sFlt1-expressing animals displayed large sheets of ß-cells along their pancreatic ducts, accompanied by impaired glucose tolerance in both models. Thus, our study reveals novel roles for the vasculature in patterning and function of the islet.

Radical-Based Coordination Polymers as a Platform for Magnetoluminescence.

Spin-correlated electronic and magnetic properties of organic radicals have been developed, but luminescence properties, based on interplay with spins, have rarely been reported. The effect of magnetic fields on luminescence (i.e., magnetoluminescence) is a rare example of such properties, observed to date only in radicals dispersed in host matrices. We now report a novel method for achieving radical magnetoluminescence involving radical-based coordination polymers (CPs). The luminescence properties of the bis(3,5-dichloro-4-pyridyl)(2,4,6-trichlorophenyl)methyl (bisPyTM) and tris(3,5-dichloro-4-pyridyl)methyl (trisPyM) radicals and their 1D and 2D ZnII CPs were investigated. Although solid-state emissions of bisPyTM and trisPyM were not affected significantly by external magnetic fields at 4.2 K, those of CPs were greatly modulated. Studies of the crystal structures, magnetic properties, and the temperature-dependence and time-resolved properties of the magnetoluminescence indicate that the reduction of radical-radical interactions in CPs would be a key method for achieving magnetoluminescence.

Gene expression profiles of the original tumors influence the generation of PDX models of lung squamous cell carcinoma.

Patient-derived xenograft (PDX) murine models are employed for preclinical research on cancers, including non-small cell lung cancers (NSCLCs). Even though lung squamous cell carcinomas (LUSCs) show the highest engraftment rate among NSCLCs, half of them nevertheless show PDX failure in immunodeficient mice. Here, using immunohistochemistry and RNA sequencing, we evaluated the distinct immunohistochemical and gene expression profiles of resected LUSCs that showed successful engraftment. Among various LUSCs, including the basal, classical, secretory, and primitive subtypes, those in the non-engrafting (NEG) group showed gene expression profiles similar to the pure secretory subtype with positivity for CK7, whereas those in the engrafting (EG) group were similar to the mixed secretory subtype with positivity for p63. Pathway analysis of 295 genes that demonstrated significant differences in expression between NEG and EG tumors revealed that the former had enriched expression of genes related to the immune system, whereas the latter had enriched expression of genes related to the cell cycle and DNA replication. Interestingly, NEG tumors showed higher infiltration of B cells (CD19+) and follicular dendritic cells (CD23+) in lymph follicles than EG tumors. Taken together, these findings suggest that the PDX cancer model of LUSC represents only a certain population of LUSCs and that CD19- and CD23-positive tumor-infiltrating immune cells in the original tumors may negatively influence PDX engraftment in immunodeficient mice.

Tet2 deficiency in immune cells exacerbates tumor progression by increasing angiogenesis in a lung cancer model.

Immune cells harboring somatic mutations reportedly infiltrate cancer tissues in patients with solid cancers and accompanying clonal hematopoiesis. Loss-of-function TET2 mutations are frequently observed in clonal hematopoiesis in solid cancers. Here, using a mouse lung cancer model, we evaluated the activity of Tet2-deficient immune cells in tumor tissues. Myeloid-specific Tet2 deficiency enhanced tumor growth in mice relative to that seen in controls. Single-cell sequencing analysis of immune cells infiltrating tumors showed relatively high expression of S100a8/S100a9 in Tet2-deficient myeloid subclusters. In turn, treatment with S100a8/S100a9 promoted Vegfa production by cancer cells, leading to a marked increase in the tumor vasculature in Tet2-deficient mice relative to controls. Finally, treatment of Tet2-deficient mice with an antibody against Emmprin, a known S100a8/S100a9 receptor, suppressed tumor growth. These data suggest that immune cells derived from TET2-mutated clonal hematopoiesis exacerbate lung cancer progression by promoting tumor angiogenesis and may provide a novel therapeutic target for lung cancer patients with TET2-mutated clonal hematopoiesis.

Structural and Magnetic Studies on Nickel(II) and Cobalt(II) Complexes with Polychlorinated Diphenyl(4-pyridyl)methyl Radical Ligands.

New magnetic metal complexes with organic radical ligands, [M(hfac)2(PyBTM)2] (M = NiII, CoII; hfac = hexafluoroacetylacetonato, PyBTM = (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical), were prepared and their crystal structures, magnetic properties, and electronic structures were investigated. Metal ions in [M(hfac)2(PyBTM)2] constructed distorted octahedral coordination geometry, where the two PyBTM molecules ligated in the trans configuration. Magnetic investigation using a SQUID magnetometer revealed that χT increased with decreasing temperature from 300 K in the two complexes, indicating an efficient intramolecular ferromagnetic exchange interaction taking place between the spins on PyBTM and M with J/kB of 21.8 K and 11.8 K for [NiII(hfac)2(PyBTM)2] and [CoII(hfac)2(PyBTM)2]. The intramolecular ferromagnetic couplings in the two complexes could be explained by density functional theory calculations, and would be attributed to a nearly orthogonal relationship between the spin orbitals on PyBTM and the metal ions. These results demonstrate that pyridyl-containing triarylmethyl radicals are key building blocks for magnetic molecular materials with controllable/predictable magnetic interactions.

[IgG-variant Bing-Neel syndrome diagnosed by detecting MYD88 L265P mutation in the cerebrospinal fluid cells].

Bing-Neel syndrome (BNS), which presents with a variety of neurological complications, is a rare manifestation of the lymphoplasmacytic lymphoma (LPL) and is characterized by the infiltration of LPL cells into the central nervous system. In this study, we report the case of a patient with BNS, which was confirmed by detecting MYD88 L265P mutation in the cerebrospinal fluid (CSF) cells. A 74-year-old patient was diagnosed with IgG-variant LPL. He achieved a very good partial response to the treatment with rituximab and bendamustine (RB) and was stable for over 5 years, when presenting a slowly progressive motor deficit in the lower limbs. It was difficult to confirm BNS from morphological analysis of the CSF cells. After detecting MYD88 L265P mutation in the CSF cells, he was subsequently diagnosed with BNS and treated with RB and intrathecal chemotherapy, resulting in rapid clinical improvement. With the onset of neurological manifestation during the clinical course of LPL, the detection of MYD88 L265P mutation in the CSF cells could be helpful for the diagnosis and management of BNS.

CNS-resident progenitors direct the vascularization of neighboring tissues.

Organ growth requires the coordinated invasion and expansion of blood vessel networks directed by tissue-resident cells and morphogenetic cues. A striking example of this intercellular communication is the vascularization of the central nervous system (CNS), which is driven by neuronal progenitors, including neuroepithelial cells and radial glia. Although the importance of neuronal progenitors in vascular development within the CNS is well recognized, how these progenitors regulate the vasculature outside the CNS remains largely unknown. Here we show that CNS-resident radial glia direct the vascularization of neighboring tissues during development. We find that genetic ablation of radial glia in zebrafish larvae leads to a complete loss of the bilateral vertebral arteries (VTAs) that extend along the ventrolateral sides of the spinal cord. Importantly, VTA formation is not affected by ablation of other CNS cell types, and radial glia ablation also compromises the subsequent formation of the peri-neural vascular plexus (PNVP), a vascular network that surrounds the CNS and is critical for CNS angiogenesis. Mechanistically, we find that radial glia control these processes via Vegfab/Vegfr2 signaling: vegfab is expressed by radial glia, and genetic or pharmacological inhibition of Vegfab/Vegfr2 signaling blocks the formation of the VTAs and subsequently of the PNVP. Moreover, mosaic overexpression of Vegfab in radial glia is sufficient to partially rescue the VTA formation defect in vegfab mutants. Thus, our findings identify a critical function for CNS-resident progenitors in the regulation of vascularization outside the CNS, serving as a paradigm for cross-tissue coordination of vascular morphogenesis and growth.

[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.

Cytoplasmic expression of epithelial cell transforming sequence 2 in lung adenocarcinoma and its implications for malignant progression.

Epithelial cell transforming sequence 2 (ECT2), a guanine nucleotide exchange factor, is predominantly localized in the nucleus of non-transformed cells and functions to regulate cytokinesis. ECT2 is also localized in the cytoplasm of cancer cells. Aberrant cytoplasmic expression of ECT2 is thought to drive tumor growth and invasion. In this study, we investigated the cytoplasmic expression of ECT2 and its prognostic and biological significance in lung adenocarcinoma. Western blotting of cellular fractions from the nucleus and cytoplasm was performed to determine the subcellular localization of ECT2 in lung adenocarcinoma cell lines. The cytoplasmic expression of ECT2 in 167 lung adenocarcinomas was evaluated by immunohistochemistry and its clinical significance was examined using Kaplan-Meier curves and Cox regression analysis. Scraping cytology specimens of 13 fresh lung adenocarcinomas were used to assess the subcellular localization of ECT2 and its phosphorylation at Thr790 (P-ECT2(T790)). We found that ECT2 was localized in both the nucleus and cytoplasm of lung adenocarcinoma cell lines and tumor tissues. Cytoplasmic expression of ECT2 was detected by immunohistochemistry in 83 (50%) of the lung adenocarcinomas, and was found to increase during cancer progression. It was expressed in 30 (29%) small adenocarcinomas ( ≤ 2 cm in diameter) and 53 (82%) advanced adenocarcinomas ( > 2 cm in diameter). Cytoplasmic positivity for ECT2 was associated with a poor outcome in terms of both disease-free and overall survival (both P < 0.001), and was an independent prognostic factor for overall survival (P = 0.025). Immunocytochemical staining for P-ECT2(T790) demonstrated cytoplasmic and membrane positivity in Calu-3 cells and scraping cytology specimens. Positive P-ECT2(T790) staining was correlated with cytoplasmic ECT2 expression in 6 of 13 scraped cytology specimens tested. In conclusion, our findings indicate that cytoplasmic ECT2 expression could promote the malignant progression of lung adenocarcinoma and may represent a potent therapeutic target for patients with lung adenocarcinoma.

Genetic evidence implies that primary and relapsed tumors arise from common precursor cells in primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is a rare subtype of lymphoma that arises within the brain or the eyes. PCNSL recurs within the central nervous system (CNS) in most relapsed cases, whereas extra-CNS relapse is experienced in rare cases. The present study aimed at identifying the presence of common precursor cells (CPC) for primary intra- and relapsed extra-CNS tumors, and further assessing the initiating events in bone marrow (BM). Targeted deep sequencing was carried out for five paired primary intra- and relapsed extra-CNS tumors of PCNSL. Two to five mutations were shared by each pair of intra- and extra-CNS tumors. In particular, MYD88 mutations, L265P in three and P258L in one, were shared by four pairs. Unique somatic mutations were observed in all five intra-CNS tumors and in four out of five extra-CNS tumors. Remarkably, IgH clones in the intra- and the extra-CNS tumors in two pairs were distinct from each other, whereas one pair of tumors shared identical monoclonal IgH rearrangement. In a cohort of 23 PCNSL patients, L265P MYD88 mutations were examined in tumor-free BM mononuclear cells (MNC) in which the PCNSL tumors had L265P MYD88 mutations. L265P MYD88 mutations were detected by a droplet digital PCR method in nine out of 23 bone marrow mononuclear cells. These results suggest that intra- and extra-tumors are derived from CPC with MYD88 mutations in most PCNSL, arising either before or after IgH rearrangement. The initiating MYD88 mutations may occur during B-cell differentiation in BM.

A Conformationally Flexible Macrocyclic Dipyrrin Tetramer and Its Unsymmetrically Twisted Luminescent Zinc(II) Complex.

A macrocyclic dipyrrin tetramer containing flexible m-phenylene linkages and its tetranuclear zinc(II) complex were synthesized. The obtained complex has an unsymmetrical figure-of-eight structure because of the conformational flexibility of the macrocyclic framework. The first µ-hydroxo- and µ-acetato-bridged dinuclear zinc(II) dipyrrin complex structure is realized in the twisted macrocyclic complex. Furthermore, the complex exhibited an efficient emission in toluene and chloroform.