SDHAF1 confers metabolic resilience to aging hematopoietic stem cells by promoting mitochondrial ATP production.

Aging generally predisposes stem cells to functional decline, impairing tissue homeostasis. Here, we report that hematopoietic stem cells (HSCs) acquire metabolic resilience that promotes cell survival. High-resolution real-time ATP analysis with glucose tracing and metabolic flux analysis revealed that old HSCs reprogram their metabolism to activate the pentose phosphate pathway (PPP), becoming more resistant to oxidative stress and less dependent on glycolytic ATP production at steady state. As a result, old HSCs can survive without glycolysis, adapting to the physiological cytokine environment in bone marrow. Mechanistically, old HSCs enhance mitochondrial complex II metabolism during stress to promote ATP production. Furthermore, increased succinate dehydrogenase assembly factor 1 (SDHAF1) in old HSCs, induced by physiological low-concentration thrombopoietin (TPO) exposure, enables rapid mitochondrial ATP production upon metabolic stress, thereby improving survival. This study provides insight into the acquisition of resilience through metabolic reprogramming in old HSCs and its molecular basis to ameliorate age-related hematopoietic abnormalities.

Context-dependent modification of PFKFB3 in hematopoietic stem cells promotes anaerobic glycolysis and ensures stress hematopoiesis.

Metabolic pathways are plastic and rapidly change in response to stress or perturbation. Current metabolic profiling techniques require lysis of many cells, complicating the tracking of metabolic changes over time after stress in rare cells such as hematopoietic stem cells (HSCs). Here, we aimed to identify the key metabolic enzymes that define differences in glycolytic metabolism between steady-state and stress conditions in murine HSCs and elucidate their regulatory mechanisms. Through quantitative 13C metabolic flux analysis of glucose metabolism using high-sensitivity glucose tracing and mathematical modeling, we found that HSCs activate the glycolytic rate-limiting enzyme phosphofructokinase (PFK) during proliferation and oxidative phosphorylation (OXPHOS) inhibition. Real-time measurement of ATP levels in single HSCs demonstrated that proliferative stress or OXPHOS inhibition led to accelerated glycolysis via increased activity of PFKFB3, the enzyme regulating an allosteric PFK activator, within seconds to meet ATP requirements. Furthermore, varying stresses differentially activated PFKFB3 via PRMT1-dependent methylation during proliferative stress and via AMPK-dependent phosphorylation during OXPHOS inhibition. Overexpression of Pfkfb3 induced HSC proliferation and promoted differentiated cell production, whereas inhibition or loss of Pfkfb3 suppressed them. This study reveals the flexible and multilayered regulation of HSC glycolytic metabolism to sustain hematopoiesis under stress and provides techniques to better understand the physiological metabolism of rare hematopoietic cells.

First report of familial mixed phenotype acute leukemia: shared clinical characteristics, Philadelphia translocation, and germline variants.

While our understanding of the molecular basis of mixed phenotype acute leukemia (MPAL) has progressed over the decades, our knowledge is limited and the prognosis remains poor. Investigating cases of familial leukemia can provide insights into the role of genetic and environmental factors in leukemogenesis. Although familial cases and associated mutations have been identified in some leukemias, familial occurrence of MPAL has never been reported. Here, we report the first cases of MPAL in a family. A 68-year-old woman was diagnosed with MPAL and received haploidentical stem cell transplantation from her 44-year-old son. In four years, the son himself developed MPAL. Both cases exhibited similar characteristics such as biphenotypic leukemia with B/myeloid cell antigens, Philadelphia translocation (BCR-ABL1 mutation), and response to acute lymphoblastic leukemia-type chemotherapy. These similarities suggest the presence of hereditary factors contributing to the development of MPAL. Targeted sequencing identified shared germline variants in these cases; however, in silico analyses did not strongly support their pathogenicity. Intriguingly, when the son developed MPAL, the mother did not develop donor-derived leukemia and remained in remission. Our cases provide valuable insights to guide future research on familial MPAL.

The Impact of Pretransplant Use of Tyrosine Kinase Inhibitors on Allogeneic Stem Cell Transplantation in Patients with Chronic Myeloid Leukemia-A Single-institution Retrospective Study.

Objective Chronic myeloid leukemia (CML) is a malignant hematological disorder, and allogeneic stem cell transplantation (allo-SCT) was its only curative treatment until the introduction of tyrosine kinase inhibitors (TKIs). Allo-SCT is still considered for CML patients who are resistant to TKIs and in an advanced phase. Currently, second- and third-generation (2/3 G) TKIs are typically incorporated into the first-line treatment of CML. However, the impact of 2/3 G TKIs on subsequent allo-SCT remains unclear. We therefore evaluated the effect of 2/3 G TKIs on allo-SCT. Methods We retrospectively evaluated the effect of pretransplant therapy with TKIs on the outcome of allo-SCT for CML using clinical data at our institution. Patients or Materials Thirty-two CML patients who received their first allo-SCT procedure at our institute from 2001 to 2020 were included. We divided the patients into three subgroups based on TKI treatment before allo-SCT. Patients receiving no TKIs, only imatinib (IM), and 2/3 G TKIs were classified into the Non-TKI, IM, and 2/3 G TKI groups, respectively. Results In a univariate analysis, the pretransplant use of 2/3 G TKIs was significantly associated with a higher 5-year overall survival (91.7%) and relapse-free survival (75.0%) than the use of IM (37.5% and 12.5%) in patients presenting with or progressing to the advanced phase. In addition, pretransplant use of 2/3 G TKIs did not increase the incidence of graft-versus-host disease (GVHD). Conclusions We demonstrated that the pretransplant use of 2/3 G TKIs was safe and improved the outcome of CML patients who presented with or progressed to the advanced phase without increasing the frequency of GVHD.

Mechanism of Drug-Eluting Stent Thrombosis Diagnosed by Histopathological Evaluation of Directional Coronary Atherectomy Specimen.

An 89-year-old man with a history of percutaneous coronary intervention using a sirolimus-eluting stent presented with recurrent in-stent occlusion. Pathological assessment of the neointima resected via directional coronary atherectomy revealed a double-layered thrombus. Clopidogrel resistance and limited antithrombotic regimen owing to high bleeding risk likely resulted in the in-stent thrombotic occlusion.

Quantitative Analysis of Sympathetic and Nociceptive Innervation Across Bone Marrow Regions in Mice.

Bone marrow (BM) innervation regulates the mobilization of hematopoietic stem and progenitor cells (HSPCs) from BM and stress hematopoiesis either by acting directly on HSPCs or by altering the niche function of mesenchymal and endothelial cells. However, the spatial distribution of BM innervation across bone regions is yet to be fully elucidated. Thus, we aimed to characterize the distribution of sympathetic and nociceptive nerves in each bone and BM region using three-dimensional quantitative microscopy. We discovered that sympathetic and nociceptive nerves were the major fibers throughout the BM. Compared with other femoral regions, central parts of the femoral BM were more densely innervated by both sympathetic and nociceptive nerves. Each region of the sternum was similarly innervated by sympathetic and nociceptive nerves. Further, the majority of sympathetic and nociceptive nerves in the BM ran parallel with arteries and arterioles, whereas the degree varied according to the bone type or BM region. In conclusion, this study provides spatial, topological, and functional information on BM innervation in a quantitative manner and illustrates that sympathetic and nociceptive nerves are two major components in BM innervation, mostly associated with arteries and arterioles.

Real-world efficacy of letermovir prophylaxis for cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation: A single-center retrospective analysis.

INTRODUCTION: Cytomegalovirus (CMV) infection is a common complication following allogeneic hematopoietic stem cell transplantation (aHSCT) and is associated with increased mortality. Letermovir (LET) is a novel antiviral drug used to prevent CMV infection. METHODS: We analyzed 111 consecutive patients who underwent aHSCT, retrospectively, to evaluate the efficacy of LET prophylaxis for clinically significant CMV infection (csCMVi) in real-world situations. In addition, we analyzed the influence of LET on transplant outcomes. Thirty-eight patients who were administered LET prophylactically were compared with 73 patients without LET prophylaxis after aHSCT. RESULTS: On day 180, the cumulative incidence of csCMVi in patients who received LET prophylaxis was significantly lower than that in patients without LET prophylaxis (29.7% vs. 56.2%, P < 0.001). Among the patients who developed csCMVi, the interval from aHSCT to the initiation of preemptive therapy was significantly longer in patients who received LET prophylaxis than in those who did not (129.5 days vs. 42 days, P < 0.001). The six-month overall survival was 86.1% in patients who received LET prophylaxis and 66.8% in the non-LET group (P = 0.035). CONCLUSION: LET prophylaxis was highly effective in preventing csCMVi and could potentially improve transplant outcomes, particularly when initiated early after transplantations.

Essential Roles of the Transcription Factor NR4A1 in Regulatory T Cell Differentiation under the Influence of Immunosuppressants.

Calcineurin inhibitors (CNIs), used as immunosuppressants, have revolutionized transplantation medicine with their strong suppressive activity on alloreactive T lymphocytes; however, they may also cause various adverse effects, including an increased risk for infection and nephrotoxicity. Regulatory T (Treg) cells can complement the deleterious side effects of CNIs with their effective Ag-specific suppressive activities. However, several studies have shown that CNIs suppress Treg cell differentiation. Therefore, an understanding of the mechanisms by which CNIs suppress Treg cell differentiation, as well as an approach for promoting the differentiation of Treg cells in the presence of CNIs, has significant clinical value. In this article, we report that the nuclear orphan receptor Nr4a1 plays a pivotal role in Treg cell differentiation in the presence of CNIs. Unlike that of its family members, Nr4a2 and Nr4a3, the expression of Nr4a1 was not suppressed by CNI treatment, thereby mediating Treg cell differentiation in the presence of CNIs. In a mouse allogeneic graft-versus-host disease model, Nr4a1 mediated tolerance by promoting Treg cell differentiation in mice administered cyclosporine A, prolonging the survival of recipients. Furthermore, activation of Nr4a1 via its agonist partially restored Treg cell differentiation, which was suppressed by cyclosporine A treatment. Finally, we found that the rs2701129 single-nucleotide polymorphism, which was shown to downregulate NR4A1 expression, showed a trend toward a higher incidence of chronic graft-versus-host disease in patients undergoing hematopoietic stem cell transplantation. Therefore, our study will be of clinical significance because we demonstrated the role of Nr4a1 in Treg cell differentiation in the presence of CNIs.

A culture platform to study quiescent hematopoietic stem cells following genome editing.

Other than genetically engineered mice, few reliable platforms are available for the study of hematopoietic stem cell (HSC) quiescence. Here we present a platform to analyze HSC cell cycle quiescence by combining culture conditions that maintain quiescence with a CRISPR-Cas9 genome editing system optimized for HSCs. We demonstrate that preculture of HSCs enhances editing efficiency by facilitating nuclear transport of ribonucleoprotein complexes. For post-editing culture, mouse and human HSCs edited based on non-homologous end joining and cultured under low-cytokine, low-oxygen, and high-albumin conditions retain their phenotypes and quiescence better than those cultured under the proliferative conditions. Using this approach, HSCs regain quiescence even after editing by homology-directed repair. Our results show that low-cytokine culture conditions for gene-edited HSCs are a useful approach for investigating HSC quiescence ex vivo.

Elevation of Early Plasma Biomarkers in Patients with Clinical Risk Factors Predicts Increased Nonrelapse Mortality after Allogeneic Hematopoietic Stem Cell Transplantation.

Early prediction of nonrelapse mortality (NRM) in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) based on the results of laboratory tests is challenging. Thus, there is a need to evaluate biomarkers for prediction of NRM, a major problem that offsets the advantages of allo-HSCT. We tested the validity and efficacy of 2 plasma biomarkers, ST2 and Reg3α, based on the Mount Sinai Acute GVHD International Consortium (MAGIC) algorithm, for early prediction of NRM in Japanese patients who underwent allo-HSCT. We conducted a multicenter retrospective study to analyze the clinical data of 112 patients with hematopoietic malignancies who underwent allo-HSCT. Patient blood samples on day 7 after allo-HSCT were obtained from 6 hospitals. The plasma concentrations of ST2 and Reg3α were used to calculate a 6-month NRM risk score. Based on the scores determined in this study, we identified 64 low-risk patients and 48 high-risk patients for the 6-month NRM. The cumulative incidence of 6-month NRM was 29.2% in the high-risk group and 10.9% in the low-risk group (P < .05). The cumulative incidence of relapse mortality was similar in the high-risk and low-risk patients. The biomarker score was predictive in patients with an unrelated donor, an HLA-mismatched donor, high/very high Disease Risk Index, and Hematopoietic Cell Transplantation Comorbidity Index ≥1. Multivariate analysis identified high biomarker probability as a significant predictor of NRM. The MAGIC algorithm based on blood samples obtained at 7 days after allo-HSCT can identify individuals at high risk for NRM among patients with clinical risk factors for NRM in a Japanese cohort.

Radiometric Calibration for a Multispectral Sensor Onboard RISESAT Microsatellite Based on Lunar Observations.

Radiometric calibration utilizing the Moon as a reference source is termed as lunar calibration. It is a useful method for evaluating the performance of optical sensors onboard satellites orbiting the Earth. Lunar calibration provides sufficient radiometric calibration opportunities without requiring any special equipment, and is suitable for nano/microsatellites. This study applies lunar calibration to a multispectral sensor, Ocean Observation Camera (OOC), on board a microsatellite named Rapid International Scientific Experiment Satellite. Simulating the brightness of the Moon based on the RObotic Lunar Observatory and SELENE/Spectrum Profiler models, sensitivity degradation was proven to be negligible in any of the four spectral bands of the OOC with the sensor temperature correction. A bluing trend in the OOC's sensor sensitivity was revealed, indicating a shorter observation wavelength shows larger irradiance. Comparing the top-of-atmosphere reflectance of Railroad Valley Playa with the Radiometric Calibration Network dataset revealed that the derived calibration parameter from the lunar calibration was valid for correcting the bluing trend in the visible range. Although the lunar and vicarious calibration parameters for the infrared band were unexpectedly inconsistent, lunar calibration could potentially contribute toward estimating the contaminated background radiance in the Earth observation images.

Multiple Myeloma with Central Nervous System Relapse Early after Autologous Stem Cell Transplantation: A Case Report and Literature Review.

Few reports have so far described central nervous system (CNS) involvement in multiple myeloma (MM), which shows a poor prognosis owing to its resistance to several treatments. We herein describe a 45-year-old woman who had MM (diagnosed with IgA-κ type) with CNS relapse early after undergoing autologous hematopoietic stem cell transplantation. Because no standard treatment for CNS lesions of MM has been established, we conducted a literature review on the cerebrospinal fluid (CSF) transferability of drugs for MM, since it was considered to be a useful tool for CNS involvement. Immunomodulatory-drugs including pomalidomide exhibit a good CSF transfer ability, and, therefore, may be beneficial against the CNS involvement of MM.

Detection of residual disease in chronic myeloid leukemia utilizing genomic next generation sequencing reveals persistence of differentiated Ph+ B cells but not bone marrow stem/progenitors.

Persistence of leukemic stem cells (LSCs) results in the recurrence of chronic myeloid leukemia (CML) after the administration of tyrosine kinase inhibitors (TKIs). Thus, the detection of minimal residual disease (MRD) with LSC potential can improve prognosis. Here, we analyzed 115 CML patients and found that CD25 was preferentially expressed on the phenotypic stem and progenitor cells (SPCs), and TKI therapy decreased the number of CD25-positive cells in the SPC fraction. To detect MRD harboring BCR-ABL1 fusion DNA, we developed a highly-sensitive method using patient-specific primers and next-generation sequencing. By using this method, we identified that in patients who achieved molecular remission, almost all residual CD25-positive SPCs were BCR-ABL1-negative. Moreover, in some patients BCR-ABL1 was detectable in peripheral B cells but not in SPCs. We conclude that CD25 marks LSCs at diagnosis but does not mark MRD following TKI treatment and that analysis of peripheral B cells can allow sensitive detection of MRD.

Refractory Chronic Lymphocytic Leukemia with Central Nervous System Involvement: A Case Report with Literature Review.

There have been few reports on central nervous system (CNS) involvement in chronic lymphocytic leukemia (CLL). This is an extremely rare disease with poor prognosis, owing to resistance to various treatments. We describe a 33-year-old man with intractable CLL with CNS involvement. He was diagnosed with CLL, with diplopia as the first manifestation. Magnetic resonance imaging revealed a contrast-enhancing tumor in the right temporal lobe, which was diagnosed as CNS involvement in CLL on brain biopsy. High-dose methotrexate therapy was ineffective for this lesion, which was also resistant to subsequent whole-brain irradiation, treatment with fludarabine-cyclophosphamide-rituximab chemoimmunotherapy, and ibrutinib administration. Because no standard protocol exists for CLL with CNS involvement, it is important to accumulate case data to verify the choice of new drugs for administration at an early stage. Therefore, we also conducted a literature review of 50 case reports of CNS lesions in the last 10 years to consider the pathophysiology, diagnosis, and treatment of CNS involvement in CLL. The possibility of new therapeutic agents, eg, ibrutinib and venetoclax, or a combination of these agents and methotrexate, can be envisioned as a treatment strategy for CLL with CNS involvement.

Effect of Transluminal Injection of Foam Sclerotherapy Combined with Endovenous Thermal Ablation of Varicose Veins.

OBJECTIVE: The combination of endovenous therapies with stab avulsion or ultrasound guided foam sclerotherapy is widely performed. However, these conventional techniques tend to result in incomplete avulsions or persistent varicosities. METHODS: One hundred and thirteen legs in 97 consecutive patients who underwent 1470 nm laser ablation for great saphenous varicose veins were enrolled. The foam sclerosing agent was injected via the sheath after endovenous laser ablation (EVLA). Patients were divided into two groups: EVLA only group (Control; n = 50) and EVLA and transluminal injection of foam sclerotherapy (TLFS) group (SCL; n = 63). RESULTS: At three month follow up, reflux was abolished throughout all treated great saphenous veins (GSVs) when assessed with Duplex ultrasound. Thrombophlebitis was observed in two patients in the SCL group (p = .13). Additional second stage sclerotherapy was needed in the Control group (n = 33, 66%) vs. SCL group (n = 2, 3%; p < .0001). The venous clinical severity score (VCSS) was significantly improved in the SCL group (changes of VCSS, Control -3.3 ± 1.7 and SCL -4.4 ± 1.0; p < .0001). Univariable and multivariable analyses revealed that, among age, sex, Clinical-Etiology-Anatomy-Pathophysiology classification, linear endovenous energy density, and TLFS, TLFS was the only significant factor of improved VCSS (hazard ratio = -0.96; 95% confidence interval = -1.4 to -0.58; p < .0001). CONCLUSIONS: TLFS combined with EVLA may be an easy, safe, and effective procedure with acceptable complications vs. EVLA alone and reduces additional second stage interventions.

A case of recurrent varicose veins due to the multiple fistulas from superficial femoral artery.

Recurrent varicose veins are considered to be caused by the recurrence of reflux but rarely may be secondary to other pathologies. A 39-year-old man complained of right lower leg skin pigmentation, pain and fatigue for several years. Duplex ultrasound revealed that the great saphenous vein diameter at the saphenofemoral junction level was 7.7 cm, and at the knee medial level was 14.4 cm. The reflux time at the proximal great saphenousvein level was 1.85 s. Endovenous laser ablation for dilated and refluxed great saphenous vein was performed. However, 1 year later, the symptoms recurred. Duplex ultrasound suspected abnormal arterial flow from the right superficial femoral artery to the recanalized segment of previously ablated great saphenous vein and anterior accessory saphenous vein. One month later, despite the successful re-endovenous laser ablation, the symptoms recurred. Computed tomography angiography showed three fistulous vessels from superficial femoral artery to anterior accessory saphenous vein. Combined treatments with endovenous laser ablation and coil embolization was performed. Ultimately, the fistulas were obliterated and the patient remained free of symptoms. Varicose veins due to the fistulas from superficial femoral artery are rare and difficult to diagnose but can be entirely treated with the percutaneous approach.

Clinical efficacy of mogamulizumab for relapsed/refractory aggressive adult T-cell leukemia/lymphoma: A retrospective analysis.

OBJECTIVES: Although phase 2 studies have confirmed the efficacy of mogamulizumab for adult T-cell leukemia/lymphoma (ATL), real-world data on its benefits are limited. We assessed the benefits of mogamulizumab for relapsed/refractory ATL in clinical practice. METHODS: We retrospectively analyzed patients with acute- and lymphoma-type ATL. Among 57 patients diagnosed with ATL between January 2008 and August 2018, 42 who received salvage therapy were eligible, including 24 who received mogamulizumab. RESULTS: The overall response rate to mogamulizumab was 54.2%. Median survival time (MST) and 1-year overall survival (OS) rate from mogamulizumab initiation were 7.7 months and 42.0%, respectively. Patients with acute-type ATL showed longer MST (15.1 months) and higher 1-year OS (63.6%). MST without skin rash was 5.0 months, and 1-year OS was 34.3%; however, MST with skin rash was not reached and 1-year OS was 66.7%. Among patients who received the salvage therapy, longer MST and higher 1-year OS were observed with mogamulizumab than without mogamulizumab (P = .078; 9.2 vs. 3.9 months; 47.9% vs. 17.6%, respectively). Mogamulizumab administration improved prognosis in patients with acute-type ATL and skin rash. CONCLUSIONS: In clinical practice, mogamulizumab improved OS in patients with relapsed/refractory ATL, especially those with acute-type ATL and skin rash.

Comparison of starting doses of anagrelide as a first-line therapy in patients with cytoreductive therapy-naïve essential thrombocythemia: difference between starting at 0.5 and 1.0 mg/day.

Anagrelide is widely used for cytoreductive therapy in patients with essential thrombocythemia who are at high risk for thrombosis. The recommended starting dose in the package insert of anagrelide varies by country. A high starting dose leads to an early onset of action, but causes a higher incidence of adverse events. This relationship indicates that both the onset of action and side effects of anagrelide are dose dependent. We retrospectively compared the efficacy and safety of anagrelide as a first-line drug between patients with essential thrombocythemia who started at 0.5 or 1.0 mg/day. Incidence of total adverse events and anagrelide-related palpitation, discontinuation rates, and the median daily dose of anagrelide were lower in the 0.5 mg/day group than in the 1.0 mg/day group; however, comparable platelet-lowering effects were achieved in both groups. These data suggest that a low starting dose of anagrelide followed by dose escalation may result in fewer adverse events and lower discontinuation rates, while providing desirable platelet-lowering effects. Initiating anagrelide at a lower dose may be a useful approach in actual clinical practice.

Identification and local manipulation of bone marrow vasculature during intravital imaging.

Physiological regulation of blood flow in bone marrow is important to maintain oxygen and glucose supplies but also the physiological hypoxic state of the hematopoietic stem cell (HSC) niche. However, regulatory mechanisms underlying microcirculation in the bone marrow (BM) niche remain unclear. Here, we identify vessels functioning in control of blood flow in bone marrow and assess their contractility. To evaluate contractile potential of Alexa Fluor 633 (AF633; an arterial marker)-positive vessels, we performed immunohistochemistry for α-smooth muscle actin (α-SMA) and found it expressed around AF633+ vessels in the femoral and calvarial marrow. To validate AF633+ vessel contractility, we developed a simple system to locally administer vasoactive agents that penetrate BM through transcalvarial vessels. After exposure of the calvarial surface to FITC-dextran (70 kDa), FITC intensity in calvarial bone marrow gradually increased. When we evaluated the effect of transcalvarial administration (TCA) of norepinephrine (NE) on vascular tone of AF633+ arteries and behavior of transplanted blood cells, NE administration decreased artery diameter and transendothelial migration of transplanted cells, suggesting that adrenergic signaling regulates the HSC niche microcirculation and blood cell migration into the BM via effects on BMarteries. We conclude that TCA is a useful tool for bone marrow research.