Search

Aging of hematopoietic stem cells (HSCs) is accompanied by impaired self-renewal ability, myeloid skewing, immunodeficiencies and increased susceptibility to malignancies. Although previous studies highlighted the pivotal roles of individual metabolites in hematopoiesis, comprehensive and high-resolution metabolomic profiles of different hematopoietic cells across ages are still lacking. In this study, we created a metabolome atlas of different blood cells across ages in mice. We reveal here that purine, pyrimidine and retinol metabolism are enriched in young hematopoietic stem and progenitor cells (HSPCs), whereas glutamate and sphingolipid metabolism are concentrated in aged HSPCs. Through metabolic screening, we identified uridine as a potential regulator to rejuvenate aged HSPCs. Mechanistically, uridine treatment upregulates the FoxO signaling pathway and enhances self-renewal while suppressing inflammation in aged HSCs. Finally, we constructed an open-source platform for public easy access and metabolomic analysis in blood cells. Collectively, we provide a resource for metabolic studies in hematopoiesis that can contribute to future anti-aging metabolite screening., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Background: Ionizing radiation (IR), including radiotherapy, can exert lasting harm on living organisms. While liposaccharide (LPS) offers resistance to radiation damage, it also induces toxic responses. Thankfully, an LPS analogue called N-formylmethionine-leucyl-phenylalanine (fMLP) holds the potential to mitigate this toxicity, offering hope for radiation protection., Methods: Survival of C57BL/6 mice exposed to IR after administration with fMLP/LPS/WR-2721 or saline was recorded. Cell viability and apoptosis assay of bone marrow (BMC), spleen and small intestinal epithelial (HIECs) cells were tested by Cell Counting Kit-8 (CCK-8) and flow cytometry assay. Tissue damage was evaluated by Hematoxilin and Eosin (H&E), Ki-67, and TUNEL staining. RNA sequencing was performed to reveal potential mechanisms of fMLP-mediated radiation protection. Flow cytometry and western blot were performed to verify the radiation protection mechanism of fMLP on the cell cycle., Results: The survival rates of C57BL/6 mice exposed to ionizing radiation after administering fMLP increased. fMLP demonstrated low toxicity in vitro and in vivo, maintaining cell viability and mitigating radiation-induced apoptosis. Moreover, it protected against tissue damage in the hematopoietic and intestinal system. RNA sequencing shed light on fMLP's potential mechanism, suggesting its role in modulating innate immunity and cell cycling. This was evidenced by its ability to reverse radiation-induced G2/M phase arrests in HIECs., Conclusion: fMLP serves as a promising radioprotective agent, preserving cells and radiosensitive tissues from IR. Through its influence on the cell cycle, particularly reversing radiation-induced arrest in G2/M phases, fMLP offers protection against IR's detrimental effects., (© 2024. The Author(s).)

Therapeutic neutralization of Oncostatin M (OSM) causes mechanism-driven anemia and thrombocytopenia, which narrows the therapeutic window complicating the selection of doses (and dosing intervals) that optimize efficacy and safety. We utilized clinical data from studies of an anti-OSM monoclonal antibody (GSK2330811) in healthy volunteers (n = 49) and systemic sclerosis patients (n = 35), to quantitatively determine the link between OSM and alterations in red blood cell (RBC) and platelet production. Longitudinal changes in hematopoietic variables (including RBCs, reticulocytes, platelets, erythropoietin, and thrombopoietin) were linked in a physiology-based model, to capture the long-term effects and variability of therapeutic OSM neutralization on human hematopoiesis. Free serum OSM stimulated precursor cell production through sigmoidal relations, with higher maximum suppression (I max ) and OSM concentration for 50% suppression (IC 50 ) for platelets (89.1% [95% confidence interval: 83.4-93.0], 6.03 pg/mL [4.41-8.26]) than RBCs (57.0% [49.7-64.0], 2.93 pg/mL [2.55-3.36]). Reduction in hemoglobin and platelets increased erythro- and thrombopoietin, respectively, prompting reticulocytosis and (partially) alleviating OSM-restricted hematopoiesis. The physiology-based model was substantiated by preclinical data and utilized in exploration of once-weekly or every other week dosing regimens. Predictions revealed an (for the indication) unacceptable occurrence of grade 2 (67% [58-76], 29% [20-38]) and grade 3 (17% [10-25], 3% [0-7]) anemias, with limited thrombocytopenia. Individual extent of RBC precursor modulation was moderately correlated to skin mRNA gene expression changes. The physiological basis and consideration of interplay among hematopoietic variables makes the model generalizable to other drug and nondrug scenarios, with adaptations for patient populations, diseases, and therapeutics that modulate hematopoiesis or exhibit risk of anemia and/or thrombocytopenia., (© 2024 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Anti-CD117 monoclonal antibody (mAb) agents have emerged as exciting alternative conditioning strategies to traditional genotoxic irradiation or chemotherapy for both allogeneic and autologous gene-modified hematopoietic stem cell transplantation. Furthermore, these agents are concurrently being explored in the treatment of mast cell disorders. Despite promising results in animal models and more recently in patients, the short- and long-term effects of these treatments have not been fully explored. We conducted rigorous assessments to evaluate the effects of an antagonistic anti-mCD117 mAb, ACK2, on hematopoiesis in wild-type and Fanconi anemia (FA) mice. Importantly, we found no evidence of short-term DNA damage in either setting following this treatment, suggesting that ACK2 does not induce immediate genotoxicity, providing crucial insights into its safety profile. Surprisingly, FA mice exhibited an increase in colony formation after ACK2 treatment, indicating a potential targeting of hematopoietic stem cells and expansion of hematopoietic progenitor cells. Moreover, the long-term phenotypic and functional changes in hematopoietic stem and progenitor cells did not differ significantly between the ACK2-treated and control groups, in either setting, suggesting that ACK2 does not adversely affect hematopoietic capacity. These findings underscore the safety of these agents when utilized as a short-course treatment in the context of conditioning, as they did not induce significant DNA damage in hematopoietic stem or progenitor cells. However, single-cell RNA sequencing, used to compare gene expression between untreated and treated mice, revealed that the ACK2 mAb, via c-Kit downregulation, effectively modulated the MAPK pathway with Fos downregulation in wild-type and FA mice. Importantly, this modulation was achieved without causing prolonged disruptions. These findings validate the safety of anti-CD117 mAb treatment and also enhance our understanding of its intricate mode of action at the molecular level.

Extensive application of rare earth element oxide nanoparticles (REE NPs) has raised a concern over the possible toxic health effects after human exposure. Once entering the body, REE NPs are primarily processed by phagocytes in particular macrophages and undergo biotic phosphate complexation in lysosomal compartment. Such biotransformation affects the target organs and in vivo fate of REE NPs after escaping the lysosomes. However, the immunomodulatory effects of intraphagolysosomal dissolved REE NPs remains insufficient. Here, europium oxide (Eu 2 O 3 ) NPs were pre-incubated with phagolysosomal simulant fluid (PSF) to mimic the biotransformation of europium oxide (p-Eu 2 O 3 ) NPs under acid phagolysosome conditions. We investigated the alteration in immune cell components and the hematopoiesis disturbance on adult mice after intravenous administration of Eu 2 O 3 NPs and p-Eu 2 O 3 NPs. Our results indicated that the liver and spleen were the main target organs for Eu 2 O 3 NPs and p-Eu 2 O 3 NPs. Eu 2 O 3 NPs had a much higher accumulative potential in organs than p-Eu 2 O 3 NPs. Eu 2 O 3 NPs induced more alterations in immune cells in the spleen, while p-Eu 2 O 3 NPs caused stronger response in the liver. Regarding hematopoietic disruption, Eu 2 O 3 NPs reduced platelets (PLTs) in peripheral blood, which might be related to the inhibited erythrocyte differentiation in the spleen. By contrast, p-Eu 2 O 3 NPs did not cause significant disturbance in peripheral PLTs. Our study demonstrated that the preincubation with PSF led to a distinct response in the immune system compared to the pristine REE NPs, suggesting that the potentially toxic effects induced by the release of NPs after phagocytosis should not be neglected, especially when evaluating the safety of NPs application in vivo., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Ionising radiation exposure can lead to acute haematopoietic radiation syndrome. Despite significant advancements in the field of radioprotection, no drugs with high efficacy and low toxicity have yet been approved by the Food and Drug Administration. FG-4592, as a proline hydroxylase inhibitor, may play an important role in radioprotection of the haematopoietic system. Mice were peritoneal injected with FG-4592 or normal saline. After irradiation, the survival time, body weight, peripheral blood cell and bone marrow cell (BMC) count, cell apoptosis, pathology were analysed and RNA-sequence technique (RNA-Seq) was conducted to explore the mechanism of FG-4592 in the haematopoietic system. Our results indicated that FG-4592 improved the survival rate and weight of irradiated mice and protected the spleen, thymus and bone marrow from IR-induced injury. The number of BMCs was increased and protected against IR-induced apoptosis. FG-4592 also promoted the recovery of the blood system and erythroid differentiation. The results of RNA-Seq and Western blot showed that the NF-κB signalling pathway and hypoxia-inducible factor-1 (HIF-1) signalling pathway were upregulated by FG-4592. Meanwhile, RT-PCR results showed that FG-4592 could promote inflammatory response significantly. FG-4592 exhibited radioprotective effects in the haematopoietic system by promoting inflammatory response and targeting the NF-κB, HIF signalling pathway., (© 2024 The Authors. Immunology published by John Wiley & Sons Ltd.)

There has been a global increase in the older population in recent decades and, as age advances, complex metabolic and epigenetic changes occur in the organism, and these may trigger some health complications commonly found among this population. Additionally, several changes occur in older people that can reduce the dietary intake or the process of nutrient absorption. In this way, tissues with high nutrient requirements are more affected. Hematopoiesis is the process of formation, development, and maturation of blood cells and is a process with a high turnover. This high demand makes the integrity of the hematopoietic process susceptible to various factors that impair physiological function, such as aging and micronutrient bioavailability. Among these micronutrients, Zinc is considered an important micronutrient, playing diverse roles across various tissues and cell types. Some of the alterations in hematopoiesis that appear as a consequence of aging and due to insufficient micronutrient intake are well described in the literature; however, not much is known about how zinc deficiency contributes towards the development of diseases seen in aging. Considering the importance of zinc to act on several biological processes, this narrative review discusses several studies related to the physiological requirements, deficiency, or excess of zinc, including studies in experimental models and humans, and aimed to shed light on the relationship between zinc and the regulation of hematopoietic tissue, exploring possible links between this mineral with common disorders that appear during aging., (© The Author(s) 2023. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Generation of hematopoietic stem and progenitor cells (HSPCs) ex vivo and in vivo, especially the generation of safe therapeutic HSPCs, still remains inefficient. In this study, we have identified compound BF170 hydrochloride as a previously unreported pro-hematopoiesis molecule, using the differentiation assays of primary zebrafish blastomere cell culture and mouse embryoid bodies (EBs), and we demonstrate that BF170 hydrochloride promoted definitive hematopoiesis in vivo. During zebrafish definitive hematopoiesis, BF170 hydrochloride increases blood flow, expands hemogenic endothelium (HE) cells and promotes HSPC emergence. Mechanistically, the primary cilia-Ca2+-Notch/NO signaling pathway, which is downstream of the blood flow, mediated the effects of BF170 hydrochloride on HSPC induction in vivo. Our findings, for the first time, reveal that BF170 hydrochloride is a compound that enhances HSPC induction and may be applied to the ex vivo expansion of HSPCs., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

We conducted this study to investigate the radioprotective effects of recombinant human thrombopoietin (rhTPO) on beagle dogs irradiated with 3.0 Gy 60Co gamma rays. Fifteen healthy adult beagles were randomly assigned to a control group with alleviating care, and 5 and 10 μg/kg rhTPO treatment group. All animals received total-body irradiation using 60Co γ-ray source at a dose of 3.0 Gy (dose rate was 69.1 cGy/min). The treatment group received intramuscular injection of rhTPO 5 and 10 μg/kg at 2 h postirradiation, and the control group was administrated the same volume of normal saline. The survival rate, clinical signs, peripheral hemogram, serum biochemistry, and histopathological examination of animals in each group were assessed. Single administration of 10 μg/kg rhTPO at 2 h postirradiation promoted the recovery of multilineage hematopoiesis and improved the survival rate of beagles irradiated with 3 Gy 60Co γ rays. The administration of 10 μg/kg rhTPO alleviated fever and bleeding, reduced the requirement for supportive care, and may have mitigated multiple organ damage., (© 2024 by Radiation Research Society. All rights of reproduction in any form reserved.)

Dysfunctional bone marrow (BM) endothelial progenitor cells (EPCs) with high levels of reactive oxygen species (ROS) are responsible for defective hematopoiesis in poor graft function (PGF) patients with acute leukemia or myelodysplastic neoplasms post-allotransplant. However, the underlying mechanism by which BM EPCs regulate their intracellular ROS levels and the capacity to support hematopoiesis have not been well clarified. Herein, we demonstrated decreased levels of peroxisome proliferator-activated receptor delta (PPARδ), a lipid-activated nuclear receptor, in BM EPCs of PGF patients compared with those with good graft function (GGF). In vitro assays further identified that PPARδ knockdown contributed to reduced and dysfunctional BM EPCs, characterized by the impaired ability to support hematopoiesis, which were restored by PPARδ overexpression. Moreover, GW501516, an agonist of PPARδ, repaired the damaged BM EPCs triggered by 5-fluorouracil (5FU) in vitro and in vivo. Clinically, activation of PPARδ by GW501516 benefited the damaged BM EPCs from PGF patients or acute leukemia patients in complete remission (CR) post-chemotherapy. Mechanistically, we found that increased expression of NADPH oxidases (NOXs), the main ROS-generating enzymes, may lead to elevated ROS level in BM EPCs, and insufficient PPARδ may trigger BM EPC damage via ROS/p53 pathway. Collectively, we found that defective PPARδ contributes to BM EPC dysfunction, whereas activation of PPARδ in BM EPCs improves their hematopoiesis-supporting ability after myelosuppressive therapy, which may provide a potential therapeutic target not only for patients with leukemia but also for those with other cancers., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests. All co-author shave seen and approved this version of the manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Angelica sinensis (AS) can improve the haematopoietic function, but the treatment mechanism is unknown. Transfusion dependency was estimated by Kaplan-Meier survival analyses and Cox proportional-hazard model in AS treated apalstic anemia (AA) patients. After that, the AA GEO database was analysed, the up differentially expressed genes (DEGs) of AA were combined with AS targets for the intersection of targets. After the AA mouse model was established, the effect of AS was confirmed by haematopoietic function tests. The same experiment plus mitochondrial apoptotic pathway tests in vivo were performed in Angelica sinensis polysaccharide (ASP)-treated mice, the key ingredient in AS. For in vitro experiment, bone marrow nucleated cells (BMNCs) were tested. Clinical data confirmed that the level of transfusion dependency and IL17A were lower in AS-users compared to non-AS users ( p < 0.001). The intersection of targets between AA and AS most concentrated on inflammation and apoptosis. Then, the same effect was found in AS treated AA mice model. In both in vivo and in vitro tests, ASP demonstrated the ability to mitigate P38/MAPK-induced Bax-associated mitochondrial apoptosis, while also reducing the levels of activated Th17 cells and alleviating abnormal cytokine levels. So, the protective effect of AS and ASP on hematopoietic function lies in their ability to prevent apoptosis.

Purpose: Mitochondrial oxidative stress is an important factor in cell apoptosis. Cerium oxide nanomaterials show great potential for scavenging free radicals and simulating superoxide dismutase (SOD) and catalase (CAT) activities. To solve the problem of poor targeting of cerium oxide nanomaterials, we designed albumin-cerium oxide nanoclusters (TPP-PCNLs) that target the modification of mitochondria with triphenyl phosphate (TPP). TPP-PCNLs are expected to simulate the activity of superoxide dismutase, continuously remove reactive oxygen species, and play a lasting role in radiation protection., Methods: First, cerium dioxide nanoclusters (CNLs), polyethylene glycol cerium dioxide nanoclusters (PCNLs), and TPP-PCNLs were characterized in terms of their morphology and size, ultraviolet spectrum, dispersion stability and cellular uptake, and colocalization Subsequently, the anti-radiation effects of TPP-PCNLs were investigated using in vitro and in vivo experiments including cell viability, apoptosis, comet assays, histopathology, and dose reduction factor (DRF)., Results: TPP-PCNLs exhibited good stability and biocompatibility. In vitro experiments indicated that TPP-PCNLs could not only target mitochondria excellently but also regulate reactive oxygen species (ROS)levels in whole cells. More importantly, TPP-PCNLs improved the integrity and functionality of mitochondria in irradiated L-02 cells, thereby indirectly eliminating the continuous damage to nuclear DNA caused by mitochondrial oxidative stress. TPP-PCNLs are mainly targeted to the liver, spleen, and other extramedullary hematopoietic organs with a radiation dose reduction factor of 1.30. In vivo experiments showed that TPP-PCNLs effectively improved the survival rate, weight change, hematopoietic function of irradiated animals. Western blot experiments have confirmed that TPP-PCNLs play a role in radiation protection by regulating the mitochondrial apoptotic pathway., Conclusion: TPP-PCNLs play a radiologically protective role by targeting extramedullary hematopoietic organ-liver cells and mitochondria to continuously clear ROS., Competing Interests: The authors report no conflicts of interest in this work., (© 2024 Yang et al.)

While myelodysplastic syndromes with del(5q) (del(5q) MDS) comprises a well-defined hematological subgroup, the molecular basis underlying its origin remains unknown. Using single cell RNA-seq (scRNA-seq) on CD34 + progenitors from del(5q) MDS patients, we have identified cells harboring the deletion, characterizing the transcriptional impact of this genetic insult on disease pathogenesis and treatment response. Interestingly, both del(5q) and non-del(5q) cells present similar transcriptional lesions, indicating that all cells, and not only those harboring the deletion, may contribute to aberrant hematopoietic differentiation. However, gene regulatory network (GRN) analyses reveal a group of regulons showing aberrant activity that could trigger altered hematopoiesis exclusively in del(5q) cells, pointing to a more prominent role of these cells in disease phenotype. In del(5q) MDS patients achieving hematological response upon lenalidomide treatment, the drug reverts several transcriptional alterations in both del(5q) and non-del(5q) cells, but other lesions remain, which may be responsible for potential future relapses. Moreover, lack of hematological response is associated with the inability of lenalidomide to reverse transcriptional alterations. Collectively, this study reveals transcriptional alterations that could contribute to the pathogenesis and treatment response of del(5q) MDS., (© 2024. The Author(s).)

Haematopoietic stem cell (HSC) transplantation (HSCT) is the only curative treatment for a broad range of haematological malignancies, but the standard of care relies on untargeted chemotherapies and limited possibilities to treat malignant cells after HSCT without affecting the transplanted healthy cells 1 . Antigen-specific cell-depleting therapies hold the promise of much more targeted elimination of diseased cells, as witnessed in the past decade by the revolution of clinical practice for B cell malignancies 2 . However, target selection is complex and limited to antigens expressed on subsets of haematopoietic cells, resulting in a fragmented therapy landscape with high development costs 2-5 . Here we demonstrate that an antibody-drug conjugate (ADC) targeting the pan-haematopoietic marker CD45 enables the antigen-specific depletion of the entire haematopoietic system, including HSCs. Pairing this ADC with the transplantation of human HSCs engineered to be shielded from the CD45-targeting ADC enables the selective eradication of leukaemic cells with preserved haematopoiesis. The combination of CD45-targeting ADCs and engineered HSCs creates an almost universal strategy to replace a diseased haematopoietic system, irrespective of disease aetiology or originating cell type. We propose that this approach could have broad implications beyond haematological malignancies., (© 2024. The Author(s).)

Abstract: Hyperproliferation of myeloid and erythroid cells in myeloproliferative neoplasms (MPN) driven by the JAK2-V617F mutation is associated with altered metabolism. Given the central role of glutamine in anabolic and catabolic pathways, we examined the effects of pharmacologically inhibiting glutaminolysis, that is, the conversion of glutamine (Gln) to glutamate (Glu), using CB-839, a small molecular inhibitor of the enzyme glutaminase (GLS). We show that CB-839 strongly reduced the mitochondrial respiration rate of bone marrow cells from JAK2-V617F mutant (VF) mice, demonstrating a marked dependence of these cells on Gln-derived ATP production. Consistently, in vivo treatment with CB-839 normalized blood glucose levels, reduced splenomegaly and decreased erythrocytosis in VF mice. These effects were more pronounced when CB-839 was combined with the JAK1/2 inhibitor ruxolitinib or the glycolysis inhibitor 3PO, indicating possible synergies when cotargeting different metabolic and oncogenic pathways. Furthermore, we show that the inhibition of glutaminolysis with CB-839 preferentially lowered the proportion of JAK2-mutant hematopoietic stem cells (HSCs). The total number of HSCs was decreased by CB-839, primarily by reducing HSCs in the G1 phase of the cell cycle. CB-839 in combination with ruxolitinib also strongly reduced myelofibrosis at later stages of MPN. In line with the effects shown in mice, proliferation of CD34+ hematopoietic stem and progenitor cells from polycythemia vera patients was inhibited by CB-839 at nanomolar concentrations. These data suggest that inhibiting GLS alone or in combination with inhibitors of glycolysis or JAK2 inhibitors represents an attractive new therapeutic approach to MPN., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

In the current geopolitical climate there is an unmet need to identify and develop prophylactic radiation countermeasures, particularly to ensure the well-being of warfighters and first responders that may be required to perform on radiation-contaminated fields for operational or rescue missions. Currently, no countermeasures have been approved by the U.S. FDA for prophylactic administration. Here we report on the efficacious nature of FSL-1 (toll-like receptor 2/6 agonist) and the protection from acute radiation syndrome (ARS) in a murine total-body irradiation (TBI) model. A single dose of FSL-1 was administered subcutaneously in mice. The safety of the compound was assessed in non-irradiated animals, the efficacy of the compound was assessed in animals exposed to TBI in the AFRRI Co-60 facility, the dose of FSL-1 was optimized, and common hematological parameters [complete blood cell (CBC), cytokines, and bone marrow progenitor cells] were assessed. Animals were monitored up to 60 days after exposure and radiation-induced damage was evaluated. FSL-1 was shown to be non-toxic when administered to non-irradiated mice at doses up to 3 mg/kg. The window of efficacy was determined to be 24 h prior to 24 h after TBI. FSL-1 administration resulted in significantly increased survival when administered either 24 h prior to or 24 h after exposure to supralethal doses of TBI. The optimal dose of FSL-1 administration was determined to be 1.5 mg/kg when administered prior to irradiation. Finally, FSL-1 protected the hematopoietic system (recovery of CBC and bone marrow CFU). Taken together, the effects of increased survival and accelerated recovery of hematological parameters suggests that FSL-1 should be developed as a novel radiation countermeasure for soldiers and civilians, which can be used either before or after irradiation in the aftermath of a radiological or nuclear event., (©2024 by Radiation Research Society. All rights of reproduction in any form reserved.)

A renewable source of porcine macrophages derived from pluripotent stem cells (PSCs) would be a valuable alternative to primary porcine alveolar macrophages (PAMs) in the research of host-pathogen interaction mechanisms. We developed an efficient and rapid protocol, within 11 days, to derive macrophages from porcine PSCs (pPSCs). The pPSC-derived macrophages (pPSCdMs) exhibited molecular and functional characteristics of primary macrophages. The pPSCdMs showed macrophage-specific surface protein expression and macrophage-specific transcription factors, similar to PAMs. The pPSCdMs also exhibited the functional characteristics of macrophages, such as endocytosis, phagocytosis, porcine respiratory and reproductive syndrome virus infection and the response to lipopolysaccharide stimulation. Furthermore, we performed transcriptome sequencing of the whole differentiation process to track the fate transitions of porcine PSCs involved in the signaling pathway. The activation of transforming growth factor beta signaling was required for the formation of mesoderm and the inhibition of the transforming growth factor beta signaling pathway at the hematopoietic endothelium stage could enhance the fate transformation of hematopoiesis. In summary, we developed an efficient and rapid protocol to generate pPSCdMs that showed aspects of functional maturity comparable with PAMs. pPSCdMs could provide a broad prospect for the platforms of host-pathogen interaction mechanisms., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The evidence supporting the biological plausibility of the association of permethrin and malathion with hematological cancer is limited and contradictory; thus, further studies are needed. This study aimed to investigate whether in vitro exposure to 0.1 μM permethrin and malathion at 0, 24, 48 and 72 h after cell culture initiation induced changes in the gene expression and DNA methylation in mononuclear cells from bone marrow and peripheral blood (BMMCs, PBMCs). Both pesticides induced several gene expression modifications in both tissues. Through gene ontology analysis, we found that permethrin deregulates ion channels in PBMCs and BMMCs and that malathion alters genes coding proteins with nucleic acid binding capacity, which was also observed in PBMCs exposed to permethrin. Additionally, we found that both insecticides deregulate genes coding proteins with chemotaxis functions, ion channels, and cytokines. Several genes deregulated in this study are potentially associated with cancer onset and development, and some of them have been reported to be deregulated in hematological cancer. We found that permethrin does not induce DNA hypermethylation but can induce hypomethylation, and that malathion generated both types of events. Our results suggest that these pesticides have the potential to modify gene expression through changes in promoter DNA methylation and potentially through other mechanisms that should be investigated.

Hematopoietic damage is a serious side effect of cytotoxic drugs, and agents promoting hematopoiesis are quite important for decreasing the death rate in cancer patients. In our previous work, we prepared the simulated digestive product of fucoidan from Sargassum fusiforme , DSFF, and found that DSFF could activate macrophages. However, more investigations are needed to further evaluate whether DSFF could promote hematopoiesis in the chemotherapy process. In this study, the protective effect of DSFF (1.8-7.2 mg/kg, i.p.) on cyclophosphamide-induced hematopoietic damage in mice and the underlying mechanisms were investigated. Our results show that DSFF could restore the numbers of white blood cells, neutrophils, and platelets in the peripheral blood, and could also retard bone marrow cell decrease in mice with cyclophosphamide-induced hematopoietic damage. UPLC/Q-Extraction Orbitrap/MS/MS-based lipidomics results reveal 16 potential lipid biomarkers in a serum that responded to hematopoietic damage in mice. Among them, PC (20:1/14:0) and SM (18:0/22:0) were the key lipid molecules through which DSFF exerted protective actions. In a validation experiment, DSFF (6.25-100 μg/mL) could also promote K562 cell proliferation and differentiation in vitro. The current findings indicated that DSFF could affect the blood cells and bone marrow cells in vivo and thus showed good potential and application value in alleviating the hematopoietic damage caused by cyclophosphamide.

Aims: Hematopoietic acute radiation syndrome (H-ARS) can cause lethality, and therefore, the necessity of a safe radioprotector. The present study was focused on investigating the role of melatonin in granulocytes colony-stimulating factor (G-CSF) and related mechanisms underlying the reduction of DNA damage in hematopoietic system of irradiated mice., Main Methods: C57BL/6 male mice were exposed to 2, 5, and 7.5Gy of whole-body irradiation (WBI), 30 min after intra-peritoneal administration of melatonin with different doses. Mice were sacrificed at different time intervals after WBI, and bone marrow, splenocytes, and peripheral blood lymphocytes were isolated for studying various parameters including micronuclei (MN), cell cycle, comet, γ-H2AX, gene expression, amino acid profiling, and hematology., Key Findings: Melatonin100mg/kg ameliorated radiation (7.5Gy and 5Gy) induced MN frequency and cell death in bone marrow without mortality. At 24 h of post-WBI (2Gy), the frequency of micronucleated polychromatic erythrocytes (mnPCE) with different melatonin doses revealed 20 mg/kg as optimal i.p. dose for protecting the hematopoietic system against radiation injury. In comet assay, a significant reduction in radiation-induced % DNA tail (p ≤ 0.05) was observed at this dose. Melatonin reduced γ-H2AX foci/cell and eventually reached to the control level. Melatonin also decreased blood arginine levels in mice after 24 h of WBI. The gene expression of G-CSF, Bcl-2-associated X protein (BAX), and Bcl2 indicated the role of melatonin in G-CSF regulation and downstream pro-survival pathways along with anti-apoptotic activity., Significance: The results revealed that melatonin recovers the hematopoietic system of irradiated mice by inducing G-CSF mediated radioprotection., (Copyright © 2021. Published by Elsevier Inc.)

Objective: The haematopoietic cytopenia (HC) of the cyclin-dependent kinase (CDK)4/6 inhibitors was evaluated using the Food and Drug Administration Adverse Event Reporting System (FAERS)., Method: Data from 1 January 2015 to 31 December 2021 has been retrieved from the FAERS database. Disproportionality analysis and Bayesian analysis were utilized in the data mining. The reporting odds ratio (ROR) with 95% confidence interval (CI) for HC was calculated for each CDK 4/6 inhibitor agent. Clinical features of the patients were collected and compared between death outcome and non-death outcome groups. Time to onset (TTO), proportion of deaths, life-threatening and hospitalizations of CDK 4/6 inhibitors-associated HC were also studied., Results: A total of 17,235 cases of HC associated with CDK 4/6 inhibitors were identified with a median age of 65 years (interquartile range [IQR] 57-73). Palbociclib appeared the strongest signal, with the highest (ROR 9.64, 95% CI 9.46-9.83), followed by ribociclib (ROR 6.38, 95% CI 6.04-6.73) and then abemaciclib (ROR 2.72, 95% CI 2.49-2.97). Patients aged 18-64 had a higher proportion of deaths than those aged 65-84 (12.21% vs. 9.91%, p = 0.001). In Africa and Asia, the proportions of deaths were higher (31.65% and 26.13%, respectively). The median TTO was 26 days (IQR 14-65) for abemaciclib, 33 days (IQR 15-134) for palbociclib and 23 days (IQR 14-69) for ribociclib, respectively. The highest proportion of deaths, life-threatening and hospitalizations all occurred in abemaciclib (13.00%, 5.42% and 44.04%, respectively)., Conclusions: Greater proportions of deaths occurred in Africa and Asia. HC may occur early in any CDK 4/6 inhibitor regimen. Abemaciclib had the highest proportion of deaths, life-threatening and hospitalizations. Health care workers should be more concerned about CDK 4/6 inhibitors. The higher proportions of serious events, including deaths, from Africa and Asia, as well as for abemaciclib, deserve further investigations through additional pharmacoepidemiological approaches.

Exposure of young C57BL/6 (B6) mice to two courses of busulfan (BSF) injections or two rounds of sublethal total-body irradiation (TBI) induced significant damage to the function of hematopoietic stem and progenitor cells (HSPCs). Fifteen weeks after treatment, BSF- and TBI-treated mice had reduced white blood cells without significant change in red blood cells or platelets, indicating that BSF and TBI hematotoxicity was chronic, with leukocytes being the major targets. Hematopoietic damage induced by BSF or TBI persisted long term. Residual adverse effects were reflected by significantly decreased CD45R B cells and reduced recovery of total bone marrow cells, especially HSPCs carrying markers for KSL (Kit + Sca-1 + Lin - ) cells, multipotent progenitor (MPP) cells (KSLCD34 + CD135 + ), myeloid progenitor (MP) cells (Kit + Sca-1 - Lin - ), and common lymphoid progenitor (CLP) cells 62 wk posttreatment. Transplantation of bone marrow (BM) cells from BSF and TBI donors at 49 weeks after treatment into lethally irradiated hosts resulted in decreased engraftment of CD45R B cells in blood and reduced reconstitution of BM HSPCs including KSL cells, short-term hematopoietic stem cells (KSLCD34 + CD135 - ), MPP cells, and MP cell subsets. TBI donor had better reconstitution of CLP cells in recipients posttransplantation than did BSF donor, suggesting an impact of TBI and BSF on B cells at different development stages. In summary, BSF and TBI exposure produced long-lasting adverse effects on hematopoiesis with pronounced effects on mature B cells, immature ST-HSCs, and hematopoietic progenitor cells. Our results may have implications for therapy of human diseases., Competing Interests: Conflict of interest disclosure The authors do not have any conflicts of interest to declare in relation to this work., (Published by Elsevier Inc.)

The two erythropoietin (EPO) receptor forms mediate different cellular responses to erythropoietin. While hematopoiesis is mediated via the homodimeric EPO receptor (EPOR), tissue protection is conferred via a heteromer composed of EPOR and CD131. In the skeletal system, EPO stimulates osteoclast precursors and induces bone loss. However, the underlying molecular mechanisms are still elusive. Here, we evaluated the role of the heteromeric complex in bone metabolism in vivo and in vitro by using Cibinetide (CIB), a non-erythropoietic EPO analogue that exclusively binds the heteromeric receptor. CIB is administered either alone or in combination with EPO. One month of CIB treatment significantly increased the cortical (~5.8%) and trabecular (~5.2%) bone mineral density in C57BL/6J WT female mice. Similarly, administration of CIB for five consecutive days to female mice that concurrently received EPO on days one and four, reduced the number of osteoclast progenitors, defined by flow cytometry as Lin - CD11b - Ly6C hi CD115 + , by 42.8% compared to treatment with EPO alone. In addition, CIB alone or in combination with EPO inhibited osteoclastogenesis in vitro. Our findings introduce CIB either as a stand-alone treatment, or in combination with EPO, as an appealing candidate for the treatment of the bone loss that accompanies EPO treatment.

Blocked cellular differentiation is a central pathologic feature of the myeloid malignancies, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Treatment regimens promoting differentiation have resulted in incredible cure rates in certain AML subtypes, such as acute promyelocytic leukemia. Over the past several years, we have seen many new therapies for MDS/AML enter clinical practice, including epigenetic therapies (e.g., 5-azacitidine), isocitrate dehydrogenase (IDH) inhibitors, fms-like kinase 3 (FLT3) inhibitors, and lenalidomide for deletion 5q (del5q) MDS. Despite not being developed with the intent of manipulating differentiation, induction of differentiation is a major mechanism by which several of these novel agents function. In this review, we examine the new therapeutic landscape for these diseases, focusing on the role of hematopoietic differentiation and the impact of inflammation and aging. We review how current therapies in MDS/AML promote differentiation as a part of their therapeutic effect, and the cellular mechanisms by which this occurs. We then outline potential novel avenues to achieve differentiation in the myeloid malignancies for therapeutic purposes. This emerging body of knowledge about the importance of relieving differentiation blockade with anti-neoplastic therapies is important to understand how current novel agents function and may open avenues to developing new treatments that explicitly target cellular differentiation. Moving beyond cytotoxic agents has the potential to open new and unexpected avenues in the treatment of myeloid malignancies, hopefully providing more efficacy with reduced toxicity., (© 2021. The Author(s).)

Benzene is a typical hematopoietic toxic substance, that can cause serious blood and circulatory system diseases such as aplastic anemia, myelodysplastic syndrome and acute myeloid leukemia, but the immunological mechanism by which this occurs is not clear. T helper cells play a key role in regulating the immune balance in the body. In this study, benzene-induced hematopoietic toxicity BALB/c mice model was established, and changes in immune organs and T helper cell subsets (Th1, Th2, Th17 and Treg cells) were explored. At 28 days after subcutaneous injection of 150 mg/kg benzene, mice showed pancytopenia and obvious pathological damage to the bone marrow, spleen, and thymus. Flow cytometry revealed that the number of CD4 + CD25 + Foxp3 + Treg cells in the spleen increased significantly. The level of IL-10 in the spleen, serum, and bone marrow increased, while the levels of IL-17 in the spleen and serum decreased. Furthermore, the levels of CD4 and CD8 proteins in the spleen decreased. Immunofluorescence results showed that levels of Foxp3, a specific transcription factor that induced the differentiation of Treg cells, increased after exposure to benzene. Our results demonstrate that immunosuppression occurred in the benzene-induced hematopoietic toxicity model mice, and Treg cells and secreted IL-10 may play a key role in the process., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We studied the possibility of using sodium deoxyribonucleate (Derinat) for improving the efficiency of co-transplantation of mesenchymal (MSC) and hematopoietic stem cells (HSC) to female F1(CBA×C57BL/6) mice with bone marrow aplasia caused by exposure to γ-radiation. It was found that immunomodulator Derinat enhanced the effect of co-transplantation, in particular, triple post-irradiation administration of Derinat accelerated hematopoiesis recovery judging from the parameters of peripheral blood, total cellularity of the bone marrow and spleen, and animal survival. Single or double administration of Derinat prior to irradiation was ineffective. The optimal result was obtained when the following scheme was applied: MSC→HSC with an interval of 48 h starting during the first hours after irradiation and triple administration of Derinat (in 10-15 min, 3 and 7 days after irradiation) in a dose of 3 mg/mouse., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature.)

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic hyper-inflammatory disorder. The mortality of HLH is higher in the elderly than in young adults. Senescence-accelerated mice (SAMP1/TA-1) exhibit characteristic accelerated aging after 30 weeks of age, and HLH-like features, including hematopoietic organ damage, are seen after lipopolysaccharide (LPS) treatment. Thus, SAMP1/TA-1 is a useful model of hematological pathophysiology in the elderly with HLH. In this study, dosing of SAMP1/TA-1 mice with LPS revealed that the suppression of myelopoiesis and B-lymphopoiesis was more severe in aged mice than in young mice. The bone marrow (BM) expression of genes encoding positive regulators of myelopoiesis (G-CSF, GM-CSF, and IL-6) and of those encoding negative regulators of B cell lymphopoiesis (TNF-α) increased in both groups, while the expression of genes encoding positive-regulators of B cell lymphopoiesis (IL-7, SDF-1, and SCF) decreased. The expression of the GM-CSF-encoding transcript was lower in aged mice than in young animals. The production of GM-CSF by cultured stromal cells after LPS treatment was also lower in aged mice than in young mice. The accumulation of the TNF-α-encoding transcript and the depletion of the IL-7-encoding transcript were prolonged in aged mice compared to young animals. LPS dosing led to a prolonged increase in the proportion of BM M1 macrophages in aged mice compared to young animals. The expression of the gene encoding p16 INK4a and the proportion of β-galactosidase- and phosphorylated ribosomal protein S6-positive cells were increased in cultured stromal cells from aged mice compared to those from young animals, while the proportion of Ki67-positive cells was decreased in stromal cells from aged mice. Thus, age-related deterioration of stromal cells probably causes the suppression of hematopoiesis in aged mice. This age-related latent organ dysfunction may be exacerbated in elderly people with HLH, resulting in poor prognosis., (© 2021. The Author(s).)

Novel interest has arisen in recent years regarding bone, which is a very complex and dynamic tissue deputed to several functions ranging from mechanical and protective support to hematopoiesis and calcium homeostasis maintenance. In order to address these tasks, a very refined, continuous remodeling process needs to occur involving the coordinated action of different types of bone cells: osteoblasts (OBs), which have the capacity to produce newly formed bone, and osteoclasts (OCs), which can remove old bone. Bone remodeling is a highly regulated process that requires many hormones and messenger molecules, both at the systemic and the local level. The whole picture is still not fully understood, and the role of novel actors, such as the components of the endocannabinoids system (ECS), including endogenous cannabinoid ligands (ECs), cannabinoid receptors (CBRs), and the enzymes responsible for endogenous ligand synthesis and breakdown, is extremely intriguing. This article reviews the connection between the ECS and skeletal health, supporting the potential use of cannabinoid receptor ligands for the treatment of bone diseases associated with accelerated osteoclastic bone resorption, including osteoporosis and bone metastasis.

Although the definitive role of epigenetic modulations in a wide range of hematologic malignancies, spanning from leukemia to lymphoma and multiple myeloma, has been evidenced, few articles reviewed the task. Given the high accessibility of histone deacetylase (HDACs) to necessary transcription factors involved in hematopoiesis, this review aims to outline physiologic impacts of these enzymes in normal hematopoiesis, and also to outline the original data obtained from international research laboratories on their regulatory role in the differentiation and maturation of different hematopoietic lineages. Questions on how aberrant expression of HDACs contributes to the formation of hematologic malignancies are also responded, because these classes of enzymes have a respectable share in the development, progression, and recurrence of leukemia, lymphoma, and multiple myeloma. The last section provides a special focus on the therapeutic perspectiveof HDACs inhibitors, either as single agents or in a combined-modal strategy, in these neoplasms. In conclusion, optimizing the dose and the design of more patient-tailored inhibitors, while maintaining low toxicity against normal cells, will help improve clinical outcomes of HDAC inhibitors in hematologic malignancies., (Copyright © 2021 Elsevier B.V. All rights reserved.)

One of the health benefits of endurance exercise training (ET) is the stimulation of hematopoiesis. However, the mechanisms underlying ET-induced hematopoietic adaptations are understudied. N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (Ac-SDKP) inhibits proliferation of early hematopoietic progenitor cells. The angiotensin I-converting enzyme (ACE) NH2-terminal promotes hematopoiesis by inhibiting the anti-hematopoietic effect of Ac-SDKP. Here we demonstrate for the first time the role of ACE NH2-terminal in ET-induced hematopoietic adaptations. Wistar rats were subjected to 10 weeks of moderate-(T1) and high-(T2) volume swimming-training. Although both protocols induced classical ET-associated adaptations, only T2 increased plasma ACE NH2-domain activity (by 40%, P=0.0003) and reduced Ac-SDKP levels (by 50%, P<0.0001). T2 increased the number of hematopoietic stem cells (HSCs; ∼200%, P=0.0008), early erythroid progenitor colonies (∼300%, P<0.0001) and reticulocytes (∼500%, P=0.0007), and reduced erythrocyte lifespan (∼50%, P=0.022). Following, Wistar rats were subjected to T2 or T2 combined with ACE NH2-terminal inhibition (captopril (Cap) treatment: 10 mg.kg-1.day-1). T2 combined with ACE NH2-terminal inhibition prevented Ac-SDKP decrease and attenuated ET-induced hematopoietic adaptations. Altogether, our findings show that ET-induced hematopoiesis was at least partially associated with increased ACE NH2-terminal activity and reduction in the hematopoietic inhibitor Ac-SDKP., (© 2021 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Protein hydrolysate injection (PH) is a sterile solution of hydrolyzed protein and sorbitol that contains 17 amino acids and has a molecular mass of 185.0-622.0 g/mol. This study investigated the effect of PH on hematopoietic function in K562 cells and mice with cyclophosphamide (CTX)-induced hematopoietic dysfunction. In these myelosuppressed mice, PH increased the number of hematopoietic cells in the bone marrow (BM) and regulated the concentration of several factors related to hematopoietic function. PH restored peripheral blood cell concentrations and increased the numbers of hematopoietic stem cells and progenitor cells (HSPCs), B lymphocytes, macrophages, and granulocytes in the BM of CTX-treated mice. Moreover, PH regulated the concentrations of macrophage colony stimulating factor (M-CSF), interleukin (IL)-2, and other hematopoiesis-related cytokines in the serum, spleen, femoral condyle, and sternum. In K562 cells, the PH-induced upregulation of hematopoiesis-related proteins was inhibited by transfection with M-CSF siRNA. Therefore, PH might benefit the BM hematopoietic system via the regulation of M-CSF expression, suggesting a potential role for PH in the treatment of hematopoietic dysfunction caused by cancer therapy.

Mitochondrial dysfunction and stem cell exhaustion are two hallmarks of aging. In the hematopoietic system, aging is linked to imbalanced immune response and reduced regenerative capacity in hematopoietic stem cells (HSCs), as well as an increased predisposition to a spectrum of diseases, including myelodysplastic syndrome and acute myeloid leukemia. Myeloid-biased differentiation and loss of polarity are distinct features of aged HSCs, which generally exhibit enhanced mitochondrial oxidative phosphorylation and increased production of reactive oxygen species (ROS), suggesting a direct role for mitochondria in the degenerative process. Here, we provide an overview of current knowledge of the mitochondrial mechanisms that contribute to age-related phenotypes in HSCs. These include mitochondrial ROS production, alteration/activation of mitochondrial metabolism, the quality control pathway of mitochondria, and inflammation. Greater understanding of the key machineries of HSC aging will allow us to identify new therapeutic targets for preventing, delaying, or even reversing aspects of this process.

Myelofibrosis (MF) is a progressive chronic myeloproliferative neoplasm characterized by hyperactivation of JAK/STAT signaling and dysregulation of the transcription factor GATA1 in megakaryocytes (MKs). TGF-β plays a pivotal role in the pathobiology of MF by promoting BM fibrosis and collagen deposition and by enhancing the dormancy of normal hematopoietic stem cells (HSCs). In this study, we show that MF-MKs elaborated significantly greater levels of TGF-β1 than TGF-β2 and TGF-β3 to a varying degree, and we evaluated the ability of AVID200, a potent TGF-β1/TGF-β3 protein trap, to block the excessive TGF-β signaling. Treatment of human mesenchymal stromal cells with AVID200 significantly reduced their proliferation, decreased phosphorylation of SMAD2, and interfered with the ability of TGF-β1 to induce collagen expression. Moreover, treatment of MF mononuclear cells with AVID200 led to increased numbers of progenitor cells (PCs) with WT JAK2 rather than mutated JAK2V617F. This effect of AVID200 on MF PCs was attributed to its ability to block TGF-β1-induced p57Kip2 expression and SMAD2 activation, thereby allowing normal rather than MF PCs to preferentially proliferate and form hematopoietic colonies. To assess the in vivo effects of AVID200, Gata1lo mice, a murine model of MF, were treated with AVID200, resulting in the reduction in BM fibrosis and an increase in BM cellularity. AVID200 treatment also increased the frequency and numbers of murine progenitor cells as well as short-term and long-term HSCs. Collectively, these data provide the rationale for TGF-β1 blockade, with AVID200 as a therapeutic strategy for patients with MF.

The impact of acute and chronic exposure of nonylphenol (NP) on behaviour, histopathology, haematology and biochemical parameters of Labeo rohita (Hamilton, 1822) was investigated in the current study. The 96 h LC 50 of NP for L. rohita was estimated to be 0.548 mg L -1 . Acute toxicity of NP induced several behavioural alternations. Further, sub-lethal NP exposure for a period of sixty days to 1/10th (0.0548 mg L -1 ), 1/15th (0.0365 mg L -1 ) and 1/20th (0.0274 mg L -1 ) of 96 h LC 50 resulted a reduction in total erythrocyte count and haemoglobin content whereas the total leukocyte count was observed to increase significantly. Among the biochemical parameters, blood glucose level increased, but there was significant decrease in total serum protein, albumin and globulin level. Significant alterations occurred in the histological architecture of gill tissue in NP exposed groups. The catalase and superoxide dismutase activity in gill tissues were elevated significantly while the concentration dependent inhibition of acetylcholinesterase activity was observed on 20th, 40th and 60th day of NP exposure. An increased glutathione-S-transferase activity in gill tissue was also observed in NP exposed groups. The present ecotoxicological study provides a reliable indication for the obligation to control the use and safe disposal of NP., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The bone marrow niche plays critical roles in hematopoietic recovery and hematopoietic stem cell (HSC) regeneration after myeloablative stress. However, it is not clear whether systemic factors beyond the local niche are required for these essential processes in vivo. Thrombopoietin (THPO) is a key cytokine promoting hematopoietic rebound after myeloablation and its transcripts are expressed by multiple cellular sources. The upregulation of bone marrow-derived THPO has been proposed to be crucial for hematopoietic recovery and HSC regeneration after stress. Nonetheless, the cellular source of THPO in myeloablative stress has never been investigated genetically. We assessed the functional sources of THPO following two common myeloablative perturbations: 5-fluorouracil (5-FU) administration and irradiation. Using a Thpo translational reporter, we found that the liver but not the bone marrow is the major source of THPO protein after myeloablation. Mice with conditional Thpo deletion from osteoblasts and/or bone marrow stromal cells showed normal recovery of HSCs and hematopoiesis after myeloablation. In contrast, mice with conditional Thpo deletion from hepatocytes showed significant defects in HSC regeneration and hematopoietic rebound after myeloablation. Thus, systemic THPO from the liver is necessary for HSC regeneration and hematopoietic recovery in myeloablative stress conditions., Competing Interests: LG, MD, HC, LD none, (© 2021, Gao et al.)

Hematopoietic ontogeny consists of two broad programs: an initial hematopoietic stem cell (HSC)-independent program followed by HSC-dependent hematopoiesis that sequentially seed the fetal liver and generate blood cells. However, the transition from HSC-independent to HSC-derived hematopoiesis remains poorly characterized. To help resolve this question, we developed Mds1 CreERT2 mice, which inducibly express Cre-recombinase in emerging HSCs in the aorta and label long-term adult HSCs, but not HSC-independent yolk-sac-derived primitive or definitive erythromyeloid (EMP) hematopoiesis. Our lineage-tracing studies indicate that HSC-derived erythroid, myeloid, and lymphoid progeny significantly expand in the liver and blood stream between E14.5 and E16.5. Additionally, we find that HSCs contribute the majority of F4/80+ macrophages in adult spleen and marrow, in contrast to their limited contribution to macrophage populations in brain, liver, and lungs. The Mds1 CreERT2 mouse model will be useful to deconvolute the complexity of hematopoiesis as it unfolds in the embryo and functions postnatally., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021. Published by Elsevier Inc.)

Chemotherapies may increase mutagenesis of healthy cells and change the selective pressures in tissues, thus influencing their evolution. However, their contributions to the mutation burden and clonal expansions of healthy somatic tissues are not clear. Here, exploiting the mutational footprint of some chemotherapies, we explore their influence on the evolution of hematopoietic cells. Cells of Acute Myeloid Leukemia (AML) secondary to treatment with platinum-based drugs show the mutational footprint of these drugs, indicating that non-malignant blood cells receive chemotherapy mutations. No trace of the 5-fluorouracil (5FU) mutational signature is found in AMLs secondary to exposure to 5FU, suggesting that cells establishing the leukemia could be quiescent during treatment. Using the platinum-based mutational signature as a barcode, we determine that the clonal expansion originating the secondary AMLs begins after the start of the cytotoxic treatment. Its absence in clonal hematopoiesis cases is consistent with the start of the clonal expansion predating the exposure to platinum-based drugs., (© 2021. The Author(s).)

Although mutations in DNA are the best-studied source of neoantigens that determine response to immune checkpoint blockade, alterations in RNA splicing within cancer cells could similarly result in neoepitope production. However, the endogenous antigenicity and clinical potential of such splicing-derived epitopes have not been tested. Here, we demonstrate that pharmacologic modulation of splicing via specific drug classes generates bona fide neoantigens and elicits anti-tumor immunity, augmenting checkpoint immunotherapy. Splicing modulation inhibited tumor growth and enhanced checkpoint blockade in a manner dependent on host T cells and peptides presented on tumor MHC class I. Splicing modulation induced stereotyped splicing changes across tumor types, altering the MHC I-bound immunopeptidome to yield splicing-derived neoepitopes that trigger an anti-tumor T cell response in vivo. These data definitively identify splicing modulation as an untapped source of immunogenic peptides and provide a means to enhance response to checkpoint blockade that is readily translatable to the clinic., Competing Interests: Declaration of interests O.A.-W. has served as a consultant for H3B Biomedicine, Foundation Medicine, Merck, Prelude Therapeutics, and Janssen, and is on the scientific advisory board of Envisagenics, Pfizer Boulder, and AIChemy. O.A.-W. has received prior research funding from Loxo Oncology and H3 Biomedicine unrelated to this work. S.X.L. has served as a consultant (uncompensated) for PTC Therapeutics. B.R. has served as a consultant for Bayer and Roche. D.Z. reports clinical research support to his institution from Astra Zeneca, Plexxikon, and Genentech and personal/consultancy fees from Merck, Synlogic Therapeutics, Tesaro, Bristol Myers Squibb (BMS), Genentech, Xencor, Memgen, Calidi Biotherapeutics, and Agenus. L.A.D. is a member of the board of directors of Personal Genome Diagnostics (PGDx) and Jounce Therapeutics. L.A.D. is a compensated consultant to PGDx, 4Paws (PetDx), Innovatus CP, Se’er, Delfi, Kinnate, and Neophore. L.A.D. is an uncompensated consultant for, but has received clinical trial support from, Merck. L.A.D. holds equity in PGDx, Jounce, Se’er, Delfi, Kinnate, and Neophore and divested equity in Thrive Earlier Detection in 2021. His spouse holds equity in Amgen. J.D.W. is a consultant for Amgen, Apricity, Arsenal IO, Ascentage Pharma, AstraZeneca, Astellas, Boehringer Ingelheim, BMS, Chugai, Dragonfly, F Star, Eli Lilly, Georgiamune, IMVAQ, Merck, Polynoma, Psioxus, Recepta, Trieza, Truvax, Sellas, and Werewolf Therapeutics. J.D.W. has grant/research support from BMS and Sephora. J.D.W. reports equity in Tizona Pharmaceuticals, Imvaq, Beigene, Linneaus, Apricity, Arsenal IO, and Georgiamune. T.M. is an inventor on patents involving the use of anti-PD-1 antibodies. T.M. is a consultant for Immunos Therapeutics and Pfizer. T.M. is a cofounder of and equity holder in IMVAQ. T.M. receives research funding from BMS, Surface Oncology, Kyn Therapeutics, Infinity Pharmaceuticals, Peregrine Pharmaceuticals, Adaptive Biotechnologies, Leap Therapeutics, and Aprea Therapeutics. S.X.L., O.A.-W., and R.K.B. are inventors on a patent application submitted by FHCRC related to this work., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Metformin, a first-line oral drug for type II diabetes mellitus, not only reduces blood glucose levels, but also has many other biological effects. Recent studies have been conducted to determine the protective effect of metformin in irradiation injuries. However, the results are controversial and mainly focus on the time of metformin administration. In this study, we aimed to investigate the protective effect of metformin in BALB/c mice exposed to 6 Gy or 8 Gy of a 60Co source of γ-rays for total body irradiation (TBI). Survival outcomes were assessed following exposure to 8 Gy or 6 Gy TBI, and hematopoietic damage and intestinal injury were assessed after exposure to 6 Gy TBI. Metformin prolonged the survival of mice exposed to 8 Gy TBI and improved the survival rate of mice exposed to 6 Gy TBI only when administered before exposure to irradiation. Moreover, pretreatment with metformin reduced the frequency of micronuclei (MN) in the bone marrow of mice exposed to 6 Gy TBI. Pretreatment of metformin also protected the intestinal morphology of mice, reduced inflammatory response and decreased the number of apoptotic cells in intestine. In conclusion, we demonstrated that pretreatment with metformin could alleviate irradiation injury., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Haematopoietic stem cells (HSCs) are normally quiescent, but have evolved mechanisms to respond to stress. Here, we evaluate haematopoietic regeneration induced by chemotherapy. We detect robust chromatin reorganization followed by increased transcription of transposable elements (TEs) during early recovery. TE transcripts bind to and activate the innate immune receptor melanoma differentiation-associated protein 5 (MDA5) that generates an inflammatory response that is necessary for HSCs to exit quiescence. HSCs that lack MDA5 exhibit an impaired inflammatory response after chemotherapy and retain their quiescence, with consequent better long-term repopulation capacity. We show that the overexpression of ERV and LINE superfamily TE copies in wild-type HSCs, but not in Mda5 -/- HSCs, results in their cycling. By contrast, after knockdown of LINE1 family copies, HSCs retain their quiescence. Our results show that TE transcripts act as ligands that activate MDA5 during haematopoietic regeneration, thereby enabling HSCs to mount an inflammatory response necessary for their exit from quiescence., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Protein malnutrition causes anemia and leukopenia as it reduces hematopoietic precursors and impairs the production of mediators that regulate hematopoiesis. Hematopoiesis occurs in distinct bone marrow niches that modulate the processes of differentiation, proliferation and self-renewal of hematopoietic stem cells (HSCs). Mesenchymal stem cells (MSCs) contribute to the biochemical composition of bone marrow niches by the secretion of several growth factors and cytokines, and they play an important role in the regulation of HSCs and hematopoietic progenitors. In this study, we investigated the effect of protein malnutrition on the hematopoietic regulatory function of MSCs. C57BL/6NTaq mice were divided into control and protein malnutrition groups, which received, respectively, a normal protein diet (12% casein) and a low protein diet (2% casein). The results showed that protein malnutrition altered the synthesis of SCF, TFG-β, Angpt-1, CXCL-12, and G-CSF by MSCs. Additionally, MSCs from the protein malnutrition group were not able to maintain the lymphoid, granulocytic and megakaryocytic-erythroid differentiation capacity compared to the MSCs of the control group. In this way, the comprehension of the role of MSCs on the regulation of the hematopoietic cells, in protein malnutrition states, is for the first time showed. Therefore, we infer that hematopoietic alterations caused by protein malnutrition are due to multifactorial alterations and, at least in part, the MSCs' contribution to hematological impairment., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A circulatory model of granulopoiesis and its regulation is presented that includes neutrophil trafficking in the lungs, liver, spleen, bone marrow, lymph nodes, and blood. In each organ, neutrophils undergo transendothelial migration from vascular to interstitial space, clearance due to apoptosis, and recycling via the lymphatic flow. The model includes cell cycling of progenitor cells in the bone marrow, granulocyte colony-stimulating factor (G-CSF) kinetics and its neutrophil regulatory action, as well as neutrophil margination in the blood. From previously reported studies, 111 In-labeled neutrophil kinetic data in the blood and sampled organs were used to estimate the organ trafficking parameters in the model. The model was further developed and evaluated using absolute neutrophil count (ANC), band cell, and segmented neutrophil time course data from healthy volunteers following four dose levels of pegfilgrastim (r 2  = 0.77-0.99), along with ANC time course responses following filgrastim (r 2  = 0.96). The baseline values of various cell types in bone marrow and blood, as well as G-CSF concentration in the blood, predicted by the model are consistent with available literature reports. After incorporating the mechanism of action of both paclitaxel and carboplatin, as determined from an in vitro bone marrow studies, the model reliably predicted the observed ANC time course following paclitaxel plus carboplatin observed in a phase I trial of 46 patients (r 2  = 0.70). The circulatory neutrophil model may provide a mechanistic framework for predicting multi-organ neutrophil homeostasis and dynamics in response to therapeutic agents that target neutrophil dynamics and trafficking in different organs., (© 2021 The Authors. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of the American Society for Clinical Pharmacology and Therapeutics.)

The ubiquitin-proteasome system (UPS) is a central part of protein homeostasis, degrading not only misfolded or oxidized proteins but also proteins with essential functions. The fact that a healthy hematopoietic system relies on the regulation of protein homeostasis and that alterations in the UPS can lead to malignant transformation makes the UPS an attractive therapeutic target for the treatment of hematologic malignancies. Herein, inhibitors of the proteasome, the last and most important component of the UPS enzymatic cascade, have been approved for the treatment of these malignancies. However, their use has been associated with side effects, drug resistance, and relapse. Inhibitors of the immunoproteasome, a proteasomal variant constitutively expressed in the cells of hematopoietic origin, could potentially overcome the encountered problems of non-selective proteasome inhibition. Immunoproteasome inhibitors have demonstrated their efficacy and safety against inflammatory and autoimmune diseases, even though their development for the treatment of hematologic malignancies is still in the early phases. Various immunoproteasome inhibitors have shown promising preliminary results in pre-clinical studies, and one inhibitor is currently being investigated in clinical trials for the treatment of multiple myeloma. Here, we will review data on immunoproteasome function and inhibition in hematopoietic cells and hematologic cancers.

The present study investigated, the anti-apoptotic activity of Ginsenoside Rg1 (Rg1) via inhibition of Bax translocation and the subsequent recovery of hematopoietic function. Mitochondrial apoptosis in bone marrow mononuclear cells (BMNCs) was observed in aplastic anemia (AA) patients. To establish a mouse model of AA, BALB/c mice were transplanted with lymph node cells from DBA/2 donor mice via vein injection after treatment with Co60 γ-radiation. After treatment with Rg1 for 14 days, the peripheral blood and Lin-Sca-1 + c-Kit + (LSK) cell counts of the treated group were increased compared with those of the untreated model mice. In in vivo and in vitro tests of LSKs, Rg1 was found to increase mitochondrial number and the ratio of Bcl-2/Bax and to decrease damage to the mitochondrial inner and outer membranes, the mitochondrial Bax level and the protein levels of mitochondrial apoptosis-related proteins AIF and Cyt-C by decreasing the ROS level. Rg1 also improved the concentration-time curve of MAO and COX and levels of ATP, ADP and AMP in an in vitro test. In addition, high levels of Bax mitochondrial translocation could be corrected by Rg1 treatment. Levels of markers of mitochondrial apoptosis in the Rg1-treated group were significantly better than those in the AA model group, implying that Rg1 might improve hematopoietic stem cells and thereby restore hematopoietic function in AA by suppressing the mitochondrial apoptosis mediated by Bax translocation.

Bone marrow adipocytes (BMAs) have recently been recognized as a niche component with a suppressive function. Obese individuals with abundant BMAs exhibit impaired hematopoietic regeneration after hematopoietic stem cell transplantation (HSCT). We hypothesized that plasminogen activator inhibitor type-1 (PAI-1), an adipokine that regulates the fibrinolytic system, contributes to impaired hematopoiesis in bone marrow (BM) microenvironment with abundant BMAs. We demonstrated that BMAs differentiated in vitro could secrete PAI-1 and were positive for PAI-1 in vivo. In addition, the abundance of BMAs was associated with high levels of PAI-1 expression. The BMA-rich microenvironment exhibited impaired hematopoietic regeneration after HSCT when compared with a BMA-less microenvironment. The impaired hematopoietic regeneration in BMA-rich microenvironment was significantly alleviated by PAI-1 knockout or PAI-1 inhibitor treatment. Obese mice with abundant BMAs, compared with normal-weight mice, exhibited higher bone marrow PAI-1 concentrations, increased fibrinolytic system suppression, and lower stem cell factor (SCF) concentrations after HSCT. PAI-1 inhibitor administration significantly activated the fibrinolytic system in obese mice, contributing to the higher SCF concentration. Moreover, PAI-1 inhibitor treatment significantly alleviated the impaired hematopoietic regeneration in obese mice both after 5-fluorouracil injection and HSCT. These results indicate that PAI-1 hinders hematopoietic regeneration in BMA-rich microenvironments. The blockade of PAI-1 activity could be a novel therapeutic means of facilitating hematopoietic reconstitution in BMA-rich patients., Competing Interests: Declaration of competing interest The PAI-1 inhibitor used in this study is protected as intellectual property. T.M, K.A., and T.Y are listed as inventors in the patent application., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The core binding factor composed of CBFβ and RUNX subunits plays a critical role in most hematopoietic lineages and is deregulated in acute myeloid leukemia (AML). The fusion oncogene CBFβ-SMMHC expressed in AML with the chromosome inversion inv(16)(p13q22) acts as a driver oncogene in hematopoietic stem cells and induces AML. This review focuses on novel insights regarding the molecular mechanisms involved in CBFβ-SMMHC-driven leukemogenesis and recent advances in therapeutic approaches to target CBFβ-SMMHC in inv(16) AML., (© 2021 by The American Society of Hematology.)

TNF is a multifunctional cytokine with its key functions attributed to inflammation, secondary lymphoid tissue organogenesis and immune regulation. However, it is also a physiological regulator of hematopoiesis and is involved in development and homeostatic maintenance of various organs and tissues. Somewhat unexpectedly, the most important practical application of TNF biology in medicine is anti-TNF therapy in several autoimmune diseases. With increased number of patients undergoing treatment with TNF inhibitors and concerns regarding possible adverse effects of systemic cytokine blockade, the interest in using humanized mouse models to study the efficacy and safety of TNF-targeting biologics in vivo is justified. This Perspective discusses the main functions of TNF and its two receptors, TNFR1 and TNFR2, in steady state, as well as in emergency hematopoiesis. It also provides a comparative overview of existing mouse lines with humanization of TNF/TNFR system. These genetically engineered mice allow us to study TNF signaling cascades in the hematopoietic compartment in the context of various experimental disease models and for evaluating the effects of various human TNF inhibitors on hematopoiesis and other physiological processes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Gogoleva, Atretkhany, Dygay, Yurakova, Drutskaya and Nedospasov.)