Search Results (506)

Background/Objectives: Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by the replacement of healthy bone marrow (BM) with malignant and fibrotic tissue. In a healthy state, bone marrow is composed of approximately 60–70% fat cells, which are replaced as disease progresses. Proton density fat fraction (PDFF), a non-invasive and quantitative MRI metric, enables analysis of BM architecture by measuring the percentage of fat versus cells in the environment. Our objective is to investigate variance in quantitative PDFF-MRI values over time as a marker of disease progression and response to treatment. Methods: We analyzed existing data from three cohorts of mice: two groups with MF that failed to respond to therapy with approved drugs for MF (ruxolitinib, fedratinib), investigational compounds (navitoclax, balixafortide), or vehicle and monitored over time by MRI; the third group consisted of healthy controls imaged at a single time point. Using in-house MATLAB programs, we performed a voxel-wise analysis of PDFF values in lower extremity bone marrow, specifically comparing the variance of each voxel within and among mice. Results: Our findings revealed a significant difference in PDFF values between healthy and diseased BM. With progressive disease non-responsive to therapy, the expansion of hematopoietic cells in BM nearly completely replaced normal fat, as determined by a markedly reduced PDFF and notable reduction in the variance in PDFF values in bone marrow over time. Conclusions: This study validated our hypothesis that the variance in PDFF in BM decreases with disease progression, indicating pathologic expansion of hematopoietic cells. We can conclude that disease progression can be tracked by a decrease in PDFF values. Analyzing variance in PDFF may improve the assessment of disease progression in pre-clinical models and ultimately patients with MF. Full article

Introduction: Acute Myeloid Leukemia (AML) is a hematologic malignancy characterized by the clonal expansion of myeloid progenitors. While it primarily affects the bone marrow, extramedullary relapse occurs in 3–5% of cases, and it is linked to poor prognosis. Central nervous system (CNS) involvement presents diagnostic challenges due to nonspecific symptoms. CNS manifestations include leptomeningeal dissemination, nerve infiltration, parenchymal lesions, and myeloid sarcoma, occurring at any disease stage and frequently asymptomatic. Methods: A 62-year-old man with a recent history of AML in remission presented with diplopia and aching paresthesias in the left periorbital region spreading to the left frontal area. The diagnostic workup included neurological and hematological evaluation, lumbar puncture, brain CT, brain magnetic resonance imaging (MRI) with contrast, and dermatological evaluation with skin biopsy due to the appearance of nodular skin lesions on the abdomen and thorax. Results: Neurological evaluation showed hypoesthesia in the left mandibular region, consistent with left trigeminal nerve involvement, extending to the periorbital and frontal areas, and impaired adduction of the left eye with divergent strabismus in the primary position due to left oculomotor nerve palsy. Brain MRI showed an equivocal thickening of the left oculomotor nerve without enhancement. Cerebrospinal fluid (CSF) analysis initially showed elevated protein (47 mg/dL) with negative cytology; a repeat lumbar puncture one week later detected leukemic cells. Skin biopsy revealed cutaneous AML localization. A diagnosis of AML relapse with CNS and cutaneous localization was made. Salvage therapy with FLAG-IDA-VEN (fludarabine, cytarabine, idarubicin, venetoclax) and intrathecal methotrexate, cytarabine, and dexamethasone was started. Subsequent lumbar punctures were negative for leukemic cells. Due to high-risk status and extramedullary disease, the patient underwent allogeneic hematopoietic stem cell transplantation. Post-transplant aplasia was complicated by septic shock; the patient succumbed to an invasive fungal infection. Conclusions: This case illustrates the diagnostic complexity and poor prognosis of extramedullary AML relapse involving the CNS. Early recognition of neurological signs, including cranial nerve dysfunction, is crucial for timely diagnosis and management. Although initial investigations were negative, further analyses—including repeated CSF examinations and skin biopsy—led to the identification of leukemic involvement. Although neuroleukemiosis cannot be confirmed without nerve biopsy, the combination of clinical presentation, neuroimaging, and CSF data strongly supports the diagnosis of extramedullary relapse of AML. Multidisciplinary evaluation remains essential for detecting extramedullary relapse. Despite treatment achieving CSF clearance, the prognosis remains unfavorable, underscoring the need for vigilant clinical suspicion in hematologic patients presenting with neurological symptoms. Full article

The rabbit is a widely used experimental model for human translational research and stem cell therapy. Many studies have focused on rabbit mesenchymal stem cells from different biological sources for their possible application in regenerative medicine. However, a minimal number of studies have been published aimed at rabbit hematopoietic stem/progenitor cells, mainly due to the lack of specific anti-rabbit CD34 antibodies. In general, CD34 antigen is commonly used to identify and isolate hematopoietic stem/progenitor cells in humans and other animal species. The aim of this study was to develop novel monoclonal antibodies highly specific to rabbit CD34 antigen. We used hybridoma technology, two synthetic peptides derived from predicted rabbit CD34 protein, and a recombinant rabbit CD34 protein as immunogens to produce monoclonal antibodies (mAbs) specific to rabbit CD34. The produced antibodies were screened for their binding activity and specificity using ELISA, flow cytometry, and Western blot analysis. Finally, four mAbs (58/47/26, 58/47/34, 182/7/80, and 575/36/8) were selected for the final purification process. The purified mAbs recognized up to 2–3% of total rabbit bone marrow cells, while about 2% of those cells exhibited CD45 expression, which are likely rabbit primitive hematopoietic stem cells and their hematopoietic progenitors, respectively. The newly generated and purified mAbs specifically recognize CD34 antigen in rabbit bone marrow or peripheral blood and can be therefore used for further immunological applications, to study rabbit hematopoiesis or to establish a new animal model for hematopoietic stem cell transplantation studies. Full article

Glial cells, once considered mere support for neurons, have emerged as key players in brain function across vertebrates. The historical study of glia dates to the 19th century with the identification of ependymal cells and astrocytes, followed by the discovery of oligodendrocytes and microglia. While neurocentric perspectives overlooked glial functions, recent research highlights their essential roles in neurodevelopment, synapse regulation, brain homeostasis, and neuroimmune responses. In teleost fish, a group comprising over 32,000 species, glial cells exhibit unique properties compared to their mammalian counterparts. Thus, the aim of this review is synthesizing the current literature on fish glial cells, emphasizing their evolutionary significance, diversity, and potential as models for understanding vertebrate neurobiology. Microglia originate from both yolk sac cells and hematopoietic stem cells, forming distinct populations with specialized functions in the adult brain. Neural stem cells, including radial glial cells (RGCs) and neuroepithelial cells, remain active throughout life, supporting continuous neuro- and gliogenesis, a phenomenon far more extensive than in mammals. Ependymocytes line brain ventricles and show structural variability, with some resembling quiescent progenitor cells. Astrocytes are largely absent in most fish species. However, zebrafish exhibit astrocyte-like glial cells which show some structural and functional features in common with mammalian astrocytes. Oligodendrocytes share conserved mechanisms with mammals in myelination and axon insulation. Full article

The BCR-ABL1 chimeric oncoprotein plays a pivotal role in the pathogenesis of Chronic Myeloid Leukemia (CML) as its constitutive kinase activity transforms the hematopoietic stem cell, promoting pro-survival signaling. We and others have previously shown that the manipulation of BCR-ABL1 catalytic activity modulates its intracellular localization, thereby transforming the culprit of CML into a pro-apoptotic protein that selectively kills leukemic cells. Here, we investigated the role of the BCR coiled-coil and C2 domains on BCR-ABL1 intracellular localization and leukemogenic potential. We performed a bioinformatic analysis that identified two putative nuclear localization signals (NLSs) in BCR. Using recombinant DNA strategies, we generated multiple BCR and BCR-ABL1 mutants that were ectopically expressed in human cells. The intracellular localization of each construct was analyzed by immunofluorescence, while their biological activity was investigated employing proliferation and transforming assays. We show that BCR displays two nuclear localization signals functionally inactivated by the coiled-coil and C2 domains. The removal of these regions reactivated the nuclear migration of both BCR and BCR-ABL1 mutants. Moreover, BCR-ABL1 constructs devoid of the coiled-coil and C2 domains displayed reduced transforming potential in Ba/F3 cells and in primary human CD34+ progenitors. Finally, we demonstrate that the deletion of the C2 domain compromises TKI efficacy. Our findings identify two nuclear localization signals in the BCR sequence that are functionally suppressed by the coiled-coil and C2 domains. Targeting these regions may provide additional therapeutic strategies to manipulate both BCR-ABL1 intracellular localization and kinase activity. Full article

Myelodysplastic syndromes are a group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, peripheral cytopenia, and dysplasia in one or more myeloid lineages, with a variable risk of progression to acute myeloid leukemia. In addition to well-characterized genetic and epigenetic abnormalities, oxidative stress has emerged as a critical contributor to the pathophysiology of myelodysplastic syndrome. Reactive oxygen species and reactive nitrogen species can induce cumulative DNA damage, mitochondrial dysfunction, and altered redox homeostasis, promoting genomic instability and clonal evolution. Elevated oxidative stress in patients with myelodysplastic syndromes has been linked to increased apoptosis of hematopoietic stem and progenitor cells, disruption of the bone marrow microenvironment, and progression toward leukemic transformation. Moreover, ROS-related pathways, such as TP53 mutations and epigenetic dysregulation, interact with the key molecular drivers of myelodysplastic syndrome. Given these findings, oxidative stress is now recognized not only as a hallmark of disease biology but also as a potential therapeutic target. Antioxidant-based strategies and agents that modulate redox signaling are being investigated for their ability to restore hematopoietic function and enhance treatment efficacy. This review provides an overview of the current biology of myelodysplastic syndrome, highlights the connections between oxidative stress and disease mechanisms, and explores emerging redox-targeted therapeutic approaches. Full article

Erythropoiesis, the process driving the differentiation of hematopoietic stem and progenitor cells to mature erythrocytes, unfolds through tightly orchestrated developmental stages, each defined by profound epigenetic remodeling. From the initial commitment of hematopoietic progenitors to the terminal enucleation of erythrocytes, dynamic changes in chromatin accessibility, transcription factor occupancy, and three-dimensional genome architecture govern lineage specification and stage-specific gene expression. Advances in our understanding of the regulatory genome have uncovered how non-coding elements, including enhancers, silencers, and insulators, shape the transcriptional landscape of erythroid cells. These elements work in concert with lineage-determining transcription factors to establish and maintain erythroid identity. Disruption of these epigenetic programs—whether by inherited mutations, somatic alterations, or environmental stress—can lead to a wide range of hematologic disorders. Importantly, this growing knowledge base has opened new therapeutic avenues, enabling the development of precision tools that target regulatory circuits to correct gene expression. These include epigenetic drugs, enhancer-targeted genome editing, and lineage-restricted gene therapies that leverage endogenous regulatory logic. As our understanding of erythroid epigenomics deepens, so too does our ability to design rational, cell-type-specific interventions for red blood cell disorders. Full article

Casein Kinase II (CK2) is a ubiquitously present serine/threonine kinase essential for mammalian development. CK2 holoenzyme is a tetramer with two highly related catalytic subunits (α or α’) and two regulatory ß subunits. Global deletion of the α or β subunit in mice is embryonically lethal. We and others have shown that CK2 is overexpressed in leukemia cells and plays an important role in cell cycle, survival, and resistance to the apoptosis of leukemia stem cells (LSCs). To study the role of CK2α in adult mouse hematopoiesis, we generated hematopoietic cell-specific CK2α-conditional knockout mice (Vav-iCreCK2 ^f/f). Here we report the generation and validation of a novel mouse model that lacks CK2α in the hematopoietic compartment. Vav-iCreCK2α ^f/f mice were viable without dysmorphic features and showed a mild phenotype under baseline conditions. In Vav-iCreCK2α ^f/f mice, the blood count showed a significant decrease in total red blood cells and platelets. The spleen was enlarged in Vav-iCreCK2α ^f/f mice with evidence of extramedullary hematopoiesis. HSC and early progenitor cell compartments showed expansion in CK2α-null bone marrow, suggesting that the absence of CK2α impaired their proliferation and differentiation. Given the established roles of CK2 in cell cycle regulation and the findings reported here, further functional studies are warranted to investigate the role of CK2α in HSC self-renewal and differentiation. This mouse model serves as a valuable tool for understanding the role of CK2α in normal and malignant hematopoiesis. Full article

Hematopoietic progenitor kinase 1 (HPK1), a negative regulator of T-cells, B-cells, and dendritic cells, has gained attention in antitumor immunotherapy research over the past decade. No HPK1 inhibitor has yet reached clinical approval, largely due to selectivity and drug-like limitations. Leveraging the available structural insights into HPK1, we conducted a rational hit identification using a structure-based virtual screening of over 600,000 drug-like molecules from ASINEX and OTAVA databases. A series of molecular docking studies, in vitro kinase assays, and molecular dynamics simulations were conducted to identify viable HPK1 inhibitor hits. This approach resulted in two promising novel hit scaffolds, 4H-Pyrido[1,2-a] thieno[2,3-d] pyrimidin-4-one (ISR-05) and quinolin-2(1H)-one (ISR-03), neither of which has previously been reported as an HPK1 inhibitor. ISR-05 and ISR-03 exhibited IC₅₀ values of 24.2 ± 5.07 and 43.9 ± 0.134 µM, respectively, in kinase inhibition assays. These hits constitute tractable starting points for future hit-to-lead optimization aimed at developing more effective HPK1 inhibitors for cancer therapy. Full article

Acute myeloid leukemia (AML) is associated with unfavorable patient outcomes primarily related to disease relapse. Since specific types of leukemic hematopoietic stem and progenitor cells (HSPCs) are suggested to contribute to AML propagation, this study aimed to identify and explore relapse-initiating HSPC subpopulations present at diagnosis, using single-cell analysis (SCA). We developed unique high-resolution techniques capable of tracking single-HSPC-derived subclones during AML evolution. Each subclone was evaluated for chemo-resistance, in vivo leukemogenic potential, mutational profile, and the cell of origin. In BM samples of 15 AML patients, GMP-like and MLP-like HSPC subpopulations were identified as prevalent at relapse, exhibiting chemo-resistance to commonly used chemotherapy agents cytosine arabinoside (Ara-C) and daunorubicin. Reconstruction of phylogenetic lineage trees combined with genetic analysis of single HSPCs and single-HSPC-derived subclones demonstrated two distinct clusters, originating from MLP-like or GMP-like subpopulations, observed both at diagnosis and relapse. These subpopulations induced leukemia development ex vivo and in vivo. Genetic SCA showed that these relapse-related subpopulations harbored mutated EZH2 and TP53, detected already at diagnosis. This study, using combined molecular, functional, and genomic analyses at the level of single cells, identified patient-specific chemo-resistant HSPC subpopulations at the time of diagnosis, promoting AML relapse. Full article

Clonal hematopoiesis (CH) is an age-related process in which hematopoietic stem/progenitor cells increase their fitness due to the acquisition of mutations that lead to a proliferative advantage and to clonal expansion. Its frequency increases with age, and it mostly affects people older than 70 years. The most mutated genes in CH are epigenetic regulators, DNA damage response genes, and splicing factors, which are all involved in the development of myeloid neoplasia. Some risk factors, including age, smoking, and prior cytotoxic therapy, increase the risk of developing CH or increase the fitness of CH. Various types of CH have been observed, associated or not with cytopenias or monocytosis. CH represents a risk factor for many pathological conditions and particularly for hematologic malignancies. A better understanding of the risks related to CH has triggered the development of research, translational, and clinical programs for the monitoring, prevention, and treatment of CH. Full article

Background/Objectives: In 2020, 595 million world citizens had osteoarthritis, and the largest growth in OA morbidity refers to the hip joint. Effective OA therapies have been sought for years. Assessing the treatment effectiveness and QoL improvement in hip OA after intra-articular administration of fresh peripheral blood hematopoietic CD34+ stem cells. Methods: The study comprised 49 adults (median age: 63). The SCs were injected into hip joints and straight to the bone. Hip manipulation was conducted. Patients were subjected to a standardized rehabilitation protocol. Hip degeneration was graded by Kellgren–Lawrence. Multi-factor statistical analyses, with replications, were performed. The study was an R&D project, co-financed by the E.U. Results: Patient-reported outcomes (HOOS, SF-36) ameliorated remarkably over 24 months (p < 0.0001). Ranges of movement improved significantly (p < 0.0001). The most noticeable improvement manifested 6 months after the SC administration. Its furtherance was maintained. Conclusions: Intra-articular administration of CD34+ cells significantly reduces pain and improves hip joint function, regardless of the severity of OA, according to K-L, over a 24-month follow-up period. The combination of CD34+ cell therapy with joint mobilization and rehabilitation allows for the postponement of hip arthroplasty by significantly improving patients’ QoL over the 24-month follow-up period. Full article

MicroRNA (miRNA), a significant class of regulatory non-coding RNA (ncRNA), can regulate the expression of numerous protein-coding messenger RNAs (mRNAs). miRNA plays an important part in shaping the human transcriptome. So far, in the human genome, about 2500 miRNAs have been found. Acute myeloid leukemia (AML) belongs to a malignant clonal disorder of hematopoietic stem cells and is characterized by the uncontrolled clonal proliferation of abnormal progenitor cells in the bone marrow and blood. For the past several years, significant scientific attention has been attracted to the role of miRNAs in AML, since alterations in the expression levels of miRNAs may contribute to AML development. This review describes the main functions of non-coding RNA classes and presents miRNA biogenesis. This study aims to review recent reports about altered microRNA expression and their influence on AML cell survival, cell cycle, and apoptotic potential. Additionally, it summarizes the correlations between miRNAs and their target mRNAs in AML and outlines the role of particular miRNAs in AML subtypes according to ELN recommendations. Full article

By the mid-1960s, hematopoietic stem cells (HSCs) were well described. They generate perhaps the most complex array of functionally mature cells in an adult organism. HSCs and their descendants have been studied extensively, and findings have provided principles that have been applied to the development of many cell systems. However, there are uncertainties about the process of HSC development. They center around when and how HSCs become affiliated with a single-cell lineage. A longstanding view is that this occurs late in development and stepwise via a series of committed oligopotent progenitor cells, which eventually give rise to unipotent progenitors. A very different view is that lineage affiliation can occur as early as within HSCs, and the development of these cells to a mature end cell is then a continuous process. A key consideration is the extent to which lineage-affiliated HSCs self-renew to make a major contribution to hematopoiesis. This review examines the above aspects in relation to our understanding of hematopoiesis. Full article