Hematopoietic Activity Research Articles

Multiparametric Immunoimaging Maps Inflammatory Signatures in Murine Myocardial Infarction Models

In the past 2 decades, research on atherosclerotic cardiovascular disease has uncovered inflammation to be a key driver of the pathophysiological process. A pressing need therefore exists to quantitatively and longitudinally probe inflammation, in preclinical models and in cardiovascular disease patients, ideally using non-invasive methods and at multiple levels. Here, we developed and employed in vivo multiparametric imaging approaches to investigate the immune response following myocardial infarction. The myocardial infarction models encompassed either transient or permanent left anterior descending coronary artery occlusion in C57BL/6 and Apoe-/-mice. We performed nanotracer-based fluorine magnetic resonance imaging and positron emission tomography (PET) imaging using a CD11b-specific nanobody and a C-C motif chemokine receptor 2-binding probe. We found that immune cell influx in the infarct was more pronounced in the permanent occlusion model. Further, using 18F-fluorothymidine and 18F-fluorodeoxyglucose PET, we detected increased hematopoietic activity after myocardial infarction, with no difference between the models. Finally, we observed persistent systemic inflammation and exacerbated atherosclerosis in Apoe-/- mice, regardless of which infarction model was used. Taken together, we showed the strengths and capabilities of multiparametric imaging in detecting inflammatory activity in cardiovascular disease, which augments the development of clinical readouts.

Abstract NG14: Dissecting immune microenvironment of T-cell acute lymphoblastic leukemia

Abstract NG14: Dissecting immune microenvironment of T-cell acute lymphoblastic leukemia

Allogeneic Hematopoietic Stem Cell Transplantation Activity in Inborn Errors of Immunity in Russian Federation.

Allogeneic hematopoietic stem cell transplantation (HSCT) is an established therapy for many inborn errors of immunity (IEI). The indications for HSCT have expanded over the last decade. The study aimed to collect and analyze the data on HSCT activity in IEI in Russia. The data were collected from the Russian Primary Immunodeficiency Registry and complemented with information from five Russian pediatric transplant centers. Patients diagnosed with IEI by the age of 18 years and who received allogeneic HSCT by the end of 2020 were included. From 1997 to 2020, 454 patients with IEI received 514 allogeneic HSCT. The median number of HSCTs per year has risen from 3 in 1997-2009 to 60 in 2015-2020. The most common groups of IEI were immunodeficiency affecting cellular and humoral immunity (26%), combined immunodeficiency with associated/syndromic features (28%), phagocyte defects (21%), and diseases of immune dysregulation (17%). The distribution of IEI diagnosis has changed: before 2012, the majority (65%) had severe combined immunodeficiency (SCID) and hemophagocytic lymphohistiocytosis (HLH), and after 2012, only 24% had SCID and HLH. Of 513 HSCTs, 48.5% were performed from matched-unrelated, 36.5% from mismatched-related (MMRD), and 15% from matched-related donors. In 349 transplants T-cell depletion was used: 325 TCRαβ/CD19+ depletion, 39 post-transplant cyclophosphamide, and 27 other. The proportion of MMRD has risen over the recent years. The practice of HSCT in IEI has been changing in Russia. Expanding indications to HSCT and SCID newborn screening implementation may necessitate additional transplant beds for IEI in Russia.

Impact of Covid 19 pandemic on hematopoietic stem cell transplantation activities: Report from a single center

The current COVID-19 pandemic has placed unprecedented stress on the healthcare system, including HSCT. Several international organizations have created guidelines for managing different aspects of HSCT in the context of the pandemic. Comparing 2019 and 2020, our transplant center performed the same number of transplants. In both periods, transplants were mainly for patients with acute leukemia; thus, the urgency criteria was respected in light of pandemic restraints. Transplants by sibling donors and cord blood units remained the same, while transplants by unrelated donors were increased, in particular from European registries, and transplants by haploidentical donors were decreased. This change was made in light of the necessity of cryopreserving all apheresis products. We decided against cryopreserving bone marrow products due to the greater risk of drastic reduction in CD34 + cell count during the process. For urgent cases with only a haploidentical donor available, we opted for the use of PBSC following stimulation with G-CSF. GvHD prophylaxis was performed with PTCY on days + 3 + 5, cyclosporine with tapering from day + 100, and mycophenolic acid until day + 90 post-HSCT. Post-transplant outcomes such as graft failure, sepsis, and GVHD were not affected by the changes implemented. As a result of logistic difficulties, we halted our Car-T program from the start of the lockdown in March 2020 until September 2020. In accord with international guidelines, we were able to continue our HSCT program in the order to ensure a lifesaving treatment for patients with hematologic diseases for whom this procedure cannot be postponed.

Hepatic hematopoiesis in the alpaca (Vicugna pacos), a species with development in hypoxic environments

Hematopoiesis occurs in different anatomical niches throughout the life of the individual. The first hematopoietic extra-embryonic stage is replaced by a intra-embryonic stage that occurs in a region that is adjacent to the dorsal aorta. Then, the prenatal hematopoietic function is continued by the liver and spleen, and later by the bone marrow. The objective of the present work was to describe the morphological characteristics of hepatic hematopoiesis in the alpaca and to analyze the proportion of the hematopoietic compartment of the organ and the cell types, at different times of ontogeny. Sixty-two alpaca samples were collected from the municipal slaughterhouse of Huancavelica, Perú. They were processed by routine histological techniques. Hematoxylin-eosin staining, special dyes, immunohistochemical techniques and supplementary analyses by lectinhistochemistry, were performed. The prenatal liver is an important structure in the expansion and differentiation of hematopoietic stem cells. Their hematopoietic activity was characterized by four stages: initiation, expansion, peak, and involution. The liver started its hematopoietic function at 21 days EGA and it was maintained until shortly before birth. Differences were found in the proportion and morphology of the hematopoietic tissue in the different groups corresponding to each gestational stage.

Osteoregenerative Potential of 3D-Printed Poly ε-Caprolactone Tissue Scaffolds In Vitro Using Minimally Manipulative Expansion of Primary Human Bone Marrow Stem Cells.

The repair of orthopedic and maxillofacial defects in modern medicine currently relies heavily on the use of autograft, allograft, void fillers, or other structural material composites. This study examines the in vitro osteo regenerative potential of polycaprolactone (PCL) tissue scaffolding, fabricated via a three-dimensional (3D) additive manufacturing technology, i.e., a pneumatic micro extrusion (PME) process. The objectives of this study were: (i) To examine the innate osteoinductive and osteoconductive potential of 3D-printed PCL tissue scaffolding and (ii) To perform a direct in vitro comparison of 3D-printed PCL scaffolding with allograft Allowash® cancellous bone cubes with regards to cell-scaffold interactions and biocompatibility with three primary human bone marrow (hBM) stem cell lines. This study specifically examined cell survival, cell integration, intra-scaffold cell proliferation, and differentiation of progenitor cells to investigate the potential of 3D-printed PCL scaffolds as an alternative to allograft bone material for the repair of orthopedic injuries. We found that mechanically robust PCL bone scaffolds can be fabricated via the PME process and the resulting material did not elicit detectable cytotoxicity. When the widely used osteogenic model SAOS-2 was cultured in PCL extract medium, no detectable effect was observed on cell viability or proliferation with multiple test groups showing viability ranges of 92.2% to 100% relative to a control group with a standard deviation of ±10%. In addition, we found that the honeycomb infill pattern of the 3D-printed PCL scaffold allowed for superior mesenchymal stem-cell integration, proliferation, and biomass increase. When healthy and active primary hBM cell lines, having documented in vitro growth rates with doubling times of 23.9, 24.67, and 30.94 h, were cultured directly into 3D-printed PCL scaffolds, impressive biomass increase values were observed. It was found that the PCL scaffolding material allowed for biomass increase values of 17.17%, 17.14%, and 18.18%, compared to values of 4.29% for allograph material cultured under identical parameters. It was also found that the honeycomb scaffold infill pattern was superior to the cubic and rectangular matrix structures, and provided a superior microenvironment for osteogenic and hematopoietic progenitor cell activity and auto-differentiation of primary hBM stem cells. Histological and immunohistochemical studies performed in this work confirmed the regenerative potential of PCL matrices in the orthopedic setting by displaying the integration, self-organization, and auto-differentiation of hBM progenitor cells within the matrix. Differentiation products including mineralization, self-organizing "proto-osteon" structures, and in vitro erythropoiesis were observed in conjunction with the documented expression of expected bone marrow differentiative markers including CD-99 (>70%), CD-71 (>60%), and CD-61 (>5%). All of the studies were conducted without the addition of any exogenous chemical or hormonal stimulation and exclusively utilized the abiotic and inert material polycaprolactone; setting this work apart from the vast majority of contemporary investigations into synthetic bone scaffold fabrication In summary, this study demonstrates the unique clinical potential of 3D-printed PCL scaffolds for stem cell expansion and incorporation into advanced microstructures created via PME manufacturing to generate a physiologically inert temporary bony defect graft with significant autograft features for enhanced end-stage healing.

Blood Cell Indices and Morphological Abnormalities Detected Among COVID-19 Patients Receiving Care

Blood cell abnormalities may occur among COVID-19 patients and could be detrimental during the disease’s progression. This study assessed complete blood count (CBC) parameters and determined abnormal changes in the peripheral blood of COVID-19 patients receiving care at Komfo Anokye Teaching Hospital (KATH), Ghana. This hospital-based descriptive cross-sectional study conducted at KATH, Kumasi, Ghana, recruited seventy-three (73) RT-PCR-confirmed COVID-19 participants. Venous blood was taken from participants into EDTA tubes and used for CBC analyses and the preparation of a thin blood film for blood cell morphological examination. Data obtained were analyzed with SPSS version 22.0, and p< 0.05 was considered statistically significant. Females were predominant (45/61.6) and had a higher COVID-19 cycle threshold (CT) value than males (p=0.027). The overall prevalence of anaemia among the study participants was 56.2% (65.5% in males and 50% in females). Geriatrics (>70 years old) had relatively lower Hb compared to other age groups in the study. Erythrocytopaenia (18/73), leucocytosis (28/73), lymphopaenia (9/73), and thrombocytopaenia (21/73) were common among the COVID-19 participants. Red cell morphological abnormalities were seen in the study participants: echinocytes (11/73), elliptocytes (6/73), stomatocytes (1/73), acanthocytes (4/73), pencil-shaped cells (5/73), schistocytes (15/73), ovalocytes (2/73) and target cells (1/73). Moreover, the acanthocytes were significantly higher in males compared to females (4 vs. 0, p=0.019). Again, reactive lymphocytes (8/73), neutrophil toxic granulation (18/73), neutrophil cytoplasmic vacuolation (42/73), smear cells (8/73), and one each of atypical lymphocyte and Dohle body were present among the COVID-19 participants. The COVID-19 CT value was lower among male participants. The overall prevalence of anaemia among COVID-19 participants was high, with males and the aged (>70 years) predominantly affected. COVID-19 patients have abnormal blood cell counts and significant morphological abnormalities in peripheral blood. Early detection of haematological abnormalities would be beneficial in the management of COVID-19 patients. Further study to assess the haematopoietic activities of COVID-19 patients is recommended. Doi: 10.28991/SciMedJ-2023-05-01-02 Full Text: PDF

514 - Hematopoietic Stem Cell Transplantation Activity for Lymphoma: A Multicentric Study By the Transplantation and Cellular Therapy Mexican Working Group

514 - Hematopoietic Stem Cell Transplantation Activity for Lymphoma: A Multicentric Study By the Transplantation and Cellular Therapy Mexican Working Group

Stimulation of B-Lymphopoiesis by Administration of a Trimecaine-Based Ionic Compound in Cyclophosphamide-Induced Hematopoietic-Depressive Model.

According to the WHO, the secondary form of hematopoietic-depressive status increases the risk of death in people with oncological, infectious, and hormonal diseases. The choice of drugs that stimulate the hematopoietic activity of B-lymphopoiesis is limited. The current leucopoiesis drugs have a number of side effects: thymic preparations stimulate the production of PGE2, which causes chronic inflammation and various autoimmune diseases through the differentiation of T helper 1 (Th1) cells, the proliferation of Th17 cells, and the production of IL-22 from Th22 cells through EP2 and EP4 receptors; cytokine preparations can cause uncontrolled immune reactions and impaired contractility of smooth and cardiac muscles; drugs based on nucleic acids can stimulate the division of all cells, including bacterial and cancerous ones. The use of oligonucleotides such as ribozymes and antisense oligodeoxynucleotides (AS-ODNs) shows promise as therapeutic moieties, but faces a number of challenges such as nuclease sensitivity, off-target effects, and efficient delivery. The search for substances that stimulate B-lymphopoiesis among ionic compounds was motivated by the discovery of the unique properties of lidocaine docusate, one of the first ionic liquid forms of the known drugs. The lidocaine docusate (protonated form of lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl) acetamide + docusate-anion (dioctylsulfosuccinate))) suppresses the division of pheochromocytoma cells and activates immunity in rats. The trimecaine-based ionic compound (TIC) demonstrates high B-lymphopoiesis-stimulating activity. The TIC compound stimulates an increase in the volume of transitional B cells, which play an important role for further differentiation and formation of a sufficient number of mature B1 cells and mature B2 cells, where mature B2 cells make up the bulk of the functional population of B lymphocytes. The TIC compound most strongly stimulated the restoration of the number of marginal zone B cells, follicular B cells, and activated germinal center B cells after the cytotoxic emptying of the follicular centers of the spleen induced cyclophosphamide. It significantly exceeds the activity of the comparison drug methyluracil. The TIC compound does not affect the level of pro-B, pre-B-I, or pre-B-II bone marrow cells, which prevents the risk of the formation of immature functionally defective cells.

Platelet-Derived Mitochondria Attenuate 5-FU-Induced Injury to Bone-Associated Mesenchymal Stem Cells.

Myelosuppression is a common condition during chemotherapy. Bone-associated mesenchymal stem cells (BA-MSCs) play an essential role in the composition of the hematopoietic microenvironment and support hematopoietic activity. However, chemotherapy-induced damage to BA-MSCs is rarely studied. Recent studies have shown that platelets promote the wound-healing capability of MSCs by mitochondrial transfer. Therefore, this study is aimed at investigating the chemotherapy-induced damage to BA-MSCs and the therapeutic effect of platelet-derived mitochondria. Material/Methods. We established in vivo and in vitro BA-MSC chemotherapy injury models using the chemotherapy agent 5-fluorouracil (5-FU). Changes in the mitochondrial dynamics were detected by transmission electron microscopy, and the expression of mitochondrial fusion and fission genes was analyzed by qRT-PCR. In addition, mitochondrial functions were also explored by flow cytometry and luminometer. Platelet-derived mitochondria were incubated with 5-FU-damaged BA-MSCs to repair the injury, and BA-MSC functional changes were examined to assess the therapy efficacy. The mechanism of treatment was explored by studying the expression of mitochondrial fission and fusion genes and hematopoietic regulatory factor genes in BA-MSCs. Stimulation with 5-FU increased the apoptosis and suppressed cell cycle progression of BA-MSCs both in vivo and in vitro. In addition, 5-FU chemotherapy inhibited the hematopoietic regulatory ability and disrupted the mitochondrial dynamics and functions of BA-MSCs. The mitochondrial membrane potential and ATP content of 5-FU-injured BA-MSCs were decreased. Interestingly, when platelet-derived mitochondria were transferred to BA-MSCs, the 5-FU-induced apoptosis was alleviated, and the hematopoietic regulatory ability of 5-FU-injured BA-MSCs was effectively improved by upregulating the expression of mitochondrial fusion genes and hematopoietic regulatory factor genes. BA-MSCs were severely damaged by 5-FU chemotherapy both in vivo and in vitro. Meanwhile, platelet-derived mitochondria could attenuate the 5-FU-induced injury to BA-MSCs, which provides future research directions for exploring the treatment strategies for chemotherapy-injured BA-MSCs and establishes a research basis for related fields.

An RPS19-edited model for Diamond-Blackfan anemia reveals TP53-dependent impairment of hematopoietic stem cell activity.

Diamond-Blackfan anemia (DBA) is a genetic blood disease caused by heterozygous loss-of-function mutations in ribosomal protein (RP) genes, most commonly RPS19. The signature feature of DBA is hypoplastic anemia occurring in infants, although some older patients develop multilineage cytopenias with bone marrow hypocellularity. The mechanism of anemia in DBA is not fully understood and even less is known about the pancytopenia that occurs later in life, in part because patient hematopoietic stem and progenitor cells (HSPCs) are difficult to obtain, and the current experimental models are suboptimal. We modeled DBA by editing healthy human donor CD34+ HSPCs with CRISPR/Cas9 to create RPS19 haploinsufficiency. In vitro differentiation revealed normal myelopoiesis and impaired erythropoiesis, as observed in DBA. After transplantation into immunodeficient mice, bone marrow repopulation by RPS19+/- HSPCs was profoundly reduced, indicating hematopoietic stem cell (HSC) impairment. The erythroid and HSC defects resulting from RPS19 haploinsufficiency were partially corrected by transduction with an RPS19-expressing lentiviral vector or by Cas9 disruption of TP53. Our results define a tractable, biologically relevant experimental model of DBA based on genome editing of primary human HSPCs and they identify an associated HSC defect that emulates the pan-hematopoietic defect of DBA.

A Pilot Study of Neurobiological Mechanisms of Stress and Cardiovascular Risk.

Coronary heart disease is a leading cause of death and disability. Although psychological stress has been identified as an important potential contributor, mechanisms by which stress increases risk of heart disease and mortality are not fully understood. The purpose of this study was to assess mechanisms by which stress acts through the brain and heart to confer increased CHD risk. Coronary Heart Disease patients (N=10) underwent cardiac imaging with [Tc-99m] sestamibi single photon emission tomography at rest and during a public speaking mental stress task. Patients returned for a second day and underwent positron emission tomography imaging of the brain, heart, bone marrow, aorta (indicating inflammation) and subcutaneous adipose tissue, after injection of [18F]2-fluoro-2-deoxyglucose for assessment of glucose uptake followed mental stress. Patients with (N=4) and without (N=6) mental stress-induced myocardial ischemia were compared for glucose uptake in brain, heart, adipose tissue and aorta with mental stress. Patients with mental stress-induced ischemia showed a pattern of increased uptake in the heart, medial prefrontal cortex, and adipose tissue with stress. In the heart disease group as a whole, activity increase with stress in the medial prefrontal brain and amygdala correlated with stress-induced increases in spleen (r=0.69, p=0.038; and r=0.69, p=0.04 respectfully). Stress-induced frontal lobe increased uptake correlated with stress-induced aorta uptake (r=0.71, p=0.016). Activity in insula and medial prefrontal cortex was correlated with post-stress activity in bone marrow and adipose tissue. Activity in other brain areas not implicated in stress did not show similar correlations. Increases in medial prefrontal activity with stress correlated with increased cardiac glucose uptake with stress, suggestive of myocardial ischemia (r=0.85, p=0.004). These findings suggest a link between brain response to stress in key areas mediating emotion and peripheral organs involved in inflammation and hematopoietic activity, as well as myocardial ischemia, in Coronary Heart Disease patients.

Phytomedicinal properties of Hygrophila schulli (Neeramulliya).

Hygrophila schulli which is known as "Neermulli'' in the vernacular is an herbaceous plant native to Sri Lanka. Ancient medicinal literature suggests the use of H. schulli whole plant or its parts for the treatment of different communicable and non-communicable diseases including diabetes mellitus and tuberculosis. Active constituents and secondary metabolites including alkaloids, tannins, steroids, proteins, flavonoids, and glycosides are identified to possess antimicrobial, antitumor, antioxidant, hepatoprotective, anthelmintic, nephroprotective, antidiabetic, anticataract, anti-inflammatory, anti-nociceptive, hematopoietic, diuretic, antiurolithiatic, antipyretic, neuroprotection, and anti-endotoxin activities. In this review, we reviewed clinical studies, patents, and analytical studies from the earliest found examples from 1886 to the end of 2021. We critically analyzed and attempt to summarize the information based on bioactivities and chemical composition of H. schulli plant extracts which will be of future use for researchers in this field.

PET/MR imaging of inflammation in atherosclerosis.

Myocardial infarction, stroke, mental disorders, neurodegenerative processes, autoimmune diseases, cancer and the human immunodeficiency virus impact the haematopoietic system, which through immunity and inflammation may aggravate pre-existing atherosclerosis. The interplay between the haematopoietic system and its modulation of atherosclerosis has been studied by imaging the cardiovascular system and the activation of haematopoietic organs via scanners integrating positron emission tomography and resonance imaging (PET/MRI). In this Perspective, we review the applicability of integrated whole-body PET/MRI for the study of immune-mediated phenomena associated with haematopoietic activity and cardiovascular disease, and discuss the translational opportunities and challenges of the technology.

Hematopoietic stem cell transplantation activity in Mexico during the COVID19 pandemic: on the way to recovery

ABSTRACT Objective: To analyze the number of HSCTs performed in 2019 vs. 2020 and report the status of transplant centers (TCs) during and a year after the COVID-19 pandemic. Methods: We performed a comprehensive cross-sectional nationwide study including active TCs interrogating HSCT activity from 2019 through September 2021. An electronic survey was sent to TCs and consisted of items regarding the number and characteristics of procedures performed and were compared yearly. Changes to their institutions’ transplant policies and practices during the COVID19 pandemic were also documented. Fifty centers were invited to participate, 33 responded. Results: Most TCs were part of the public health system (63.7%). Almost half are in the country’s capital, Mexico City (45.5%). Most centers performed <10 procedures per year. The number of HSCTs decreased from 835 in 2019–505 in 2020 (p < .001), representing a 40% reduction in transplant activity. The monthly transplant rate in 2021 increased to 58.3, compared to 42 in 2020 and close to 69.5 in 2019 (p < .001). All types of HSCTs decreased excluding haploidentical transplants. All institutions treated patients with COVID19, and over two-thirds experienced some form of hospital reconversion. Transplant activity stopped completely in 23 TCs (70%) during the pandemic with a median closure duration of 9.9 months (range, 1-21). In 2021, 9.1% of TCs remained closed, all of them in the public setting. Conclusion(s): The limited transplant activity in Mexico decreased significantly during the pandemic but is recovering and nearly in pre-pandemic levels.

Research Progress of Single-cell Transcriptome Sequencing Technology in Physiological Hematopoiesis--Review

Hematopoiesis starts from the embryo and runs through the entire life of a living body, which is a multi-stage and complex dynamic process that is regulated by multiple pathways, involving a variety of cells and hematopoietic anatomical locations. During the development of the mammalian hematopoietic system, the currently known hematopoietic anatomical locations mainly include yolk sac, aorta-gonad-mesonephros, fetal liver, bone marrow, and thymus. The first three are mainly responsible for hematopoiesis during the embryonic and fetal period, while bone marrow is the main place for postnatal hematopoiesis, and thymus is mainly responsible for the differentiation of T lymphocytes. Integrating flow cytometry, in vitro cell culture and in vivo animal transplantation models, early researchers conducted an in-depth analysis of the differentiation pathways of hematopoietic cells. However, due to technical limitations, it is difficult to track the single-cell hematopoietic activity of hematopoietic organs. Transcriptome sequencing at the single-cell level provides researchers with a unique perspective, making it possible to draw the most detailed cell fate transition maps of the hematopoietic development of living organisms, and providing new ideas for the diagnosis and treatment of hematological tumors. In this article, we reviewed the research progress in the use of large-scale single-cell transcriptome sequencing in the field of physiological hematopoiesis in recent years.

Hematopoietic Stem Cell Transplantation Activity in China 2020–2021 During the SARS-CoV-2 Pandemic: A Report From the Chinese Blood and Marrow Transplantation Registry Group

Between 2020 and 2021, 31,525 hematopoietic stem cell transplantations (HSCTs) were reported to the Chinese Blood and Marrow Transplantation Registry Group throughout mainland China. In this report, we describe the activity and current trends for HSCT in China during the SARS-CoV-2 pandemic. In 2020, a total of 13,415 cases of HSCT were reported from 166 transplantation teams, and 75% (10,042 cases) were allogeneic HSCTs. In 2021, a total of 18,110 cases of HSCT were reported from 174 transplantation teams, and 70% (12,744 cases) were allogeneic HSCTs. Haploidentical donor (HID) transplantation accounted for 63% (7977 cases) of allogeneic HSCTs in 2021. The most common indications for allogeneic HSCT for malignant disease were acute myeloid leukemia (37%) and acute lymphoblastic leukemia (23%), and the largest proportion of nonmalignant disease comprised aplastic anemia (13%). The peripheral blood stem cell source accounted for 41% of HIDs and 75% of matched sibling donors. The BuCy-based regimen (57%) was the most popular conditioning regimen for allogeneic HSCT, followed by the BuFlu-based regimen (28%) and total body irradiation-based regimen (11%). This survey provides comprehensive information about the current activities and might benefit clinical physicians' decision planning for HSCT.

BCLAF1 Regulates Expression of AP-1 Genes and Fetal Hematopoietic Stem Cell Repopulation Activity

BCLAF1 Regulates Expression of AP-1 Genes and Fetal Hematopoietic Stem Cell Repopulation Activity

Hematopoietic Stem Cell Transplantation Activity for Lymphoma: A Multicentric Study By the Transplantation and Cellular Therapy Mexican Working Group

Introduction: Despite recent advances in the treatment of Hodgkin and non-Hodgkin lymphoma, hematopoietic stem cell transplantation (HSCT) remains the cornerstone of therapy for relapsed and refractory (R/R) disease. Furthermore, in Mexico, the use of targeted therapies like check point inhibitors or monoclonal antibodies is restricted by costs. In addition, information regarding outcomes after HSCT is needed but scarce. Thus, we aimed to register transplantation activity for lymphomas in Mexico. The primary objective was to assess overall survival (OS) and Progression-Free Survival (PFS). Secondary outcomes included to describe and compare the conditioning employed and differences between relapsed and refractory patients. Material and methods: We conducted a retrospective analysis performed by Transplantation and Cellular Therapy Mexican working group (TCTMX), including 8 HSCT transplant centers in Mexico. Patients with HL or NHL who received HSCT from 2016 to 2021 were analyzed. Responses were assessed per the Lugano criteria. Pre-transplant status was defined as relapsed if pateints were in complete response (CR) or partial response (PR) after ≥1 line of treatment, and refractory if they had stable (SD) or progressive disease (PD). Demographic and transplantation data were collected, including the type of transplant, conditioning, maintenance, engraftment, relapse, and death. The OS and PFS were estimated using the Kaplan-Meier method. Results: We included 262 patients from 8 HSCT centers around the country. 148 were men, and 114 were women. The median age was 36 years (range, 16-77). There was an increasing number of transplants by year (108 transplants were performed between 2016 and 2018 and 154 between 2019 and 2021). There were 135 (51.5%) NHL and 127 (48.5%) HL patients, n=227 had relapsed and n=35 refractory disease. Response before HSCT was evaluated with PET-CT in 148 cases (56.4%) and CT scan in 114 patients (43.5%). Autologous transplantation was performed in 200 (76.3%) patients, and 62 (23.7%) received allogeneic HSCT. Among allogeneic HSCT recipients, 19 (30.6%) were MSD, 42 (67.7%) were haploidentical, and 1 (1.61%) matched unrelated donor (MUD). Conditioning regimens included BEAM/BEAM-like in 90 (34.4%), melphalan-based in 87 (33.2%), busulfan-based in 36 (13.7%), and 8 (3.1%) received other regimens. Five-year OS was 79.6% for HL (92% for autologous, and 79.5% for allogeneic), and 69% for NHL (79.5% for autologous, and 43% for allogeneic). Five-year EFS was 37% for HL (72% for autologous, and 30% for allogeneic), and 50.9% for NHL (54.4% for autologous, and 38.3% for allogeneic). The main cause of death was relapse or progressive disease (n= 37, 67.2%). For refractory patients, the median OS was 30 months (95%CI: 3.3-56 months), and the median EFS was 30 months (95%CI: 3.5-6.4 months). Median OS and EFS were not reached for those in CR or PR. The OS and EFS were not significantly different between conditioning regimens. Conclusion: Transplant activity for lymphoma in Mexico is increasing. For relapsed patients, autologous transplantation remains the best option, the lack of carmustine was not an obstacle for favorable outcomes. The prognosis for refractory patients was dismal independently of the type of transplant, and the use of new targeted therapies before transplantation is desirable in this population. Developing outcomes registries in Mexico and other Latin American countries is crucial to better guide treatment decisions in our reality. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Endothelial mTOR Preserves Hematopoietic Stem Cell Fitness By Suppressing Thrombospondin1

Hematopoietic stem cells (HSC) reside in close proximity to blood vessels within the bone marrow (BM) termed 'perivascular niches' which provide instructive cues for maintaining HSC self-renewal potential. The perivascular niche is comprised of endothelial cells (ECs) lining the BM blood vessels (BMECs), and an array of perivascular stromal cells that collectively serve to regulate balanced HSC self-renewal and differentiation. While young HSCs are endowed with robust self-renewal potential, aging is associated with a significant decline in HSC fitness including a loss of their self-renewal ability and a biased differentiation towards the myeloid lineages at the expense of lymphopoiesis. These aging related HSC defects result in anemias, impaired response to immunizations, and an increased risk for developing clonal disorders including acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS). However, mechanisms that drive HSC defects during aging remain poorly understood, and represents a critical barrier towards developing strategies for preservation of hematopoietic fitness during aging. While HSC aging was generally assumed as a predominantly cell-intrinsic process, recent studies have identified that aging of the BM niche plays an instructive role in promoting age-related HSC defects. Supporting this, we recently discovered that aging is associated with a significant decline in mTOR activity within BMECs that impairs their capacity to serve as a HSC-supportive niche. Our findings showed that deletion of mTOR specifically within ECs of young (4 month old) mice (Endothelial Cell specific mTOR Knock Out; mTORECKO) is sufficient to recapitulate HSC aging phenotypes including loss of HSC self-renewal, and a myeloid-biased differentiation. Here, we sought to identify the mechanisms by which endothelial mTOR preserves HSC fitness. To identify candidate factors that promote HSC aging in mTORECKO mice, we performed a plasma proteomic analysis that revealed a putative role for Thrombospondin1 (Thbs1) wherein mTORECKO mice displayed elevated levels of Thbs1. Analysis of cultured BMECs revealed that inhibition of mTOR signaling within BMECs was sufficient to increase Thbs1 expression. Thbs1 is a well-defined antiangiogenic factor that has recently been identified to play a critical role in promoting a multitude of age-related cardiovascular and inflammatory disorders. However, whether Thbs1 regulates HSC activity is not known. To this end, we performed ex vivo HSC expansion transplantation assays which revealed that Thbs1 causes a significant decline in long term HSC engraftment. RNA Seq analysis of HSC expansions revealed that Thbs1 activates chronic inflammatory responses within HSCs that have been suggested to promote aging related HSC defects. To determine whether Thbs1 promotes HSC aging in mTORECKO mice, we crossed them with Thbs1 global knockout mice (Thbs1KO) to generate mTORECKOThbs1KO mice. Analysis of mTORECKOThbs1KO mice revealed that deletion of Thbs1 was sufficient to restore hematopoietic defects in mTORECKO mice including restoration of peripheral blood myeloid bias, BM HSC frequency and hematopoietic progenitor activity. Furthermore, serial HSC transplantation analysis confirmed that deletion of Thbs1 was sufficient to restore HSC self-renewal and lymphoid output in mTORECKO mice, identifying a putative role for Thbs1 as a pro-geronic factor for HSCs. To determine whether Thbs1 promotes HSC dysfunction during physiological aging, we aged Thbs1KO mice for 18 months and analyzed their hematopoietic parameters. Our analysis revealed that deletion of Thbs1 was able to prevent the age-associated increase in peripheral blood myeloid bias and BM HSC frequency. Notably, HSCs derived from aged (18 month old) Thbs1KO mice demonstrated a suppression of inflammatory responses by RNA Seq analysis, and a restoration of self-renewal ability and balanced lineage output in serial HSC transplantation assays, that are indistinguishable from HSCs derived from young (3 month old) mice. Our findings identify Thbs1 as a novel pro-geronic factor for HSC aging that can be targeted to preserve hematopoietic healthspan.