Hemolysis Of Red Cells Research Articles

Quantification of hemolysis rates from pulsed field ablation

Abstract Introduction Pulsed electric fields induce hemolysis of red blood cells as a dose-dependent effect of the electric field. Voltage pulsations induce a transmembrane potential across the cell membrane and either open up or create pores in the red cells. In isotonic conditions, the pores allow passage of potassium and sodium ions but not sucrose or hemoglobin, and leakage of ions leads to an osmotic imbalance which in turn causes a colloidal hemolysis of the red cells. Objective To quantify hemolysis rates during pulsed field ablation (PFA). Methods We created a computational model of PFA to determine the total volume of blood hemolyzed from each pulse during catheter ablation using pulsed field energy. The percentage hemolysis was calculated as a function of electric field intensity utilizing existing published experimental data. A single electrode delivering a single pulse of 100 microseconds duration was modeled at voltages of 1 kV, 1.5 kV, and 2 kV. Results The total volume of hemolyzed blood per pulse increased with increasing applied voltage (Figure). For 2 electrodes in direct tissue contact, the electrode surface exposed to the blood pool generated 19 microliters of hemolyzed red blood cells with a single pulse of a 2 kV field strength. In the case of a single pulse train consisting of 50 pulses, using a catheter configuration with 20 electrodes, an estimate of total volume per pulse train is approximately 9.5 mL of hemolyzed blood. In the case of electrodes not in direct contact with endocardial tissue, and exposed to the blood pool, up to double this volume could be anticipated per pulse train. Hemolyzed volume can be reduced with better tissue contact (reducing exposure to blood), or potentially with the use of irrigation to dilute the local red blood cell concentration. Increased tonicity of the irrigant fluid may also reduce the osmotic pressure increases that result in hemolysis. Conclusions Typical voltages utilized in pulsed field ablation can cause significant hemolysis, which is exacerbated by inadequate tissue contact. A greater number of electrodes and number of pulses delivered increases the risk, whereas better tissue contact, and the use of irrigation, may reduce it.

Nitrosyl hemoglobin formation from nitrite in normal and sickle blood

Sickle cell anemia is caused by a single mutation in the gene encoding the beta subunit of hemoglobin. Due to this mutation, sickle cell hemoglobin (HbS) polymerizes under hypoxic conditions, decreasing red blood cell deformability and leading to multiple pathological effects that cause substantial morbidity and mortality. Several pre-clinical and human studies have demonstrated that the anion nitrite has potential therapeutic benefits for patients with sickle cell disease. Nitrite is reduced to nitric oxide (NO) by deoxygenated hemoglobin contributing to vasodilation, decreasing platelet activation, decreasing cellular adhesion to activated endothelium, and decreasing red cell hemolysis; all of which could ameliorate patient morbidities. Previous work on extracellular hemoglobin has shown that solution phase HbS reduces nitrite to NO faster than normal adult hemoglobin (HbA), while polymerized HbS reduces nitrite slower than HbA. In this work, we compared the rate of nitrite reduction to NO measured by the formation of nitrosyl hemoglobin in sickle and normal red blood cells at varying hemoglobin oxygen saturations. We found the overall rate of nitrite reduction between normal and sickle red blood cells was similar and confirmed this result under partially oxygenated conditions, but normal red blood cells reduced nitrite faster than sickle red blood cells under anoxia where HbS polymerization is maximal. These results are consistent with previous work using extracellular hemoglobin where the rate of reduction by solution phase HbS makes up for the slower reduction by polymer phase HbS under partially oxygenated conditions, but the polymer phase kinetics dominates in the complete absence of oxygen.

Detectability of white matter cerebral blood flow using arterial spin labeling MRI in patients with sickle cell disease: Relevance of flow territory, bolus arrival time, and hematocrit.

Sickle cell disease (SCD) is the most common genetic blood disorder, characterized by red cell hemolysis, anemia, and corresponding increased compensatory cerebral blood flow (CBF). SCD patients are at high risk for cerebral infarcts and CBF quantification is likely critical to assess infarct risk. Infarcts primarily localize to white matter (WM), yet arterial spin labeling (ASL) MRI, the most common non-invasive CBF approach, has poor WM CBF sensitivity owing to low WM CBF and long WM bolus arrival time (BAT). We hypothesize that anemia, and associated cerebral hyperemia, in SCD leads to improved WM detection with ASL. We performed 3-Tesla multi-delay pulsed ASL in SCD (n = 35; age = 30.5 ± 8.3 years) and control (n = 15; age = 28.7 ± 4.5 years) participants and applied t-tests at each inversion time within different flow territories, and determined which regions were significantly above noise floor (criteria: one-sided p < 0.05). Total WM CBF-weighted signal was primarily detectable outside of borderzone regions in SCD (CBF = 17.7 [range = 12.9-25.0] mL/100 g/min), but was largely unphysiological in control (CBF = 8.1 [range = 7.6-9.9)] mL/100 g/min) participants. WM BAT was reduced in SCD versus control participants (ΔBAT = 37 [range = 46-70] ms) and BAT directly correlated with hematocrit (Spearman's-ρ = 0.62; p < 0.001). Findings support the feasibility of WM CBF quantification using ASL in SCD participants for appropriately parameterized protocols.

The current landscape of the antimicrobial peptide melittin and its therapeutic potential.

Melittin, a main component of bee venom, is a cationic amphiphilic peptide with a linear α-helix structure. It has been reported that melittin can exert pharmacological effects, such as antitumor, antiviral and anti-inflammatory effects in vitro and in vivo. In particular, melittin may be beneficial for the treatment of diseases for which no specific clinical therapeutic agents exist. Melittin can effectively enhance the therapeutic properties of some first-line drugs. Elucidating the mechanism underlying melittin-mediated biological function can provide valuable insights for the application of melittin in disease intervention. However, in melittin, the positively charged amino acids enables it to directly punching holes in cell membranes. The hemolysis in red cells and the cytotoxicity triggered by melittin limit its applications. Melittin-based nanomodification, immuno-conjugation, structural regulation and gene technology strategies have been demonstrated to enhance the specificity, reduce the cytotoxicity and limit the off-target cytolysis of melittin, which suggests the potential of melittin to be used clinically. This article summarizes research progress on antiviral, antitumor and anti-inflammatory properties of melittin, and discusses the strategies of melittin-modification for its future potential clinical applications in preventing drug resistance, enhancing the selectivity to target cells and alleviating cytotoxic effects to normal cells.

Oxidative stress and antioxidant parameters in dogs with lymphoma during chemotherapy

Purpose: Oxidative stress is a contributor in the development of neoplasms. OS is involved in multidrug resistance, adverse events, and outcome. Methods: Forty- two dogs with lymphoma have been included in the study, 30 of which were treated by Cyclophosphamide - Hydroxyldaunorubicin® (doxorubicin) - Oncovin® (vincristine) - Prednisolone (CHOP)-based protocol. Tumor samples were excised for histopatholgy, immunophenotyping, Ki67%, and biochemical analyses. Thiobarbituric acid reactive substances (TBARS), reduced and oxidized glutathione (GSH, GSSG), glutathione peroxidase (GSH-Px), Cu-Zn-superoxide dismutase (SOD), ferric reducing ability (FRAP), vitamin-C, -E, retinyl palmitate and trans-retinol in red blood cell hemolysates, lymph node homogenates, and blood plasma have been measured. The results were correlated with the outcome of the chemotherapy. Results: Median overall survival time (OST), relapse-free period (RFP) were 862 and 280 days, respectively, with adverse effects in 18 cases. Plasma GSH levels increased with age (dogs from 1 to 6 years vs 9 to 13 years, p = 0.0385). Lymph node FRAP levels were higher in samples with higher Ki67%, and plasma GSH/GSSG ratio was lower in dogs with increased OST and RFP. Plasma retinyl palmitate levels were lower in dogs with increased RFP. Overall survival time was increased with lower lymph node TBARS (cut off: 53 nmol/mg protein), GHS-Px (cut off: 16 U/mg protein), and higher plasma all-trans-retinol (cut off: 4 mg/ml). Relapse-free period was increased with lower lymph node TBARS (cut off: 53 nmol/mg protein), lower FRAP (cut off: 6 µmol/mg) and higher SOD (cut off: 70 U/mg protein). During chemotherapy a gradual increase in plasma vitamin E and C concentrations was detected, while GSH and GSSG showed a decrease before adverse events. Conclusion: Although oxidative stress parameters varied, some parameters, i.e. TBARS, GSH-Px, SOD, FRAP measured in lymph node samples, and plasma all-trans retinol might be used as prognostic indices.

High Rate of Passenger Lymphocyte Syndrome after ABO Minor Incompatible Lung Transplantation.

Rationale: Passenger lymphocyte syndrome (PLS) may complicate minor ABO mismatched lung transplantation (LuTX) via donor-derived red cell antibody-induced hemolysis.Objectives: To ascertain the incidence and specificity of PLS-relevant antibodies among the study population as well as the dynamics of hemolysis parameters and the transfusion requirement of patients with or without PLS.Methods: In this cohort study, 1,011 patients who received LuTX between January 2010 and June 2019 were studied retrospectively. Prospectively, 87 LuTX (July 2019 to June 2021) were analyzed. Postoperative ABO antibody and hemolytic marker determinations, transfusion requirement, and duration of postoperative hospital care were analyzed. Retrospectively, blood group A recipients of O grafts with PLS were compared with those without.Measurements and Main Results: PLS affected 18.18% (retrospective) and 30.77% (prospective) of A recipients receiving O grafts, 5.13% of B recipients of O grafts, and 20% of AB patients receiving O transplants. Anti-A and anti-A1 were the predominant PLS-inducing antibodies, followed by anti-B and anti-A,B. Significantly lower hemoglobin values (median, 7.4 vs. 8.3 g/dl; P = 0.0063) and an approximately twice as high percentage of patients requiring blood transfusions were seen in PLS. No significant differences in other laboratory markers, duration of hospital stay, or other complications after LuTX were registered.Conclusions: Minor ABO incompatible LuTX recipients are at considerable risk of developing clinically significant PLS. Post-transplant monitoring combining red cell serology and hemolysis marker determination appears advisable so as not to overlook hemolytic episodes that necessitate antigen-negative transfusion therapy.

P-selectin level in haemoglobin-S variants steady-state subjects in Port Harcourt Nigeria

Introduction: P-selectin is a cell adhesion molecule that play key roles in vaso-occlusive crisis, atherosclerosis, inflammation and is highly implicated in sickle cell diseases. This cross-sectional study determines the level of P-selectin in haemoglobin-S variants steady state subjects in Port Harourt Nigeria. Materials and Methods: Eighty (80) subjects comprising of haemoglobin-S variants in steady-state and apparently healthy haemoglobin A (HbAA) male and female aged within 5-60years were recruited for the study. Five millilitres (5mls) of venous blood were aseptically collected by venepuncture from each participant into plain tube and analysed using Elabsceince ELISA kits. Data obtained were analysed using SPSS version 24, and results considered to be significant at p&lt;0.05. Results: P-selectin levels were all within detectable normal reference ranges with highest value observed in HbSS subjects (10.98±2.72ng/ml) followed by HbSC subjects (9.58±3.51ng/ml), HbAA subjects (9.42±3.17ng/ml) and lowest value in HbAS subjects (8.01±3.19ng/ml) respectively (p=0.037). Comparison of P-selectin level based on gender showed no statistically significant difference across the various groups (p&gt;0.05). Conclusion: The study revealed a higher P-selectin level in HbSS and HbSC subjects although all within normal detectable reference ranges. It further demonstrated that gender has no effect on the expression of P-selectin in haemoglobin-S variant steady state subjects and normal haemoglobin A (HbAA). Measurement of P-selectin level in sickle cell diesease is recommended as an indirect way of investigating and monitoring red cell haemolysis, platelet aggregation and degree of inflammation in haemoglobin-S variants subjects.

Regulation of kynurenine metabolism by blood donor genetics and biology impacts red cell hemolysis in vitro and in vivo

AbstractIn the field of transfusion medicine, the clinical relevance of the metabolic markers of the red blood cell (RBC) storage lesion is incompletely understood. Here, we performed metabolomics of RBC units from 643 donors enrolled in the Recipient Epidemiology and Donor Evaluation Study, REDS RBC Omics. These units were tested on storage days 10, 23, and 42 for a total of 1929 samples and also characterized for end-of-storage hemolytic propensity after oxidative and osmotic insults. Our results indicate that the metabolic markers of the storage lesion poorly correlated with hemolytic propensity. In contrast, kynurenine was not affected by storage duration and was identified as the top predictor of osmotic fragility. RBC kynurenine levels were affected by donor age and body mass index and were reproducible within the same donor across multiple donations from 2 to 12 months apart. To delve into the genetic underpinnings of kynurenine levels in stored RBCs, we thus tested kynurenine levels in stored RBCs on day 42 from 13 091 donors from the REDS RBC Omics study, a population that was also genotyped for 879 000 single nucleotide polymorphisms. Through a metabolite quantitative trait loci analysis, we identified polymorphisms in SLC7A5, ATXN2, and a series of rate-limiting enzymes (eg, kynurenine monooxygenase, indoleamine 2,3-dioxygenase, and tryptophan dioxygenase) in the kynurenine pathway as critical factors affecting RBC kynurenine levels. By interrogating a donor-recipient linkage vein-to-vein database, we then report that SLC7A5 polymorphisms are also associated with changes in hemoglobin and bilirubin levels, suggestive of in vivo hemolysis in 4470 individuals who were critically ill and receiving single-unit transfusions.

Differences in the Circulating Proteome in Individuals with versus without Sickle Cell Trait.

Sickle cell trait affects approximately 8% of Black individuals in the United States, along with many other individuals with ancestry from malaria-endemic regions worldwide. While traditionally considered a benign condition, recent evidence suggests that sickle cell trait is associated with lower eGFR and higher risk of kidney diseases, including kidney failure. The mechanisms underlying these associations remain poorly understood. We used proteomic profiling to gain insight into the pathobiology of sickle cell trait. We measured proteomics ( N =1285 proteins assayed by Olink Explore) using baseline plasma samples from 592 Black participants with sickle cell trait and 1:1 age-matched Black participants without sickle cell trait from the prospective Women's Health Initiative cohort. Age-adjusted linear regression was used to assess the association between protein levels and sickle cell trait. In age-adjusted models, 35 proteins were significantly associated with sickle cell trait after correction for multiple testing. Several of the sickle cell trait-protein associations were replicated in Black participants from two independent cohorts (Atherosclerosis Risk in Communities study and Jackson Heart Study) assayed using an orthogonal aptamer-based proteomic platform (SomaScan). Many of the validated sickle cell trait-associated proteins are known biomarkers of kidney function or injury ( e.g. , hepatitis A virus cellular receptor 1 [HAVCR1]/kidney injury molecule-1 [KIM-1], uromodulin [UMOD], ephrins), related to red cell physiology or hemolysis (erythropoietin [EPO], heme oxygenase 1 [HMOX1], and α -hemoglobin stabilizing protein) and/or inflammation (fractalkine, C-C motif chemokine ligand 2/monocyte chemoattractant protein-1 [MCP-1], and urokinase plasminogen activator surface receptor [PLAUR]). A protein risk score constructed from the top sickle cell trait-associated biomarkers was associated with incident kidney failure among those with sickle cell trait during Women's Health Initiative follow-up (odds ratio, 1.32; 95% confidence interval, 1.10 to 1.58). We identified and replicated the association of sickle cell trait with a number of plasma proteins related to hemolysis, kidney injury, and inflammation.

Red cell haemolysis secondary to intraosseous (IO) blood transfusion in adult patients with major trauma: a systematic review

IntroductionIntraosseous (IO) administration of medications and blood products is accepted practice in major trauma when intravenous access is not immediately available. However, there is a concern that the high infusion...

Reticulocyte mitochondrial retention increases reactive oxygen species and oxygen consumption in mouse models of sickle cell disease and phlebotomy-induced anemia

Sickle cell disease (SCD) is caused by a mutation of the β-globin gene that results in the production of hemoglobin S (HbS). People with SCD experience anemia, severe acute pain episodes, persistent chronic pain, multiorgan damage, and a reduced life span. The pathophysiology of SCD caused by the polymerization of HbS on deoxygenation results in red cell deformability and the generation of reactive oxygen species (ROS). These 2 factors lead to red cell fragility and hemolysis. Reticulocytosis is an independent predictor of disease morbidity and mortality in SCD. We previously established that humans and mice with SCD exhibit abnormal mitochondrial retention in erythrocytes increasing ROS-associated hemolysis. Here, we investigated the hypothesis that mitochondrial retention and increased ROS are a consequence of stress erythropoiesis. Our results show clearly that stress erythropoiesis in phlebotomized, anemic AA mice results in mitochondrial retention and increased ROS in reticulocytes. We observed that elevated mitochondrial retention in reticulocytes also alters oxygen consumption and potentially contributes to increased HbS polymerization and red blood cell hemolysis. Therefore, these events occurring due to stress erythropoiesis contribute significantly to the pathology of SCD and suggest new therapeutic targets.

New-Generation Ektacytometry Study of Red Blood Cells in Different Hemoglobinopathies and Thalassemia

Next-generation ektacytometry provided by the osmoscan module of the Laser Optical Rotational Red Cell Analyser (LoRRca) MaxSis is, so far, one of the best complementary diagnostic tools for congenital rare anaemias due to red blood cell defects. Osmotic gradient ektacytometry (OGE) is currently considered the gold standard for the diagnosis of red cell membrane disorders, especially hereditary spherocytosis (HS). Impairment of red cell deformability, leading to a decrease in red cell survival rate, is the common trait of hereditary haemolytic anaemias; in general, it is the consequence of an abnormal cell shape, increased rigidity or dehydration. Up to now, the next-generation ektacytometry has been mainly used for the differential diagnosis of red blood cell membranopathies, but experience with structural hemoglobinopathies and thalassemia is still scarce. However, recently, many new forms of therapy are being developed for the treatment of hemoglobinopathies, particularly sickle-cell disease and β-thalassemia; clinical interest in ektacytometry is increasing and should be further explored. Here, we have evaluated the OGE profiles provided by the osmoscan module of the LoRRca ektacytometer in 96 patients with different hemoglobinopathies, both structural and thalassemia, with the aim of analysing their usefulness for the early diagnosis of these disorders either individually or in co-inheritance with other hereditary RBC defects. In addition, this study aims to improve our knowledge of the contribution of red cell deformability, osmotic fragility and intracellular viscosity to the physiopathology of haemolysis, especially when these disorders are a cause of rare anaemia. From this study, we conclude that the osmoscan profile provides complementary information on red cell deformability and hydration homeostasis that may contribute to the better understanding of the physiopathology of decreased red cell survival and hemolysis which is present in some patients.

Essential Oil from Croton blanchetianus Leaves: Anticandidal Potential and Mechanisms of Action.

Antimicrobial drugs are becoming ineffective given the resistance acquired by microorganisms. As such, it is imperative to seek new antimicrobial molecules that could provide a basis for the development of new drugs. Therefore, this work aimed to evaluate the antimicrobial potential and the mechanisms of action of the essential oil extracted from leaves of Croton blanchetianus (named CbEO) on different fungi and bacteria of clinical importance in both planktonic and biofilm lifestyles. GC-MS/MS analysis revealed the presence of twenty-two different compounds in the CbEO, which were identified using the Kovats retention index. Among these, the most abundant were amorphene (20.03%), spathulenol (5%), bicyclogermacrene (1.49%), caryophyllene oxide (4.55%), and eucalyptol (5.62%). CbOE (50 µg mL-1) barely inhibited the growth of Bacillus subtilis (23%), Pseudomonas aeruginosa (27%), and Salmonella enterica (28%), and no inhibition was obtained against Enterobacter aerogenes and Klebsiella pneumoniae. Additionally, no activity against bacterial biofilm was detected. In contrast, CbEO was active against Candida species. C. albicans and C. parapsilosis were inhibited by 78 and 75%, respectively. The antibiofilm potential also was favorable against C. albicans and C. parapsilosis, inhibiting 44 and 74% of biofilm formation and reducing around 41 and 27% of the preformed biofilm, respectively. CbOE caused membrane damage and pore formation, overproduction of ROS, and apoptosis on C. albicans and C. parapsilosis cells, as well as not inducing hemolysis in human red cells. The results obtained in this work raise the possibility of using the essential oil of C. blanchetianus leaves as an alternative to fight infections caused by C. albicans and C. parapsilosis.

Red cells manufactured from lipaemic whole blood donations: Do they have higher haemolysis?

Lipaemia in blood donations is thought to influence haemolysis in stored red blood cell (RBC) components. Higher lipid concentrations are believed to increase red cell fragility, exacerbating haemolysis during collection and subsequent red cell storage. This study aimed to investigate associations between lipoproteins in plasma and haemolysis of red cells stored in saline-adenine-glucose-mannitol (SAGM). Fifty-four plasma and matched RBCs were obtained from lipaemic whole blood donations. Plasma was tested for coagulation factors, triglycerides and cholesterol. Haemolysis, glucose, lactate, extracellular potassium, lactate dehydrogenase and adenosine triphosphate (ATP) were measured in RBC on Days 7, 21 and 42 of storage. Additionally, 20 plasma and matched RBCs from non-lipaemic donations were tested as controls. Lipaemic plasma had significantly higher triglyceride concentrations compared with non-lipaemic plasma. However, there was no significant difference in plasma cholesterol between the two groups. There were no significant differences in glucose, extracellular potassium or ATP concentrations in RBC from either group. There was no significant difference in haemolysis at expiry in lipaemic-derived and control RBC, with a weak correlation between haemolysis and either triglycerides or cholesterol. There was no significant difference in haemolysis in RBC manufactured from lipaemic and non-lipaemic whole blood donations when stored in SAGM; however, the proportion of RBC from lipaemic donations with higher haemolysis was greater than in the controls. There was a weak correlation between red cell haemolysis and plasma triglycerides. Therefore, RBCs derived from lipaemic donations are suitable for blood bank inventories.

Antioxidant system and lipid peroxidation in rat erythrocytes under low-dose exposure to mercury acetate

BACKGROUND: Low-dose exposure of mercury compounds to the human body for a long time leads to the accumulation of a toxicant in tissues, causing damage to health. Mercury can be delivered to a developing fetus through the placenta or to an infant through breast milk. Erythrocytes are the preferred cell for mercury accumulation, reaching a concentration 20 times higher than the concentration in blood plasma. Erythrocytes have powerful antioxidant protection. The antioxidant protection system of the cell plays an important role in maintaining of homeostasis in the cell. Despite of the apparent vastness of researches of the antioxidant system and lipid peroxidation, changes after subacute poisoning with heavy metals have not been sufficiently studied.&#x0D; AIM: Study changes in biochemical parameters in Wistar rats erythrocytes with subacute poisoning with mercury acetate.&#x0D; MATERIALS AND METHODS: 30 days and 44 days after the administration of mercury acetate at a dose of 4 mg/kg in the hemolysate of red blood cells of rats, the indicators of the antioxidant system and lipid peroxidation were determined.&#x0D; RESULTS: The administration of mercury acetate for 30 days significantly increased the activity of SOD, GP and reduced the activity of GT. An increase of DC concentration was noted. 14 days after the end of the injection of the toxicant, the imbalance of the AOS enzyme link persists. An increase of DC and MDA concentrations was revealed.&#x0D; CONCLUSIONS: The data obtained demonstrate a violation of the antioxidant balance in erythrocytes after a 30-day administration of mercury acetate. 14 days after the end of the injection of the toxicant, changes in the enzyme link of AOS persist. Intensification of the processes of lipoperoxidation of erythrocyte membranes has been established. In the delayed period after poisoning, there is a tendency to disturbance the balance of AOS of erythrocytes, the intensity of LPO processes increases.

Kinetics of disappearance and appearance of isoagglutinins A and B after ABO-incompatible hematopoietic stem cell transplantation

ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT) can be complicated by poor red cell engraftment and hemolysis, both mediated by isoagglutinins. Anecdotally, isoagglutinins indicates an activation of donor’s immunity or even relapse. Consequently, the routine monitoring of isoagglutinins could help physicians to predict the risk of complications. The purpose of this study is to investigate the time to disappearance and appearance of isoagglutinins after ABO-incompatible allogeneic HSCT. In a one-year follow-up, data of 136 ABO-incompatible hematopoietic stem cell (HSC) allogeneic transplanted patients were studied, of which 60 had major, 61 minor and 15 bidirectional incompatibility. Survival analyses were conducted and association with hematological diseases, HLA-compatibility and transplantation strategy was investigated. We observed a disappearance of isoagglutinin A in 82.0% of cases at one year with a median and 75th percentile of 38.4 and 138.6 days, respectively. For isoagglutinin B, these same values were 96.4%, 15.9 and 29.1 days, respectively. The appearance of isoagglutinin A occurred in 10.7% of cases. Disappearance of isoagglutinin A was significantly slower in patients with myeloid diseases compared to other diseases. The results of this study provide useful values to detect early risks of preventable immunohematological complications and possibly, in exceptional cases, relapse.

Mitapivat (AG-348) Demonstrates Safety, Tolerability, and Improvements in Anemia, Hemolysis, Oxygen Affinity, and Hemoglobin S Polymerization Kinetics in Adults with Sickle Cell Disease: A Phase 1 Dose Escalation Study

Background. Hemoglobin S (HbS) polymerization causes red cell sickling, hemolysis, and vaso-occlusion, key pathological features of sickle cell disease (SCD). Mitapivat (AG-348) has potential as an oral anti-sickling agent in SCD via increasing glycolytic activity, which reduces intracellular levels of 2,3-diphosphoglycerate (2,3-DPG) in parallel with increasing adenosine triphosphate (ATP). Reducing 2,3-DPG decreases HbS polymerization, while increasing ATP improves red cell membrane integrity. Here, we report the complete results of our single-center Phase 1 study of multiple ascending doses of mitapivat in subjects with SCD.Methods. We enrolled adult subjects (age ≥ 18 years) with confirmed SCD (HbSS) and baseline Hb ≥ 7 g/dL; with no recent transfusions, erythropoietin therapy, or changes in SCD-specific therapies including hydroxyurea (HU) and L-glutamine. Subjects received either 3 or 4 ascending dose levels of mitapivat (5 mg BID, 20 mg BID, 50 mg BID, 100 mg BID) for 2 weeks' duration each, followed by a 12-15 day drug taper. Safety and tolerability were assessed by frequency and severity of adverse events (AEs) and changes in hemoglobin (Hb) level and hemolytic markers. For each dose level, pharmacokinetics (PK), pharmacodynamics (PD; 2,3-DPG and ATP levels), and markers of oxygen (O 2) affinity (p50) and HbS polymerization (t50) were assessed pre-dose, post-dose, at end of taper, and at end of study. p50 is the partial pressure of O 2 at which 50% of the hemes in the Hb molecule have O 2 bound; t50 is the time at which 50% of erythrocytes are sickled in response to gradual deoxygenation with nitrogen to a final O 2 partial pressure of 38 torr.Results. Out of 17 subjects enrolled, 16 escalated to 50 mg BID. One subject, withdrawn 3 days after starting the study for a pre-existing pulmonary embolus, was not evaluable for response. After a protocol amendment, 9/10 eligible subjects completed the 100 mg BID dose level; 1 subject self-discontinued treatment after completing 3 dose levels. Mean age of the 17 subjects was 39 years (range 23-55 years); 11 were male, and 12 were on HU. Mitapivat was well tolerated; the most commonly reported drug-related AEs were insomnia (n=6 subjects, Grades 1-2), arthralgia (n=3, Grades 1-2), and hypertension (n=3, Grades 1-3). Six serious AEs (SAEs) were reported in 6/17 subjects, including 4 vaso-occlusive crises (VOCs), 1 non-VOC-related pain, and 1 pre-existing pulmonary embolism; 2/6 SAEs were deemed possibly drug-related. Of the 4 VOCs, 2 occurred during drug taper and were possibly drug-related, and 2 occurred during the 28-day safety follow up post-treatment in the setting of known VOC triggers.In 16 evaluable subjects, a dose-dependent decrease in mean 2,3-DPG levels and increase in mean ATP levels were consistently observed, followed by a return to near baseline by end of study (Figure 1A-B). There was a mean decrease in p50 and increase in t50 (Figure 1D-E), indicating increased oxygen affinity and slower sickling, respectively. The mean Hb increase at the 50 mg BID dose level was 1.2 g/dL (range -0.3-2.9 g/dL; Figure 1C). Over half (9/16, 56.3%) of subjects achieved a Hb response, defined as a ≥ 1 g/dL increase in Hb at any dose level compared to baseline. Subjects also experienced a mean reduction in the hemolytic markers of lactate dehydrogenase, total serum bilirubin, absolute reticulocyte count, and aspartate aminotransferase during the dose escalation period (Figure 1F-I), though responses were variable. Mean corpuscular volume (MCV) and HbF levels remained relatively stable throughout the study, supporting the notion that hydroxyurea exposure remained stable throughout the treatment period.Conclusion. During a 6-8 week treatment period, mitapivat demonstrated an acceptable safety and tolerability profile at multiple ascending dose levels in subjects with SCD. Mitapivat improved anemia, reduced markers of hemolysis, decreased 2,3-DPG and increased ATP levels, improved oxygen affinity, and decreased sickling rate, signaling its potential to improve clinically meaningful outcomes in SCD. Long-term disease modifying effects of mitapivat treatment in SCD are being evaluated in an ongoing extension study (ClinicalTrials.gov NCT04610866). [Display omitted] DisclosuresIyer: Novartis: Current equity holder in publicly-traded company; Agios Pharmaceuticals: Current Employment, Current holder of stock options in a privately-held company. Mangus: Agios Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company; Bristol-Myers Squibb: Current equity holder in publicly-traded company. Kung: Agios Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Dang: Agios Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Kosinski: Agios Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Hawkins: Bristol-Myers Squibb: Current equity holder in publicly-traded company; Agios: Current equity holder in publicly-traded company.

Ion Mobility Mass Spectrometry Analysis of Oxygen Affinity-Associated Structural Changes in Hemoglobin

Hemoglobin (Hb) is a major oxygen-transporting protein with allosteric properties reflected in the structural changes that accompany binding of O2. Glycated hemoglobin (GHb), which is a minor component of human red cell hemolysate, is generated by a nonenzymatic reaction between glucose and hemoglobin. Due to the long lifetime of human erythrocytes (∼120 days), GHb is widely used as a reliable biomarker for monitoring long-term glucose control in diabetic patients. Although the structure of GHb differs from that of Hb, structural changes relating to the oxygen affinity of these proteins remain incompletely understood. In this study, the oxygen-binding kinetics of Hb and GHb are evaluated, and their structural dynamics are investigated using solution small-angle X-ray scattering (SAXS), electrospray ionization mass spectrometry equipped with ion mobility spectrometry (ESI-IM-MS), and molecular dynamic (MD) simulations to understand the impact of structural alteration on their oxygen-binding properties. Our results show that the oxygen-binding kinetics of GHb are diminished relative to those of Hb. ESI-IM-MS reveals structural differences between Hb and GHb, which indicate the preference of GHb for a more compact structure in the gas phase relative to Hb. MD simulations also reveal an enhancement of intramolecular interactions upon glycation of Hb. Therefore, the more rigid structure of GHb makes the conformational changes that facilitate oxygen capture more difficult creating a delay in the oxygen-binding process. Our multiple biophysical approaches provide a better understanding of the allosteric properties of hemoglobin that are reflected in the structural alterations accompanying oxygen binding.

GWAS of Osmotic Hemolysis in 12,352 Healthy Blood Donors Identifies Red Cell Genetic Variants Associated with Steady State Hemolysis in Patients with Sickle Cell Disease

Background: The evolutionary pressure of endemic malaria has produced highly variable genes encoding erythrocyte proteins and enzymes, many of which modulate cellular structure and function. We hypothesized that a high throughput screen of red blood cell susceptibility to osmotic hemolysis, coupled with a GWAS study, would identify rare and common genetic variants associated with cellular structure and function during red blood cell storage and in hemolytic diseases like sickle cell and malaria.Methods: The REDS III RED Blood Cell Omics (RBC-Omics) study enrolled 13,403 successful blood donors at 4 major hubs. Two labs were used for red blood cell phenotyping of leukoreduced RBC unit-derived samples stored for ~42 days under blood bank conditions. Red blood cell osmotic fragility was assayed in 12,352 donors, including 1,483 African American, 1,477 Asian and 960 Hispanic donors. DNA was isolated and genotyped using a custom Affymetrix Axiom TM-Array, which contained approximately 875,000 SNPs enriched for blood and transfusion related polymorphisms.Results: Genome wide association analysis in the complete RBC-omics data set revealed 18 genes/loci to be associated with osmotic hemolysis at a genome wide significance threshold of P<5x10-8. The genes included candidates with clear internal validity such as HBB (specifically rs344 the HbS variant) and promotor regions of HBA2 (thalassemic variants), as well as SNPs in logical candidates, such as Ankyrin, Spectrin, and Aquaporin 1, mutations in which are responsible for spherocytosis and red cell membrane water transport defects, among others. To test the potential relevance of these finding to human disease, we evaluated the top 100 regions in the RBC-Omics studies in the 852 pediatric and adult patients with sickle cell disease enrolled in the PUSH and Walk-PHASST screening studies with genome SNP data, and analyzed the association of the SNPs with the intensity of steady state hemolysis, as measured by a principle component analysis of reticulocyte count, bilirubin, lactate dehydrogenase and aspartate amino transferase. After multiple testing correction, numerous genes were associated with the intensity of hemolysis in both studies, including SNPs in red cell metabolism enzymes genes (HK1, TKTL1 MTOR signaling), ion channels (PIEZO1), as well as regulatory gene (ZNF573) and less obvious genes (FLN, SBF2, GAB3, and TMEM116).Conclusion: An analysis of the genetic variability underlying normal human red cell susceptibility to osmotic stress hemolysis identified new candidate genes that are also associated with the severity of red blood cell hemolysis during the disease stress of human SCD. We hypothesize that many of these candidate SNPs may modulate the severity of red cell hemolysis in other diseases like malaria and potential outcomes after routine red blood cell storage and transfusion. These studies highlight the discovery of a number of new metabolic and ion/water transport variants that are associated with the severity of steady state hemolysis and under disease stress. DisclosuresMast:Novo Nordisk: Research Funding. Gordeuk:Emmaus Life Sciences: Consultancy.

Access to Care for Medicaid and Commercially-Insured United States Patients with Sickle Cell Disease

Access to Care for Medicaid and Commercially-Insured United States Patients with Sickle Cell Disease