Pulmonary hypertension (PH) is a progressive and potentially fatal complication of sickle cell disease (SCD) affecting 6-10% of adult SCD patients. Various mechanisms and theories have been evaluated to explain the pathophysiology of the disease. However, questions remain, particularly regarding the clinical heterogeneity of the disease in terms of symptoms, complications, and survival. Beyond the classical mechanisms that have been thoroughly investigated and include hemolysis, nitric oxide availability, endothelial disorders, thrombosis, and left heart failure, attention is focused nowadays on the potential role of the genes involved in such processes. Potential candidate genes are investigated through next-generation sequencing, with the TGF-β pathway being the initial target. This field of research may also provide novel targets for pharmacologic agents in the future as is already the case with idiopathic PH. The collection and processing of data and samples from multiple centers can yield safe results that will allow a better understanding of SCD-related PH as a part of the disease’s clinical spectrum. The following review attempts to capture the most recent findings of studies on gene polymorphisms that have been associated with PH in SCD patients.

Sickle cell disease is characterized by stiff, “sickled” red blood cells that have difficulty moving through the bloodstream and do not efficiently carry oxygen. It is an inherited disease with severely limited treatment options, and is caused by a point mutation. Its prevalence in black and brown communities makes the already limited treatment options even less accessible. Base editing and prime editing are two relatively recent discoveries in the field of genome editing and were developed after the groundbreaking discovery of the CRISPR Cas9 system. While not fully tested, they hold a lot of promise in providing alternative treatment options for sickle cell disease. Both editing systems are able to install individual point mutations in the beta globin gene, which is where the sickle cell mutation occurs, and can thus cure sickle cell disease (in theory). In this paper we outline the mechanisms of CRISPR-Cas9 systems and base and prime editing, and provide insight into how to apply them to treat SCD. Further investigation should be done on specific editing systems and designs to use to ensure optimal treatment of SCD.

Pregnancy in women with Sickle Cell Disease (SCD) is a high-risk situation, especially during the third trimester of gestation and in the post-partum period, due to chronic hypoxia and vaso-occlusive phenomena occurring in the maternal-fetal microcirculation: as a result, unfavorable outcomes, such as intra-uterine growth restriction, prematurity or fetal loss are more frequent in SCD pregnancies. Therefore, there is a consensus on the need for a strict and multidisciplinary follow-up within specialized structures. Transfusion support remains the mainstay of treatment of SCD pregnancies, although most appropriate modalities are still controversial: the benefit of prophylactic management, either by simple transfusions or by automated Red Blood Cell Exchange (aRBCX), is not unanimously recognized. We illustrate the cases of three SCD pregnant patients who underwent aRBCX procedures at our institution in different clinical scenarios. Moreover, we carried out a careful literature revision to investigate the management of pregnancy in SCD, particularly regarding the practice of aRBCX. Our experience and current literature support using aRBCX in pregnancy as a feasible and safe procedure provided that specialized equipment and an experienced apheresis team are available. However, further research in this high-risk population, with appropriately powered prospective trials, will be desirable to refine indications and timing of aRBCX and confirm this approach's advantages on other transfusion modalities.

The aim of our study was to describe our experience using a Spectra Optia® automated apheresis system in children with sickle cell disease (SCD). We used automated red blood cell exchange (RCE) to treat acute and chronic complications in 75 children with SCD who had a median age of 10 years [7-13]. We analysed 649 exchange sessions. Peripheral venous access was limited in a number of the children, thus requiring a femoral central double‐lumen venous catheter (CVC). We recommend the use of heparin locking, with 500 units in each lumen of a CVC. This method was well tolerated, with few complications during the procedures. For preoperative prevention, all of the patients had achieved a post-RCE HbS level of <30% since this is a mandatory condition imposed by the anaesthesiologist. With a post-RCE Hb level of approximately 10-11 g/dL, a blood exchange volume of ≥32 mL/kg, and an interval between each RCE procedure of ≤30 days, it was able to maintain the residual HbS level below 30%. Despite a target pre‐exchange HbS level of 47%, we did not encounter a single stroke recurrence. Erythrocytapheresis is useful and safe for children with SCD.

The consequences of Sickle Cell Disease (SCD), including ongoing hematopoietic stress and hemolysis, vascular damage and chronic therapies , such as blood transfusions and Hydroxyurea on hematopoietic stem and progenitor cell (HSPC) have not been characterized. We have quantified the frequencies of nine HSPC populations by flow cytometry in the peripheral blood of pediatric and adult patients stratified by treatment and controls. We observed broad differences between SCD patients and healthy controls. SCD is associated with 10 to 20-fold increase in CD34dim cells, and two to five-fold more CD34bright cells, a depletion in Megakaryocyte-Erythroid Progenitors and an increase in hematopoietic stem cells, when compared to controls. SCD is also associated with abnormal expression of CD235a and by very high levels of expression of the CD49f antigen. These findings were present to varying degrees in all patients, whether or not they were naïve or on chronic therapy. HU treatment tended to normalizes many of these parameters. Chronic stress erythropoiesis, inflammation caused by SCD and hydroxyurea therapy have long been suspected of causing premature aging of the hematopoietic system, and potentially increasing the risk of hematological malignancies. An important finding of this study was that the observed concentration of CD34bright cells and of all the HSPCs decreased logarithmically with time of treatment with HU. This correlation was independent of age and specific to HU treatment. Although the number of circulating HSPCs is influenced by many parameters, our findings suggest that HU treatment may decrease premature aging and hematologic malignancy risk compared to the other therapeutic modalities in SCD.

Sickle cell disease (SCD) is the most common hereditary disorder of hemoglobin (Hb) that affects approximately a millions people worldwide. It is characterized by a single nucleotide substitution on the β-globin gene, leading to the production of abnormal sickle hemoglobin with multi-system consequences. Mutated Hb leads to profound changes in: i) red blood cell metabolism and physiology; ii) endothelial signaling; and iii) immune response. Oxidative stress is an important hallmark of SCD. It plays a key role in the pathophysiology of hemolysis, vessel occlusion and the following organ damage in sickle cell patients. For this reason, reactive oxidizing species and the (end)-products of their oxidative reactions have been proposed as markers of both tissue pro-oxidant status and disease severity. Although more studies are needed to clarify their role, antioxidant agents have been shown to be effective in reducing pathological consequences of the disease by preventing oxidative damage in SCD, i.e. by decreasing the oxidant formation or repairing the induced damage. An improved understanding of oxidative stress will lead to targeted antioxidant therapies that should prevent or delay the development of organ complications in this patient population.

Background and objectives: sickle cell disease is the most common hemoglobinopathy in the world. It is considered to be a real public health problem. Sickle cell patients are subjected to several factors causing inflammation such as iron metabolism. The study aimed to look for inflammation in children with sickle cell disease in Cameroon, identify the factors associated with inflammation, and raise the consequences for the patient including the iron profile and the profile of the hemogram. Materials and methods: We conducted an analytical cross-sectional study for 03 months. The sickle cell disease patients coming and/or followed at the Hematology Department of the Regional Hospital of Bafoussam and the Central Hospital of Yaoundé have been recruited. The exploration of inflammation was made by determining CRP, IL6, and ferritin concentrations. The hematological parameters and iron profile were evaluated using standard methods. Statistical analysis of the data was performed; Univariate and multivariate logistic regression analyses allowed to identification of factors associated with inflammation in patients, using the statistical tool R version 4.1.1.. The proportions were compared with the chi-square test when the expected numbers were greater than 5 and the Fisher test when not. Results: The frequency of inflammation in the population was 42.3%. Hyperferritinemia was significantly greater (p<0.001) in patients with inflammation compared to the non-inflammatory patients (96.8% and 76.7% respectively). Patients with inflammation showed a significant elevation of iron parameters (p<0.05). In addition, ferritin and IL6 elevation were associated with inflammation during sickle cell disease respectively (Or = 4.96; 95% CI [1.15-36.42]; p=0.056) and (Or =6.23; 95% CI [1.43-45.96]; p=0.030). Conclusions: The elevated iron in plasma is an effect of inflammation in sickle cell patients. Hence the need of controlling inflammation and iron in the latter is necessary.

Sickle cell disease (SCD) is an inherited disorder of major health challenge in Nigeria. Micronutrients deficiencies often associated with the disorder may cause inflammation and abnormal metabolisms in the body. The copper-to-zinc ratio is a more important assessment than the concentrations of either of the metals in clinical practice. This study seeks to evaluate serum levels of c-reactive protein (CRP), copper, zinc and copper-to-zinc ratio and to correlate copper-to-zinc ratio with CRP in adult subjects with SCD. Serum copper, zinc, CRP and plasma fibrinogen were assayed in 100 confirmed SCD patients in steady clinical state and 100 age and sex matched subjects with normal haemoglobin. Serum copper and zinc were assayed by colorimetric method using reagents supplied by Centronic, Germany while CRP and fibrinogen were assayed using reagents supplied by Sigma (St. Louis, MO, USA) and Anogen (Ontario, Canada), respectively. The copper to zinc ratio was calculated from serum levels of copper and zinc. The measured parameters were compared between the groups using Students t-test and Pearson correlation coefficient was used to relate CRP with the other parameters. Serum copper, CRP, fibrinogen and copper-to-zinc ratio were significantly higher (p < 0.001) while zinc level was lower in SCD patients than controls. Serum CRP concentration correlated with copper (r = 0.10; p < 0.02), zinc (r = −0.199; p < 0.05) and Copper-to-zinc ratio (r = 0.312; p < 0.002) but the correlation between CRP and fibrinogen was not significant. Inflammatory condition may modulate copper and zinc homeostasis and copper-to-zinc ratio may be used as marker of nutritional deficiency and inflammation in SCD patients.

Background: Millions of people worldwide suffer from a genetic hemoglobinopathy known as sickle cell disease (SCD). It is a long-term condition marked by progressive multiorgan failure. Among SCD patients, cardiovascular complications are the main leading cause of death. Cardiovascular complication raises cardiac markers level as well as sickle cell vaso-occlusive crisis (VOC). This makes it challenging to determine the source. Methods: This research aims to identify the association between cardiac markers and myocardial infarction in SCD patients At King Abdulaziz University (KAUH) in Jeddah, Saudi Arabia. This retrospective study was conducted from June 2022 to March 2023. All patients with SCD who were 18 years and above were enrolled. Cardiac markers' associations with age, emergency room visits, ECG, blood transfusion, hydroxyurea, anticoagulants, and mortality were analyzed. Result: 537 patient records were screened during the study period, of which 270 met the inclusion criteria. Among these, 144 (53.3%) were female. The prevalence of elevated LDH, troponin, and CK-MB among the SCD patients who visited ER for the VOC was 78.5%, 9.3%, and 6.3%, respectively. Overall, there was a significant relationship between the cardiac marker level and the number of ER visits, age and mortality (p= 0.01), but there was no significant association between the cardiac marker level and for each of the following: hydroxyurea use, antiplatelet/anticoagulant use, needing of blood transfusion and ECG abnormalities. This retrospective research shed light on the significance of cardiac marker levels in patients with SCD. The level of cardiac markers was remarkably linked with age, frequency of ER visits, and patients' states.

Sickle cell disease (SCD) is an inherited condition characterized by chronic haemolytic anaemia. SCD is associated with moderate to severe anaemia, hypercoagulable state and inconsistent platelet count and function. However, studies have yielded conflicting results with regards to the effect of anaemia on coagulation in SCD. The purpose of this study was to determine the effect of anaemia severity on selected coagulation parameters of SCD patients. Four milliters of venous blood samples were taken from the participants (SCD and non-SCD patients) and used for analysis of full blood count and coagulation parameters. Data was analyzed using SPSS version-16. From the results, it was seen that individuals with SCD had a prolonged mean PT, APTT and high platelet count compared to the controls. There was also significant difference in the mean PT (p=0.039), APTT (p=0.041) and platelet count (p=0.010) in HbSS participants with severe anaemia. Mean APTT also showed significant difference (p=0.044) with severe anaemia in HbSC participants. It can be concluded that SCD patients have prolonged PT, APTT and increased platelet count which might predispose them to bleeding episodes and thrombocytosis. Significant difference was also seen between severity of anaemia and mean PT, APTT and platelet count in HbSS individuals.

Sickle cell disease (SCD) is a blood disorder caused by a point mutation on the beta globin gene resulting in the synthesis of abnormal hemoglobin. Fetal hemoglobin (HbF) reduces disease severity, but the levels vary from one individual to another. Most research has focused on common variants which differ across populations and hence do not fully account for HbF variation. To investigate rare and common variants influencing HbF levels in SCD, we performed targeted next generation sequencing covering exonic and other significant fetal hemoglobin-associated loci, including BCL11A, MYB, HOXA9, HBB, HBG1, HBG2, CHD4, KLF1, MBD3, ZBTB7A and PGLYRP1. Results revealed a range of functionally relevant genetic variants. Notably, there were significantly more deletions in individuals with high HbF levels (11% vs 0.9%). We identified frameshift deletion in individuals with high HbF levels and frameshift insertions in individuals with low HbF. CHD4 and MBD3 genes, interacting in the same sub-network, were identified to have a significant number of pathogenic or non-synonymous mutations in individuals with low HbF levels, suggesting an important role of epigenetic pathways in the regulation of HbF synthesis. This study provides new insights in selecting essential variants associated with extreme HbF levels in SCD.

Background: Sickle cell disease is a major public health issue in the DRC while it is still poorly understood by health professionals. The objective of this study was to assess the knowledge and practices of Congolese physicians treating sickle cell disease (SCD) in order to identify areas for improvement in clinical care. Methods: This is a descriptive observational study conducted on Congolese physicians using a questionnaire. Participants were evaluated on a pre-established answer grid. Results: A total of 460 physicians participated, including 81 women (18%) with an average age of 35 years (range 25–60 years). Most physicians were general practitioners. Although self-assessment of their level of knowledge on SCD was estimated as average to good, less than half of the participants (n= 460; 46%) reported adequate management of vaso-occlusive crisis but only 1% of them had received specific training on SCD. Most physicians reported difficulties both in terms of diagnostic (65%) and management (79%) options of SCD patients. This study showed also that 85% of them did not have access to diagnostic tools for SCD. Conclusions: Insufficient knowledge on SCD, poor diagnostic and treatment options may contribute to morbidity and mortality of patients living in the DRC. Interventions aiming at improving physician’s knowledge, patient’s follow-up and treatment access are needed. Specific training alongside existing programs (HIV, malaria), early diagnosis of the disease, and creation of patients’ advocacy groups should improve SCD patient’s care.

Hematological and biochemical reference values in sickle cell disease (SCD) are crucial for patient management and evaluation of interventions. This study was conducted at Muhimbili National Hospital (MNH) in Dar es Salaam, to establish laboratory reference ranges in SCD at steady-state. Patients were grouped into five age groups with respects to their sex. Aggregate functions were used to handle repeated measures within the indi-vidual level in each age group. A nonparametric approach was used to smooth the curves and a parametric approach was used to determine SCD normal ranges. Comparison between males and females and against the general population was documented. Data from 4,422 patients collected from 2004-2015 were analyzed. The majority of the patients (35.41%) were children aged between 5-11 years. There were no significant differences (p≥0.05) in mean corpuscular hemoglobin concentration (MCHC), lymphocytes, basophils and bilirubin direct observed between males and females. Significant differences (p<0.05) were observed in all selected parameters across age groups except neutrophils and MCHC in adults, as well as platelets and alkaline phosphatase in infants when SCD estimates were compared to the general population. Laboratory reference ranges in SCD at steady-state were different from those of the general population and varied with sex and age. The established reference ranges for SCD at steady-state will be a helpful in the management and monitoring of the progress of SCD.

Abstract: Sickle cell disease (SCD) is an autosomal recessive monogenic disorder caused by a homozygous mutation in the β-globin gene, which leads to erythrocyte sickling, hemolysis, vaso-occlusion and sterile inflammation. Oral l-glutamine administration has been shown to reduce the frequency of pain crisis in SCD patients, however, the long-term effect of l-glutamine in SCD remains to be determined. To understand the long-term effect of l-glutamine administration in SCD liver we used quantitative liver intravital microscopy and biochemical analysis in humanized SCD mice. We here show that chronic l-glutamine administration reduces hepatic hemoglobin-heme-iron level, but fails to ameliorate ischemic liver injury. Remarkably, we find that this failure in resolution of hepatobiliary injury and persistent liver fibrosis is associated with reduced expression of hepatic Kupffer cells post l-glutamine treatment. These findings establish the importance to investigate the long-term effects of l-glutamine therapy on liver pathophysiology in SCD patients.

Background: Sickle cell disease (SCD) is a public health problem in the Democratic Republic of Congo. While reference sickle cell centers have been implemented in capital cities of African countries and have proven to be beneficial for SCD patients, they have never been set up in rural areas for families with very low sources of income. Method: A cohort of 143 children with SCD aged 10 years old (IQR (interquartile range): 6–15 years) (sex ratio male/female = 1.3) were clinically followed for 12 months without any specific intervention aside from the management of acute events, and then for 12 months with a monthly medical visit, biological follow-up, and regular prophylaxis. Results: The median age of patients at the diagnosis of SCD was 2 years (IQR: 1–5). The implementation of standardized and regular follow-ups in a new sickle cell referral center in a remote city showed an increase in the annual mean hemoglobin level from 50 to 70 g/L (p = 0.001), and a decrease in the lymphocyte count and spleen size (p < 0.001). A significant decrease (p < 0.001) in the average annual number of hospitalizations and episodes of vaso-occlusive crises, blood transfusions, infections, and acute chest syndromes were also observed. Conclusions: Creation of a sickle cell referral center and the regular follow-up of children with SCD are possible and applicable in the context of a remote city of an African country and represent simple and accessible measures that can reduce the morbimortality of children with sickle cell disease.

Abstract Sickle cell anaemia (SCD) is a life-threatening haematological disorder which is predominant in sub-Saharan Africa and is triggered by a genetic mutation of the β-chain haemoglobin gene resulting in the substitution of glutamic acid with valine. This mutation leads to the production of an abnormal haemoglobin molecule called haemoglobin S (HbS). When deoxygenated, haemoglobin S (HbS) polymerizes and results in a sickle-shaped red blood cell which is rigid and has a significantly shortened life span. Various reports have shown a strong link between oxidative stress, inflammation, the immune response, and the pathogenesis of sickle cell disease. The consequence of these processes lead to the development of vasculopathy (disease of the blood vessels) and several other complications. The role of the immune system, particularly the innate immune system, in the pathogenesis of SCD has become increasingly clear in recent years of research, However, little is known about the roles of the adaptive immune system in this disease. This review examines the interaction between the immune system, inflammation, oxidative stress, blood transfusion, and their effects on the pathogenesis of sickle cell anaemia

Sickle cell disorder (SCD) is a multisystem disease with heterogeneous phenotypes. Although all patients have the mutated haemoglobin (Hb) in the SS phenotype, the severity and frequency of complications are variable. When exposed to low oxygen tension, the Hb molecule becomes dense and, forms tactoids which, lead to the peculiar sickled shapes of the affected red blood cells, giving the disorder its name. This sickle cell morphology is responsible for the profound and widespread pathologies associated with this disorder, such as vaso-occlusive crisis, (VOC). How much of the clinical manifestation is due to sickled erythrocytes and what is due to the relative contributions of other elements in the blood, especially in the microcapillary circulation, is usually not visualized and quantified for each patient during clinical management. Here, we used a microfluidic microcirculation mimetic (MMM) which has 187 capillary-like constrictions to impose deformations on erythrocytes of SCD patients, visualizing and characterizing the morpho-rheological properties of the cells in normoxic, hypoxic (using of sodium meta-bisulfite) and in treatment conditions (using hydroxyurea). The MMM enabled a patient-specific quantification of shape descriptors (circularity and roundness) and transit time through the capillary constrictions, which are readouts for morphorheological properties implicated in VOC. Our results demonstrate the feasibility of microfluidics-based monitoring of individual patients for personalized care in the context of SCD complications such as VOC, even in re-source-challenged settings.

Sickle cell disease (SCD) is a pathophysiological condition of chronic hemolysis, oxidative stress, and elevated inflammation. The transcription factor Nrf2 is a master regulator of oxidative stress. Here we reported that the FDA-approved, oral agent simvastatin, an inhibitor of hydroxymethyl-glutaryl coenzyme A reductase, significantly activates the expression of Nrf2 and antioxidant enzymes. Simvastatin also induces fetal hemoglobin expression in SCD patient erythroid progenitors and a transgenic mouse model. Simvastatin alleviates SCD symptoms by decreasing hemoglobin S sickling, oxidative stress, and inflammation stress in erythroblasts. Particularly, simvastatin increases cellular levels of cystine, the precursor for the biosynthesis of antioxidant reduced glutathione and decreases the iron content in SCD mouse spleen and liver tissues. Mechanistic studies suggest that simvastatin suppresses the expression of critical histone methyltransferase, Enhancer of zeste homolog 2 to reduce both global and gene-specific histone H3 lysine 27 trimethylation. These chromatin structural changes promote the assembly of transcription complexes to fetal γ-globin and antioxidant genes regulatory regions, in an antioxidative response element-dependent manner. In summary, our findings suggest that simvastatin activates fetal hemoglobin and antioxidant protein expression and modulates iron and cystine/reduced glutathione levels to improve the phenotype of SCD and represents a therapeutic strategy for further development.

Cardiopulmonary complications remain the major cause of mortality despite newer therapies and improvements in lifespan of patients with sickle cell disease (SCD). Inflammation has been identified as a major risk modifier in the pathogenesis of SCD associated cardiopulmonary complications in recent mechanistic and observational studies. In this review, we discuss recent cellular and molecular mechanisms of cardiopulmonary complications in SCD and summarize the most recent evidence from clinical and laboratory studies. We emphasize the role of inflammation in the onset and progression of these complications to better understand the underlying pathobiological processes. We also discuss future basic and translational research in addressing questions about the complex role of inflammation in the development of SCD cardiopulmonary complications, which may lead to promising therapies and reduce morbidity and mortality in this vulnerable population.

People with sickle cell disease (SCD) are at greater risk of severe illness and death from respiratory infections, including COVID-19 than people without SCD (Centers for Disease Control and Prevention, USA). Vaso-occlusive crises (VOC) in SCD and severe SARS-CoV-2 infection are both characterized by thrombo-inflammation mediated by endothelial injury, complement activation, inflammatory lipid storm, platelet activation, platelet-leukocyte adhesion, and activation of the coagulation cascade. Notably, lipid mediators, including thromboxane A2, significantly increase in severe COVID-19 and SCD. In addition, the release of thromboxane A2 from endothelial cells and macrophages stimulates platelets to release microvesicles which are harbingers of multicellular adhesion and thrombo-inflammation. Currently, there are limited therapeutic strategies targeting platelet-neutrophil activation and thrombo-inflammation in either SCD or COVID-19 during acute crisis. However, due to many similarities between the pathobiology of thrombo-inflammation in SCD and COVID-19, therapies targeting one disease may likely be effective in the other. Therefore, the preclinical and clinical research spurred by the COVID-19 pandemic, including clinical trials of anti-thrombotic agents, are potentially applicable to VOC. Here, we first outline the parallels between SCD and COVID-19; second, review the role of lipid mediators in the pathogenesis of these diseases and lastly, examine the therapeutic targets and potential treatments for the two diseases.