Sickle cell anaemia: progress in pathogenesis and treatment

Utility of Perl's Prussian Blue Stain in Exfoliated Buccal Cells of Thalassemia and Sickle Cell Anemia Patients and Their Correlation With Serum Ferritin Levels

Introduction Iron is essential for all living beings. Excess iron, on the other hand, is dangerous because it causes the creation of free radicals. As a result, iron absorption is carefully managed to maintain a balance between absorption and iron loss in the body. Due to the lack of particular excretory channels for iron in humans, iron excess in the tissues is common. It can be caused by a number of factors, including increased iron absorption, as seen in hemochromatosis, or frequent parenteral iron treatment, as seen in thalassemia and sickle cell anemia patients (a transfusional overload). Aim The study aims to demonstrate Perl's Prussian blue stain to identify iron overload at a preliminary stage and correlate with serum ferritin levels in patients with thalassemia and sickle cell anemia who frequently receive blood transfusions. Materials and methods The present study comprised 62 confirmed cases of thalassemia and sickle cell anemia patients undergoing repeated blood transfusions of a minimum of 15/more, along with 62 clinically healthy individuals between December 2016 and November 2018. The patients with thalassemia and sickle cell anemia were confirmed by hemoglobin electrophoresis (Bio-Rad D-10, Bio-Rad Laboratories, Inc, California, United States). The buccal smears were obtained from these patients along with the controls, and these slides were stained by Perl's Prussian blue stain and were examined under a light microscope. Results Sixty-two cases and 62 controls were considered in the current investigation. Forty-seven of the 62 people had thalassemia, and 15 had sickle cell anemia. Thirty-nine out of the 47 patients with thalassemia and six of the 15 individuals with sickle cell anemia had positive results for Perl's Prussian blue stain. All patients had elevated blood ferritin levels, with varying ranges associated with positive results for Perl's Prussian blue stain. Conclusion The objective of this study was to demonstrate the utility of oral exfoliative cytology in thalassemia and sickle cell anemia patients who often receive blood transfusions as a screening and diagnostic tool. The exfoliative cytology methods' acceptability and simplicity, along with their correlation with serum ferritin levels and Perl's Prussian blue reaction, make this noninvasive procedure an excellent screening and diagnostic tool for all patients who receive repeated blood transfusions.

Understanding Sickle cell disease: Causes, symptoms, and treatment options

Sickle cell disease (SCD) is a hereditary blood disorder characterized by the production of abnormal hemoglobin molecules that cause red blood cells to take on a crescent or sickle shape. This condition affects millions of people worldwide, particularly those of African, Mediterranean, Middle Eastern, and South Asian descent. This paper aims to provide an overview of SCD by exploring its causes, symptoms, and available treatment options. The primary cause of SCD is a mutation in the gene responsible for producing hemoglobin, the protein that carries oxygen in red blood cells. This mutation has abnormal hemoglobin called hemoglobin S, which causes red blood cells to become stiff and sticky, leading to various health complications. Patients with SCD may experience recurrent pain, fatigue, anemia, and increased infection susceptibility. Treatment options for SCD focus on managing symptoms and preventing complications. This includes pain management with analgesics, hydration, and blood transfusions to improve oxygen delivery. Hydroxyurea, a medication that increases the production of fetal hemoglobin, is commonly used to reduce the frequency and severity of pain crises. Additionally, bone marrow or stem cell transplants can cure select individuals with severe SCD. Finally, understanding the causes, symptoms, and treatment options for SCD is crucial for healthcare professionals, patients, and their families. It enables early diagnosis, effective symptom management, and improved quality of life for individuals with this chronic condition.

Health-Related Quality of Life Among Patients With Sickle Cell Disease in an Adult Hematology Clinic in a Tertiary Hospital in Lagos, Nigeria

Background

Sickle cell disease (SCD) is a genetic disease of public health concern. Improved quality healthcare has increased the life expectancy of these patients; however, they also face an increased frequency of vaso-occlusive crises and other SCD complications. These complications affect their quality of life, an area of care, which healthcare providers often overlook. We sought to determine the health-related quality of life among patients living with sickle cell disease in Lagos, Nigeria. 

Materials and methods

We conducted a cross-sectional study of 198 patients with sickle cell disease who attended the adult sickle cell clinic at a tertiary hospital in Lagos, Nigeria, during the period from October 1, 2018, to February 28, 2019. A self-administered questionnaire was used to obtain the clinical and socio-demographic characteristics of the patients and the 35-item Short-Form Health Survey (SF-36) questionnaire was used to determine their health-related quality of life (HRQoL). Determinants of HRQoL were established using bivariate and multivariate regression analysis. 

Results

The mean age of the 198 patients who participated in the study was 28.4±9.1 years, mean steady-state hemoglobin was 8.2 ± 1.3 g/dl, and 85 (42.9%) patients had a monthly income of 150 USD or less. In the previous year, 65 (32.1 %) and 33 (16.6%) patients, respectively, suffered one to two episodes (s) of acute bone pain crises and acute chest syndrome, and 43 (24.7%) had blood transfusion. Using the scoring system for SF-36 provided by RAND Health, role limitation due to physical health had the lowest median score of 50 (interquartile range {IQR}: 0-100). On bivariate analysis, bone pain crisis was associated with statistically significant low scores across all the 8 HRQoL domains of the SF36 questionnaire. Other variables, including having received blood transfusion, recent hospitalization, acute chest syndrome, lower level of income, and younger age, were also associated with significantly low scores. On regression analysis, bone pain crisis, level of income, and acute chest syndrome were found to be independent determinants of quality of life in the patients.

Conclusion

Sickle cell disease has a negative impact on the health-related quality of life of those affected. The presence of bone pain crisis is an important predictor of health-related quality of life in sickle cell disease patients. To improve patient outcomes, healthcare providers should take a holistic approach in evaluating and managing this disease, taking into cognizance how the complications and the financial burden of this disease impact the quality of life of affected patients.

Naturally-derived targeted therapy for wound healing: Beyond classical strategies

This review summarizes the four processes of wound healing in the human body (hemostasis, inflammatory, proliferation, and remodeling) and the most current research on the most important factors affecting cutaneous wound healing and the underlying cellular and/or molecular pathways. Local factors, including temperature, oxygenation, and infection, and systemic factors, such as age, diabetes, sex hormones, genetic components, autoimmune diseases, psychological stress, smoking and obesity are also addressed. A better understanding of the role of these factors in wound repair could result in the development of therapeutics that promote wound healing and resolve affected wounds. Additionally, natural products obtained from plants and animals are critical targets for the discovery of novel biologically significant pharmacophores, such as medicines and agrochemicals. This review outlines the most recent advances in naturally derived targeted treatment for wound healing. These are plant-derived natural products, insect-derived natural products, marine-derived natural products, nanomaterial-based wound-healing therapeutics (metal- and non-metal-based nanoparticles), and natural product-based nanomedicine to improve the future direction of wound healing. Natural products extracted from plants and animals have advanced significantly, particularly in the treatment of wound healing. As a result, the isolation and extraction of bioactive compounds from a variety of sources can continue to advance our understanding of wound healing. Undescribed bioactive compounds or unexplored formulations that could have a role in today's medicinal arsenal may be contained in the abundance of natural products and natural product derivatives.

Impact of oral L-arginine supplementation on blood pressure dynamics in children with severe sickle cell vaso-occlusive crisis

Sickle cell anaemia (SCA) patients generally have lower blood pressures compared to those with the AA haemoglobin genotype. However, during vaso-occlusive crises (SCA-VOC), blood pressures (BP) may elevate transiently to levels beyond the 95^th percentile. The risk of stroke or even death increases with increasing systolic BP in SCA. Therefore, interventions targeted at BP reduction may be essential during severe vaso-occlusive episodes. Reduction in BP was achieved with arginine therapy in a meta-analysis of randomized controlled trials (RCT) in non-sickle cell adults. The impact of oral arginine (given for pain control) on the BP of children with SCA-VOC has not been documented.

METHODS

A double-blind RCT of oral _L-arginine hydrochloride as adjuvant therapy for pain reduction was conducted in children with SCA-VOC, aged 5-17 years, over a 2-year period. The mean change in BP and the time to achieve BP <90^th percentile was added as part of the outcome variables. The anthropometry, pain scores and mercury sphygmomanometry were done following standard procedures. BP percentiles were generated using the Fourth Report guidelines. Differences in the time to normalization of BP in the treatment arms were tested with Kaplan-Meier analysis.

RESULTS

Sixty-six children (57.6% male) were randomized into _L-arginine (35 patients) or placebo (31 patients) arm. The prevalence of hypertension (BP ≥95^th percentile) at presentation tended to increase as the pain scores increased, from a prevalence of 50% in patients with a score of 7 to 65% in those with score of 10 (systolic hypertension) and from 44.4% in patients with pain score of 7 to 50% in patients with pain score of 10 (diastolic hypertension). Patients that received arginine recorded a 12.8±3.2 mmHg decline in mean systolic BP compared to the placebo group, where a mean difference of 7.6±1.5 mmHg was observed, P<0.001. Similarly, the mean diastolic BP reduced by 13% in the arginine group and 7.5% in the placebo group, P<0.001. Children who received arginine tended to achieve BP normalization much faster than the placebo group (P=0.112), and no serious adverse events were documented related to the hypertension or arginine administration.

CONCLUSIONS

High blood pressure (≥95^th percentile) is common amongst children with SCA-VOC and are mostly asymptomatic. Administration of oral arginine given for pain control achieves a reduction of the BP at a faster rate in children compared to placebo and it is safe.

Prevalence and Predictive Factors for Leg Ulcers in Sickle Cell Disease Patients in Saudi Arabia: A Cross-Sectional Observational Study

Introduction

Saudi Arabia has a high prevalence of sickle cell disease (SCD). Leg ulceration is one of the complications associated with SCD. There is a gap in the literature in regard to the prevalence of leg ulcers among SCD patients in Saudi Arabia.

Objectives

The primary objective of this study was to evaluate the lifetime prevalence of leg ulcers in SCD patients in our population and to study the predictive factors of leg ulcers by using sociodemographic factors, clinical manifestations of SCD, and other relevant factors like hydroxyurea.

Methods

A cross-sectional study design was utilized. Data collection was done using an electronic survey to collect self-reported information for the prevalence of leg ulcers and possible associated factors. The survey was distributed using social media platforms. Chi-square test was used to test for the presence of an association between having leg ulcers and sociodemographic variables as well as SCD related history. Furthermore, binary logistic regression was utilized to determine factors predicting the incidence of leg ulcers among SCD.

Results

A total of 790 valid responses were included in the study. Among these, 646 were included in the analysis of leg ulcers prevalence. From them, 52 (8%) SCD patients reported a history of leg ulcers. The male to female ratio was (9.7% vs 7.2%). The age group most affected by leg ulcers was those older than 50 (16.7%). There was no significant association between a history of leg ulcers and sociodemographic variables. The only predictive factors for leg ulcers were having six to eight vaso-occlusive crises per month and having more than eight vaso-occlusive crises per month.

Conclusion

Leg ulcers among SCD patients in Saudi Arabia were considerably prevalent (8%). There was no statistically significant correlation between leg ulceration and sociodemographic variables. Leg ulcers were more likely in patients with a history of highly frequent vaso-occlusive crises. No association was found between the incidence of leg ulcers and other complications of sickle cell disease or hydroxyurea.

The Evolving Pharmacotherapeutic Landscape for the Treatment of Sickle Cell Disease

Sickle cell disease (SCD) is an extremely heterogeneous disease that has been associated with global morbidity and early mortality. More effective and inexpensive therapies are needed. During the last five years, the landscape of the pharmacotherapy of SCD has changed dramatically. Currently, 54 drugs have been used or under consideration to use for the treatment of SCD. These fall into 3 categories: the first category includes the four drugs (Hydroxyurea, L-Glutamine, Crizanlizumab tmca and Voxelotor) that have been approved by the United States Food and Drug Administration (FDA) based on successful clinical trials. The second category includes 22 drugs that failed, discontinued or terminated for now and the third category includes 28 drugs that are actively being considered for the treatment of SCD. Crizanlizumab and Voxelotor are included in the first and third categories because they have been used in more than one trial. New therapies targeting multiple pathways in the complex pathophysiology of SCD have been achieved or are under continued investigation. The emerging trend seems to be the use of multimodal drugs (i.e. drugs that have different mechanisms of action) to treat SCD similar to the use of multiple chemotherapeutic agents to treat cancer.

Hypoxia-inducible factor (HIF): how to improve osseointegration in hip arthroplasty secondary to avascular necrosis in sickle cell disease

Many studies in the literature have been carried out to evaluate the various cellular and molecular processes involved in osteogenesis.

Angiogenesis and bone formation work closely together in this group of disorders. Hypoxia-inducible factor (HIF) which is stimulated in tissue hypoxia triggers a cascade of molecular processes that helps manage this physiological deficiency.

However, there still remains a paucity of knowledge with regard to how sickle cell bone pathology, in particular avascular necrosis, could be altered when it comes to osseointegration at the molecular level.

Hypoxia-inducible factor has been identified as key in mediating how cells adapt to molecular oxygen levels.

The aim of this review is to further elucidate the physiology of hypoxia-inducible factor with its various pathways and to establish what role this factor could play in altering the disease pathophysiology of avascular necrosis caused by sickle cell disease and in improving osseointegration.

This review article also seeks to propose certain research methodology frameworks in exploring how osseointegration could be improved in sickle cell disease patients with total hip replacements and how it could eventually reduce their already increased risk of undergoing revision surgery.

Cite this article: EFORT Open Rev 2019;4:567-575. DOI: 10.1302/2058-5241.4.180030

Serum Hepcidin Concentration in Individuals with Sickle Cell Anemia: Basis for the Dietary Recommendation of Iron

Dietary iron requirements in patients with sickle cell disease (SCD) remain unclear. SCD is a neglected hemoglobinopathy characterized by intense erythropoietic activity and anemia. Hepcidin is the hormone mainly responsible for iron homeostasis and intestinal absorption. Intense erythropoietic activity and anemia may reduce hepcidin transcription. By contrast, iron overload and inflammation may induce it. Studies on SCD have not evaluated the role of hepcidin in the presence and absence of iron overload. We aimed to compare serum hepcidin concentrations among individuals with sickle cell anemia, with or without iron overload, and those without the disease. Markers of iron metabolism and erythropoietic activity such as hepcidin, ferritin, and growth differentiation factor 15 were evaluated. Three groups participated in the study: the control group, comprised of individuals without SCD (C); those with the disease but without iron overload (SCDw); and those with the disease and iron overload (SCDio). Results showed that hepcidin concentration was higher in the SCDio > C > SCDw group. These data suggest that the dietary iron intake of the SCDio group should not be reduced as higher hepcidin concentrations may reduce the intestinal absorption of iron.

Application of phospho-CyTOF to characterize immune activation in patients with sickle cell disease in an ex vivo model of thrombosis

Sickle cell disease (SCD) is a genetic disease caused by mutations in the beta globin gene, and inflammation plays a key role in driving many aspects of disease pathology. Early immune activation is believed to be associated with hemodynamic stresses and thrombus formation as cells traffic through blood vessels. We applied an extracorporeal perfusion system to model these effects ex vivo, and combined this with a phospho-CyTOF workflow to comprehensively evaluate single-cell signatures of early activation across all major circulating immune subsets. These approaches showed immune activation following passage through the perfusion chamber, most notably in monocytes, which exhibited platelet aggregation and significantly elevated expression of multiple phospho-proteins. Overall, these studies outline a robust and broadly applicable workflow to leverage phospho-CyTOF to characterize immune activation in response to ex vivo or in vivo perturbations and may facilitate identification of novel therapeutic targets in SCD and other inflammatory diseases.

Tachon Syndrome: Rare Side Effect of Articular Injections of Corticosteroids. A Report of Two Cases

Epidural or intra-articular injections of corticosteroids are an option for the treatment of several pain conditions but are not without adverse effects. Here, we discuss a rare systemic side effect of this therapy: Tachon syndrome. We report two cases, a 64-year-old woman and a 43-year-old man, who presented with Tachon syndrome after receiving, respectively, a shoulder and a lumbar injection of cortivazol 3.75 mg/1.5 ml suspension for injection in pre-filled syringes. The indication for this therapy was, respectively, tendinopathy of the supraspinatus and a mechanical L5 lumbosciatica. A few minutes after receiving the injection, patients experienced acute low back pain, chest tightness, facial erythema and profuse sweating. All vital and biologic parameters were normal. In the first case, improvement was spontaneous and all symptoms resolved in 20 min. The second patient remained under observation and received an intravenous ‘physiological’ infusion. Both patients recovered fully and returned home. A causal relationship between the corticosteroid injections and the patients’ symptoms was very likely because of the acute clinical presentation and the rapid improvement in the patients’ conditions and that no further signs indicating other serious complications developed.

Hydroxyurea-Lactose Interaction Study: In Silico and In Vitro Evaluation

The Maillard reaction between hydroxyurea (a primary amine-containing drug) and lactose (used as an excipient) was explored. The adduct of these compounds was synthesized by heating hydroxyurea with lactose monohydrate at 60 °C in borate buffer (pH 9.2) for 12 h. Synthesis of the adduct was confirmed using UV-visible spectroscopy and Fourier transform infrared, differential scanning calorimetry, high-pressure liquid chromatography, and liquid chromatography-mass spectrometry studies. An in silico investigation of how the adduct formation affected the interactions of hydroxyurea with its biological target oxyhemoglobin, to which it binds to generate nitric oxide and regulates fetal hemoglobin synthesis, was carried out. The in silico evaluations were complemented by an in vitro assay of the anti-sickling activity. Co-incubation of hydroxyurea with deoxygenated blood samples reduced the percentage of sickled cells from 38% to 12 ± 1.6%, whereas the percentage of sickled cells in samples treated with the adduct was 17 ± 1.2%. This indicated loss of anti-sickling activity in the case of the adduct. This study confirmed that hydroxyurea can participate in a Maillard reaction if lactose is used as a diluent. Although an extended study at environmentally feasible temperatures was not carried out in the present investigation, the partial loss of the anti-sickling activity of hydroxyurea was investigated along with the in silico drug-target interactions. The results indicated that the use of lactose in hydroxyurea formulations needs urgent reconsideration and that lactose must be replaced by other diluents that do not form Maillard adducts.

Insulin Secretion and Resistance in Normoglycemic Patients with Sickle Cell Disease

Diabetes mellitus has been described in chronic hemolytic anemias, but data are scarce regarding glucose metabolism in normoglycemic patients. To address this issue, we evaluated insulin sensitivity and secretion in patients with sickle cell disease (SCD) and normal oral glucose tolerance test (OGTT). Forty-five adult patients with homozygous sickle cell disease and Hb S/β-thalassemia (β-thal) (mean age 42.5 ± 9.5 years) and 45 healthy individuals matched for age and body mass index (BMI) were included in the study. All participants underwent an oral glucose tolerance test (OGTT) after an overnight fast. All patients had normal OGTT. Fasting glucose values did not differ significantly between groups, however, fasting insulin levels were significantly lower in the patient group compared to the control group (5.1 ± 2.7 μUI/mL vs. 11.3 ± 6.6 μUI/mL, p <0.005, respectively). Pancreatic β-cell insulin secretion index in the fasting state was significantly lower in patients with sickle cell disease compared with controls as assessed by calculations of the homeostatic model assessment for β-cell function (HOMA β%) (77.0 vs. 106.0%, respectively, p <0.001), while HOMA insulin resistance (HOMA IR), was lower in the sickle cell disease patients, albeit not statistically significant (0.8 vs. 1.1, respectively, p = 0.054). The HOMA β% was significantly correlated with ferritin levels (r = -526, p <0.001) (negative correlation) and with 25-hydroxy (OH)-vitamin D levels (r = 0.479, p <0.001) (positive correlation), even when adjusted for serum ferritin levels. Normoglycemic patients with sickle cell disease demonstrated impaired β-cell function with reduced insulin secretion even before OGTT was impaired.

Impaired wound healing: facts and hypotheses for multi-professional considerations in predictive, preventive and personalised medicine

Whereas the physiologic wound healing (WH) successfully proceeds through the clearly defined sequence of the individual phases of wound healing, chronic non-healing wounds/ulcers fail to complete the individual stages and the entire healing process. There are many risk factors both modifiable (such as stress, smoking, inappropriate alcohol consumption, malnutrition, obesity, diabetes, cardio-vascular disease, etc.) and non-modifiable (such as genetic diseases and ageing) strongly contributing to the impaired WH. Current statistics demonstrate that both categories are increasingly presented in the populations, which causes dramatic socio-economic burden to the healthcare sector and society at large. Consequently, innovative concepts by predictive, preventive and personalised medicine are crucial to be implemented in the area. Individual risk factors, causality, functional interrelationships, molecular signature, predictive diagnosis, and primary and secondary prevention are thoroughly analysed followed by the expert recommendations in this paper.

Relationship between Neutrophil-to-Lymphocyte Ratio and Inflammatory Markers in Sickle Cell Anaemia Patients with Proteinuria

The renal functions and structure in sickle cell anaemia (SCA) patients may be affected by chronic haemodynamic changes and consequences of vaso-occlusive events in the renal medulla. Few reports on neutrophil-to-lymphocyte (NLR) and platelet-to-lymphocyte (PLR) ratios in SCA patients in Africans exist in the literature. This study correlates the values of NLR and PLR with measured traditional inflammatory markers in SCA patients with and without proteinuria and impaired kidney function (defined in this study as estimated glomerular filtration rate (eGFR), less than 60 mL/min/1.73 m². Full blood count, C-reactive protein (CRP), and fibrinogen were assayed in 150 SCA patients and 50 control subjects using Coulter Haematology analyser (CELL DYE 37000) and ELISA method, respectively. The NLR and PLR were calculated by dividing absolute neutrophil or platelet counts by absolute lymphocyte count. Fibrinogen, CRP, NLR, and PLR increased progressively (p < 0.001) in SCA patients with or without proteinuria, with the highest values seen in those with impaired renal function. NLR correlated positively with CRP and fibrinogen in SCA patients without proteinuria (p < 0.001), with proteinuria (p < 0.001), and impaired renal function (p < 0.05). A positive relationship was also observed between NLR and fibrinogen in the control subjects. The need to determine cut-off values for these leukocyte ratios to be used in identifying those patients at risk and in the general management of SCA patients is suggested.

Anemias

Anemias continue to present a challenge to the health care profession. Anemia is defined as a reduction in one or more of the RBC indices. Patients presenting with a mild form of anemia may be asymptomatic; however, in more serious cases the anemia can become life threatening. In many cases the clinical presentation also reflects the underlying cause. Anemia may be attributed to various causes, whereas autoimmune RBC destruction may be attributed to intrinsic and extrinsic factors. Laboratory tests are essential in facilitating early detection and differentiation of anemia.

Deafness and sickle cell disease: three case reports and review of the literature

The otological complications of sickle cell disease (SCD) in general and the audiological complications in particular are not well documented and studied. Because the general management of patients with SCD has improved after the advent of newborn screening, antibiotic prophylaxis, safer blood transfusion and hydroxyurea therapy, patients with SCD are doing better in general and living longer than before. With longer longevity, the incidence of new complications of SCD became apparent and previously milder complications became more severe and more common. The dental and otological complications of SCD are examples of these changes that have become more common than before. Unfortunately with this increase, there are no guidelines or recommendations based on evidence on how to manage and treat these complications. The aim of this study was to describe three patients with SCD and deafness due to three different causes that were not adequately treated and to review the literature of deafness in SCD. We hope this may initiate more controlled trials on the incidence, prevalence and management of these complications.

Randomized trial of hypnosis as a pain and symptom management strategy in adults with sickle cell disease

Sickle cell disease (SCD) is the most common genetic disease in African-Americans, characterized by recurrent painful vaso-occlusive crises. Medical therapies for controlling or preventing crises are limited because of efficacy and/or toxicity. This is a randomized, controlled, single-crossover protocol of hypnosis for managing pain in SCD patients. Participants receive hypnosis from a trained hypnosis therapist followed by six weeks of self-hypnosis using digital media. Those in the control arm receive SCD education followed by a six-week waiting period before crossing over to the hypnosis arm of the study. Outcome measures include assessments of pain (frequency, intensity and quality), anxiety, coping strategies, sleep, depression, and health care utilization. To date, there are no published randomized, controlled trials evaluating the efficacy of hypnosis on SCD pain modulation in adults. Self-hypnosis for pain management may be helpful in modulating chronic pain, improving sleep quality, and decreasing use of narcotics in patients with SCD.

The Cellie Coping Kit for Sickle Cell Disease: Initial acceptability and feasibility

Sickle Cell Disease (SCD) and its treatment can place physical and psychosocial strain on children and their families, underlining the need for behavioral and emotional support. Much of SCD is often managed at home, which may prevent children from obtaining supportive services from medical and psychosocial teams. Children with SCD report a restricted number of coping strategies specific to managing SCD and may benefit from education on adaptive coping. To address this unmet need, a coping tool for children with cancer (Cellie Cancer Coping Kit) was adapted for children with SCD. The Cellie Coping Kit for SCD (Cellie Coping Kit) includes a stuffed "Cellie" toy, coping cards for children, and a book for caregivers. This study sought to assess the acceptability and feasibility of an intervention utilizing the Cellie Coping Kit. Fifteen children with SCD (ages 6-14) and their caregivers participated in a baseline assessment including semi-structured interviews to examine SCD-related stressors and coping strategies. Next, families received a brief introduction to the Cellie Coping Kit and were provided with a kit to use independently over the next four weeks before completing a follow-up assessment. Results indicated strong intervention acceptability overall. While families reported using and learning information and skills from the Cellie Coping Kit, several challenges were identified (e.g., child's living situation, busy schedules). The Cellie Coping Kit is a promising tool to support children with SCD and their families. Future research should examine whether use of the Cellie Coping Kit impacts behavioral change and improved health outcomes.

Emerging drugs for sickle cell anemia

INTRODUCTION

The search for effective therapeutic interventions for sickle cell disease (SCD) has been an ongoing endeavor for over 50 years. During this period, only hydroxyurea (HU), which received US FDA approval in February 1998, was identified as an effective therapeutic agent in preventing or ameliorating the frequency of vaso-occlusive crises, acute chest syndrome and the need for blood transfusion. Approximately 25% of patients with sickle cell anemia (SCA), however, do not respond to HU and some patients experiencing serious side effects of this chemotherapeutic agent. Nevertheless, the success of HU opened the sluice gates to identify other effective drug therapies. The objective of this review is to describe the emerging drug therapies for SCA.

AREAS COVERED

In this review, we describe the pathophysiology of SCD and provide an in-depth analysis of the current and new pharmacologic therapies in the field. Literature searches involved multiple databases including Medline In-Process & Other Non-Indexed Citations, MEDLINE, Embase, Cochrane Database of Systematic Reviews, and Scopus.

EXPERT OPINION

SCA is a heterogeneous disease that has caused tremendous global morbidity and early mortality. More effective, individualized and inexpensive therapies are needed. New therapies targeting multiple pathways in its complex pathophysiology are under investigation.

Clinical biomarkers in sickle cell disease

Sickle cell disease (SCD) is a hereditary blood disorder caused by a single gene. Various blood and urine biomarkers have been identified in SCD which are associated with laboratory and medical history. Biomarkers have been proven helpful in identifying different interconnected disease-causing mechanisms of SCD, including hypercoagulability, hemolysis, inflammation, oxidative stress, vasculopathy, reperfusion injury and reduced vasodilatory responses in endothelium, to name just a few. However, there exists a need to establish a panel of validated blood and urine biomarkers in SCD. This paper reviews the current contribution of biochemical markers associated with clinical manifestation and identification of sub-phenotypes in SCD.

A biopsychosocial-spiritual model of chronic pain in adults with sickle cell disease

Chronic pain in adults with sickle cell disease (SCD) is a complex multidimensional experience that includes biologic, psychologic, sociologic, and spiritual factors. To date, three models of pain associated with SCD (i.e., biomedical model, biopsychosocial model for SCD pain, and Health Beliefs Model) have been published. The biopsychosocial multidimensional approach to chronic pain developed by Turk and Gatchel is a widely used model of chronic pain. However, this model has not been applied to chronic pain associated with SCD. In addition, a spiritual/religious dimension is not included in this model. Because spirituality/religion is central to persons affected by SCD, that dimension needs to be added to any model of chronic pain in adults with SCD. In fact, data from one study suggest that spirituality/religiosity is associated with decreased pain intensity in adults with chronic pain from SCD. A biopsychosocial-spiritual model is proposed for adults with chronic pain from SCD, because it embraces the whole person. This model includes the biologic, psychologic, sociologic, and spiritual factors relevant to adults with SCD based on past and current research. The purpose of this paper is to describe an adaptation of Turk and Gatchel's model of chronic pain for adults with SCD and to summarize research findings that support each component of the revised model (i.e., biologic, psychologic, sociologic, spiritual). The paper concludes with a discussion of implications for the use of this model in research.

β-Globin sleeping beauty transposon reduces red blood cell sickling in a patient-derived CD34(+)-based in vitro model

The ultimate goal of gene therapy for sickle cell anemia (SCA) is an improved phenotype for the patient. In this study, we utilized bone marrow from a sickle cell patient as a model of disease in an in vitro setting for the hyperactive Sleeping Beauty transposon gene therapy system. We demonstrated that mature sickle red blood cells containing hemoglobin-S and sickling in response to metabisulfite can be generated in vitro from SCA bone marrow. These cells showed the characteristic morphology and kinetics of hemoglobin-S polymerization, which we quantified using video microscopy and imaging cytometry. Using video assessment, we showed that delivery of an IHK-β^T87Q antisickling globin gene by Sleeping Beauty via nucleofection improves metrics of sickling, decreasing percent sickled from 53.2 ± 2.2% to 43.9 ± 2.0%, increasing the median time to sickling from 8.5 to 9.6 min and decreasing the maximum rate of sickling from 2.3 x 10^-3 sickling cells/total cells/sec in controls to 1.26 x 10^-3 sickling cells/total cells/sec in the IHK-β^T87Q-globin group (p < 0.001). Using imaging cytometry, the percentage of elongated sickled cells decreased from 34.8 ± 4.5% to 29.5 ± 3.0% in control versus treated (p < 0.05). These results support the potential use of Sleeping Beauty as a clinical gene therapy vector and provide a useful tool for studying sickle red blood cells in vitro.

Thyroid Doppler indices in patients with sickle cell disease

OBJECTIVE

To evaluate the intrathyroidal hemodynamic changes and thyroidal volume in sickle cell disease (SCD) patients.

METHODS

Thirty-two patients with homozygous SCD and 32 control subjects were examined with color Doppler ultrasonography. None of the patients and control subjects had clinical or laboratory evidence of thyroid disease.

RESULTS

SCD patients had significantly higher resistance index (RI) and pulsatility index (PI) values and lower thyroid volume compared with control group.

CONCLUSION

Increased intrathyroidal RI and PI and decreased thyroid volume may be due to impaired thyroidal microcirculation. Further and follow-up studies are needed to explain the relationship between Doppler parameters and thyroid functions.

Two assays to evaluate potential genotoxic effects of hydroxyurea in sickle cell disease patients

Hydroxycarbamide, well known in clinical settings as hydroxyurea (HU), is an antineoplastic agent inhibiting the ribonucleotide reductase enzyme, and thus, the conversion of ribonucleotides into deoxyribonucleotides. A concern about long term side effects of HU treatment in sickle cell disease patients, particularly genotoxicity, has often been evoked. The present study assessed two suitable methods to evaluate oxidative DNA damage associated with HU: the comet assay on blood lymphocytes and the quantification of urinary excretion of 8-oxodeoxyguanosine (8-oxodG). Both methods were applied in a preliminary study including seven sickle cell disease patients treated with HU, seven untreated sickle cell disease patients and five healthy volunteers. Concerning DNA damage, the comet assay and the 8-oxodG assay did not reveal any significant differences among the three groups. Methodologies used in this pilot study could be suitable to carry out further research in this area including a larger size sample setting.

Possible links between sickle cell crisis and pentavalent antimony

For over 60 years, pentavalent antimony (Sb(v)) has been the first-line treatment of leishmaniasis. Sickle cell anemia is a disease caused by a defect in red blood cells, which among other things can cause vasooclusive crisis. We report the case of a 6-year-old child with leishmaniasis who during treatment with meglumine antimoniate developed a sickle cell crisis (SCC). No previous reports describing the relationship between antimonial drugs and sickle cell disease were found. Reviews of both the pathophysiology of SCC and the mechanism of action of Sb(v) revealed that a common pathway (glutathione) may have resulted in the SCC. ChemoText, a novel database created to predict chemical-protein-disease interactions, was used to perform a more expansive and systematic review that was able to support the association between glutathione, Sb(v), and SCC. Although suggestive evidence to support the hypothesis, additional research at the bench would be needed to prove Sb(v) caused the SCC.

Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management

The sickle hemoglobin is an abnormal hemoglobin due to point mutation (GAG → GTG) in exon 1 of the β globin gene resulting in the substitution of glutamic acid by valine at position 6 of the β globin polypeptide chain. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of sickle cell disease in general and sickle cell anemia in particular. The disease itself is chronic in nature but many of its complications are acute such as the recurrent acute painful crises (its hallmark), acute chest syndrome, and priapism. These complications vary considerably among patients, in the same patient with time, among countries and with age and sex. To date, there is no well-established consensus among providers on the management of the complications of sickle cell disease due in part to lack of evidence and in part to differences in the experience of providers. It is the aim of this paper to review available current approaches to manage the major complications of sickle cell disease. We hope that this will establish another preliminary forum among providers that may eventually lead the way to better outcomes.

Cardiovascular abnormalities in sickle cell disease

Sickle cell disease is characterized by recurrent episodes of ischemia-reperfusion injury to multiple vital organ systems and a chronic hemolytic anemia, both contributing to progressive organ dysfunction. The introduction of treatments that induce protective fetal hemoglobin and reduce infectious complications has greatly prolonged survival. However, with increased longevity, cardiovascular complications are increasingly evident, with the notable development of a progressive proliferative systemic vasculopathy, pulmonary hypertension (PH), and left ventricular diastolic dysfunction. Pulmonary hypertension is reported in autopsy studies, and numerous clinical studies have shown that increased pulmonary pressures are an important risk marker for mortality in these patients. In epidemiological studies, the development of PH is associated with intravascular hemolysis, cutaneous leg ulceration, renal insufficiency, iron overload, and liver dysfunction. Chronic anemia in sickle cell disease results in cardiac chamber dilation and a compensatory increase in left ventricular mass. This is often accompanied by left ventricular diastolic dysfunction that has also been a strong independent predictor of mortality in patients with sickle cell disease. Both PH and diastolic dysfunction are associated with marked abnormalities in exercise capacity in these patients. Sudden death is an increasingly recognized problem, and further cardiac investigations are necessary to recognize and treat high-risk patients.

Oocyte cryopreservation in a patient with sickle cell disease prior to hematopoietic stem cell transplantation: first report

PURPOSE

To report the first occurrence of successful ovarian stimulation, oocyte retrieval and oocyte cryopreservation for fertility preservation in an adolescent with severe sickle cell disease scheduled to undergo a hematopoietic stem cell transplant

METHODS

Case report.

RESULTS

A 19 year old female with severe sickle cell disease presented for fertility preservation counseling prior to hematopoietic stem cell transplantation. She ultimately underwent ovarian stimulation using a minimal stimulation GnRH antagonist protocol resulting in the successful banking of oocytes prior to transplant. The unique hazards associated with ovarian stimulation in patients with sickle cell disease, such as thrombosis and vaso-occlusive events, are discussed and the methods undertaken to minimize these risks are described.

CONCLUSIONS

Controlled ovarian hyperstimulation and oocyte banking for fertility preservation is feasible in young women with sickle cell disease requiring hematopoietic stem cell transplant and deserves further investigation. Given the elevated risk of thrombosis and predisposition to painful vaso-occlusive events, controlled ovarian hyperstimulation in patients with sickle cell disease is not straightforward and requires a multi-disciplinary team approach to adequately address and minimize the risks in this unique patient population.

Genomics and pain research in sickle cell disease: an explanation of heterogeneity?

Sickle cell disease (SCD) is a chronic illness, and the major complication, pain, results in complex multidimensional problems that affect an individual's ability to maintain adequate quality of life in multiple areas. Chronic SCD pain is inadequately treated, because it is not well understood, and the degree of chronic pain, clinical presentation, and sequela complications can vary from patient to patient, even among individuals with the same SCD genotype. The reason for this variation is unknown, but the underlying cause might be genetic. Researchers have not explored the contribution of a genomic variable to the occurrence of heterogeneous chronic SCD pain. Previous research on the guanosine triphosphate cyclohydrolase (GCH1) gene suggests that in some cases, phenotypic heterogeneity in human sensitivity to pain correlates with underlying genotypic variations in the GCH1 gene. These findings imply that genotypic variations might also explain why some SCD patients experience more chronic pain than others.

Improving care for children with sickle cell disease/acute chest syndrome

BACKGROUND

Acute chest syndrome (ACS) is a leading cause of hospitalization and death of children with sickle cell disease (SCD). An evidence-based ACS/SCD guideline was established to standardize care throughout the institution in February 2008. However, by the summer of 2009 use of the guideline was inconsistent, and did not seem to have an impact on length of stay. As a result, an implementation program was developed.

OBJECTIVE

This quality-improvement project evaluated the influence of the development and implementation of a clinical practice guideline for children with SCD with ACS or at risk for ACS on clinical outcomes.

METHODS

Clinical outcomes of 139 patients with SCD were evaluated before and after the development of the implementation program. Outcomes included average length of stay, number of exchange transfusions, average cost per SCD admission, and documentation of the clinical respiratory score and pulmonary interventions.

RESULTS

Average length of stay decreased from 5.8 days before implementation of the guideline to 4.1 days after implementation (P = .033). No patients required an exchange transfusion. Average cost per SCD admission decreased from $30 359 before guideline implementation to $22 368. Documentation of the clinical respiratory score increased from 31.0% before implementation to 75.5%, which is an improvement of 44.5% (P < .001). Documentation of incentive spirometry and positive expiratory pressure increased from 23.3% before implementation to 50.4%, which is an improvement of 27.1% (P < .001).

CONCLUSIONS

Implementation of a guideline for children with SCD with ACS or at risk for ACS improved outcomes for patients with SCD.

Can Heterogeneity of Chronic Sickle-Cell Disease Pain Be Explained by Genomics? A Literature Review

This literature review explores the potential of genomics to explain, or at least contribute to the discussion about, heterogeneity in chronic pain in sickle-cell disease (SCD). Background: Adults with SCD, a single-gene disorder, are living longer than in years past, yet report being burdened by chronic pain. With only a few studies on chronic pain in this population, the epidemiology is unclear. However, research in the area of pain genetics continues to advance since the conclusion of the Human Genome Project. Two pain susceptibility genes, catechol-O-methyltransferase (COMT) and cytochrome P450, have, to date, been discovered that can increase individual susceptibility to the development of chronic pain. Method: A search was conducted in PubMed, CINAHL, and EBSCO using the terms ``sickle cell,'' ``chronic pain,'' ``polymorphism,'' ``genetics,'' ``pain genetics,'' ``human,'' ``adult,'' ``association studies,'' and ``pain susceptibility genes'' to search for articles published between 1970 and 2008. Findings: Chronic pain generally is more prevalent and severe than previously reported, and individuals with SCD report daily pain. The genomic era has made it possible for scientists to identify pain susceptibility genes that contribute to variability in the interindividual experience of chronic pain. Conclusion: Nurses are well positioned to generate and translate genomic research, thus improving care delivery. Such research may lead to the identification of polymorphisms associated with pain sensitivity in individuals with SCD.

[Genetic causes of impaired wound healing. Rare differential diagnosis of the non-healing wound]

Chronic leg ulcers affect about 1% of the German population. The intense search for the underlying cause of impaired wound healing is an essential requirement for successful therapy. The most common causes comprise chronic venous insufficiency (70%), peripheral arterial occlusive disease (10%) and diabetes mellitus. Besides vasculitis, infectious diseases and tumors, genetic diseases may constitute the underlying cause for impaired wound healing. In this review various rare genetic diseases causing chronic wounds like the Klinefelter-Syndrome, immunological diseases including the TAP-deficiency-syndrome and the leukocyte adhesion deficiency-syndromes, red blood cell disorders, thalassemia, thrombotic diseases, progeroid syndromes and inherited connective tissue disorders are presented.

Age- and Sex-Specific Nociceptive Response to Endothelin-1

Endothelin-1 (ET-1) is a chemical mediator released by the body at sites of injury and disease. This study tests the hypothesis that ET-1-induced nociception changes with age and sex. Intraplantar ET-1 (1.1 and 3.3 nmol) produced age-specific paw flinching and licking (postnatal day 7 > 21 > 60). The onset and duration of the nociceptive responses was dependent on age. Postnatal day (P) 21 and 60 rats displayed an immediate onset of behavior that subsided with time, whereas the P7 rats had a delayed behavioral response that onset at 20 minutes after ET-1 administration and continued beyond the 75 minute observation period. P7 males showed greater paw flinching compared with females. In addition to spontaneous nociceptive behaviors, ET-1 produced mechanical allodynia in all ages. As with spontaneous nociception, ET-1-induced mechanical allodynia was of a longer duration in the younger aged rats compared with adult rats. These findings show that ET-1 produces both spontaneous nociceptive behaviors and evoked mechanical allodynia in both young and adult rats but that the temporal profile and the size of the responses are age- and sex-dependent. These findings are the first description of age- and sex-specific ET-1-induced nociception.

PERSPECTIVE

Endothelin-1 is a vasoactive peptide released into the systemic circulation after stress and cold pain as well as locally in tissue after injury and disease. These findings suggest greater pain to stimuli that release endogenous endothelin in younger versus older organisms. This developmental approach to studying ET-1-induced pain further illustrates the need for understanding pain mechanisms as a function of the development of the organism so as to better treat pain across the life span.

Sickle cell anemia: targeting the role of fetal hemoglobin in therapy

Sickle cell anemia results from the single amino acid substitution of valine for glutamic acid in the beta-chain owing to a nucleotide defect that causes the production of abnormal beta-chains in hemoglobin S. Abnormal hemoglobin chains form polymers in the deoxygenated state, leading to the characteristic sickle cells. The polymerization of deoxygenated hemoglobin S accounts for the pathologic changes in sickle cell disease. The main-stay of therapy in sickle cell disease aims to reduce the amount of sickled hemoglobin present through the prevention of polymerization and reversal of this process. One way of discouraging polymerization is to increase the level of fetal hemoglobin, which because of its high oxygen affinity, does not participate in the polymerization process. Fetal hemoglobin production may be induced pharmacologically or by the use of gene therapy and genetic engineering techniques.

Immunomodulatory drug CC-4047 is a cell-type and stimulus-selective transcriptional inhibitor of cyclooxygenase 2

COX2 (prostaglandin G/H synthase, PTGS2) is a well-validated target in the fields of both oncology and inflammation. Despite their significant toxicity profile, non-steroidal anti-inflammatory drugs (NSAIDs) have become standard of care in the treatment of many COX2-mediated inflammatory conditions. In this report, we show that one IMiDs((R)) immunomodulatory drug, CC-4047, can reduce the levels of COX2 and the production of prostaglandins (PG) in human LPS-stimulated monocytes. The inhibition of COX2 by CC-4047 occurs at the level of gene transcription, by reducing the LPS-stimulated transcriptional activity at the COX2 gene. Because it is a transcriptional rather than an enzymatic inhibitor of COX2, CC-4047 inhibition of PG production is not susceptible to competition by exogenous arachadonic acid (AA). The distinct mechanisms of action allow CC-4047 and a COX2-selective NSAID to work additively to block PG secretion from monocytes. CC-4047 does not, however, block COX2 induction in or prostacyclin secretion from IL-1beta stimulated human umbilical vein endothelial cells (HUVEC) cells, nor does it inhibit COX1 in either monocytes or HUVEC cells. CC-4047 also inhibits COX2 and PG production in monocytes derived from patients with sickle cell disease (SCD). Taken together, the data in this manuscript suggest CC-4047 will provide important anti-inflammatory benefit to patients and will improve the safety of NSAIDs in the treatment of SCD or other inflammatory conditions.

Histamine increases sickle erythrocyte adherence to endothelium

Complications of sickle cell anaemia include vascular occlusion triggered by the adherence of sickle erythrocytes to endothelium in the postcapillary venules. Adherence can be promoted by inflammatory mediators that induce endothelial cell adhesion molecule expression and arrest flowing erythrocytes. The present study characterised the effect of histamine stimulation on the kinetics of sickle cell adherence to large vessel and microvascular endothelium under physiological flow. Increased sickle cell adherence was observed within minutes of endothelial activation by histamine and reached a maximum value within 30 min. At steady state, sickle cell adherence to histamine-stimulated endothelium was 47 +/- 4 adherent cells/mm(2), 2.6-fold higher than sickle cell adherence to unstimulated endothelial cells. Histamine-induced sickle cell adherence occurred rapidly and transiently. Studies using histamine receptor agonists and antagonists suggest that histamine-induced sickle cell adhesion depends on simultaneous stimulation of the H(2) and H(4) histamine receptors and endothelial P-selectin expression. These data show that histamine release may promote sickle cell adherence and vaso-occlusion. In vivo histamine release should be studied to determine its role in sickle complications and whether blocking of specific histamine receptors may prevent clinical complications or adverse effects from histamine release stimulated by opiate analgesic treatment.

Transfusion Management in Sickle Cell Disease

Sickle cell disease (SCD) is the most commonly inherited hemoglobinopathy in the United States. Blood transfusion is a critical part of the multidisciplinary approach necessary in the management of SCD; however, blood transfusions are not without complications. The successful use of transfusion as a treatment strategy in SCD requires the critical review and knowledge of transfusion methods, generally accepted indications, clinical situations in which transfusion generally is not considered, the selection of blood products, and strategies to prevent transfusion-related complications.

Tachon's syndrome (suracute back and/or thoracic pain following local injections of corticosteroids). A report of 318 French cases

OBJECTIVES

To assess the frequency, features, and outcome of excruciating lumbar, dorsal, and/or thoracic pain following injections of local corticosteroids in rare instances.

METHODS

A questionnaire mailed to 500 French rheumatologists.

RESULTS

Three hundred and eighteen cases were reported by 92 rheumatologists (one event per 8000 injections or 6.5 years of practice), following injections into lumbar epidural space (39%), an upper limb (30%), a lower limb (mostly the heel) (24%), or other locations (7%), of cortivazol (67%), hydrocortisone (25%), betamethasone (7%), or paramethasone (1%). Symptoms occurred 1-5 min (78%) or less than 1 min (22%) after injection, and highly acute axial pain usually lasted for less than 5 min (34%) or 5-15 min (51%). In addition to pain in lumbar (84%) and/or dorsal regions (25%) [often preceded or associated with thoracic pain (36%)], other signs were: anxiety (87%), shortness of breath (64%), facial flushing (64%), diffuse sweating (41%), agitation (29%), transient cough (23%), abdominal pain (20%), transient hypertension (15%), paleness (10%), hypotension (8%), diarrhoea (3%) and headache (3%). None of these patients was known to be allergic, and urticaria developed in only 2%. Outcome was favourable in all cases (even though 4/318 patients were transiently hospitalised) with an overall duration of 25 +/- 71 min. Another injection was performed later in 146/318 cases (46%), but Tachon's syndrome recurred in only 20 of these 146 patients (14%).

CONCLUSION

The outcome of this impressive syndrome seems excellent. Tachon's syndrome might be the venous counterpart of Nicolau's syndrome (injection of corticosteroids in an artery).

Evaluación de veintitrés episodios de síndrome torácico agudo en pacientes con drepanocitosis

INTRODUCTION

Acute thoracic syndrome (pneumonia and/or lung infarction) is a significant cause of morbidity and mortality in sickle cell anemia.

OBJECTIVE

To review the clinical manifestations, management and outcome of episodes of acute thoracic syndrome in our hospital.

METHODS

We performed a retrospective review of all the episodes of acute thoracic syndrome diagnosed at our center in patients younger than 18 years of age with sickle cell anemia. Clinical, laboratory and radiological findings, outcome and treatment were analyzed. Data from patients < 3 years and > 3 years of age were compared (Fisher's exact test and the Mann-Whitney U test).

RESULTS

Twenty-three episodes of acute thoracic syndrome were evaluated in eight out of 12 patients with sickle cell anemia followed-up in our hospital. These episodes represented 36 % of the total time of admission in these patients. The most frequent cause was infection. The most frequent symptoms were fever (87 %), cough (61 %) and cold (35 %) symptoms. Seventy-four percent of the patients were not diagnosed at admission, either because the chest X-ray was normal (52 %) or because it was not performed (22 %) due to the absence of pulmonary manifestations. Patients aged more than 3 years old had more severe episodes, with greater clinical compromise and radiological involvement and increased use of analgesia. Transfusions were administered in 65 % of the episodes and in five patients (> 3 years) a partial exchange transfusion was performed. In five patients corticoid treatment was associated with febrile relapses.

CONCLUSIONS

Acute thoracic syndrome is frequent in sickle cell disease and is more severe in children older than 3 years. Its diagnosis requires a high index of suspicion, due to multiple forms of clinical presentations and normal chest radiology at admission.

Purified Poloxamer 188 for Sickle Cell Vaso-Occlusive Crisis

OBJECTIVE

To review available literature on the pharmacology, pharmacokinetics, efficacy, toxicology, adverse effects, drug interactions, and dosage guidelines for purified poloxamer 188, a product in Phase III trials.

DATA SOURCES

Reviewers searched the following databases for English-language studies: MEDLINE (1966–November 2003), International Pharmaceutical Abstracts (1970–November 2003), and the Cochrane Library Database (3rd quarter 2003). Key search terms included purified poloxamer 188, Flocor, CRL-5861, poloxamer 188, RheothRx, and pluronic F-68.

STUDY SELECTION AND DATA EXTRACTION

Data on efficacy, adverse effects, and pharmacokinetics were obtained from randomized, open-label, and blinded clinical trials. Toxicology data were obtained from unpublished studies with purified poloxamer 188 and from available data on poloxamer 188 (nonpurified form).

DATA SYNTHESIS

Purified poloxamer 188 is a highly purified form of the nonionic block copolymer poloxamer 188. It lowers blood viscosity, decreases red blood cell (RBC) aggregation, and decreases friction between RBCs and vessel walls to increase microvascular blood flow and decrease cell injury. In clinical trials, purified poloxamer 188 demonstrated safety, but little efficacy for the treatment of sickle cell vaso-occlusive crisis. Increased efficacy has been shown in patients on concurrent hydroxyurea therapy and those <15 years of age.

CONCLUSIONS

Purified poloxamer 188 represents a new approach to the management of the sickle cell vaso-occlusive crisis. Children and patients on hydroxyurea may benefit most from purified poloxamer 188 therapy. Further studies are needed to confirm its efficacy and to determine whether the drug decreases sickle cell disease severity and complications.