Von Willebrand Factor in Sickle Cell Disease - Relationship to Sleep Hypoxia.

Abstract Introduction: Despite the intriguing in vitro data implicating vWF in sickle-RBC-endothelial adhesion and in animal models of vasoocclusion, there are few clinical studies characterizing the role of vWF in SCD pathophysiology. Rationale: Plasma vWF is mainly endothelial-derived, upto 95% of newly synthesized vWF being secreted constitutively. Since in vitro studies have shown that hypoxia mediates release of ultra-large vWF multimers stored in endothelial Weibel Palade bodies, we hypothesized that changes in the plasma vWF profile of patients with sickle cell disease (SCD) could potentially be related to their oxygenation status and subsequent clinical events. Patient groups: Following informed consent blood samples were obtained from 20 children with SCD who were enrolled in an investigation of sleep hypoxia. After an awake blood oxgygen saturation by pulse oximetry (SaO2), an overnight recording was performed and a histogram generated showing proportions of time spent at various SaO2s. On the basis of mean sleeping SaO2s, the study population was divided into Group I (Normoxia, sleeping SaO2>94%, n=10) and Group II (Hypoxia, sleeping SaO2 <94%, n=10). Methods: VWF antigen level (vWF antigen) was determined by a latex enhanced immunoassay and Ristocetin Cofactor activity (RCof) was evaluated by platelet aggregometry. VWF multimer analysis was performed on SDS- 1.6% agarose gels and visualized using a polyclonal rabbit anti-human VWF antibody (Dako) followed by chemiluminescent detection using horse radish peroxidase-conjugated anti-rabbit IgG (Amersham). The presence of high molecular weight VWF multimers had to fulfill the following three criteria: (a) vWF multimers larger than the largest vWF multimers present in pooled normal plasma;(b)vWF multimers similar to the largest multimers present in a post-DDAVP infusion plasma sample analyzed on the same gel;(c) assessment by three independent investigators. Student’s t-test was performed to compare the mean values of vWFAg, vWF:RCof, and vWF RCof:Ag ratio of Gps I and II. Results: We observed significant differences between normoxic vs. hypoxic children with SCD as depicted in the table below where results are shown as Mean values(1SD). vWF antigen levels correlated inversely (r2=0.28) and vWF RCof:Ag ratios correlated positively (r2=0.2) with sleeping SaO2s. vWF:Ag* vWF RCof vWF RCof:Ag Ratios** HMW-vWF *p <0.003; **p <0.006 Group I >/94% 120.8(30.9) 116.7 (36.8) 0.96(0.1) 0/7 (performed to date) Group II <94% 192.2 (69.4) 147.3 (71.3) 0.77(0.14) 4/5 (performed to date) Conclusions: Children with SCD and sleep hypoxia showed abnormalities in their vWF profiles when compared to normoxic children with SCD including elevated vWF antigen and qualitatively increased HMW multimers suggestive of hypoxia-mediated endothelial response. In addition, there is an unexpected discordance between these findings and decreased vWF RCof:Ag ratios. Since children with SCD and nocturnal hypoxemia have an increased rate of pain-associated vasoocclusion and CNS complications, our findings of vWF-related perturbations could provide an explanation for hypoxia-induced modulation of the proadhesive and prothrombotic state in these children.

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Right-To-Left Shunts (Extra-Cardiac Arterial-Venous Malformations) Are Highly Common In Adults With Sickle Cell Disease

Blood ◽

10.1182/blood.v122.21.1004.1004 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1004-1004

Author(s):

Nathan Langer ◽

MaryAnn O'Riordan ◽

Santosh K. Rao ◽

Jane A. Little ◽

Robert Schilz

Keyword(s):

Sickle Cell Disease ◽

General Population ◽

Oxygen Saturation ◽

Sickle Cell ◽

Morbidity And Mortality ◽

Acute Chest Syndrome ◽

Venous Malformations ◽

Cell Disease ◽

Group I ◽

Group Ii

Abstract Introduction Cardiopulmonary complications are a major cause of morbidity and mortality in sickle cell disease (SCD) as shown by worse prognosis in patients who have experienced acute chest syndrome or who have an elevated tricuspid regurgitant jet velocity (TRV) on echocardiogram at clinical baseline. Here we describe an unexpected and novel cardio-pulmonary complication in HbSS, right-to-left shunting through extra-cardiac arterial-venous malformations (AVMs), which may contribute to pathophysiology. Extracardiac AVMs are rare in the general population, with an estimated incidence of 1/5000. Of 2111 shunt evaluation echocardiograms performed at our institution over 12 months only 81 (3.8%) of individual studies were positive. Methods We evaluated 36 HbSS patients who presented with subjective dyspnea or hypoxia with clinical exam and with echocardiogram utilizing agitated saline to assess for vascular right-to-left shunts. We compared this group with the remaining 81 HbSS patients in our database. 19 of 36 symptomatic patients were found to have an extracardiac right-to-left shunt. We then compared these 19 patients with the 17 symptomatic HbSS patients who did not have a shunt. 10 HbSC and 5 S-beta-thalassemia patients were also studied and did not have a right-to-left shunt; only HbSS are included in comparative analyses. Results Patients with symptoms did not differ in age (32.7±10.3 years vs 31.7±11.7 years) from patients who did not present with hypoxia or subjective dyspnea (n=81). Symptomatic patients were more likely to have macroalbuminuria (>300 mg/g albumin-to-creatinine, 9/36 vs 8/63 evaluable, p=0.05), more likely to have a TRV ≥3 meters/second (9/36 vs 11/74 evaluable, p=0.09), and were more hypoxic at rest (96 ±5% vs 98±2% oxygen saturation, p=0.07). We found delayed left-sided bubble visualization in 19/36 symptomatic HbSS subjects (53%) consistent with extra-cardiac AVMs. HbSS subjects with (n=19, Group I) or without (n=17, Group II) a positive bubble study were clinically and demographically similar (age, gender, WBC, total Hgb, HgbF%, LDH, eGFR, proportion with macroalbuminuria, baseline oxygen saturation, and elevated TRV). However, group I patients had a higher reticulocyte count (15.4±5.5% vs 9.8±6.7% p<0.005). Of Group I patients, 42.1% had history of acute chest while 70.6% of Group II had such history (p=0.09). Group I patients were less likely to be on hydroxyurea (52.78% vs 47.22% p<0.05). Conclusion Extra-cardiac AVMs are observed in 16% of all subjects with HbSS, compared with 3.8% of general medical patients at a tertiary center undergoing shunt evaluation and .02% in the general population. In HbSS, symptomatic subjects are more likely to have evidence for vasculopathy (macroalbuminuria, elevated TRV) and hypoxia; one-half of these symptomatic patients have extracardiac AVMs. We speculate that this finding is unlikely to be clinically silent, and a bubble-echocardiogram may be an important additional clinical evaluation for symptomatic dyspnea or hypoxia. The impact of this novel clinical finding on morbidity and mortality in this disease remains under investigation. Disclosures: No relevant conflicts of interest to declare.

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The Use Of Transcranial Doppler Ultrasonography In Adult Patients With Sickle Cell Disease: A Retrospective Analysis

Blood ◽

10.1182/blood.v122.21.4692.4692 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4692-4692 ◽

Cited By ~ 1

Author(s):

Sofia Galli ◽

Soundrie Padayachee ◽

Jo Howard

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Stroke Risk ◽

Cell Disease ◽

Carotid Duplex ◽

Group I ◽

Ultrasound Findings ◽

Group Ii ◽

Ica Stenosis ◽

Extracranial Ica

Background Unlike in children, Transcranial Doppler Ultrasound (TCD) can not currently be used to predict stroke risk in adults with Sickle Cell Disease, and this is confounded by an age related decline in TCD and lack of an established normal TCD velocity range for adults. In addition abnormalities in the extracranial circulation have been associated with increased incidence of stroke in children with SCD, but this has not been shown in adults. Aims To retrospectively review TCD and carotid duplex ultrasound results from adults with SCD and to correlate with neurological outcome. Methods TCD and carotid duplex data were collected from 112 patients from January 2003 to December 2012 and analysed retrospectively. Imaging and non-imaging TCD and carotid duplex were performed as a routine out-patient investigation as part of an annual review in the comprehensive adult sickle cell clinic in our unit. STOP velocity criteria were used for stroke risk stratification. Carotid disease was defined as non-significant (<50%), moderate stenosis (50-69%) and severe disease (≥70%). Results The mean age of patients was 35.4 (range 17-79) years; 65% were female and 78% had HbSS. There were 5 patient exclusions based on the TCD findings; two were non-diagnostic and three had abnormal scans as part of childhood screening. The remaining 107 patients were divided into two groups; Group I patients had a normal neurological examination (n = 95) and Group II had an abnormal neurological examination with a clinical diagnosis of stroke that preceded TCD/carotid duplex examination (n = 12). In Group I there were 4 abnormal TCD scans according to STOP criteria; two showed significant asymmetry (>25%) and two showed abnormally low velocities (<50cm/s), one of whom subsequently developed a silent stroke. Although the remaining 91 patients had normal TCD findings; a limited TCD examination was noted in 6 patients and asymmetrical velocities that fell below the 25% threshold were observed in 7 patients, one of whom subsequently developed a symptomatic lacunar infarct. A further eight patients showed extracranial (ICA) disease and one of these also had evidence of a silent stroke on MRI. In Group II, 5 patients showed abnormal TCD findings; four had low velocities (<50cm/sec) and one had low velocities and significant asymmetry. Six patients had severe extracranial ICA stenosis or occlusion on carotid duplex. There was a significant increase in the incidence of abnormal TCD (C2=19.4, p<0.001) and duplex findings (C2=16.2, p<0.001) in patients in Group II compared to Group I. Conclusions Routine screening of adults with SCD using TCD did not show any asymptomatic patients with elevated TCD flow-velocities (>170cm/s), confirming previous studies. However, other abnormal ultrasound findings were observed including; abnormally low or asymmetric TCD velocities and extracranial ICA disease. These abnormalities were associated with stroke in three cases; TCD asymmetry preceded a lacunar infarct by five years, abnormally low velocities preceded a silent infarct by two years and severe extracranial ICA stenosis was associated with a silent infarct. There was a significantly increased incidence of abnormal ultrasound findings in patients who had neurological symptoms (91.6% versus 12.6%). Further investigation of the incidence and implications of abnormal TCD and extracranial carotid duplex findings in adults with sickle cell disease is required. Longitudinal follow-up of patients with low or asymmetric velocities and ICA disease will clarify if these abnormalities are associated with increased neurological morbidity; if so, intervention may be justified. The traditional STOP criteria of raised TCD velocities are inadequate in the adult sickle population, new velocity criteria are required to stratify the risk of stroke in this population. Disclosures: Howard: Sangart: Membership on an entity’s Board of Directors or advisory committees.

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Characterization of Pain, Vasculature and Innervation in Sickle Cell Disease.

Blood ◽

10.1182/blood.v110.11.2248.2248 ◽

2007 ◽

Vol 110 (11) ◽

pp. 2248-2248

Author(s):

Kalpna Gupta ◽

Chunsheng Chen ◽

Marna E. Ericson ◽

Robert P. Hebbel ◽

Yunfang Li

Keyword(s):

Sickle Cell Disease ◽

Blood Vessels ◽

Sickle Cell ◽

Thermal Hyperalgesia ◽

Cell Disease ◽

Morphine Treatment ◽

Group I ◽

Group Ii ◽

And Control

Abstract Pain in sickle cell disease (SCD) is characterized by chronic vasculopathy. Characterization of pain and vasculature may be critical to improve the analgesic ability of opioids in treating pain in SCD. Therefore, we examined the association between vasculature, innervation and pain in a transgenic mouse model of SCD (BERK) and control mice (HbABERK). Pain behavior was analyzed using paw withdrawal latencies (PWL) using Hargreave’s device for thermal hyperalgesia. A radiant heat stimulus was applied to the plantar surface of each hind paw from underneath the glass floor with a projector lamp bulb (CXL/CXR, 8 V, 50 W). PWL to the nearest 0.1 s was automatically recorded upon paw withdrawal. Paws were alternated randomly to preclude “order” effects. We observed that 5 mo old sickle mice showed significantly lower thresholds to noxious heat than controls (p=0.002 for females; and p=0.04 for males; n=5–7 and 15 observations/mouse). Females showed a significantly shorter latency than their respective males (control, p=0.03 and sickle, p=0.01), i.e., they were more sensitive to thermal stimuli. No significant difference was observed between sickle and control nor male and female mice (p > 0.05, n = 5–7) for mechanical allodynia using von Frey filaments, suggesting that sickle mice show increased sensitivity to thermal hyperalgesia. BERK mice were subcutaneously injected with 0.7 mg morphine/Kg mice/day (equivalent to 50 mg/70 kg /day/ human adult) with an added increment of 0.14 mg/day/Kg for each week for three different time periods; Group I, treated for 6 weeks, Group II treated for 6 weeks followed by withdrawal for 6 weeks and Group III treated for 12 weeks. Morphine treatment for 6 weeks as well as 12 weeks resulted in a ∼50–75% increase in PWL vs PBS, suggesting that chronic morphine treatment decreased hyperalgesia in sickle mice. The anti-hyperalgesic effect of morphine was antagonized by simultaneous co-administration of naloxone (2 mcg/Kg/day), suggesting an opioid receptor mediated effect. Naloxone treatment alone did not show any significant effect on PWL. In Group II, withdrawal of morphine for 6 weeks following 6 wks of treatment showed about 35% increase in PWL vs PBS (p<0.005), suggesting that the anti-hyperalgesic effect of morphine continues after its withdrawal. The continued anti-hyperalgesic effect of morphine following withdrawal could be secondary to its vasoregulatory effect. Indeed, confocal microscopy of skin sections revealed disorganized and stringy blood vessels, nerves and lymphatics in sickle mice vs. control. Deep blood vessels and nerve plexus, as well as the skin, were appreciably thicker in controls vs sickle. The diameter of lymphatics and densities of both blood vessels and nerves were significantly lower in sickle vs HbA controls (p= 0.0001 and 0.002, for sub-epidermal and dermal blood vessels, respectively; p=0.04 for lymphatic diameter; p=0.0001 for sub-epidermal, dermal and deep dermal nerve fibers). Functionally, we observed about 30% decrease in subcutaneous O2 measured by Laser Doppler (in real-time) in BERK vs HbA control (p<0.05). Thus, complementary alteration in vasculature and innervation may underlie the chronic pain in SCD. Given that morphine promotes angiogenesis and vasodilation, its prolonged anti-hyperalgesic activity could be due to its vasoregulatory function. Together, these data suggest that intermittent therapy with morphine in SCD may provide analgesia similar to continued therapy and may even be devoid of side-effects.

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Hypoxia-induced acute lung injury in murine models of sickle cell disease

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00288.2002 ◽

2004 ◽

Vol 286 (4) ◽

pp. L705-L714 ◽

Cited By ~ 57

Author(s):

Kirkwood A. Pritchard ◽

Jingsong Ou ◽

Zhijun Ou ◽

Yang Shi ◽

James P. Franciosi ◽

...

Keyword(s):

Sickle Cell Disease ◽

Lung Injury ◽

Sickle Cell ◽

Globin Gene ◽

Heat Shock Protein 90 ◽

Cell Disease ◽

Vascular Congestion ◽

Nitrite Nitrate ◽

Endothelial Nitric Oxide

Vaso-occlusive events are the major source of morbidity and mortality in sickle cell disease (SCD); however, the pathogenic mechanisms driving these events remain unclear. Using hypoxia to induce pulmonary injury, we investigated mechanisms by which sickle hemoglobin increases susceptibility to lung injury in a murine model of SCD, where mice either exclusively express the human α/sickle β-globin (hαβS) transgene (SCD mice) or are heterozygous for the normal murine β-globin gene and express the hαβStransgene (mβ+/-, hαβS+/-; heterozygote SCD mice). Under normoxia, lungs from the SCD mice contained higher levels of xanthine oxidase (XO), nitrotyrosine, and cGMP than controls (C57BL/6 mice). Hypoxia increased XO and nitrotyrosine and decreased cGMP content in the lungs of all mice. After hypoxia, vascular congestion was increased in lungs with a greater content of XO and nitrotyrosine. Under normoxia, the association of heat shock protein 90 (HSP90) with endothelial nitric oxide synthase (eNOS) in lungs of SCD and heterozygote SCD mice was decreased compared with the levels of association in lungs of controls. Hypoxia further decreased association of HSP90 with eNOS in lungs of SCD and heterozygote SCD mice, but not in the control lungs. Pretreatment of rat pulmonary microvascular endothelial cells in vitro with xanthine/XO decreased A-23187-stimulated nitrite + nitrate production and HSP90 interactions with eNOS. These data support the hypotheses that hypoxia increases XO release from ischemic tissues and that the local increase in XO-induced oxidative stress can then inhibit HSP90 interactions with eNOS, decreasing ·NO generation and predisposing the lung to vaso-occlusion.

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Endothelial Barrier Integrity Is Disrupted In Vitro by Heme and by Serum From Sickle Cell Disease Patients

Frontiers in Immunology ◽

10.3389/fimmu.2020.535147 ◽

2020 ◽

Vol 11 ◽

Author(s):

Vanessa Araujo Gomes Santaterra ◽

Maiara Marx Luz Fiusa ◽

Bidossessi Wilfried Hounkpe ◽

Francine Chenou ◽

Wouitchekpo Vincent Tonasse ◽

...

Keyword(s):

Sickle Cell Disease ◽

Healthy Volunteers ◽

Sickle Cell ◽

Endothelial Barrier ◽

Acute Chest Syndrome ◽

Cell Disease ◽

Experimental Conditions ◽

Cell Monolayers ◽

Junction Protein

Free extracellular heme has been shown to activate several compartments of innate immunity, acting as a danger-associated molecular pattern (DAMP) in hemolytic diseases. Although localized endothelial barrier (EB) disruption is an important part of inflammation that allows circulating leukocytes to reach inflamed tissues, non-localized/deregulated disruption of the EB can lead to widespread microvascular hyperpermeability and secondary tissue damage. In mouse models of sickle cell disease (SCD), EB disruption has been associated with the development of a form of acute lung injury that closely resembles acute chest syndrome (ACS), and that can be elicited by acute heme infusion. Here we explored the effect of heme on EB integrity using human endothelial cell monolayers, in experimental conditions that include elements that more closely resemble in vivo conditions. EB integrity was assessed by electric cell-substrate impedance sensing in the presence of varying concentrations of heme and sera from SCD patients or healthy volunteers. Heme caused a dose-dependent decrease of the electrical resistance of cell monolayers, consistent with EB disruption, which was confirmed by staining of junction protein VE-cadherin. In addition, sera from SCD patients, but not from healthy volunteers, were also capable to induce EB disruption. Interestingly, these effects were not associated with total heme levels in serum. However, when heme was added to sera from SCD patients, but not from healthy volunteers, EB disruption could be elicited, and this effect was associated with hemopexin serum levels. Together our in vitro studies provide additional support to the concept of heme as a DAMP in hemolytic conditions.

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Mineral Content and Antisickling Activity of Annona senegalensis, Alchornea cordifolia and Vigna unguiculata Used in the Management of Sickle Cell Disease in the Kwilu Province (Congo, DR)

International Blood Research & Reviews ◽

10.9734/ibrr/2020/v11i330131 ◽

2020 ◽

pp. 18-27

Author(s):

Jules M. Kitadi ◽

Clément L. Inkoto ◽

Emmanuel M. Lengbiye ◽

Damien S. T. Tshibangu ◽

Dorothée D. Tshilanda ◽

...

Keyword(s):

Sickle Cell Disease ◽

Mineral Composition ◽

Sickle Cell ◽

Mineral Elements ◽

Spectrometric Method ◽

Spectrometric Analysis ◽

Composition Analysis ◽

Cell Disease ◽

Republic Of The Congo

Aims: To determine the mineral composition of some plants (Annona senegalensis Pers., Alchornea cordifolia (Schumach. & Thonn.) Müll. Arg. and Vigna unguiculate (L.) Walp.) used in the management of sickle cell disease by traditional practitioners in Kwilu province and to evaluate their antisickling activity in vitro. Study Design: Plant collection in the Kwilu province, sample preparation, antisickling tests and fluorescence spectrometric analysis. Place and Duration of Study: This work was performed at the Faculty of Science, University of Kinshasa, Congo DR, from October 2016 to January 2018. Methodology: These three plants were harvested in the province of Kwilu in Democratic Republic of the Congo. The mineral composition analysis was carried out using the fluorescence spectrometric method while the in vitro antisickling activity was evaluate using Emmel and hemolysis tests. Results: Twenty three mineral elements were identified in each of these three plants: Potassium (K), Phosphorus (P), Calcium (Ca), Sodium (Na), Magnesium (Mg), Sulphur (S), Chlorine (Cl) and trace elements as: Aluminum (Al), Silicon (Si), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Nickel (Ni), Copper (Cu), Zinc (Zn), Selenium (Se), Brome (Br), Molybdenum (Mo), Tin (Sn), Iodine (I), Barium (Ba) and Lead (Pb). Annona senegalensis Pers., Alchornea cordifolia (Schumach. & Thonn.) Müll.Arg. and Vigna unguiculate (L.) Walp. aqueous extracts showed the capacity to prevent the sickling and the hemolysis of red blood cells. Conclusion: The obtained results confirm the antisickling activity thus justifying the use of these plants in Traditional Medicine for the management of sickle cell disease. The presence of some mineral elements like Fe, Zn, Mg and Se are useful for sickle cell disease patients.

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In vivo survival studies of 51Cr-labeled methyl acetimidate treated erythrocytes in patients with sickle cell disease

Blood ◽

10.1182/blood.v56.6.1041.1041 ◽

1980 ◽

Vol 56 (6) ◽

pp. 1041-1047 ◽

Cited By ~ 5

Author(s):

TG Gabuzda ◽

TL Chao ◽

MR Berenfeld ◽

T Gelbart

Keyword(s):

Sickle Cell Disease ◽

Survival Time ◽

Sickle Cell ◽

Clinical Testing ◽

Cell Disease ◽

Show Evidence ◽

Survival Studies ◽

Circulating Antibody

Abstract Studies of the survival time of 51Cr labeled erythrocytes treated in vitro with methyl acetimidate (MAI) were conducted in 13 patients with sickle cell disease in order to assess the suitability of this antisickling agent for more extensive clinical testing. In comparison with previously measured control values (average t1/2 8.4 +/- 1.1 days a), the survival time of the treated erythrocytes in 10 of the patients who were not transfused was initially prolonged (average t1/2 24.4 +/- 4.6 days). However, 5 of the 13 patients studied developed circulating antibody against the MAI treated erythrocytes, markedly reducing the survival time of MAI treated erythrocytes in subsequent studies. Two patients, each challenged 3 times with infused MAI treated erythrocytes, failed to show evidence of antibody production, suggesting that not all subjects become immunized even after repeated exposure. In spite of many other promising properties of MAI as an antisickling agent of potential value, consideration of its use in further clinical testing must depend on successful avoidance of immunization in patients receiving infusions of treated erythrocytes.

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Placenta growth factor in sickle cell disease: association with hemolysis and inflammation

Blood ◽

10.1182/blood-2009-04-217950 ◽

2010 ◽

Vol 115 (10) ◽

pp. 2014-2020 ◽

Cited By ~ 35

Author(s):

Julia E. Brittain ◽

Ben Hulkower ◽

Susan K. Jones ◽

Dell Strayhorn ◽

Laura De Castro ◽

...

Keyword(s):

Growth Factor ◽

Sickle Cell Disease ◽

Sickle Cell ◽

Predictive Accuracy ◽

Cross Sectional Study ◽

Acute Chest Syndrome ◽

Cell Disease ◽

Placenta Growth Factor ◽

Cross Sectional

Abstract Placenta growth factor (PlGF) is released by immature erythrocytes and is elevated in sickle cell disease (SCD). Previous data generated in vitro suggest that PlGF may play a role in the pathophysiology of SCD-associated pulmonary hypertension (PHT) by inducing the release of the vasoconstrictor, endothelin-1. In this cross-sectional study of 74 patients with SCD, we confirm that PlGF is significantly elevated in SCD compared with healthy control subjects. We found significantly higher levels of PlGF in SCD patients with PHT but observed no association of PlGF with the frequency of acute pain episodes or history of acute chest syndrome. The observed correlation between PlGF and various measures of red cell destruction suggests that hemolysis, and the resultant erythropoietic response, results in the up-regulation of PlGF. Although relatively specific, PlGF, as well as N-terminal pro-brain natriuretic peptide and soluble vascular cell adhesion molecule, has low predictive accuracy for the presence of PHT. Prospective studies are required to conclusively define the contribution of PlGF to the pathogenesis of PHT and other hemolytic complications in SCD.

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Voxelotor Treatment Interferes With Quantitative and Qualitative Hemoglobin Variant Analysis in Multiple Sickle Cell Disease Genotypes

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqaa067 ◽

2020 ◽

Vol 154 (5) ◽

pp. 627-634

Author(s):

Nicola J Rutherford-Parker ◽

Sean T Campbell ◽

Jennifer M Colby ◽

Zahra Shajani-Yi

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

High Performance ◽

Clinical Laboratory ◽

The United States ◽

Cell Disease ◽

Hemoglobin Variant ◽

Hbd Punjab ◽

The Impact

Abstract Objectives Voxelotor was recently approved for use in the United States as a treatment for sickle cell disease (SCD) and has been shown to interfere with the quantitation of hemoglobin (Hb) S percentage. This study aimed to determine the effect of voxelotor on the quantitation of hemoglobin variant levels in patients with multiple SCD genotypes. Methods In vitro experiments were performed to assess the impact of voxelotor treatment on hemoglobin variant testing. Whole blood samples were incubated with voxelotor and then analyzed by routinely used quantitative and qualitative clinical laboratory methods (high-performance liquid chromatography [HPLC], capillary zone electrophoresis [CZE], and acid and alkaline electrophoresis). Results Voxelotor modified the α-globin chain of multiple hemoglobins, including HbA, HbS, HbC, HbD-Punjab, HbE, HbA2, and HbF. These voxelotor-hemoglobin complexes prevented accurate quantitation of multiple hemoglobin species, including HbS, by HPLC and CZE. Conclusions Technical limitations in quantifying HbS percentage may preclude the use of HPLC or CZE for monitoring patients treated with voxelotor. Furthermore, it is unclear whether HbS-voxelotor complexes are clinically equivalent to HbS. Consensus guidelines for reporting hemoglobin variant percentages for patients taking voxelotor are needed, as these values are necessary for determining the number of RBC units to exchange in acute situations.

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