A Precision Medicine Tool for Measurement and Monitoring of Hemoglobin S in Sickle Cell Disease Patients Receiving Transfusion Therapy
Summary
We have developed a point-of-care immunoassay to rapidly quantify hemoglobin S (HbS) levels during transfusion therapy for sickle cell disease (SCD) patients. By applying a small amount of treated blood to the device, the healthcare provider can determine the %HbS in a SCD patient to immediately inform clinical decisions.
Abstract
Sickle cell disease (SCD) causes many severe health complications, including anemia, stroke, and acute chest syndrome. Red blood cell transfusion is the most commonly used therapy to treat or prevent these devastating complications. Other therapies include hydroxyurea therapy as well as bone marrow transplantation. Chronic intermittent transfusion is especially indicated to prevent recurrent strokes. However, transfusion therapy is associated with significant adverse effects (e.g., alloimmunization and iron overload). The point-of-care (POC) lateral flow immunoassay used here quantifies the %HbS in 15 min using a small patient blood sample. Utilizing this information, the healthcare provider is able to adjust blood transfusion volume for SCD patients to achieve the desired target HbS (most often <30%), while reducing the risk of transfusion-related complications. When compared to laboratory hemoglobin electrophoresis data for 38 whole blood samples, the POC test performed with very high correlation and linear fit (slope = 0.9949, R2 = 0.9751). The strong agreement between the two hemoglobin S percentage (%HbS) quantifying methods shows that 89.5% of samples fall within ±5.2% HbS bias. The calibration for quantifying %HbS is built into the device to allow for an automated quantification of %HbS. This time- and cost-effective POC test thus allows the healthcare provider to make timely informed decisions when treating SCD patients, using accurate and updated data.
Introduction
Sickle cell disease (SCD) is a hereditary blood disorder characterized by hemolytic anemia due to the propensity of the mutant hemoglobin to polymerize when deoxygenated, leading to deformation and ultimately hemolysis of red blood cells (RBCs).1 Approximately two out of every 1000 births worldwide and more than 10 of every 1,000 births in Africa are affected by SCD.2 SCD is characterized by the presence of hemoglobin S (HbS), a structural variant of normal adult hemoglobin, and occurs when mutated versions of the hemoglobin gene are inherited from both parents.3 Inheriting the HbS gene results in production of abnormal beta globin chains that polymerize when deoxygenated. The polymerization results in sickle shaped RBCs that have a markedly shortened life span, leading to moderate to severe anemia. Other effects of this process and the RBC abnormalities it engenders include increased RBC adhesion, activation of leukocytes and platelets, oxidative damage, and activation of coagulation and inflammatory pathways,4 all of which contribute to vaso-occlusion, as well as to complications such as strokes and acute chest syndrome.3
The severity of SCD varies greatly amongst individuals and correlates with a number of both hematologic and non-hematologic factors.5,6 The rate of stroke and other complications in high-risk patients could effectively be reduced by more than 80% through the implementation of transfusion therapy.7 Chronic RBC transfusion limits the rate of stroke and consequently improves the life of SCD patients, but alloimmunization and severe iron overload have severe adverse effects.7-10 Implementation of this valuable therapy appropriately and judiciously is therefore critical in prevention of both stroke and reducible complications. The goal of chronic RBC transfusion for patients with SCD is to: (i) increase the [Hb] (to 9-10 g/dL) to improve the oxygen-carrying capacity of blood; (ii) dilute sickle Hb (to HbS <30%) to decrease the multiple downstream effects listed above that contribute to stroke and vaso-occlusion; and (iii) increase tissue oxygenation to suppress the production of hemoglobin polymers.7,8
Determining the need for transfusion therapy and the appropriate volume to transfuse for SCD patients is largely based on the pretransfusion Hb level, the pretransfusion %HbS, body weight, and clinical condition. Common methods used for monitoring the efficiency of transfusion therapy are Hb electrophoresis,11 high performance liquid chromatography,12 or isoelectric focusing.13,14 These tests are performed at a high cost with long processing times. Thus, determining a SCD patient's need for transfusion therapy and the appropriate volume to transfuse is still largely based on the pretransfusion Hb level, body weight, and previous quantitative HbS measurements. Basing these decisions instead on the current %HbS could help tailor chronic transfusion for stroke prophylaxis, as well as acute transfusion for other SCD complications, more directly and effectively.15
Development of a rapid, cost effective, and point of care (POC) test used to quantify %HbS before, during and after transfusion therapy would ensure that current and accurate results are available to the healthcare provider when they are most valuable for decision-making. Several platforms have been developed to offer improved evaluations of SCD treatment.16–18 We previously reported the development of a lateral flow immunoassay (LFIA) test15 to quantify and monitor HbS levels for patients going transfusion therapy as a SCD treatment. In this paper, we develop the technology of the POC quantitative HbS test and compare the LFIA test results with results from hemoglobin electrophoresis for 38 whole blood samples from SCD patients.
Protocol
Representative Results
Discussion
The major goal of chronic RBC transfusion for SCD patients is to maintain a low %HbS (<30%) in order to reduce the rate of stroke and other severe complications.7,21 Generally, the chronic exchange transfusion of 2-4 RBC units every 3-5 weeks is sufficient to keep the %HbS less than 30% and the [Hb] at 9-10 g/dL, thereby reducing the severe complications of SCD.7,21 The transfusion frequency and volum…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors acknowledge the North Carolina Biotechnology Center for its Small Business Loan support. This work was supported by an award from the National Institutes of Health Small Business Innovation Research Grant# 1R43HL128670-01.
Materials
| HbS test kit | BioMedomics | HLX020 | Includes capillary samplers and pretreatment buffer modules |
| BioMedomics Quantitative Reader | BioMedomics | XJF-M | |
| PreTreatment Buffer | BioMedomics | PT001 | Contained within Pretreatment Module |
| K2-EDTA anticoagulant vacutainer tube | BD | 367835 | Please use as per Manufacturer instructions or your institution's standard operating procedures |
| Sterile Alcohol Prep Pads | Fisher Scientific | 22-363-750 | Please use as per Manufacturer instructions or your institution's standard operating procedures |
References
- Rees, D. C., Williams, T. N., Gladwin, M. T. Sickle-cell disease. Lancet. 376 (9757), 2018-2031 (2010).
- Modell, B., Darlison, M. Global epidemiology of haemoglobin disorders and derived service indicators. Bull World Health Organ. 86 (6), 480-487 (2008).
- Stuart, M. J., Nagel, R. L. Sickle-cell disease. Lancet. 364 (9442), 1343-1360 (2004).
- Connes, P., et al. The role of blood rheology in sickle cell disease. Blood Rev. 30 (2), 111-118 (2016).
- Karacaoglu, P. K., et al. East Mediterranean region sickle cell disease mortality trial: retrospective multicenter cohort analysis of 735 patients. Ann Hematol. 95 (6), 993-1000 (2016).
- Elmariah, H., et al. Factors associated with survival in a contemporary adult sickle cell disease cohort. Am J Hematol. 89 (5), 530-535 (2014).
- Josephson, C. D., Su, L. L., Hillyer, K. L., Hillyer, C. D. Transfusion in the patient with sickle cell disease: a critical review of the literature and transfusion guidelines. Transfus Med Rev. 21 (2), 118-133 (2007).
- Danielson, C. F. The role of red blood cell exchange transfusion in the treatment and prevention of complications of sickle cell disease. Ther Apher. 6 (1), 24-31 (2002).
- Fung, E. B., et al. Morbidity and mortality in chronically transfused subjects with thalassemia and sickle cell disease: A report from the multi-center study of iron overload. Am J Hematol. 82 (4), 255-265 (2007).
- Vichinsky, E. P. Current issues with blood transfusions in sickle cell disease. Semin Hematol. 38, 14-22 (2001).
- Clarke, G. M., Higgins, T. N. Laboratory investigation of hemoglobinopathies and thalassemias: review and update. Clin Chem. 46, 1284-1290 (2000).
- Head, C. E., Conroy, M., Jarvis, M., Phelan, L., Bain, B. J. Some observations on the measurement of haemoglobin A2 and S percentages by high performance liquid chromatography in the presence and absence of alpha thalassaemia. J clin. 57 (3), 276-280 (2004).
- Rodriguez-Diaz, R., Wehr, T., Zhu, M. Capillary isoelectric focusing. Electrophoresis. 18 (12-13), 2134-2144 (1997).
- Jenkins, M. A., Ratnaike, S. Capillary isoelectric focusing of haemoglobin variants in the clinical laboratory. Clinica chimica acta. 289 (1-2), 121-132 (1999).
- Yang, X., Reavis, H. D., Roberts, C. L., Quantitative Kim, J. S. Point-of-Care Immunoassay Platform to Guide and Monitor Sickle Cell Disease Therapy. Anal Chem. 88 (16), 7904-7909 (2016).
- Piety, N. Z., Yang, X., Lezzar, D., George, A., Shevkoplyas, S. S. A rapid paper-based test for quantifying sickle hemoglobin in blood samples from patients with sickle cell disease. Am J Hematol. 90 (6), 478-482 (2015).
- Bartolucci, P., et al. Erythrocyte density in sickle cell syndromes is associated with specific clinical manifestations and hemolysis. Blood. 120 (15), 3136-3141 (2012).
- Wood, D. K., Soriano, A., Mahadevan, L., Higgins, J. M., Bhatia, S. N. A biophysical indicator of vaso-occlusive risk in sickle cell disease. Sci Transl Med. 4 (123), (2012).
- Kanter, J., et al. Validation of a novel point of care testing device for sickle cell disease. BMC Med. 13, 225 (2015).
- Wanko, S. O., Telen, M. J. Transfusion management in sickle cell disease. Hematol Oncol Clin North Am. 19 (5), 803-826 (2005).
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