Red cell exchange for patients with sickle cell disease: an international survey of current practices.

INTRODUCTION: Red cell exchange (RCE) therapy is increasingly used to treat patients with acute or chronic manifestations of sickle cell disease (SCD). However, little is known regarding the most safe and effective practice parameters associated with this particular therapy. METHODS: A SCD subcommittee of members of the American Society for Apheresis (ASFA) developed a 122-question survey and administered it via email to other ASFA members. The survey inquired about clinical indications for treatment, practice patterns, and transfusion policies for RCE when used for patients with SCD. RESULTS: Ninety-nine distinct institutions completed the survey. Twenty-one (21%) were from outside of the US. Twenty-two (22%) provided chronic transfusion therapy to >10 patients, and both adult (25%) and pediatric-focused services (20%) were represented. Common acute indications for RCE included acute chest syndrome, acute ischemic stroke, and pre-surgical prophylaxis. Common chronic indications included primary stroke prophylaxis, secondary stroke prophylaxis, and recurrent acute chest syndrome. Respondents most commonly set a post-RCE treatment target of 30% for the hematocrit and hemoglobin S levels, regardless of the therapeutic indication. Units for RCE were phenotypically matched in 95% of cases. About 40% of respondents reported using isovolemic hemodilution. CONCLUSIONS: This survey solicited the current practice variations in RCE from a diverse range of practice sites. Many sites reported similar practice patterns and challenges but some variations emerged. To our knowledge, this survey represents the largest and most in-depth investigation of the use of RCE for patients with SCD, and could inform future studies in the field.

Use of dual lumen ports for red blood cell exchange: A comparison of adults and children with sickle cell disease.

PURPOSE: Sickle cell patients receiving chronic RBC exchange require a form of long-term central venous access if peripheral access is inadequate. In adults, dual lumen (DL) ports have been utilized but associated with greater procedure complications and duration when compared to other forms of access. In the pediatric sickle cell population, the use of DL ports for RBC exchange has not been well described. In this retrospective cohort study, RBC exchange procedures utilizing DL ports in the pediatric vs adult sickle cell population were compared. METHODS: Medical records were reviewed for 685 RBC exchange procedures performed on 25 patients (11 pediatric and 14 adult) between November 2014 to November 2018. Patient-level characteristics and outcomes were compared between pediatric and adult patients using the Fisher-exact and Wilcoxon-rank sum test. Linear/logistic regression models examined procedure-level parameters and port characteristics with adjustment for clustering. RESULTS: Compared to adults, pediatric patients had slower average maximum inlet speed (42 vs 53 mL/min, P < .01), but shorter procedure time (60 vs 75 minutes, P < .01) and lower rate of access alarms (1% vs 11%, P < .01). Overall, 0.29 thrombotic events per 1000 port days and 0.04 infections per 1000 port days were observed. CONCLUSION: For adult and pediatric sickle cell patients, a DL port provides a viable option for RBC exchange. In comparison to adults, pediatric procedures with a DL port will typically be shorter and with less procedural complications due to smaller blood volumes and lower flow requirements.

Critical developments of 2018: A review of the literature from selected topics in transfusion. A committee report from the AABB's Clinical Transfusion Medicine Committee.

BACKGROUND: The AABB compiles an annual synopsis of the published literature covering important developments in the field of transfusion medicine. An abridged version of this work is being made available in TRANSFUSION, with the full-length report available as Appendix S1 (available as supporting information in the online version of this paper). STUDY DESIGN AND METHODS: Papers published in late 2017 and 2018 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed. RESULTS: The following topics are covered: "big data" and "omics" studies, emerging infections and testing, platelet transfusion and pathogen reduction, transfusion therapy and coagulation, transfusion approach to hemorrhagic shock and mass casualties, therapeutic apheresis, and chimeric antigen receptor T-cell therapy. CONCLUSION: This synopsis may be a useful educational tool.

Critical developments of 2017: a review of the literature from selected topics in transfusion. A committee report from the AABB Clinical Transfusion Medicine Committee.

BACKGROUND: The AABB compiles an annual synopsis of the published literature covering important developments in the field of Transfusion Medicine. For the first time, an abridged version of this work is being made available in TRANSFUSION, with the full-length report available as an Appendix S1 (available as supporting information in the online version of this paper). STUDY DESIGN AND METHODS: Papers published in 2016 and early 2017 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed. RESULTS: The following topics are covered: duration of red blood cell storage and clinical outcomes, blood donor characteristics and patient outcomes, reversal of bleeding in hemophilia and for patients on direct oral anticoagulants, transfusion approach to hemorrhagic shock, pathogen inactivation, pediatric transfusion medicine, therapeutic apheresis, and extracorporeal support. CONCLUSION: This synopsis may be a useful educational tool.

Physicians' Perspectives on HL7 Information Policy Sensitive Value Set: A Validation Study through Health Concept Categorization.

The Health Level 7 (HL7) organization introduced the Information Sensitivity Policy Value Set with 45 sensitive data categories to facilitate the implementation of granular electronic consent technology. The goal is to allow patients to have control over the sharing of their sensitive medical records. This study represents the first attempt to explore physicians' viewpoints on these categories. Twelve physicians participated in a survey, leading to revisions in 21 HL7 categories. They later classified 600 clinical data items through a second survey using the updated categories. Participants' perspectives were documented, and data analysis included descriptive measures and heat maps. In the first survey, six participants suggested adding 19 new categories (e.g., personality disorder), and modifying 25 category definitions. Two new categories and sixteen revised category definitions were incorporated to support more patient-friendly content and inclusive language. Fifteen new category recommendations were addressed through a revision of category definitions (e.g., personality disorder described as a behavioral health condition). In the second survey, data categorizations led to recommendations for more categories from ten participants. Future revisions of the HL7 categories should incorporate physicians' viewpoints, validate the categories using patient data or/and include patients' perspectives, and develop patient-centric category specifications.

Sickle cell disease resulting from uniparental disomy in a child who inherited sickle cell trait.

Sickle cell disease (SCD) is a classic example of a disorder with recessive Mendelian inheritance, in which each parent contributes one mutant allele to an affected offspring. However, there are exceptions to that rule. We describe here the first reported case of conversion of inherited sickle cell trait to SCD by uniparental disomy (UPD) resulting in mosaicism for SS and AS erythrocytes. A 14-year-old boy presented with splenomegaly and hemolysis. Although his father has sickle cell trait, his mother has no abnormal hemoglobin (Hb). DNA sequencing, performed to rule out Hb S/ß-thalassemia, detected homozygous Hb SS. Further studies revealed mosaic UPD of the ß-globin locus, more SS erythroid progenitors than AS, but a reverse ratio of erythrocytes resulting from the survival advantage of AS erythrocytes. This report exemplifies non-Mendelian genetics wherein a patient who inherited sickle cell trait has mild SCD resulting from postzygotic mitotic recombination leading to UPD.

A novel human gamma-globin gene vector for genetic correction of sickle cell anemia in a humanized sickle mouse model: critical determinants for successful correction.

We show that lentiviral delivery of human gamma-globin gene under beta-globin regulatory control elements in hematopoietic stem cells (HSCs) results in sufficient postnatal fetal hemoglobin (HbF) expression to correct sickle cell anemia (SCA) in the Berkeley "humanized" sickle mouse. Upon de-escalating the amount of transduced HSCs in transplant recipients, using reduced-intensity conditioning and varying gene transfer efficiency and vector copy number, we assessed critical parameters needed for correction. A systematic quantification of functional and hematologic red blood cell (RBC) indices, organ pathology, and life span was used to determine the minimal amount of HbF, F cells, HbF/F-cell, and gene-modified HSCs required for correcting the sickle phenotype. We show that long-term amelioration of disease occurred (1) when HbF exceeded 10%, F cells constituted two-thirds of the circulating RBCs, and HbF/F cell was one-third of the total hemoglobin in sickle RBCs; and (2) when approximately 20% gene-modified HSCs repopulated the marrow. Moreover, we show a novel model using reduced-intensity conditioning to determine genetically corrected HSC threshold that corrects a hematopoietic disease. These studies provide a strong preclinical model for what it would take to genetically correct SCA and are a foundation for the use of this vector in a human clinical trial.

Genetic correction of sickle cell anemia and beta-thalassemia: progress and new perspective.

Gene therapy for beta-globinopathies, particularly Beta-thalassemia and sickle cell anemia, holds promise for the future as a definitive corrective approach for these common and debilitating disorders. Correction of the beta-globinopathies using lentivirus vectors carrying the beta- or y-globin genes and elements of the locus control region has now been well established in murine models, and an understanding of "what is required to cure these diseases" has been developed in the first decade of the 21st century. A clinical trial using one such vector has been initiated in France with intriguing results, while other trials are under development. Vector improvements to enhance the safety and efficiency of lentivirus vectors are being explored, while new strategies, including homologous recombination in induced pluripotent cells, for correction of sickle cell anemia have shown proof-of-concept in vitro. Here, a review is provided of the current substantial progress in genetic correction of beta-globin disorders.

Vasculopathy-associated hyperangiotensinemia mobilizes haematopoietic stem cells/progenitors through endothelial AT2R and cytoskeletal dysregulation.

Patients with organ failure of vascular origin have increased circulating haematopoietic stem cells and progenitors (HSC/P). Plasma levels of angiotensin II (Ang-II), are commonly increased in vasculopathies. Hyperangiotensinemia results in activation of a very distinct Ang-II receptor set, Rho family GTPase members, and actin in bone marrow endothelial cells (BMEC) and HSC/P, which results in decreased membrane integrin activation in both BMEC and HSC/P, and in HSC/P de-adhesion and mobilization. The Ang-II effect can be reversed pharmacologically and genetically by inhibiting Ang-II production or signalling through BMEC AT2R, HSCP Ang-II receptor type 1 (AT1R)/AT2R or HSC/P RhoA, but not by interfering with other vascular tone mediators. Hyperangiotensinemia and high counts of circulating HSC/P seen in sickle cell disease (SCD) as a result of vascular damage, is significantly decreased by Ang-II inhibitors. Our data define for the first time the role of Ang-II HSC/P traffic regulation and redefine the haematopoietic consequences of anti-angiotensin therapy in SCD.

Therapy for beta-globinopathies: a brief review and determinants for successful and safe correction.

Gene therapy for beta-globinopathies, particularly beta-thalassemia and sickle cell anemia, hold much promise for the future, as a one time cure for these common and debilitating disorders. Correction of the beta-globinopathies using lentivirus vectors (LV) carrying the beta- or gamma-globin genes and elements of the locus control region has been well established in murine models, and a good idea of "what it will take to cure these diseases" has been developed in the first decade of the twenty-first century. A clinical trial using one such vector has been initiated in France while other trials are in development. Vector improvements to enhance the safety and efficiency of LV are being explored, while newer strategies, like homologous recombination in induced pluripotent cells for correction of sickle cell anemia, has been shown as a proof-of-concept. Here we provide a review of current progress in genetic correction of beta-globin disorders.