The EHA Research Roadmap: Transfusion Medicine.

In 2016, the European Hematology Association (EHA) published the EHA Roadmap for European Hematology Research 1 aiming to highlight achievements in the diagnostics and treatment of blood disorders, and to better inform European policy makers and other stakeholders about the urgent clinical and scientific needs and priorities in the field of hematology. Each section was coordinated by 1-2 section editors who were leading international experts in the field. In the 5 years that have followed, advances in the field of hematology have been plentiful. As such, EHA is pleased to present an updated Research Roadmap, now including eleven sections, each of which will be published separately. The updated EHA Research Roadmap identifies the most urgent priorities in hematology research and clinical science, therefore supporting a more informed, focused, and ideally a more funded future for European hematology research. The 11 EHA Research Roadmap sections include Normal Hematopoiesis; Malignant Lymphoid Diseases; Malignant Myeloid Diseases; Anemias and Related Diseases; Platelet Disorders; Blood Coagulation and Hemostatic Disorders; Transfusion Medicine; Infections in Hematology; Hematopoietic Stem Cell Transplantation; CAR-T and Other Cell-based Immune Therapies; and Gene Therapy.

Jon van Rood: The pioneer and his personal view on the early developments of HLA and immunogenetics.

A single observation in a patient with an unusual transfusion reaction led to a life-long fascination with immunogenetics, and a strong wish to improve the care for patients needing a transplantation. In 2017, Jon van Rood, one of the pioneers in the field of HLA and immunogenetics of transplantation, passed away. Several obituaries have appeared describing some of the highlights of his career. However, the details of the early developments leading among others to the routine use of HLA as an important parameter for donor selection in organ- and hematopoietic stem cell transplantation are largely unknown to the community. After his retirement as Chair of the Department of Immunohaematology and Blood Transfusion (IHB) in 1991, Jon van Rood wrote regularly in the "Crosstalk", the departmental journal, and gave his personal view on the history of the discovery and implications of HLA. These autobiographic descriptions were originally written in Dutch and have been translated, while texts from other sources and the relevant references have been added to illustrate the historical perspective. This special issue of Transplant Immunology combines the autobiographic part, Jon's own version of the history, with other facts of his scientific life and the impact of his findings on the field of clinical transplantation. Hopefully, this knowledge of the history will be of benefit for future developments in transplantation immunology.

The role of pathogen-reduced platelet transfusions on HLA alloimmunization in hemato-oncological patients.

BACKGROUND: Platelet transfusions can induce alloimmunization against HLA antigens. The use of pathogen-reduced platelet concentrates (PCs) was suggested to reduce HLA alloimmunization and concomitant transfusion refractoriness. METHODS: This study investigated HLA alloimmunization in available samples from 448 hemato-oncological patients who were randomized for the Pathogen Reduction Evaluation and Predictive Analytical Rating Score (PREPAReS) trial to receive either untreated or pathogen-reduced PCs (Mirasol, Terumo BCT Inc.). Anti-HLA Class I and II antibodies were determined before the first platelet transfusion and weekly thereafter using multiplex assay with standard cutoffs to detect low- as well as high-level antibodies. RESULTS: When using the lower cutoff, in patients who were antibody negative at enrollment, 5.4% (n = 12) developed anti-HLA Class I antibodies after receiving untreated PCs, while this was significantly higher in patients receiving pathogen-reduced PCs, 12.8% (n = 29; p = 0.009, intention-to-treat [ITT] analysis). A similar but nonsignificant trend was observed in the per-protocol (PP) analysis (5.4% vs. 10.1%; p = 0.15). HLA class II antibody formation was similar between both types of PCs in the ITT analysis, while the PP analysis showed a trend toward lower immunization after receiving pathogen-reduced PCs. Multivariate analysis identified receiving pathogen-reduced platelets as an independent risk factor for HLA Class I alloimmunization (ITT: odds ratio [95% confidence interval] = 3.02 [1.42-6.51], PP: odds ratio [95% confidence interval] = 2.77 [1.00-5.40]), without affecting HLA Class II alloimmunization. When using the high cutoff value, the difference in HLA Class I alloimmunization between study arms remained significant in the ITT analysis and again was not significant in the PP analysis. CONCLUSION: Our data clearly indicate that Mirasol pathogen inactivation does not prevent HLA Class I or II alloimmunization after platelet transfusions.

Hemostatic efficacy of pathogen-inactivated vs untreated platelets: a randomized controlled trial.

Pathogen inactivation of platelet concentrates reduces the risk for blood-borne infections. However, its effect on platelet function and hemostatic efficacy of transfusion is unclear. We conducted a randomized noninferiority trial comparing the efficacy of pathogen-inactivated platelets using riboflavin and UV B illumination technology (intervention) compared with standard plasma-stored platelets (control) for the prevention of bleeding in patients with hematologic malignancies and thrombocytopenia. The primary outcome parameter was the proportion of transfusion-treatment periods in which the patient had grade 2 or higher bleeding, as defined by World Health Organization criteria. Between November 2010 and April 2016, 469 unique patients were randomized to 567 transfusion-treatment periods (283 in the control arm, 284 in the intervention arm). There was a 3% absolute difference in grade 2 or higher bleeding in the intention-to-treat analysis: 51% of the transfusion-treatment periods in the control arm and 54% in the intervention arm (95% confidence interval [CI], -6 to 11; P = .012 for noninferiority). However, in the per-protocol analysis, the difference in grade 2 or higher bleeding was 8%: 44% in the control arm and 52% in the intervention arm (95% CI -2 to 18; P = .19 for noninferiority). Transfusion increment parameters were ∼50% lower in the intervention arm. There was no difference in the proportion of patients developing HLA class I alloantibodies. In conclusion, the noninferiority criterion for pathogen-inactivated platelets was met in the intention-to-treat analysis. This finding was not demonstrated in the per-protocol analysis. This trial was registered at The Netherlands National Trial Registry as #NTR2106 and at www.clinicaltrials.gov as #NCT02783313.

Platelets from donors with consistently low HLA-B8, -B12, or -B35 expression do not undergo antibody-mediated internalization.

Patients refractory to platelet transfusions because of alloimmunization require HLA-matched platelets, which is only possible if a large HLA-typed donor pool is available. However, even then, patients with broad immunization or rare haplotypes may not have suitable donors. In these patients, transfusions with platelets showing low HLA class I expression may be an alternative to fully HLA-matched transfusions. In this study, we quantified the proportion of donors with consistently low HLA-B8, -B12, and -B35 expression on platelets using human monoclonal antibodies specific for these antigens. Furthermore, as model for in vivo clearance, antibody-mediated internalization of these platelets by macrophages was investigated. The expression of HLA-B8, -B12, or -B35 on platelets was extremely variable between individuals (coefficients of variation, 41.4% to 73.6%). For HLA-B8, but not for HLA-B12 or -B35, this variation was in part explained by zygosity. The variation was most pronounced in, but not exclusive to, platelets. Expression within one donor was consistent over time. Remarkably, 32% of 113 HLA-B8, 34% of 98 HLA-B12, and 9% of 66 HLA-B35 donors showed platelet antigen expression that was not or only minimally above background. Antibody-mediated internalization of platelets by macrophages correlated with antibody opsonization and antigen expression and was absent in platelets with low or minimal HLA expression. In conclusion, our findings indicate that a substantial proportion of donors have platelets with consistently low expression of specific HLA class I antigens. These platelets may be used to treat refractory patients with antibodies directed against these particular antigens, despite HLA mismatches.

D antibodies in pregnant women in multiethnic Suriname: the observational RheSuN study.

BACKGROUND: Maternal antibodies against the D antigen are the most common cause of severe hemolytic disease of the fetus and newborn (HDFN). In high-income countries, the risk of D immunization has been reduced by routine antenatal and postpartum administration of RhIG from 13% to less than 0.5%. In less-resourced countries, such as Suriname, red blood cell (RBC) antibody screening during pregnancy and prophylactic RhIG administration are not routine. Accurate data on D immunization risk is not available. In the RheSuN (Rhesus Surinamese Neonates) study, the prevalence and the hemolytic potential of maternal D antibodies were investigated. STUDY DESIGN AND METHODS: A multicenter cross-sectional study in four major hospitals in Paramaribo, Suriname, covering 90% of approximately 10,000 births yearly in Suriname. Included were D- pregnant women of various ethnicities seeking routine prenatal care and/or their newborns. RESULTS: D antibodies were detected in 19 of 214 D- pregnancies (8.9%; 95% confidence interval, 5.1%-12.7%), in 2.0% of primigravid and 11.7% of multigravid women. The direct antiglobulin test was positive in 11 of 13 tested D+ newborns. Determination of D antibody titers and antibody-dependent cell mediated cytotoxicity (ADCC) assay revealed three newborns at high risk for HDFN (ADCC > 50%). CONCLUSION: D immunization risk in Suriname women is comparable to the pre-anti-D prophylaxis era in high-income countries. Recommended is free-of-charge routine RBC antibody screening and prophylactic RhIG administration for women at risk for D antibody formation as part of standard of ante- and postnatal care.

Predictors for successful PBSC collection on the fourth day of G-CSF-induced mobilization in allogeneic stem cell donors.

Peripheral blood stem cells (PBSCs) used for allogeneic transplantation are collected by apheresis after pre-treatment of donors with G-CSF. Using modern apheresis devices stem cells can be collected more efficiently. It was studied whether collection on the 4th instead of the 5th day after initiation of G-CSF treatment might be feasible. Stem cell yields that could have been collected on day 4 were calculated in two cohorts treated with 10 µg/kg G-CSF once daily (n = 106, cohort I) or 5 µg/kg twice daily schedule (n = 85, cohort II). Harvests were predicted using the median collection efficiency (CE) of the apheresis machine and regarded successful when > 5.0 x106 CD34+/ kg recipient body weight. Successful harvests at day 4 could have been obtained in only 22.6% and 41.2% of donors in cohort I and II respectively, while the expected successful collections on day 5 were 55.7% and 76.5%. Individual donor factors that correlated with a successful harvest on day 4 were weight, BMI, age, ratio donor/recipient weight and total G-CSF dose in cohort I, whereas ratio donor/recipient weight was the only significant predictor in cohort II. Donor weight, BMI and total G-CSF dose correlated positively with CD34+ values in the blood on day 4 in all donors. However, donor characteristics were not able to be used as strong predictors in daily practice. In conclusion, PBSC collection on day 4 will not result in a successful harvest in most stem cell donors, however using a twice daily G-CSF scheme increases the yield.

Does a Platelet Transfusion Independently Affect Bleeding and Adverse Outcomes in Cardiac Surgery?

BACKGROUND: Conflicting results have been reported concerning the effect of platelet transfusion on several outcomes. The aim of this study was to assess the independent effect of a single early intraoperative platelet transfusion on bleeding and adverse outcomes in cardiac surgery patients. METHODS: For this observational study, 23,860 cardiac surgery patients were analyzed. Patients who received one early (shortly after cardiopulmonary bypass while still in the operating room) platelet transfusion, and no other transfusions, were defined as the intervention group. By matching the intervention group 1:3 to patients who received no early transfusion with most comparable propensity scores, the reference group was identified. RESULTS: The intervention group comprised 169 patients and the reference group 507. No difference between the groups was observed concerning reinterventions, thromboembolic complications, infections, organ failure, and mortality. However, patients in the intervention group experienced less blood loss and required vasoactive medication 139 of 169 (82%) versus 370 of 507 (74%; odds ratio, 1.65; 95% CI, 1.05 to 2.58), prolonged mechanical ventilation 92 of 169 (54%) versus 226 of 507 (45%; odds ratio, 1.47; 94% CI, 1.03 to 2.11), prolonged intensive care 95 of 169 (56%) versus 240 of 507 (46%; odds ratio, 1.49; 95% CI, 1.04 to 2.12), erythrocytes 75 of 169 (44%) versus 145 of 507 (34%; odds ratio, 1.55; 95% CI, 1.08 to 2.23), plasma 29 of 169 (17%) versus 23 of 507 (7.3%; odds ratio, 2.63; 95% CI, 1.50-4.63), and platelets 72 of 169 (43%) versus 25 of 507 (4.3%; odds ratio, 16.4; 95% CI, 9.3-28.9) more often compared to the reference group. CONCLUSIONS: In this retrospective analysis, cardiac surgery patients receiving platelet transfusion in the operating room experienced less blood loss and more often required vasoactive medication, prolonged ventilation, prolonged intensive care, and blood products postoperatively. However, early platelet transfusion was not associated with reinterventions, thromboembolic complications, infections, organ failure, or mortality.

The increase of the global donor inventory is of limited benefit to patients of non-Northwestern European descent.

Between 2001 and 2012, the number of unrelated donors registered worldwide increased from 7 to 21 million, and the number of public cord blood units increased to over 500,000. We addressed the question of whether this expansion resulted in higher percentages of patients reaching transplantation. Unrelated donor searches were evaluated for 3,124 eligible patients in the Netherlands in two cohorts (2001-2006, n=995; 2007-2012, n=2129), comparing results for patients of Northwestern European and non-Northwestern European origin. Endpoints were 'donor found' and 'transplantation reached'. The substantial growth of the donor inventory over the period studied did not increase the median number of potential unrelated donors (n=7) for non-Northwestern European patients, but almost doubled the number for Northwestern European patients from 42 to 71. Before and after 2007, an unrelated donor or cord blood was identified for 91% and 95%, respectively, of Northwestern European patients and for 65% and 82% of non-Northwestern European patients (P<0.0001). Non-Northwestern European patients more often needed a cord blood transplant. The degree of HLA matching was significantly lower for non-Northwestern European patients (P<0.0006). The time needed to identify a donor decreased for both populations. The percentage of Northwestern European patients reaching transplantation increased from 77% to 83% and for non-Northwestern European patients from 57% to 72% (P=0.0003). The increase of the global inventory resulted in more transplants for patients lacking a family donor, although the quality and quantity of (potential) haematopoietic cell grafts for patients of a non-Northwestern European descent remained inferior, indicating the need for adaptation of recruitment.

Immunological complications of blood transfusions.

Most adverse blood transfusion (BT) events are immune-mediated and in the majority of severe reactions antibodies can be identified as causal factors. Alloimmunization not only causes symptomatic reactions, transfused cells can also be (silently) destroyed. Immunization by BT can contribute to hemolytic disease of the newborn as well as to allograft rejection after transplantation. Reversely, pregnancy and transplantation may evoke immunity hampering transfusion therapy. Besides causing mortality and morbidity, alloimmunization has a huge economic impact. Transfusion reactions prolong hospital stay, require diagnostic tests and complex donor selection procedures and create the need for typed donor registries. In the 1970s, Opeltz and colleagues described that pre-transplantation BT impaired rejection of renal transplants. Leukocytes were essential for this immunosuppressive BT effect that raised concern about negative effects on cancer growth and resistance against infections. Studies on the mechanism were however preliminary abandoned when calcineurin inhibitors for prevention of graft rejection became available and since all blood products underwent leukoreduction in most countries as precautionary measure against transmission of variant Creutzfeldt-Jacob disease. Whether current leukoreduced BT are immunosuppressive and for which patients or circumstances this may contribute to worse outcome, is unknown. The last decades of the previous century, leukoreduction of cellular blood products for leukemia patients significantly reduced the incidence of immunological platelet transfusion refractoriness. The first decade of this century the avoidance of plasma- and platelet-products from females, that may contain donor-derived leukocyte antibodies, decreased transfusion related acute lung injury (TRALI) by more than 30%. These were major achievements. Challenge for the near future is to further reduce alloimmunization in particular against red blood cells (RBC) as a cause of severe hemolytic transfusion reactions and problems to find compatible donors. This can be achieved by extended matching. Inventory limitations prevent to match all BT for clinically relevant RBC antigens. A (European-wide) registration of clinical and genetic risk factors associated with alloimmunization could support effective use of matched blood products.

A study protocol for a randomised controlled trial evaluating clinical effects of platelet transfusion products: the Pathogen Reduction Evaluation and Predictive Analytical Rating Score (PREPAReS) trial.

INTRODUCTION: Patients with chemotherapy-induced thrombocytopaenia frequently experience minor and sometimes severe bleeding complications. Unrestrictive availability of safe and effective blood products is presumed by treating physicians as well as patients. Pathogen reduction technology potentially offers the opportunity to enhance safety by reducing bacterial and viral contamination of platelet products along with a potential reduction of alloimmunisation in patients receiving multiple platelet transfusions. METHODS AND ANALYSIS: To test efficacy, a randomised, single-blinded, multicentre controlled trial was designed to evaluate clinical non-inferiority of pathogen-reduced platelet concentrates treated by the Mirasol system, compared with standard plasma-stored platelet concentrates using the percentage of patients with WHO grade ≥ 2 bleeding complications as the primary endpoint. The upper limit of the 95% CI of the non-inferiority margin was chosen to be a ≤ 12.5% increase in this percentage. Bleeding symptoms are actively monitored on a daily basis. The adjudication of the bleeding grade is performed by 3 adjudicators, blinded to the platelet product randomisation as well as by an automated computer algorithm. Interim analyses evaluating bleeding complications as well as serious adverse events are performed after each batch of 60 patients. The study started in 2010 and patients will be enrolled up to a maximum of 618 patients, depending on the results of consecutive interim analyses. A flexible stopping rule was designed allowing stopping for non-inferiority or futility. Besides analysing effects of pathogen reduction on clinical efficacy, the Pathogen Reduction Evaluation and Predictive Analytical Rating Score (PREPAReS) is designed to answer several other pending questions and translational issues related to bleeding and alloimmunisation, formulated as secondary and tertiary endpoints. ETHICS AND DISSEMINATION: Ethics approval was obtained in all 3 participating countries. Results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NTR2106; Pre-results.

The European Hematology Association Roadmap for European Hematology Research: a consensus document.

The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at €23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap.The EHA Roadmap identifies nine 'sections' in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders.The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients.

Hemostatic alterations during coronary artery bypass grafting.

INTRODUCTION: The origination of blood loss after cardiac surgery is not fully explained, but is related to operation trauma and use of cardiopulmonary bypass (CPB). However, the extent of their contribution is incompletely known and might differ between distinct operation procedures. MATERIALS AND METHODS: Three groups of CABG procedures were studied: 1) off-pump coronary artery bypass surgery (OPCAB, n=11) without CPB, 2) CABG with use of CPB (CABG, n=11) and 3) CABG with use of CPB combined with aortic valve replacement (AVR, n=11). Activation of coagulation and fibrinolysis was measured at various time points by flow cytometry, platelet aggregometry, thrombelastography, the Nijmegen Hemostasis Assay, prothrombin fragment 1+2 and tissue plasminogen activator. RESULTS AND CONCLUSIONS: The use of CPB during cardiac surgery decreased platelet counts, clot strength, fibrinogen, hematocrit and albumin concentrations during the procedure. No perioperative platelet activation was observed and functional (collagen induced) platelet aggregation was transiently impaired, but recovered after surgery in all groups. Patients operated with use of CPB showed increased tissue plasminogen activator concentrations after reperfusion followed by minor and transient fibrinolysis. After all types of surgery coagulation parameters and platelet aggregation showed a rebound above preoperative levels. To conclude, no evident platelet activation, dysfunction or consumption was demonstrated. In patients using tranexamic acid the most prominent factor impairing hemostasis after CABG surgery was hemodilution associated with CPB.

Intraoperative Anemia and Single Red Blood Cell Transfusion During Cardiac Surgery: An Assessment of Postoperative Outcome Including Patients Refusing Blood Transfusion.

OBJECTIVES: Increasing evidence suggests benefits from restrictive red blood cell transfusion (RBC) thresholds in major surgery and critically ill patients. However, these benefits are not obvious in cardiac surgery patients with intraoperative anemia. The authors examined the association between uncorrected hemoglobin (Hb) levels and selected postoperative outcomes as well as the effects of RBCs. DESIGN: Cohort study with prospectively collected data from a cardiac surgery registry. SETTING: A major cardiac surgical hospital within the Netherlands, which is also a referral center for Jehovah's Witnesses. PARTICIPANTS: Patients (23,860) undergoing cardiac surgery between 1997 and 2013. INTERVENTIONS: Comparisons were done in patients with intraoperative nadir Hb<8 g/dL and/or an Hb decrease ≥ 50%. Comparison (A) between Jehovah's Witnesses (Witnesses) and matched non-Jehovah's Witnesses (non-Witnesses) transfused with 1 unit of RBC, and comparison (B) between patients given 1 unit of RBC intraoperatively versus matched non-transfused patients. MEASUREMENTS AND MAIN RESULTS: Postoperative outcomes were myocardial infarction, renal replacement therapy, stroke, and death. With propensity matching, the authors optimized exchangeability of the compared groups. Adverse outcomes increased with a decreasing Hb both among Witnesses and among non-Witnesses. The incidence of postoperative complications did not differ between Witnesses and matched non-Witnesses who received RBC (adjusted odds ratio 1.44, 95% confidence interval 0.63-3.29). Similarly, postoperative complications did not differ between patients who received a red cell transfusion and matched patients who did not (adjusted odds ratio 0.94, confidence interval 0.72-1.23). CONCLUSION: Intraoperative anemia is associated with adverse outcomes after cardiac surgery, and a single RBC transfusion does not seem to influence these outcomes.

Stopping antiplatelet medication before coronary artery bypass graft surgery: is there an optimal timing to minimize bleeding?

OBJECTIVES: As the indication for antiplatelet medication expands, patients may be exposed to an increased risk of excessive blood loss when cardiac surgery is required. The optimal timing to stop acetylsalicylic acid (ASA) or ASA combined with clopidogrel (ASA+Clo) before surgery is the subject of controversy. METHODS: A total of 1065 patients were selected from a prospective randomized study on the effect of a fibrin sealant application in coronary artery bypass graft surgery [Fibrin sealant Induced Blood Exposure Reduction study; REGISTRATION NUMBER: NTR1386 (http://www.trialregister.nl)], and divided into three groups according to the use of antiplatelet medication within 10 days prior to surgery: (i) ASA only (n = 662), (ii) ASA+Clo (n = 290) or (iii) no antiplatelet medication (n = 113). To investigate if an optimal stop day could be established, we fitted a series of multiple linear regression models, one for each preoperative day (running from Day -10 up to -1). The specific day corresponding to the best fitting model (highest adjusted R(2), with blood loss in the first 48 h postoperatively as the dependent variable) was considered as the best estimate for the optimal stop day. Bootstrap analysis (1000 times) was performed to calculate the corresponding confidence interval. Furthermore, major adverse cardiovascular and cerebral events (MACCE) were evaluated. RESULTS: We could not estimate an optimal stop day for patients using ASA or ASA+Clo prior to their operation. Last use of ASA on Day -2 or earlier significantly decreased the percentage of patients receiving platelet transfusions compared with continuation until surgery (7 vs 13% for Day -1, P = 0.007). In patients using ASA+Clo, this percentage was reduced from 41 to 10 (P < 0.001). There was no association between stop day and the occurrence of MACCE. CONCLUSIONS: There is no clinically relevant effect on blood loss indicating an optimal stop day for ASA alone or in combination with Clo. Last use on Day -2 resulted in the reduction of percentage of patients receiving platelet transfusions, especially in the ASA+Clo group.

Cryopreservation of cord blood CD34+ cells before or after thrombopoietin expansion differentially affects early platelet recovery in NOD SCID mice.

BACKGROUND: Expansion of human cord blood (CB) CD34+ cells with thrombopoietin (TPO) can accelerate delayed platelet (PLT) recovery after transplantation into immunodeficient mice. Clinical implementation, however, will depend on practical and effective protocols. The best timing of TPO expansion in relation to cryopreservation in this respect is unknown. STUDY DESIGN AND METHODS: In this study, we evaluated whether the order of cryopreservation and TPO expansion affected the expansion rate and numbers of clonogenic hematopoietic progenitor cells in vitro or PLT and longer-term hematopoietic repopulation in NOD SCID mice in vivo. RESULTS: Our results demonstrate higher expansion rates and the generation of higher numbers of multilineage and megakaryocytic progenitors (granulocyte, erythrocyte, monocyte, megakaryocyte colony-forming units and megakaryocyte colony-forming units) in vitro when freshly isolated CB CD34+ cells are first cultured with TPO and then cryopreserved and thawed as compared to TPO expansion after CD34+ cell cryopreservation. In contrast, the cells produced with the latter strategy showed higher expression of CD62L and a superior stromal cell-derived factor-1α-mediated migration. This might play a role in an also observed superior early PLT recovery after transplantation of these cells into NOD SCID mice. The hematopoietic engraftment in the marrow 6 weeks after transplantation was not different between the two strategies. CONCLUSION: Although TPO expansion before cryopreservation would yield higher nucleated cell and clonogenic myeloid and megakaryocyte cell numbers and enable earlier availability, CB TPO expansion after cryopreservation is likely to be clinically more effective, despite the lower number of cells obtained after expansion. Moreover, the latter strategy is logistically more feasible.

A new preparation method for red blood cells for intrauterine transfusion enabling reduction of donor exposure.

BACKGROUND: Severe hemolytic anemia of the fetus, caused by maternal red blood cell (RBC) alloantibodies, is treated with intrauterine transfusion (IUT) of RBCs. Because IUT is associated with additional antibody formation, RBCs with the closest match between donor and mother are preferred. Because one fetus needs a median of three IUTs, finding such RBCs is complicated. Collection of repeated low-volume donations from one selected donor during the entire IUT treatment period would reduce donor exposure and possibly IUT-associated alloimmunization. STUDY DESIGN AND METHODS: Whole blood (WB) donations of 100 and 200 mL were diluted with saline, filtered, centrifuged, and separated to prepare experimental RBCs. Before and after gamma irradiation, the RBCs were sampled for comparison of in vitro quality with standard RBCs for IUT. An additional washing procedure was investigated to remove anti-A/-B. RESULTS: Experimental RBCs were leukoreduced to levels conforming with current guidelines and had final volumes of 44 (n = 12) and 84 (n = 8) mL with hematocrit levels between 0.80 and 0.88 L/L. Hemolysis was lower (0.12% vs. 0.42%), potassium leakage comparable, adenosine triphosphate levels lower (4.8 µmol/g Hb vs. 6.1 µmol/g Hb), and 2,3-diphosphoglycerate levels higher (10.3 µmol/g Hb vs 7.7 µmol/g Hb) at 6 hours after irradiation (product expiration time) compared to standard RBCs for IUT (n = 3). Anti-A/-B titers decreased substantially by the washing procedure. CONCLUSION: RBCs for IUT can be prepared from 100- or 200-mL WB donations, showing the potential of this new blood product to reduce donor exposure. A washing procedure is recommended to remove anti-A/-B.

No Synergistic Effect of Cotransplantation of MSC and Ex Vivo TPO-Expanded CD34(+) Cord Blood Cells on Platelet Recovery and Bone Marrow Engraftment in NOD SCID Mice.

After cord blood (CB) transplantation, early platelet recovery in immune-deficient mice is obtained by expansion of CB CD34(+) cells with thrombopoietin (TPO) as single growth factor. Moreover, improvement of hematopoietic engraftment has been shown by cotransplantation of mesenchymal stem cells (MSC). We investigated whether a combination of both approaches would further enhance the outcome of CB transplantation in NOD SCID mice. NOD SCID mice were transplanted with either CB CD34(+) cells, CD34(+) cells with MSC, TPO-expanded CD34(+) cells or TPO-expanded CD34(+) cells with MSC. We analyzed human platelet recovery in the peripheral blood (PB) from day 4 after transplantation onward and human bone marrow (BM) engraftment at week 6. The different transplants were assessed in vitro for their migration capacity and expression of CXCR4. TPO expansion improved the early platelet recovery in the PB of the mice. Cotransplantation of MSC with CD34(+) cells improved BM engraftment and platelet levels in the PB 6 weeks after transplantation. Combining TPO expansion and MSC cotransplantation, however, neither resulted in a more efficient early platelet recovery, nor in a better BM engraftment, nor even very low or absent BM engraftment occurred. In vitro, MSC boosted the migration of CD34(+) cells, suggesting a possible mechanism for the increase in engraftment. Our results show that cotransplantation of MSC with TPO-expanded CD34(+) cells at most combines, but does not increase the separate advantages of these different strategies. A combination of both strategies even adds a risk of non engraftment.