Lysis of human erythrocytes due to Piezo1-dependent cytosolic calcium overload as a mechanism of circulatory removal.

Hematopoietic stem cells surrender organelles during differentiation, leaving mature red blood cells (RBC) devoid of transcriptional machinery and mitochondria. The resultant absence of cellular repair capacity limits RBC circulatory longevity, and old cells are removed from circulation. The specific age-dependent alterations required for this apparently targeted removal of RBC, however, remain elusive. Here, we assessed the function of Piezo1, a stretch-activated transmembrane cation channel, within subpopulations of RBC isolated based on physical properties associated with aging. We subsequently investigated the potential role of Piezo1 in RBC removal, using pharmacological and mechanobiological approaches. Dense (old) RBC were separated from whole blood using differential density centrifugation. Tolerance of RBC to mechanical forces within the physiological range was assessed on single-cell and cell population levels. Expression and function of Piezo1 were investigated in separated RBC populations by monitoring accumulation of cytosolic Ca2+ and changes in cell morphology in response to pharmacological Piezo1 stimulation and in response to physical forces. Despite decreased Piezo1 activity with increasing cell age, tolerance to prolonged Piezo1 stimulation declined sharply in older RBC, precipitating lysis. Cell lysis was immediately preceded by an acute reversal of density. We propose a Piezo1-dependent mechanism by which RBC may be removed from circulation: Upon adherence of these RBC to other tissues, they are uniquely exposed to prolonged mechanical forces. The resultant sustained activation of Piezo1 leads to a net influx of Ca2+, overpowering the Ca2+-removal capacity of specifically old RBC, which leads to reversal of ion gradients, dysregulated cell hydration, and ultimately osmotic lysis.

PIEZO Ion Channels in Cardiovascular Functions and Diseases.

The cardiovascular system provides blood supply throughout the body and as such is perpetually applying mechanical forces to cells and tissues. Thus, this system is primed with mechanosensory structures that respond and adapt to changes in mechanical stimuli. Since their discovery in 2010, PIEZO ion channels have dominated the field of mechanobiology. These have been proposed as the long-sought-after mechanosensitive excitatory channels involved in touch and proprioception in mammals. However, more and more pieces of evidence point to the importance of PIEZO channels in cardiovascular activities and disease development. PIEZO channel-related cardiac functions include transducing hemodynamic forces in endothelial and vascular cells, red blood cell homeostasis, platelet aggregation, and arterial blood pressure regulation, among others. PIEZO channels contribute to pathological conditions including cardiac hypertrophy and pulmonary hypertension and congenital syndromes such as generalized lymphatic dysplasia and xerocytosis. In this review, we highlight recent advances in understanding the role of PIEZO channels in cardiovascular functions and diseases. Achievements in this quickly expanding field should open a new road for efficient control of PIEZO-related diseases in cardiovascular functions.

Assessment of stored red blood cells through lab-on-a-chip technologies for precision transfusion medicine.

Transfusion of red blood cells (RBCs) is one of the most valuable and widespread treatments in modern medicine. Lifesaving RBC transfusions are facilitated by the cold storage of RBC units in blood banks worldwide. Currently, RBC storage and subsequent transfusion practices are performed using simplistic workflows. More specifically, most blood banks follow the "first-in-first-out" principle to avoid wastage, whereas most healthcare providers prefer the "last-in-first-out" approach simply favoring chronologically younger RBCs. Neither approach addresses recent advances through -omics showing that stored RBC quality is highly variable depending on donor-, time-, and processing-specific factors. Thus, it is time to rethink our workflows in transfusion medicine taking advantage of novel technologies to perform RBC quality assessment. We imagine a future where lab-on-a-chip technologies utilize novel predictive markers of RBC quality identified by -omics and machine learning to usher in a new era of safer and precise transfusion medicine.

Reconsidering red blood cells as the diagnostic potential for neurodegenerative disorders.

BACKGROUND: Red blood cells (RBCs) are usually considered simple cells and transporters of gases to tissues. HYPOTHESIS: However, recent research has suggested that RBCs may have diagnostic potential in major neurodegenerative disorders (NDDs). RESULTS: This review summarizes the current knowledge on changes in RBC in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and other NDDs. It discusses the deposition of neuronal proteins like amyloid-ß, tau, and α-synuclein, polyamines, changes in the proteins of RBCs like band-3, membrane transporter proteins, heat shock proteins, oxidative stress biomarkers, and altered metabolic pathways in RBCs during neurodegeneration. It also highlights the comparison of RBC diagnostic markers to other in-market diagnoses and discusses the challenges in utilizing RBCs as diagnostic tools, such as the need for standardized protocols and further validation studies. SIGNIFICANCE STATEMENT: The evidence suggests that RBCs have diagnostic potential in neurodegenerative disorders, and this study can pave the foundation for further research which may lead to the development of novel diagnostic approaches and treatments.

Novel secretory organelles of parasite origin - at the center of host-parasite interaction.

Reorganization of cell organelle-deprived host red blood cells by the apicomplexan malaria parasite Plasmodium falciparum enables their cytoadherence to endothelial cells that line the microvasculature. This increases the time red blood cells infected with mature developmental stages remain within selected organs such as the brain to avoid the spleen passage, which can lead to severe complications and cumulate in patient death. The Maurer's clefts are a novel secretory organelle of parasite origin established by the parasite in the cytoplasm of the host red blood cell in order to facilitate the establishment of cytoadherence by conducting the trafficking of immunovariant adhesins to the host cell surface. Another important function of the organelle is the sorting of other proteins the parasite traffics into its host cell. Although the organelle is of high importance for the pathology of malaria, additional putative functions, structure, and genesis remain shrouded in mystery more than a century after its discovery. In this review, we highlight our current knowledge about the Maurer's clefts and other novel secretory organelles established within the host cell cytoplasm by human-pathogenic malaria parasites and other parasites that reside within human red blood cells.

Functional asymmetry of the urea transporter UT-B in human red blood cells.

We studied urea, thiourea, and methylurea transport and interaction in human red blood cells (RBCs) under conditions of self-exchange (SE), net efflux (NE), and net influx (NI) at pH 7.2. We combined four methods, a four-centrifuge technique, the Millipore-Swinnex filtering technique, the continuous flow tube method, and a continuous pump method to measure the transport of the 14C-labeled compounds. Under SE conditions, both urea and thiourea show perfect Michaelis-Menten kinetics with half-saturation constants, K½,SE (mM), of ≈300 (urea) and ≈20 (thiourea). The solutes show no concentration-dependent saturation under NE conditions. Under NI conditions, transport displays saturation or self-inhibition kinetics with a K½,NI (mM) of ≈210 (urea) and ≈20 (thiourea). Urea, thiourea, and methylurea are competitive inhibitors of the transport of analog solutes. This study supports the hypothesis that the three compounds share the same urea transport system (UT-B). UT-B functions asymmetrically as it saturates from the outside only under SE and NI conditions, whereas it functions as a high-capacity channel-like transporter under NE conditions. When the red blood cell enters the urea-rich kidney tissue, self-inhibition reduces the urea uptake in the cell. When the cell leaves the kidney, the channel-like function of UT-B implies that intracellular urea rapidly equilibrates with external urea. The net result is that the cell during the passage in the kidney capillaries carries urea to the kidney to be excreted while the urea transfer from the kidney via the bloodstream is minimized.NEW & NOTEWORTHY The kinetics of urea transport in red blood cells was determined by means of a combination of four methods that ensures a high time resolution. In the present study, we disclose that the urea transporter UT-B functions highly asymmetric being channel-like with no saturation under conditions of net efflux and saturable under conditions of net influx and self-exchange in the concentration range 1-1,000 mM (pH 7.2 and 25-38 °C).

Red blood cells as oxygen carrier during normothermic machine perfusion of kidney grafts: Friend or foe?

Renal ex vivo normothermic machine perfusion (NMP) is under development as an assessment tool for high-risk kidney grafts and as a means of achieving more physiologically accurate organ preservation. On-going hemolysis has been reported during NMP, as this technique relies on red blood cells for oxygen delivery. In this study, we confirm the occurrence of progressive hemolysis during 6-hour kidney NMP. NMP-associated erythrostasis in the glomeruli and in peri-glomerular vascular networks points to an interaction between the red blood cells and the graft. Continuous hemolysis resulted in prooxidative changes in the perfusate, which could be quenched by addition of fresh frozen plasma. In a cell-based system, this hemolysis induced redox stress and exhibited toxic effects at high concentrations. These findings highlight the need for a more refined oxygen carrier in the context of renal NMP.

Could oxygen gradient ektacytometry help to detect sickle cell trait carriers at risk for kidney disorders or exercise-related complications?

The study of Ellsworth et al. (Br J Haematol, 2024) demonstrated the usefulness of oxygen gradient ektacytometry technique to better identify the physiological parameters that could increase the risk of sickling of red blood cells (RBCs) from sickle cell trait (SCT) carriers. Oxygen gradient ektacytometry combined with pH and osmolality modulations could help in identifying SCT carriers at risk for kidney disorders or exercise-related complications. Other factors than the percentages of haemoglobin S are probably involved in the propensity of RBCs from SCT carriers to sickle during deoxygenation. Commentary on: Ellsworth et al. Hypertonicity and/or acidosis induce marked rheological changes under hypoxic conditions in sickle trait red blood cells. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19669.

Circular RNAs exhibit limited evidence for translation, or translation regulation of the mRNA counterpart in terminal hematopoiesis.

Each day, about 1012 erythrocytes and platelets are released into the bloodstream. This substantial output from hematopoietic stem cells is tightly regulated by transcriptional and epigenetic factors. Whether and how circular RNAs (circRNAs) contribute to the differentiation and/or identity of hematopoietic cells is to date not known. We recently reported that erythrocytes and platelets contain the highest levels and numbers of circRNAs among hematopoietic cells. Here, we provide the first detailed analysis of circRNA expression during erythroid and megakaryoid differentiation. CircRNA expression not only significantly increased upon enucleation, but also had limited overlap between progenitor cells and mature cells, suggesting that circRNA expression stems from regulated processes rather than resulting from mere accumulation. To study circRNA function in hematopoiesis, we first compared the expression levels of circRNAs with the translation efficiency of their mRNA counterpart. We found that only one out of 2531 (0.04%) circRNAs associated with mRNA-translation regulation. Furthermore, irrespective of thousands of identified putative open reading frames, deep ribosome-footprinting sequencing, and mass spectrometry analysis provided little evidence for translation of endogenously expressed circRNAs. In conclusion, circRNAs alter their expression profile during terminal hematopoietic differentiation, yet their contribution to regulate cellular processes remains enigmatic.

A comparative study of two routinely used protocols for ex vivo erythroid differentiation.

BACKGROUND: Erythropoiesis is a complex developmental process in which a hematopoietic stem cell undergoes serial divisions and differentiates through well-defined stages to give rise to red blood cells. Over the last decades, several protocols have been developed to perform ex vivo erythroid differentiation, allowing investigation into erythropoiesis and red cell production in health and disease. RESULTS: In the current study, we compared the two commonly used protocols by assessing the differentiation kinetics, synchronisation, and cellular yield, using molecular and cellular approaches. Peripheral blood CD34+ cells were cultured in a two-phase (2P) or a four-phase (4P) liquid culture (LC) and monitored for 20 days. Both protocols could recapitulate all stages of erythropoiesis and generate reticulocytes, although to different extents. Higher proliferation and viability rates were achieved in the 4P-LC, with a higher degree of terminal differentiation and enucleation, associated with higher levels of the erythroid-specific transcription factors GATA-1, KLF-1, and TAL-1. Although the 2P-LC protocol was less efficient regarding terminal erythroid differentiation and maturation, it showed a higher yield of erythroid progenitors in the erythropoietin (EPO)-free expansion phase. CONCLUSIONS: We provide data supporting the use of one protocol or the other to study the biological processes occurring in the early or late stages of erythroid differentiation, depending on the physiological process or pathological defect under investigation in a given study.

Calcium flux alterations in erythrocytes from sickle cell mice: The relevance of mean corpuscular volume.

Red blood cells (RBC) from patients with sickle cell disease (SCD) have elevated calcium levels at baseline, which are further elevated upon deoxygenation. Here we examined baseline calcium levels and calcium flux in RBCs from a mouse model of SCD mice. We found that akin to humans with SCD, sickle (HbSS) Townes mice, have higher baseline levels and increased calcium flux in RBCs compared to control (HbAA) animals. As HbSS mice, unlike humans with SCD, have high mean corpuscular volume compared with HbAA, we highlight the importance of adjusting biochemical results to number of RBCs rather than hematocrit during the analysis and interpretation of the results. Our findings add to the face validity of humanized sickle cell mice and support its use for studies of RBC calcium flux in SCD.

Measurement and analysis of ionic leakage profiles in refrigerated human red blood cells using dielectrophoresis and inductively coupled mass spectroscopy.

Human red blood cells (RBCs) undergo ionic leakage through passive diffusion during refrigerated storage, affecting their quality and health. We investigated the dynamics of ionic leakage in human RBCs over a 20-day refrigerated storage period using extracellular ion quantification and dielectrophoresis (DEP). Four type O- human blood donors were examined to assess the relationship between extracellular ion concentrations (Na+, K+, Mg2+, Ca2+, and Fe2+), RBC cytoplasm conductivity, and membrane conductance. A consistent negative correlation between RBC cytoplasm conductivity and membrane conductance, termed the "ionic leakage profile" (ILP), was observed across the 20-day storage period. Specifically, we noted a gradual decline in DEP-measured RBC cytoplasm conductivity alongside an increase in membrane conductance. Further examination of the electrical origins of this ILP using inductively coupled plasma mass spectrometry revealed a relative decrease in extracellular Na+ concentration and an increase in K+ concentration over the storage period. Correlation of these extracellular ion concentrations with DEP-measured RBC electrical properties demonstrated a direct link between changes in the cytoplasmic and membrane domains and the leakage and transport of K+ and Na+ ions across the cell membrane. Our analysis suggests that the inverse correlation between RBC cytoplasm and membrane conductance is primarily driven by the passive diffusion of K+ from the cytoplasm and the concurrent diffusion of Na+ from the extracellular buffer into the membrane, resulting in a conductive reduction in the cytoplasmic domain and a subsequent increase in the membrane. The ILP's consistent negative trend across all donors suggests that it could serve as a metric for quantifying blood bank storage age, predicting the quality and health of refrigerated RBCs.

The impact of infused red blood cell volume on major and bidirectional ABO-mismatched bone marrow transplantation.

BACKGROUND AIMS: ABO incompatibility does not hinder bone marrow transplantation (BMT), but it has been associated with worse outcomes and additional adverse events. This study aimed to verify the impact of incompatible red blood cells (iRBCs) in allogeneic BMT and to determine a safe number of iRBCs to be infused. METHODS: We compared ABO-incompatible (iABO) allogeneic BMT (n = 42) with ABO-compatible allogeneic BMT (n = 44) and evaluated the impact of the number of infused iRBCs on outcomes and adverse events. RESULTS: The iABO patients demonstrated delayed time to transfusion independence at 30 days and 60 days, increased requirement for red blood cell (RBC) transfusion and greater hemolysis signals and incidence of pure red cell aplasia. Neutrophil/platelet engraftment, length of hospitalization post-transplant, platelet units required, graft-versus-host disease occurrence and overall survival were similar in both groups. Patients in the iABO group received 1.03 × 1010 iRBCs/kg (range, 0.36-3.88). Infusion of iRBCs >1.0 × 1010 /kg was related to graft failure or death before neutrophil engraftment or platelet engraftment or both as well as increased plasma requirement and increased creatinine. Our results also suggest that antibody titers impact the transplantation scenario. CONCLUSIONS: The iABO transplantation showed some unfavorable outcomes. It is important to monitor the value of iRBCs to be infused, considering the recipient antibody titers. We propose using the number of iRBCs (iRBCs/kg) as a dose parameter with regard to infused iRBCs. Further studies are necessary to clarify the maximum safe number of iRBCs in iABO transplants.

Erythrocytic α-Synuclein and the Gut Microbiome: Kindling of the Gut-Brain Axis in Parkinson's Disease.

BACKGROUND: Progressive spreading of α-synuclein via gut-brain axis has been hypothesized in the pathogenesis of Parkinson's disease (PD). However, the source of seeding-capable α-synuclein in the gastrointestinal tract (GIT) has not been fully investigated. Additionally, the mechanism by which the GIT microbiome contributes to PD pathogenesis remains to be characterized. OBJECTIVES: We aimed to investigate whether blood-derived α-synuclein might contribute to PD pathology via a gut-driven pathway and involve GIT microbiota. METHODS: The GIT expression of α-synuclein and the transmission of extracellular vesicles (EVs) derived from erythrocytes/red blood cells (RBCs), with their cargo α-synuclein, to the GIT were explored with various methods, including radioactive labeling of RBC-EVs and direct analysis of the transfer of α-synuclein protein. The potential role of microbiota on the EVs transmission was further investigated by administering butyrate, the short-chain fatty acids produced by gut microbiota and studying mice with different α-synuclein genotypes. RESULTS: This study demonstrated that RBC-EVs can effectively transport α-synuclein to the GIT in a region-dependent manner, along with variations closely associated with regional differences in the expression of gut-vascular barrier markers. The investigation further revealed that the infiltration of α-synuclein into the GIT was influenced significantly by butyrate and α-synuclein genotypes, which may also affect the GIT microbiome directly. CONCLUSION: By demonstrating the transportation of α-synuclein through RBC-EVs to the GIT, and its potential association with gut-vascular barrier markers and gut microbiome, this work highlights a potential mechanism by which RBC α-synuclein may impact PD initiation and/or progression. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Differences in endothelial function between patients with Type 1 and Type 2 diabetes: effects of red blood cells and arginase.

The mechanisms underlying endothelial dysfunction in Type 1 and Type 2 diabetes (T1DM and T2DM) are unresolved. The red blood cells (RBCs) with increased arginase activity induce endothelial dysfunction in T2DM, but the implications of RBCs and the role of arginase inhibition in T1DM are unexplored. We aimed to investigate the differences in endothelial function in patients with T1DM and T2DM, with focus on RBCs and arginase. Thirteen patients with T1DM and twenty-six patients with T2DM, matched for HbA1c and sex were included. In vivo endothelium-dependent and -independent vasodilation (EDV and EIDV) were assessed by venous occlusion plethysmography before and after administration of an arginase inhibitor. RBCs were co-incubated with rat aortic segments for 18h followed by evaluation of endothelium-dependent (EDR) and -independent relaxation (EIDR) in isolated organ chambers. In vivo EDV, but not EIDV, was significantly impaired in patients with T2DM compared with patients with T1DM. Arginase inhibition resulted in improved EDV only in T2DM. RBCs from patients with T2DM induced impaired EDR but not EIDR in isolated aortic segments, whereas RBCs from patients with T1DM did not affect EDR nor EIDR. The present study demonstrates markedly impaired EDV in patients with T2DM in comparison with T1DM. In addition, it highlights the divergent roles of RBCs and arginase in mediating endothelial dysfunction in T1DM and T2DM. While endothelial dysfunction is mediated via RBCs and arginase in T2DM, these phenomena are not prominent in T1DM thereby indicating distinct differences in underlying mechanisms.

Prevalence and clinical implications of heightened plastic chemical exposure in pediatric patients undergoing cardiopulmonary bypass.

BACKGROUND: Phthalate chemicals are used to manufacture plastic medical products, including many components of cardiopulmonary bypass (CPB) circuits. We aimed to quantify iatrogenic phthalate exposure in pediatric patients undergoing cardiac surgery and examine the link between phthalate exposure and postoperative outcomes. STUDY DESIGN AND METHODS: The study included pediatric patients undergoing (n=122) unique cardiac surgeries at Children's National Hospital. For each patient, a single plasma sample was collected preoperatively and two additional samples were collected postoperatively upon return from the operating room and the morning after surgery. Concentrations of di(2-ethylhexyl) phthalate (DEHP) and its metabolites were quantified using ultra high-pressure liquid chromatography coupled to mass spectrometry. RESULTS: Patients were subdivided into three groups, according to surgical procedure: (1) cardiac surgery not requiring CPB support, (2) cardiac surgery requiring CPB with a crystalloid prime, and (3) cardiac surgery requiring CPB with red blood cells (RBCs) to prime the circuit. Phthalate metabolites were detected in all patients, and postoperative phthalate levels were highest in patients undergoing CPB with an RBC-based prime. Age-matched (<1 year) CPB patients with elevated phthalate exposure were more likely to experience postoperative complications. RBC washing was an effective strategy to reduce phthalate levels in CPB prime. DISCUSSION: Pediatric cardiac surgery patients are exposed to phthalate chemicals from plastic medical products, and the degree of exposure increases in the context of CPB with an RBC-based prime. Additional studies are warranted to measure the direct effect of phthalates on patient health outcomes and investigate mitigation strategies to reduce exposure.

Absence of blood donors' anti-SARS-CoV-2 antibodies in pre-storage leukoreduced red blood cell units indicates no role of passive immunity for blood recipients.

Transfer of vaccine antibodies (Ab) from donors to recipients after transfusion of packed red blood cells (RBC) is supposed, thus affecting the recipients' response to vaccinations. In this prospective study, SARS-CoV-2 IgG level in donors' serum and RBC supernatant samples was assessed. Among 346 subjects, 280 were referred for hyperimmune plasma donation and 30 for whole blood donations. All units underwent pre-storage filtration, and residual plasma volume was 18±18 mL. The mean total IgG and IgM levels were 171.43 ± 48.79 and 11.43 ± 10.69 mg/dL respectively, with significant reduction after plasma depletion and filtration (IgG 5.86 ± 5.2 and IgM 1.43 ± 3.78, p < 0.05). Anti-COVID-19 Ab were identified in serum of 28/30 (93.5%) blood donors but were absent in all blood units. The mean value of anti-SARS-CoV-2 IgG level in donors' serum samples and in RBC units was 8.80 S/C (range 0.01-23.4) and 0.11 (range 0.01-0.37) S/C, respectively (p<0.05). This study shows deplasmation and leukodepletion of RBC units ensured removal of IgG content and no red blood cell unit was reactive for anti-COVID-19 antibodies even from donors with high serum titre. These findings demonstrate that deplasmated and leukodepleted RBCs are not to be considered blood products containing substantial amounts of immune globulin, and differently from other blood derived-products containing Ab, transfusions with deplasmated and leukodepleted RBCs do not require delayed vaccinations and a revision of current recommendations is requested.

Erythronecroptosis: an overview of necroptosis or programmed necrosis in red blood cells.

Necroptosis is considered a programmed necrosis that requires receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and pore-forming mixed lineage kinase domain-like protein (MLKL) to trigger a regulated cell membrane lysis. Membrane rupture in necroptosis has been shown to fuel innate immune response due to release of damage-associated molecular patterns (DAMPs). Recently published studies indicate that mature erythrocytes can undergo necroptosis as well. In this review, we provide an outline of multiple cell death modes occurring in erythrocytes, discuss possible immunological aspects of diverse erythrocyte cell deaths, summarize available evidence related to the ability of erythrocytes to undergo necroptosis, outline key involved molecular mechanisms, and discuss the potential implication of erythrocyte necroptosis in the physiology and pathophysiology. Furthermore, we aim to highlight the interplay between necroptosis and eryptosis signaling in erythrocytes, emphasizing specific characteristics of these pathways distinct from their counterparts in nucleated cells. Thus, our review provides a comprehensive summary of the current knowledge of necroptosis in erythrocytes. To reflect critical differences between necroptosis of nucleated cells and necroptosis of erythrocytes, we suggest a term erythronecroptosis for necroptosis of enucleated cells.

Management of massive haemorrhage in transfusion medicine services in the Middle East and North Africa.

BACKGROUND AND OBJECTIVES: Massive transfusion protocols (MTPs) are critical in managing haemorrhage, yet their utilization varies. There is lack of data on the utilization of MTPs in the Middle East and North Africa (MENA) region. This study aims to assess the degree of utilization of MTPs in the region. MATERIALS AND METHODS: We conducted a survey to collect data on MTP use, inviting medical directors of transfusion services from various hospitals. Data were analysed to determine the prevalence of MTP utilization, their compositions, challenges in application and areas of future need. RESULTS: Eighteen respondents participated, representing 11 countries in the region. Thirteen hospitals implemented MTP, and eight included paediatrics. Eleven institutions used more than one definition of massive haemorrhage, with the most common being ≥10 red blood cell (RBC) units transfused for adults and replacement of >50% total blood volume in paediatrics. The majority of sites with MTPs utilized 1:1:1 RBCs:platelets:plasma ratio (70%). Variations were observed in the types and blood groups of components used. Two sites utilized whole blood, while six are considering it for future use. Utilization of adjunctive agents and frequency of laboratory testing varied among the sites. Challenges included the lack of medical expertise in protocol development, adherence and paediatric application. The need assessment emphasized the need for developing regional guidelines, standardized protocols and training initiatives. CONCLUSION: Although several hospitals have adopted MTPs, variations exist in activation criteria, blood product ratios and monitoring. Challenges include the lack of medical expertise, protocol adherence and addressing paediatric needs. Standardizing protocols, enhancing training and paediatric application are crucial for improving massive transfusion management in the region.

Patient-tailored platelet transfusion practices for children supported by extracorporeal membrane oxygenation.

BACKGROUND AND OBJECTIVES: Extracorporeal membrane oxygenation (ECMO) serves as cardiopulmonary therapy in critically ill patients with respiratory/heart failure and often necessitates multiple blood product transfusions. The administration of platelet transfusions during ECMO is triggered by the presence or risk of significant bleeding. Most paediatric ECMO programmes follow guidelines that recommend a platelet transfusion threshold of 80-100 × 109/L. To reduce exposure to platelets, we developed a practice to dynamically lower the threshold to ~20 × 109/L. We describe our experience with patient-tailored platelet thresholds and related bleeding outcomes. MATERIALS AND METHODS: We retrospectively evaluated our platelet transfusion policy, bleeding complications and patient outcome in 229 ECMO-supported paediatric patients in our unit. RESULTS: We found that more than 97.4% of patients had a platelet count <100 × 109/L at some point during their ECMO course. Platelets were transfused only on 28.5% of ECMO days; and 19.2% of patients never required a platelet transfusion. The median lowest platelet count in children who had bleeding events was 25 × 109/L as compared to 33 × 109/L in children who did not bleed (p < 0.001). Our patients received fewer platelet transfusions and did not require more red blood cell transfusions, nor did they experience more haemorrhagic complications. CONCLUSION: We have shown that a restrictive, 'patient-tailored' rather than 'goal-directed' platelet transfusion policy is feasible and safe, which can greatly reduce the use of platelet products. Although there was a difference in the lowest platelet counts in children who bled versus those who did not, the median counts were much lower than current recommendations.