Publications by authors named "Thomas R L Klei"

Article Synopsis
  • The study aimed to investigate how fresh and stored platelet concentrates (PCs) behave during inflammation, specifically in a controlled human model of endotoxemia induced by lipopolysaccharide (LPS).
  • Researchers found that LPS increased markers related to coagulation and clotting, leading to a generally lower clotting ability in subjects compared to controls, while platelet transfusions improved clotting time and strength in those with endotoxemia.
  • Despite these improvements in coagulation, there were no significant differences noted between the effects of fresh versus stored platelets on coagulation parameters like thrombin-antithrombin complex (TATc) or extracellular vesicles (EVs).
View Article and Find Full Text PDF

Background And Objectives: Plasma components are visually inspected, and non-transparent, turbid units are rejected for transfusion and fractionation. Additionally, in case a plasma component is deemed lipaemic, there is conflicting data on the accompanying red cell concentrate (RCC) in vitro quality. As visual inspection of plasma turbidity is a subjective method, we aimed to devise an objective measurement using a quick, non-invasive, table-top spectrophotometry-based method.

View Article and Find Full Text PDF
Article Synopsis
  • - Thrombocytopenia in preterm newborns can lead to increased bleeding risk, and recent findings suggest that using adult-derived platelet transfusions may be harmful due to developmental mismatches; hence there's interest in using cord blood-derived platelet concentrates (CBPCs) as a safer alternative.
  • - The study conducted various methods to produce CBPCs from cord blood collected after near-term and full-term pregnancies and compared these to adult-derived platelet concentrates (PCs) in terms of quality parameters during storage.
  • - Results showed that while CBPCs were generally comparable to control PCs, they exhibited lower pH and platelet concentration along with elevated apoptosis markers, indicating a need for improved processing and storage practices for low-volume platelets.
View Article and Find Full Text PDF

Background And Objectives: Near-infrared (NIR) light has been successfully applied to improve the quality of mouse platelets during storage. Because it is suspected that the mitochondria contain the primary photon acceptor, we hypothesized that human platelets for transfusion may be affected similarly and could benefit from NIR light treatment.

Materials And Methods: The optimal light dose was determined using portions of platelet concentrates (PCs) in PAS-E.

View Article and Find Full Text PDF

Thrombocytopenia (defined as a platelet count <150×10/L) is a common condition in preterm neonates and may occur in 18-35% of all infants admitted to the Neonatal Intensive Care Unit (NICU). Neonatal platelet functionality in terms of reactivity is often described as reduced compared to adults, even in healthy, term neonates. However, this platelet "hyporeactivity" does not correspond to a global functional impairment of the normal delicately balanced neonatal hemostatic system.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

Introduction: In 2018, platelet (PLT) additive solution-E (PAS-E) was introduced. The implementation of PAS-E was expected to diminish the number of allergic reactions in recipients following a PLT transfusion. Here, we evaluated the efficacy and safety of transfusions with PLTs stored in PAS-E.

View Article and Find Full Text PDF

Introduction: Allogeneic serum from blood donors is starting to be used to treat patients with dry eye disease (DED). However, the optimal dose is not known. We therefore aimed to evaluate the clinical efficaciousness and user-friendliness of micro-sized versus conventional-sized allogeneic serum eye drops (SEDs).

View Article and Find Full Text PDF

Background And Objectives: DEHP, di(2-ethylhexyl) phthalate, is the most common member of the class of ortho-phthalates, which are used as plasticizers. The Medical Device Regulation has restricted the use of phthalates in medical devices. Also DEHP has been added to the Annex XIV of REACH, "Registration, Evaluation, Authorisation and Restriction of Chemicals" due to its endocrine disrupting properties to the environment.

View Article and Find Full Text PDF

Background: Platelets (PLTs) differ in glycolytic activity, resulting in rapid acidification of 'poor' storing PLT concentrates (PCs) in plasma, or depletion of glucose when stored in PLT additive solution (PAS). We aimed to understand why PLT glycolysis rates vary between donors and how this affects storage performance.

Study Design And Methods: Buffy coats from donors <45, 45-70 and >70 years were selected and single-donor PCs in plasma or PAS-E were prepared.

View Article and Find Full Text PDF

Background And Objectives: Di-ethyl-hexyl-phthalate (DEHP) is currently the main plasticizer used for whole blood collection systems. However, in Europe, after May 2025, DEHP may no longer be used above 0.1% (w/w) in medical devices.

View Article and Find Full Text PDF

The buffy coat method as a source for platelet concentrates was developed in the 1970s and is still used in many blood centres around the world. Development of the method sparked various technological advances in blood collection, processing and storage. At the time, the need for platelet concentrates sharply increased because of better treatment regimens for (onco)haematological diseases, which forced blood centres to standardize and automate their production processes as much as the technology would allow.

View Article and Find Full Text PDF

Severe malarial anemia (SMA) is the main cause of malaria-associated infant mortality in malaria endemic countries. One major factor that contributes to SMA is the accumulation of uninfected red blood cells (uRBCs) in the spleen. We report the activation of adhesion molecules Lutheran/basal cell adhesion molecule (Lu/BCAM) and CD44 on uRBCs from Plasmodium falciparum in vitro cultures and patients with malaria that mediates adherence to the splenic extracellular matrix (ECM) components laminin-α5 and hyaluronic acid (HA), respectively.

View Article and Find Full Text PDF

Senescence of erythrocytes is characterized by a series of changes that precede their removal from the circulation, including loss of red cell hydration, membrane shedding, loss of deformability, phosphatidyl serine exposure, reduced membrane sialic acid content, and adhesion molecule activation. Little is known about the mechanisms that initiate these changes nor is it known whether they are interrelated. In this study, we show that Ca2+-dependent K+ efflux (the Gardos effect) drives erythrocyte senescence.

View Article and Find Full Text PDF

A 4-year-old boy, a β-thalassemia (β-thal) carrier, with an unexplained severe chronic microcytic anemia was referred to us. Sequencing of the α-globin genes revealed a Hb Charlieu [α106(G13)Leu→Pro, : c.320T>C, p.

View Article and Find Full Text PDF

Red blood cell (RBC) clearance is known to occur primarily in the spleen, and is presumed to be executed by red pulp macrophages. Erythrophagocytosis in the spleen takes place as part of the homeostatic turnover of RBCs to remove old RBCs. It can be strongly promoted by immunoglobulin G (IgG) opsonization of RBCs, a condition that can occur as a consequence of autoantibody or alloantibody formation.

View Article and Find Full Text PDF

Background: Red blood cell (RBC) transfusion is associated with organ failure, in particular in the critically ill. We hypothesized that endotoxemia contributes to increased trapping of RBCs in organs. Furthermore, we hypothesized that this effect is more pronounced following transfusion of stored RBCs compared with fresh RBCs.

View Article and Find Full Text PDF

Objective: Here, we present a 7-year-old patient suffering from severe haemolytic anaemia. The most common cause of chronic hereditary non-spherocytic haemolytic anaemia is red blood cell pyruvate kinase (PK-R) deficiency. Because red blood cells rely solely on glycolysis to generate ATP, PK-R deficiency can severely impact energy supply and cause reduction in red blood cell lifespan.

View Article and Find Full Text PDF

Erythropoiesis is a highly regulated process where sequential events ensure the proper differentiation of hematopoietic stem cells into, ultimately, red blood cells (RBCs). Macrophages in the bone marrow play an important role in hematopoiesis by providing signals that induce differentiation and proliferation of the earliest committed erythroid progenitors. Subsequent differentiation toward the erythroblast stage is accompanied by the formation of so-called erythroblastic islands where a central macrophage provides further cues to induce erythroblast differentiation, expansion, and hemoglobinization.

View Article and Find Full Text PDF

Even though red blood cell (RBC) vesiculation is a well-documented phenomenon, notably in the context of RBC aging and blood transfusion, the exact signalling pathways and kinases involved in this process remain largely unknown. We have established a screening method for RBC vesicle shedding using the Ca(2+) ionophore ionomycin which is a rapid and efficient method to promote vesiculation. In order to identify novel pathways stimulating vesiculation in RBC, we screened two libraries: the Library of Pharmacologically Active Compounds (LOPAC) and the Selleckchem Kinase Inhibitor Library for their effects on RBC from healthy donors.

View Article and Find Full Text PDF