Plasmatic and cell-based enhancement by microparticles originated from platelets and endothelial cells under simulated in vitro conditions of a dilutional coagulopathy.

BACKGROUND: Aggressive fluid management and other external factors may lead to hypothermia, acidosis and hemodilution (defined as Lethal Triad, LT) contributing to a trauma-induced coagulopathy (TIC) that worsens patients' outcomes. Procoagulant microparticles (MP) are crucial players at the interface of cellular and plasmatic coagulation. However, their functions remain largely unexplored. This study aimed to characterize effects of MP subtypes and concentrations on functional coagulation under in vitro simulated conditions. METHODS: Blood from eleven volunteers were collected to simulate in vitro conditions of hemodilution (HD) and LT, respectively. HD was induced by replacing a blood volume of 33% by crystalloids and for LT, samples were further processed by reducing the temperature to 32 °C and lowering the pH to 6.8. MP were obtained either from platelet concentrates (platelet-derived MP, PDMP) or from cell culture (ECV304 cells for endothelial-derived MP, EDMP) by targeted stimulation. After introducing MP to in vitro conditions, we measured their concentration-dependent effects (1.000, 10.000 and 15.000 MP/µl blood) on coagulation compared to whole blood (WB). For each condition, coagulation was characterized by flow cytometric platelet activation and by quantification of fibrin clot propagation using Thrombodynamics® technology. RESULTS: MP originated from platelets and endothelial cells affected blood coagulation in a concentration-dependent manner. Particularly, high PDMP quantities (10.000 and 15.000 PDMP/µl blood) significantly induced platelet activation and fibrin clot growth and size in HD conditions. In LT conditions as well, only high PDMP concentration induced platelet activation, clot growth and size. In contrast, EDMP did not induce platelet activation, but resulted in enhanced formation of spontaneous clots, irrespective of simulated condition. With increasing EDMP concentration, the time until the onset of spontaneous clotting decreased in both HD and LT conditions. DISCUSSION: The study demonstrates an essential role of MP within the coagulation process under simulated coagulopathic conditions. PDMP affected platelets promoting clot formation likely by providing a surface enlargement. EDMP presumably affected clotting factors of the plasmatic coagulation resulting in an increased formation of spontaneous clots. CONCLUSION: Under simulated conditions of a dilutional coagulopathy, MP from different cellular origin indicate a divergent but both procoagulant mechanism within the coagulation process.

Simulated Hypergravity Activates Hemostasis in Healthy Volunteers.

Background Hypergravity may promote human hemostasis thereby increasing thrombotic risk. Future touristic suborbital spaceflight will expose older individuals with chronic medical conditions, who are at much higher thromboembolic risk compared with professional astronauts, to hypergravity. Therefore, we tested the impact of hypergravity on hemostasis in healthy volunteers undergoing centrifugation. Methods and Results We studied 20 healthy seated men before and after 15 minutes under 3 Gz hypergravity on a long-arm centrifuge. We obtained blood samples for hemostasis testing before, immediately after, and 30 minutes after centrifugation. Tests included viscoelastic thromboelastometry, platelet impedance aggregometry, endothelial activation markers, blood rheology testing, microparticle analyses, and clotting factor analysis. Exposure to hypergravity reduced plasma volume by 12.5% (P=0.002) and increased the red blood cell aggregation index (P<0.05). With hypergravity, thrombelastographic clotting time of native blood shortened from 719±117 seconds to 628±89 seconds (P=0.038) and platetet reactivity increased (P=0.045). Hypergravity shortened partial thromboplastin time from 28 (26-29) seconds to 25 (24-28) seconds (P<0.001) and increased the activity of coagulation factors (eg, factor VIII 117 [93-134] versus 151 [133-175] %, P<0.001). Tissue factor concentration was 188±95 pg/mL before and 298±136 pg/mL after hypergravity exposure (P=0.023). Antithrombin (P=0.005), thrombin-antithrombin complex (P<0.001), plasmin-alpha2-antiplasmin complex (0.002), tissue-plasminogen activatior (P<0.001), and plasminogen activator inhibitor-1 (P=0.002) increased with centrifugation. Statistical adjustment for plasma volume attenuated changes in coagulation. Conclusions Hypergravity triggers low-level hemostasis activation through endothelial cell activation, increased viscoelasticity, and augmented platelet reactivity, albeit partly counteracted through endogenous coagulation inhibitors release. Hemoconcentration may contribute to the response.

Microparticles profiling in trauma patients: high level of microparticles induce activation of platelets in vitro.

PURPOSE: Trauma-induced coagulopathy (TIC) is recognised as an own clinical entity which includes all components of haemostasis following rapidly tissue injury, hypoperfusion and shock. Microparticles (MP) are known to be released in large quantities from different cell types after trauma. The present study aimed to perform a phenotypic MP profiling after major trauma and to elucidate potential procoagulative function of MP under simulated conditions of lethal triad. METHODS: For MP isolation, 20 trauma patients (median ISS 24) were included. To produce a Standard MP Phenotype Profile after trauma, samples were pooled, extracted and concentrated by using an ultracentrifuge protocol. Specific cell surface markers were measured by flow cytometry. Our Standard MP Phenotype Profile was subsequently added in high and low concentration to an in vitro lethal triad assay, simulating coagulopathy via induced hypothermia, dilution and acidosis. A comprehensive analysis of coagulation function was performed. RESULTS: Within our Standard MP Phenotype Profile, PDMP (56%) were found as predominant phenotype followed by EDMP (33%) and MDMP (11%). EDMP characterized by CD144, CD62E and Annexin were determined most frequently but also EDMP expressing CD62P. In addition, tissue factor (TF) was expressed on all MP entities (EDMP 63%, PDMP 30%, MDMP 7%). Within our lethal triad simulation assay, the addition of low and high concentrated MP did not cause any significant alteration in standard coagulation assays, coagulation initiation, clot kinetics or stability. Addition of high concentrated MP increased platelet function and P-selectin expression significantly. CONCLUSION: Our data confirm the assumption that there is a characteristic MP phenotype pattern in trauma, which may alter haemostatic capacity at least in part mediated via augmenting in primary haemostasis resulting in an improved contribution of platelets to clot formation. There are indications that expression of selectins on MP surface is involved in this activation process, but this pathway needs to be investigated in more detail.

How do external factors contribute to the hypocoagulative state in trauma-induced coagulopathy? - In vitro analysis of the lethal triad in trauma.

BACKGROUND: External factors following trauma and iatrogenic intervention influence blood coagulation and particularly clot formation. In particular, three external factors (in detail dilution via uncritical volume replacement, acidosis and hypothermia), in combination, referred to as the "lethal triad", substantially aggravate the hypocoagulative state after trauma. Contribution of these external factors to the resulting hypocoagulative state in trauma and especially their influence on primary haemostasis has still not been investigated systematically. This study aims to assess this contribution to the aggravating hypocoagulative state in trauma-induced coagulopathy (TIC) using an in vitro simulation assay. Emphasis is given to platelet contribution to clot formation and to the investigation of how platelet activation alters under the respective conditions. METHODS: To simulate the conditions of lethal triad in vitro, whole blood samples taken from five healthy volunteers were introduced to the respective conditions. Besides standard coagulation testing, thrombelastometric analysis and differentiated platelet mapping were performed. RESULTS: All three simulated conditions induced significant impairments of clot formation (clot formation time, CFT; α -angle) and propagation (maximum clot firmness, MCF; Diameter A5-A25), with the highest impact under hypothermia and dilution. Consistently, lethal triad resulted in an additive effect of all conditions. None of the simulated conditions induced a statistically relevant change in coagulation initiation assessed by EXTEM and FIBTEM thrombelastometry. Platelet contribution to clot formation decreased gradually under the respective conditions, reaching statistical significance for simulated dilution, and attaining its greatest extent under the conditions of lethal triad (Δtrias/baseline 0.59; p = 0.01). Consistent, reduced CD62 expression levels were observed under experimental acidosis (Δacidosis/baseline 0.32; p = 0.006), dilution (Δdilution/baseline 0.34; p = 0.01) and lethal triad (Δlethal triad/baseline 0.24; p = 0.01). CONCLUSION: The respective external factors of lethal triad play a pivotal role in the development of coagulopathy, essentially influencing the kinetics of clot formation, and to a varying extent clot diameter, as measured by thrombelastometry. Moreover, impairment of platelet function under the conditions of lethal triad plays a key role in the pathophysiology of TIC, resulting in reduced responsiveness to stimulation with ADP that might also be present after trauma. Our data indicate that impairment of primary haemostasis contribute to the hypocoagulative state in TIC after trauma aggravated by external factors of lethal triad.

A case of anti-Rd causing fetal anemia.

BACKGROUND: Rd (SC4) is a low-frequency antigen of the Scianna blood group system. Only very few reports on anti-Rd in pregnancy exist. Mild to moderate hemolytic disease of the newborn caused by anti-Rd has been reported. This report may add further information on the clinical significance of anti-Rd for the fetus. CASE REPORT: In a case of severe fetal anemia (hemoglobin concentration, 3.0 g/dL) repeated intrauterine transfusions were required. The strongly positive direct antiglobulin test (DAT) of the fetal red blood cells led to the diagnosis of hemolytic disease. The routine antibody screen was negative, extended testing revealed a maternal anti-Rd with a titer of 256. Both the newborn and her father were confirmed to carry the SC*01.04 allele. CONCLUSION: Anti-Rd can cause fetal anemia. Low-frequency antigens including Rd are normally not present on screening cells. Antibodies directed against low-frequency antigens will usually not be detected by routine antibody screening in pregnancy. Thus, in cases of fetal anemia the DAT should always be included in the diagnostic workup.

Functional capacity of reconstituted blood in 1:1:1 versus 3:1:1 ratios: a thrombelastometry study.

INTRODUCTION: Different transfusion ratio concepts of packed red blood cells (pRBCs), fresh frozen plasma (FFP) and platelets (PLTs) have been implemented in trauma care, but the optimal ratios are still discussed. In this study the hemostatic potential of two predefined ratios was assessed by using an in vitro thrombelastometric approach. Furthermore, age effects of reconstituted blood were analyzed. METHODS: Whole blood (WB) of voluntary donors was separated into pRBCs, FFP and PLTs and reconstituted into the ratios 1:1:1 and 3:1:1 at day 1, 4, 14, and 24. Standard blood count, electrolytes and coagulation proteins were quantified. The functional coagulation in ratio- and age-specific groups was evaluated using rotational thromboelastometry (ROTEM). RESULTS: Several coagulation factors reduced significantly in the 3:1:1 ratio and were consistent with increased INR, decelerated clot formation times and A10 (amplitude 10 minutes after clotting time (CT)), flattened α-angle during the EXTEM and diminished MCF for distinct time points during the INTEM, FIBTEM and APTEM assays. With rising age of pRBCs the pH, sodium and potassium reached non-physiological levels. CONCLUSION: Under standardized in vitro conditions the higher amount of pRBCs in the 3:1:1 ratio diluted coagulation factors significantly on the expense of its functional coagulation capacity as revealed by ROTEM results. Thus, the coagulation functionality of the 1:1:1 ratio predominated.

Vulval intestinal/enteric heterotopia with a 10-yr follow-up: a case report and review of the literature.

The occurrence of ectopic intestinal/enteric-type epithelium at the vulva is a rare entity sometimes mimicking intraepithelial neoplasia or malignant disease. Here, we report a case of an 82-yr-old woman with a long-standing (10 yr) white papillary lesion with some reddish areas at her left labium, extending into the vaginal introitus. Biopsy reports revealed colonic-type glandular epithelium with positive immunostaining against CDX-2, p53, CK 7, and CEA, whereas staining against estrogen and progesterone receptor, mammoglobin, GCDFP-15, and CK 20 was reported to be negative. A follow-up of 10 yr appeared uneventful. The occurrence of celomic-type glandular epithelium at the vulva may represent the result of dysontogenetic replacement of embryonic stem cells, which undergo mucinous differentiation. Thus, the proper diagnostic term may be glandular heterotopia. Although some lesions, especially in the proximity to orthotopic vulval glands, may be of metaplastic origin. Immunohistochemical staining patterns (CEA, CK 7 positive, and CK 20 negative) indicate an intestinal/enteric phenotype (i.e. intestinal/enteric heterotopia). Because of the reported increased risk of malignant transformation of glandular vulval lesions, close clinical follow-up is recommended.

25 Years of Kidney Transplantation--A Period of Change.

At the University of Cologne Hospital, 1062 kidney transplants in adults and 136 pediatric transplants were performed between 1990 and 2014. Immunosuppressive therapy was changed during this time period from a therapy with anti-lymphocyte globulin induction followed by a triple therapy to a period using induction (IL2 receptor antagonists) followed by low dose tacrolimus, mycophenolate mofetil and steroids. Antiviral therapy has been constant during the 25 years, consisting of ganciclovir or valganciclovir. Major change occurred in the age of donors and recipients, with more than a third of both now being older than 65 years. Living donation has increased in number and proportion, at the same time the number of deceased donors rapidly declined. Longer time periods on dialysis resulted not only in an increased risk profile of the recipients, but were also accompanied by a significantly higher number of mismatches for the allocated kidney, since the relative importance of waiting time in the allocation process increased. Multivariate analysis showed that immunological factors such as HLA-match and panel reactive antibody are relevant factors, even in a single center analysis.

Impact of de novo donor-specific HLA antibodies detected by Luminex solid-phase assay after transplantation in a group of 88 consecutive living-donor renal transplantations.

De novo donor-specific HLA antibodies (DSA) after renal transplantation are known to be correlated with poor graft outcome and the development of acute and chronic rejection. Currently, data for the influence of de novo DSA in patient cohorts including only living-donor renal transplantations (LDRT) are limited. A consecutive cohort of 88 LDRT was tested for the occurrence of de novo DSA by utilizing the highly sensitive Luminex solid-phase assay for antibody detection. Data were analyzed for risk factors for de novo DSA development and correlated with acute rejection (AR) and graft function. Patients with de novo DSA [31 (35%)] showed a trend for inferior graft function [mean creatinine change (mg/dL/year) after the first year: 0.15 DSA (+) vs. 0.02 DSA (-) (P = 0.10)] and a higher rate of AR episodes, especially in case of de novo DSA of both class I and II [6 (55%), (P = 0.05)]. Antibody-mediated rejection (AMR) appeared in five patients and was significantly correlated with de novo DSA (P = 0.05). Monitoring for de novo DSA after LDRT may help to identify patients at risk of declining renal function. Especially patients with simultaneous presence of de novo DSA class I and class II are at a high risk to suffer AR episodes.

Flow cytometric assay for the simultaneous determination of residual white blood cells, red blood cells, and platelets in fresh-frozen plasma: validation and two years' experience.

BACKGROUND: A fully automated single-tube assay with tubes (BD TruCOUNT, BD Biosciences) for absolute counting of residual cells in freshly prepared plasma by flow cytometry was developed (BD Plasma Count). STUDY DESIGN AND METHODS: The nucleic acid dye thiazole orange stains white blood cells (WBCs). The monoclonal antibodies anti-CD41a-peridinin chlorophyll protein-Cy5.5 and anti-glycophorin A-fluorescein isothiocyanate label platelets (PLTs) and red blood cells (RBCs), respectively. No fixation, permeabilization, or washing steps were required. Validation was done according to guidelines of the International Conference on Harmonization and the National Committee for Clinical Laboratory Standards. Cell-free plasma was spiked with each cell type for accuracy, reproducibility, and linearity measurements. RESULTS: Results showed no carryover or drift under automated sample acquisition conditions. Nonspecific background was fewer than 0.3 cells per microL for residual WBCs (rWBCs), fewer than 2.7 cells per microL for rRBCs, and fewer than 85 cells per microL for rPLTs. Determinations of rWBC and rPLT counts were linear with a coefficient of variation of less than 12 percent for the imprecision. Owing to cross-linking of the anti-glycophorin A antibody, linearity and precision for rRBCs diverged up to 21 percent at a count of 6000 rRBCs per microL. In a 2-year period, five operators investigated 2666 quality control (QC) samples of fresh-frozen plasma on 108 working days. Maximum cell numbers found were 196 for rWBCs, 3960 for rRBCs, and 28,952 for rPLTs per microL. In 31 cases (1.2%) rWBCs were out of specification. No outlier was observed for rRBCs and rPLTs. Residual RBC cell numbers determined were always within the acceptable concentration range of the assay. CONCLUSION: These data demonstrate that the single-tube test is suitable for routine QC assessment of the cellular contaminants of therapeutic plasma according to the European recommendations.

Bacterial contamination of platelet concentrates: results of a prospective multicenter study comparing pooled whole blood-derived platelets and apheresis platelets.

BACKGROUND: The GERMS Group initiated a prospective multicenter study to assess prevalence and nature of bacterial contamination of pooled buffy-coat platelet concentrates (PPCs) and apheresis platelet concentrates (APCs) by routine screening with a bacterial culture system. STUDY DESIGN AND METHODS: In nine centers overall, 52,243 platelet (PLT) concentrates (15,198 APCs, 37,045 PPCs) were analyzed by aerobic and anaerobic cultures (BacT/ALERT, bioMérieux). RESULTS: In 135 PLT concentrates (PCs; 0.26%), bacteria could be identified in the first culture (0.4% for APCs vs. 0.2% for PPCs; p < 0.001). In 37 (0.07%) of these PC units, the same bacteria strain could be identified in a second culture from the sample bag and/or the PC unit. The rate of confirmed-positive units did not differ significantly between APC (0.09%; 1/1169) and PPC units (0.06%; 1/1544). Bacteria from skin flora (Propionibacterium acnes, Staphylococcus epidermidis) were the most prevalent contaminants. Median times to first positive culture from start of incubation were 0.7 and 3.7 days in aerobic and anaerobic cultures for confirmed-positive units. With a "negative-to-date" issue strategy, most PC units (55%) had already been issued by time of the first positive culture. CONCLUSION: The rate of confirmed bacterial contamination of PC units was low. Nevertheless, clinicians must be aware of this risk. The risk of bacterial contamination does not warrant universal preference of APCs. It must be questioned whether routine bacterial screening by a culture method can sufficiently prevent contaminated products from being transfused due to the delay until a positive signal in the culture system and due to false-negative results.

In-frame triplet deletions in RHD alter the D antigen phenotype.

BACKGROUND: The deletion of three adjacent nucleotides in an exon may cause the lack of a single amino acid, while the protein sequence remains otherwise unchanged. Only one such in-frame deletion is known in the two RH genes, represented by the RHCE allele ceBP expressing a "very weak e antigen." STUDY DESIGN AND METHODS: Blood donor samples were recognized because of discrepant results of D phenotyping. Six samples came from Switzerland and one from Northern Germany. The molecular structures were determined by genomic DNA nucleotide sequencing of RHD. RESULTS: Two different variant D antigens were explained by RHD alleles harboring one in-frame triplet deletion each. Both single-amino-acid deletions led to partial D phenotypes with weak D antigen expression. Because of their D category V-like phenotypes, the RHD(Arg229del) allele was dubbed DVL-1 and the RHD(Lys235del) allele DVL-2. These in-frame triplet deletions are located in GAGAA or GAAGA repeats of the RHD exon 5. CONCLUSION: Partial D may be caused by a single-amino-acid deletion in RhD. The altered RhD protein segments in DVL types are adjacent to the extracellular loop 4, which constitutes one of the most immunogenic parts of the D antigen. These RhD protein segments are also altered in all DV, which may explain the similarity in phenotype. At the nucleotide level, the triplet deletions may have resulted from replication slippage. A total of nine amino acid positions in an Rhesus protein may be affected by this mechanism.

Weak D type 1.1 exemplifies another complexity in weak D genotyping.

BACKGROUND: Weak D expression is caused by a large number of RHD alleles. Increasingly recommendations for D+ or D- transfusions are based on polymerase chain reaction (PCR) identification of certain RHD alleles. Possible sources of error are rare D variants that are inadvertently carrying known polymorphisms of frequent weak D types. STUDY DESIGN AND METHODS: Weak D donors were checked by direct column agglutination. In donors with unusually weak expression of D, the molecular weak D type was determined by weak D PCR and nucleotide sequencing. The serologic profile of a weak D type 1 variant was determined by agglutination serology and flow cytometry. RESULTS: Several donors in whom direct agglutination barely revealed any D expression were shown to carry the new RHD(L18V,V270G) allele dubbed weak D type 1.1. Initially, such donors had been mistyped as weak D type 1 by PCR. In a systematic study, weak D type 1.1 was shown to be present in 7 of 23 donors with very weak D expression who all lived in a restricted area of Northern Germany. Although weak D type 1.1 was typed D- or barely D+ by direct agglutination, it was easily detected by antiglobulin technique and was shown to carry about 600 antigens D per red blood cell. CONCLUSION: The observation of weak D type 1.1 with its distinct phenotype pinpointed to two general problems of current RHD genotyping strategies: Mistyping of alleles with additional mutations and striking geographic variation of the allele distributions.