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Platelets Nov 2018While there are many bench and bedside tests to assess platelet reactivity, ex vivo light transmission aggregometry (LTA) remains the gold standard. LTA, however, is... (Review)
Review
While there are many bench and bedside tests to assess platelet reactivity, ex vivo light transmission aggregometry (LTA) remains the gold standard. LTA, however, is expensive, time-consuming and requires dedicated equipment and staff, making it impractical in many situations. In addition, there is significant variability between data generated at different testing sites meaning that tests often need to be repeated if a patient is transferred to the care of a different hospital. As such, there is clearly an unmet need for standardization of platelet testing. Using the principles of LTA, aggregometry can be conducted in 96-well plates with readings being made in a standard plate reader. This approach allows for the assessment of multiple concentrations of agonists, since the volume of platelets required for each test is significantly lower than for LTA. Furthermore, the lyophilization of a set panel of agonists to a 96-well plate to produce a stable assay substrate allows the production of portable, standardized plates that can be used to generate reproducible tests at multiple sites. In this review, we will discuss the methods and uses of 96-well plate aggregometry for both research and the clinic.
Topics: Animals; Humans; Platelet Aggregation; Platelet Function Tests; Research
PubMed: 29543546
DOI: 10.1080/09537104.2018.1445838 -
Seminars in Cell & Developmental Biology Apr 2021The ability to study the behavior of cells, proteins, and cell-cell or cell-protein interactions under dynamic forces such as shear stress under fluid flow, provides a... (Review)
Review
The ability to study the behavior of cells, proteins, and cell-cell or cell-protein interactions under dynamic forces such as shear stress under fluid flow, provides a more accurate understanding of the physiopathology of hemostasis. This review touches upon the traditional methods for studying blood coagulation and platelet aggregation and provides an overview on cellular and protein response to shear stress. We also elaborate on the biological aspects of how cells recognize mechanical forces and convert them into biochemical signals that can drive various signaling pathways. We give a detailed description of the various types of microfluidic devices that are employed to study the complex processes of platelet aggregation and blood coagulation under flow conditions as well as to investigate endothelial shear-response. We also highlight works mimicking artificial vessels as platforms to study the mechanisms of coagulation, and finish our review by describing anticipated clinical uses of microfluidics devices and their standardization.
Topics: Blood Coagulation; Hemostasis; Humans; Lab-On-A-Chip Devices; Platelet Aggregation; Signal Transduction; Thrombosis
PubMed: 32563678
DOI: 10.1016/j.semcdb.2020.06.002 -
Arteriosclerosis, Thrombosis, and... May 2019
Topics: Platelet Aggregation; Platelet Membrane Glycoproteins
PubMed: 31017825
DOI: 10.1161/ATVBAHA.119.312621 -
Blood Advances Feb 2019
Topics: Blood Platelets; Humans; Platelet Aggregation; Protein Serine-Threonine Kinases; Pyruvate Dehydrogenase Acetyl-Transferring Kinase; Thrombosis
PubMed: 30792189
DOI: 10.1182/bloodadvances.2018025155 -
Journal of Thrombosis and Haemostasis :... Jul 2023The circulating form of human endoglin (sEng) is a cleavage product of membrane-bound endoglin present on endothelial cells. Because sEng encompasses an RGD motif...
BACKGROUND
The circulating form of human endoglin (sEng) is a cleavage product of membrane-bound endoglin present on endothelial cells. Because sEng encompasses an RGD motif involved in integrin binding, we hypothesized that sEng would be able to bind integrin αIIbβ3, thereby compromising platelet binding to fibrinogen and thrombus stability.
METHODS
In vitro human platelet aggregation, thrombus retraction, and secretion-competition assays were performed in the presence of sEng. Surface plasmon resonance (SPR) binding and computational (docking) analyses were carried out to evaluate protein-protein interactions. A transgenic mouse overexpressing human sEng (hsEng) was used to measure bleeding/rebleeding, prothrombin time (PT), blood stream, and embolus formation after FeCl-induced injury of the carotid artery.
RESULTS
Under flow conditions, supplementation of human whole blood with sEng led to a smaller thrombus size. sEng inhibited platelet aggregation and thrombus retraction, interfering with fibrinogen binding, but did not affect platelet activation. SPR binding studies demonstrated that the specific interaction between αIIbβ3 and sEng and molecular modeling showed a good fitting between αIIbβ3 and sEng structures involving the endoglin RGD motif, suggesting the possible formation of a highly stable αIIbβ3/sEng. hsEng mice showed increased bleeding time and number of rebleedings compared to wild-type mice. No differences in PT were denoted between genotypes. After FeCl injury, the number of released emboli in hsEng mice was higher and the occlusion was slower compared to controls.
CONCLUSIONS
Our results demonstrate that sEng interferes with thrombus formation and stabilization, likely via its binding to platelet αIIbβ3, suggesting its involvement in primary hemostasis control.
Topics: Humans; Animals; Mice; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Endoglin; Endothelial Cells; Blood Platelets; Thrombosis; Fibrinogen
PubMed: 36990159
DOI: 10.1016/j.jtha.2023.03.023 -
Journal of Experimental & Clinical... Oct 2023Tumor cell-induced platelet aggregation (TCIPA) is not only a recognized mechanism for paraneoplastic thrombocytosis but also a potential breakthrough alternative for a...
BACKGROUND
Tumor cell-induced platelet aggregation (TCIPA) is not only a recognized mechanism for paraneoplastic thrombocytosis but also a potential breakthrough alternative for a low response to immune checkpoint inhibitors (ICIs) in hematogenous metastasis of malignant melanoma (MM). However, there is no TCIPA-specific model for further investigation of the relationship among TCIPA, the tumor immune microenvironment (TIME), and metastasis.
METHODS
We developed a TCIPA metastatic melanoma model with advanced hematogenous metastasis and enhanced TCIPA characteristics. We also investigated the pathway for TCIPA in the TIME.
RESULTS
We found that TCIPA triggers the recruitment of tumor-associated macrophages (TAMs) to lung metastases by secreting B16 cell-educated platelet-derived chemokines such as CCL2, SDF-1, and IL-1β. Larger quantities of TAMs in the TCIPA model were polarized to the M2 type by B16 cell reprocessing, and their surface programmed cell death 1 ligand 1 (PD-L1) expression was upregulated, ultimately assisting B16 cells in escaping host immunity and accelerating MM hematogenous metastasis.
CONCLUSIONS
TCIPA accelerates MM lung metastasis via tumor-educated platelets (TEPs), triggering TAM recruitment, promoting TAM polarization (M2), and remodeling the suppressive TIME in lung metastases.
Topics: Humans; Platelet Aggregation; Melanoma; Lung Neoplasms; Macrophages; Tumor Microenvironment; Melanoma, Cutaneous Malignant
PubMed: 37872588
DOI: 10.1186/s13046-023-02856-1 -
Microbiology Spectrum Dec 2022Streptococcus bovisStreptococcus equinus complex (SBSEC) is a common cause of infective endocarditis (IE). For IE-pathogens, the capacity to activate and aggregate...
Streptococcus bovisStreptococcus equinus complex (SBSEC) is a common cause of infective endocarditis (IE). For IE-pathogens, the capacity to activate and aggregate platelets is believed to be an important virulence mechanism. While the interactions between bacteria and platelets have been described in detail for many Gram-positive pathogens, little research has been carried out with SBSEC in this respect. Twenty-six isolates of the four most common species and subspecies of SBSEC identified in bacteremia were collected, and interactions with platelets were investigated in platelet rich plasma (PRP) from three donors. Aggregation was studied using light-transmission aggregometry and platelet activation using flow cytometry detecting surface upregulation of CD62P. Platelets and serum were treated with different inhibitors to determine mechanisms involved in platelet aggregation and activation. Twenty-two of 26 isolates induced aggregation in at least one donor, and four isolates induced aggregation in all three donors. In PRP from donor 1, isolate SL1 induced a rapid aggregation with a median time of 70 s to reach 50% aggregation. Blockade of the platelet Fc-receptor or enzymatic cleavage of IgG abolished platelet activation and aggregation. The capacity for bacteria-induced platelet aggregation was also shown to be transferable between donors through serum. SBSEC mediates platelet aggregation in an IgG and IgG-Fc-receptor dependent manner. Bacterial activation of platelets through this pathway is common for many bacteria causing IE and could be a potential therapeutic target for the prevention and treatment of this infection. The capacity of bacteria to activate and aggregate platelets is believed to contribute to the pathogenesis of IE. The Streptococcus bovis/Streptococcus equinus complex (SBSEC) contains known IE-pathogens, but there is limited research on the different subspecies ability to interact with platelets and what signaling pathways are involved. This study reports that 22 of 26 tested isolates of different subspecies within SBSEC can induce aggregation, and that aggregation is host dependent. The Fc-IgG-receptor pathway was shown essential for platelet activation and aggregation. To the best of our knowledge, this is the first study that reports on platelet interactions of SBSEC-isolates other than Streptococcus gallolyticus subspecies as well as the first study to report of mechanisms of platelet interaction of SBSEC-isolates. It adds SBSEC to a group of bacteria that activate and aggregate platelets via the platelet Fc-receptor. This could be a potential therapeutic target for prevention of IE.
Topics: Streptococcus bovis; Platelet Activation; Platelet Aggregation; Blood Platelets; Immunoglobulin G
PubMed: 36374116
DOI: 10.1128/spectrum.01861-22 -
Biomedicine & Pharmacotherapy =... Oct 2020Numerous epidemiological and clinical studies demonstrate the beneficial effects of naturally occurring, polyphenol supplementations, on cardiovascular system. The... (Meta-Analysis)
Meta-Analysis Review
Numerous epidemiological and clinical studies demonstrate the beneficial effects of naturally occurring, polyphenol supplementations, on cardiovascular system. The present review emphasizes on the risk factors associated with cardiovascular disorders (involving heart and blood vessels), and overview of preclinical and clinical trials on polyphenols for the treatment of cardiovascular diseases. The review collaborates PUBMED, Google Scholar and Research gate databases, which were explored using keywords and their combinations such as polyphenols, cardiovascular disease, flavonoids, atherosclerosis, cardiovascular risk factors and several others, to create an eclectic manuscript. The potency and efficacy of these polyphenols are mainly depending upon the amount of consumption and bioavailability. Recent data showed that polyphenols also exert beneficial actions on vascular system by blocking platelet aggregation and oxidation of low-density lipoprotein (LDL), ameliorating endothelial dysfunction, reducing blood pressure, improving antioxidant defenses and alleviating inflammatory responses. Several studies evidently support the cardioprotective actions mediated by polyphenols, however, some studies or long-term follow-up of human studies, did not demonstrate decisive outcomes because of variations in dose regimen and lack of appropriate controls. Therefore, more data is required to explore the therapeutic benefits of bioactive compounds as a preventive therapy for CVDs.
Topics: Animals; Biomarkers; Blood Platelets; Cardiovascular Diseases; Cardiovascular System; Disease Management; Disease Susceptibility; Humans; Oxidation-Reduction; Oxidative Stress; Platelet Aggregation; Polyphenols; Risk Factors
PubMed: 34321158
DOI: 10.1016/j.biopha.2020.110714 -
Haematologica Feb 2022
Topics: Blood Platelets; Humans; Platelet Aggregation; Platelet Function Tests
PubMed: 35100793
DOI: 10.3324/haematol.2021.280198 -
Hamostaseologie Feb 2022In patients with normal plasmatic coagulation and bleeding tendency, platelet function defect can be assumed. Congenital platelet function defects are rare. Much more... (Review)
Review
In patients with normal plasmatic coagulation and bleeding tendency, platelet function defect can be assumed. Congenital platelet function defects are rare. Much more commonly they are acquired. The clinical bleeding tendency of platelet function defects is heterogeneous, which makes diagnostic approaches difficult. During the years, a large variety of tests for morphological phenotyping and functional analysis have been developed. The diagnosis of platelet function defects is based on standardized bleeding assessment tools followed by a profound morphological evaluation of the platelets. Platelet function assays like light transmission aggregation, luminoaggregometry, and impedance aggregometry followed by flow cytometry are commonly used to establish the diagnosis in these patients. Nevertheless, despite great efforts, standardization of these tests is poor and in most cases, quality control is lacking. In addition, these tests are still limited to specialized laboratories. This review summarizes the approaches to morphologic phenotyping and platelet testing in patients with suspected platelet dysfunction, beginning with a standardized bleeding score and ending with flow cytometry testing. The diagnosis of a functional defect requires a good collaboration between the laboratory and the clinician.
Topics: Blood Platelet Disorders; Blood Platelets; Humans; Laboratories; Platelet Aggregation; Platelet Function Tests
PubMed: 35196730
DOI: 10.1055/a-1700-7036