Comparison of ultrastructural and nanomechanical signature of platelets from acute myocardial infarction and platelet activation

Morphometric and Nanomechanical Screening of Peripheral Blood Cells with Atomic Force Microscopy for Label-Free Assessment of Alzheimer's Disease, Parkinson's Disease, and Amyotrophic Lateral Sclerosis

Neurodegenerative disorders (NDDs) are complex, multifactorial disorders with significant social and economic impact in today's society. NDDs are predicted to become the second-most common cause of death in the next few decades due to an increase in life expectancy but also to a lack of early diagnosis and mainly symptomatic treatment. Despite recent advances in diagnostic and therapeutic methods, there are yet no reliable biomarkers identifying the complex pathways contributing to these pathologies. The development of new approaches for early diagnosis and new therapies, together with the identification of non-invasive and more cost-effective diagnostic biomarkers, is one of the main trends in NDD biomedical research. Here we summarize data on peripheral biomarkers, biofluids (cerebrospinal fluid and blood plasma), and peripheral blood cells (platelets (PLTs) and red blood cells (RBCs)), reported so far for the three most common NDDs-Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). PLTs and RBCs, beyond their primary physiological functions, are increasingly recognized as valuable sources of biomarkers for NDDs. Special attention is given to the morphological and nanomechanical signatures of PLTs and RBCs as biophysical markers for the three pathologies. Modifications of the surface nanostructure and morphometric and nanomechanical signatures of PLTs and RBCs from patients with AD, PD, and ALS have been revealed by atomic force microscopy (AFM). AFM is currently experiencing rapid and widespread adoption in biomedicine and clinical medicine, in particular for early diagnostics of various medical conditions. AFM is a unique instrument without an analog, allowing the generation of three-dimensional cell images with extremely high spatial resolution at near-atomic scale, which are complemented by insights into the mechanical properties of cells and subcellular structures. Data demonstrate that AFM can distinguish between the three pathologies and the normal, healthy state. The specific PLT and RBC signatures can serve as biomarkers in combination with the currently used diagnostic tools. We highlight the strong correlation of the morphological and nanomechanical signatures between RBCs and PLTs in PD, ALS, and AD.

Platelet morphology, ultrastructure and function changes in acute ischemic stroke patients based on structured illumination microscopy

Acute ischemic stroke (AIS) is the second leading cause of death worldwide. This study aims at assessing platelet morphology, ultrastructure and function changes of platelets in acute ischemic stroke (AIS) patients by the technique of Structured Illumination Microscopy (SIM). This assay collected platelet-rich plasma (PRP) from 11 AIS patients and 12 healthy controls. Each PRP sample was divided into 7 groups:1) rest group; 2) Thrombin-treated 5 min group; 3) Thrombin plus 2MeSAMP-treated 5 min group; 4) Thrombin plus Aspirin-treated 5 min group; 5) Thrombin-treated 1 h group; 6) Thrombin plus 2MeSAMP-treated 1 h group; 7) Thrombin plus Aspirin-treated 1 h group. SIM was applied to observe dense granules and α-granules morphology changes of platelet in AIS patients. FIJI was used to quantify the image data. We finally observed 1448 images of platelets within the 7 groups. In rest group, 7162 platelets were calculated platelet diameter, CD63 dots, average CD63-positive dots area, CD63-positive area per platelet, CD63-positive area Fov, VWF dots, average VWF-positive dots area, VWF-positive area per platelet and VWF-positive area Fov. ELISA was used to detect release of platelet factor 4 (PF4) of α-granules. The results showed that AIS patients had lower number and smaller area of platelet granules. Platelet α-granules of AIS patients concentrated to parenchymal-like fluorescent blocks in Thrombin-treated 1 h group. Antiplatelet drug treatment could reverse the concentration of platelets α-granules, and 2MeSAMP was more powerful than Aspirin in vitro. This study complemented detail information of platelet ultrastructure of AIS patients, provided a new perspective on the pathogenesis of AIS and the mechanism of antiplatelet drugs based on SIM and provided a reference for future related studies. SIM-based analysis of platelet ultrastructure may be useful for detecting antiplatelet drugs and AIS in the future.

Effect of pretreatment with a P2Y12 inhibitor in patients with non-ST-elevation acute coronary syndrome: a systematic review and network meta-analysis

Background

This study aimed to systematically evaluate the effects of different types and doses of pretreatment with P2Y12 inhibitors in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) undergoing percutaneous coronary intervention (PCI).

Methods

Electronic databases were searched for studies comparing pretreatment with different types and doses of P2Y12 inhibitors or comparison between P2Y12 inhibitor pretreatment and nonpretreatment. Electronic databases included the Cochrane Library, PubMed, EMBASE, and Web of Science. Literature was obtained from the establishment of each database until June 2022. The patients included in the study had pretreatment with P2Y12 inhibitors with long-term oral or loading doses, or conventional aspirin treatment (non-pretreatment). The primary endpoint was major adverse cardiac and cerebrovascular events (MACCEs) during follow-up within 30 days after PCI, which included determining the composite endpoints of cardiac death, myocardial infarction, ischemia-driven revascularization, and stroke. The safety endpoint was a major bleeding event.

Results

A total of 119,014 patients from 21 studies were enrolled, including 13 RCTs and eight observational studies. A total of six types of interventions were included-nonpretreatment (placebo), clopidogrel pretreatment, ticagrelor pretreatment, prasugrel pretreatment, double loading pretreatment (double loading dose of clopidogrel, ticagrelor, prasugrel) and P2Y12 inhibitors pretreatment (the included studies did not distinguish the types of P2Y12 inhibitors, including clopidogrel, ticagrelor, and prasugrel). The network meta-analysis results showed that compared to patients without pretreatment, patients receiving clopidogrel pretreatment (RR = 0.78, 95% CI:0.66, 0.91, P < 0.05) and double-loading pretreatment (RR = 0.62, 95% CI:0.41, 0.95, P < 0.05) had a lower incidence of MACCEs. There was no statistically significant difference in the incidence of major bleeding events among the six pretreatments (P > 0.05).

Conclusions

In patients with NSTE-ACS, pretreatment with P2Y12 inhibitors before percutaneous intervention reduced the incidence of recurrent ischemic events without increasing the risk of major bleeding after PCI compared with nonpretreatment. Clopidogrel or double loading dose P2Y12 inhibitors can be considered for the selection of pretreatment drugs.

Platelets for advanced drug delivery in cancer

INTRODUCTION

Cancer-related drug expenses are rising with the increasing cancer incidence and cost may represent a severe challenge for drug access for patients with cancer. Consequently, strategies for increasing therapeutic efficacy of already available drugs may be essential for the future health-care system.

AREAS COVERED

In this review, we have investigated the potential for the use of platelets as drug-delivery systems. We searched PubMed and Google Scholar to identify relevant papers written in English and published up to January 2023. Papers were included at the authors' discretion to reflect an overview of state of the art.

EXPERT OPINION

It is known that cancer cells interact with platelets to gain functional advantages including immune evasion and metastasis development. This platelet-cancer interaction has been the inspiration for numerous platelet-based drug delivery systems using either drug-loaded or drug-bound platelets, or platelet membrane-containing hybrid vesicles combining platelet membranes with synthetic nanocarriers. Compared to treatment with free drug or synthetic drug vectors, these strategies may improve pharmacokinetics and selective cancer cell targeting. There are multiple studies showing improved therapeutic efficacy using animal models, however, no platelet-based drug delivery systems have been tested in humans, meaning the clinical relevance of this technology remains uncertain.

Platelets’ Nanomechanics and Morphology in Neurodegenerative Pathologies

The imaging and force–distance curve modes of atomic force microscopy (AFM) are explored to compare the morphological and mechanical signatures of platelets from patients diagnosed with classical neurodegenerative diseases (NDDs) and healthy individuals. Our data demonstrate the potential of AFM to distinguish between the three NDDs—Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), and normal healthy platelets. The common features of platelets in the three pathologies are reduced membrane surface roughness, area and height, and enhanced nanomechanics in comparison with healthy cells. These changes might be related to general phenomena associated with reorganization in the platelet membrane morphology and cytoskeleton, a key factor for all platelets’ functions. Importantly, the platelets’ signatures are modified to a different extent in the three pathologies, most significant in ALS, less pronounced in PD and the least in AD platelets, which shows the specificity associated with each pathology. Moreover, different degree of activation, distinct pseudopodia and nanocluster formation characterize ALS, PD and AD platelets. The strongest alterations in the biophysical properties correlate with the highest activation of ALS platelets, which reflect the most significant changes in their nanoarchitecture. The specific platelet signatures that mark each of the studied pathologies can be added as novel biomarkers to the currently used diagnostic tools.

Morphometric and Nanomechanical Features of Platelets from Women with Early Pregnancy Loss Provide New Evidence of the Impact of Inherited Thrombophilia

Pregnancy is associated with hypercoagulation states and increased thrombotic risk, especially in women with thrombophilia. We combine atomic force microscopy (AFM) and flow cytometry to examine the morphology and nanomechanics of platelets derived from women with early pregnancy loss (EPL) and control pregnant (CP) and non-pregnant (CNP) women. Both control groups exhibit similar morphometric parameters (height and surface roughness) and membrane stiffness of platelets. EPL patients’ platelets, on the other hand, are more activated than the control groups, with prominent cytoskeletal rearrangement. In particular, reduced membrane roughness (22.9 ± 6 nm vs. 39.1 ± 8 nm) (p < 0.05) and height (692 ± 128 nm vs. 1090 ± 131 nm) (p < 0.05), strong alteration in the membrane Young modulus, increased production of platelets’ microparticles, and higher expression of procoagulant surface markers, as well as increased occurrence of thrombophilia (FVL, FII20210A, PLA1/A2, MTHFR C677T or 4G/5G PAI-1) polymorphisms were found. We suggest that the carriage of thrombophilic mutations triggers structural and nanomechanical abnormalities in platelets, resulting in their increased activation. The activation state of platelets can be well characterized by AFM, and the morphometric and nanomechanical characteristics might serve as a new criterion for evaluation of the cause of miscarriage and offer the prospect of an innovative approach serving for diagnostic purposes.

Binding and antiplatelet activity of quercetin, rutin, diosmetin, and diosmin flavonoids

Platelets exert an essential role in vascular inflammation and thrombosis. Flavonoids are natural compounds employed for the clinical management of vascular disorders preventing capillary permeability, working as phlebotonics and improving the blood rheology, although their mechanism of action remains partially unknown. The effects of quercetin, rutin, diosmetin and diosmin were investigated in platelet activation utilizing blood from healthy and non-treated volunteers. The arrangement of the different activation states of platelets and GPIIb/IIIa receptor occupation was computed by flow cytometry working with calcium ionophore as pro-aggregant to provoke platelet activation and aggregation. The flavonoids studied demonstrated relevant antiplatelet activity through the blocked of GPIIb/IIIa receptors, the suppression of the platelet activation, as well as the pro-aggregate effect of calcium ionophore. Therefore, whichever of the active ingredients examined could be beneficious in the prevention of cardiovascular disease and this article also contributes to elucidate a new mechanism of action for these drugs.

Investigating the effect of age on platelet ultrastructure using transmission electron microscopy

In the present study, the age- and sex-related differences in platelet ultrastructure were investigated using transmission electron microscopy (TEM). A total of 15 healthy volunteers were grouped according to age, with 5 people in each of the following groups: young group (25-45 years), middle-aged group (46-65 years), and old-aged group (> 65 years). In the TEM micrographs, the internal components, specifically the α-granules, dense granules, and lysosomal granules, of 20 platelets were counted for each group. Two-way analysis of variance of age and sex variance was used to compare the results. The ultrastructure of the platelets in the old-aged group was observed to be quite different from those of the young and middle-aged groups. Specifically, with ageing, the platelet membrane becomes more irregular in shape and non-smooth, and multiple platelet membrane ruptures are observed. Furthermore, the pseudopodia and protuberances become more numerous and slender, and the number of α-granules is significantly reduced. These morphological changes indicate that ageing may affect the function of platelets, which in turn affects the efficacy of platelet concentrates. Thus, the effects of age should be considered when using platelet concentrates prepared from elderly autologous blood.

A single-cell analysis platform for electrochemiluminescent detection of platelets adhesion to endothelial cells based on Au@DL-ZnCQDs nanoprobes

A novel single-cell analysis platform (SCA) was developed for the investigation of platelets adhesion to single human umbilical vein endothelial cell (HUVEC) via using the adhesion molecule (E-selectin) on the damaged HUVEC as the marker site, and integrating electrochemiluminescence (ECL) with the ultrasensitive Au@DL-ZnCQDs nanoprobes. The Au@DL-ZnCQDs nanocomposite, a kind of double layer zinc-coadsorbed carbon quantum dot (ZnCQDs) core-shell nanoprobe, was firstly constructed by using gold nanoparticles (AuNPs) as the core to load with ZnCQDs and then the citrate-modified silver nanoparticles (AgNPs) as the bridge to link AuNPs-ZnCQDs with ZnCQDs to form the core-shell with double layer ZnCQDs (DL-ZnCQDs) nanoprobe, revealed a 10-fold signal amplification. The H₂O₂-induced oxidative damage HUVECs were utilized as the cellular model on which anti-E-selectin functionalized nanoprobes specially recognized E-selectin, the SCA showed that the ECL signals decreased with platelets adhesion to single HUVEC. The proposed SCA could effectively and dynamically monitor the adhesion between single HUVEC and platelets in the absence and presence of collagen activation, moreover, be able to quantitatively detect the number of platelets adhesion to single HUVEC, and show a good analytical performance with linear range from 1 to 15 platelets. In contrast, the HUVEC was down-regulated the expression of adhesion molecules by treating with quercetin inhibitor, and the SCA also exhibited the feasibility for analysis of platelets adhesion to single HUVEC. Therefore, the single-cell analysis platform provided a novel and promising protocol for analysis of the single intercellular adhesion, and it will be beneficial to elucidate the pathogenesis of cardiovascular diseases.