Design of a Microfluidic Bleeding Chip to Evaluate Antithrombotic Agents for Use in COVID-19 Patients

Evaluating thrombosis risk and patient-specific treatment strategy using an atherothrombosis-on-chip model

Platelets play an essential role in thrombotic processes. Recent studies suggest a direct link between increased plasma glucose, lipids, and inflammatory cytokines with platelet activation and aggregation, resulting in an increased risk of atherothrombotic events in cardiovascular patients. Antiplatelet therapies are commonly used for the primary prevention of atherosclerosis. Transitioning from a population-based strategy to patient-specific care requires a better understanding of the risks and advantages of antiplatelet therapy for individuals. This proof-of-concept study evaluates the potential to assess an individual's risk of forming atherothrombosis using a dual-channel microfluidic model emulating multiple atherogenic factors in vitro, including high glucose, high cholesterol, and inflammatory cytokines along with stenosis vessel geometry. The model shows precise sensitivity toward increased plasma glucose, cholesterol, and tumour necrosis factor-alpha (TNF-α)-treated groups in thrombus formation. An in vivo-like dose-dependent increment in platelet aggregation is observed in different treated groups, benefiting the evaluation of thrombosis risk in the individual condition. Moreover, the model could help decide the effective dosing of aspirin in multi-factorial complexities. In the high glucose-treated group, a 50 μM dose of aspirin could significantly reduce platelet aggregation, while a 100 μM dose of aspirin was required to reduce platelet aggregation in the glucose-TNF-α-treated group, which proves the model's potentiality as a tailored tool for customised therapy.

Hemostasis-on-a-chip / incorporating the endothelium in microfluidic models of bleeding

Currently, point-of-care assays for human platelet function and coagulation are used to assess bleeding risks and drug testing, but they lack intact endothelium, a critical component of the human vascular system. Within these assays, the assessment of bleeding risk is typically indicated by the lack of or reduced platelet function and coagulation without true evaluation of hemostasis. Hemostasis is defined as the cessation of bleeding. Additionally, animal models of hemostasis also, by definition, lack human endothelium, which may limit their clinical relevance. This review discusses the current state-of-the-art of hemostasis-on-a-chip, specifically, human cell-based microfluidic models that incorporate endothelial cells, which function as physiologically relevant in vitro models of bleeding. These assays recapitulate the entire process of vascular injury, bleeding, and hemostasis, and provide real-time, direct observation, thereby serving as research-enabling tools that enhance our understanding of hemostasis and also as novel drug discovery platforms.

Hyperviscosity syndromes; hemorheology for physicians and the use of microfluidic devices

PURPOSE OF REVIEW

Hyperviscosity syndromes can lead to significant morbidity and mortality. Existing methods to measure microcirculatory rheology are not readily available and limited in relevance and accuracy at this level. In this review, we review selected hyperviscosity syndromes and the advancement of their knowledge using microfluidic platforms.

RECENT FINDINGS

Viscosity changes drastically at the microvascular level as the physical properties of the cells themselves become the major determinants of resistance to blood flow. Current, outdated viscosity measurements only quantify whole blood or serum. Changes in blood composition, cell number, or the physical properties themselves lead to increased blood viscosity. Given the significant morbidity and mortality from hyperviscosity syndromes, new biophysical tools are needed and being developed to study microvascular biophysical and hemodynamic conditions at this microvascular level to help predict those at risk and guide therapeutic treatment.

SUMMARY

The use of 'lab-on-a-chip' technology continues to rise to relevance with point of care, personalized testing and medicine as customizable microfluidic platforms enable independent control of many in vivo factors and are a powerful tool to study microcirculatory hemorheology.

Microfluidics Technology in SARS-CoV-2 Diagnosis and Beyond: A Systematic Review

With the progression of the COVID-19 pandemic, new technologies are being implemented for more rapid, scalable, and sensitive diagnostics. The implementation of microfluidic techniques and their amalgamation with different detection techniques has led to innovative diagnostics kits to detect SARS-CoV-2 antibodies, antigens, and nucleic acids. In this review, we explore the different microfluidic-based diagnostics kits and how their amalgamation with the various detection techniques has spearheaded their availability throughout the world. Three other online databases, PubMed, ScienceDirect, and Google Scholar, were referred for articles. One thousand one hundred sixty-four articles were determined with the search algorithm of microfluidics followed by diagnostics and SARS-CoV-2. We found that most of the materials used to produce microfluidics devices were the polymer materials such as PDMS, PMMA, and others. Centrifugal force is the most commonly used fluid manipulation technique, followed by electrochemical pumping, capillary action, and isotachophoresis. The implementation of the detection technique varied. In the case of antibody detection, spectrometer-based detection was most common, followed by fluorescence-based as well as colorimetry-based. In contrast, antigen detection implemented electrochemical-based detection followed by fluorescence-based detection, and spectrometer-based detection were most common. Finally, nucleic acid detection exclusively implements fluorescence-based detection with a few colorimetry-based detections. It has been further observed that the sensitivity and specificity of most devices varied with implementing the detection-based technique alongside the fluid manipulation technique. Most microfluidics devices are simple and incorporate the detection-based system within the device. This simplifies the deployment of such devices in a wide range of environments. They can play a significant role in increasing the rate of infection detection and facilitating better health services.

Point of care whole blood microfluidics for detecting and managing thrombotic and bleeding risks

Point-of-care diagnostics of platelet and coagulation function present demanding challenges. Current clinical diagnostics often use centrifuged plasmas or platelets and frozen plasma standards, recombinant protein standards, or even venoms. Almost all commercialized tests of blood do not recreate the in vivo hemodynamics where platelets accumulate to high densities and thrombin is generated from a procoagulant surface. Despite numerous drugs that target platelets, insufficient coagulation, or excess coagulation, POC blood testing is essentially limited to viscoelastic methods that provide a clotting time, clot strength, and clot lysis, while used mostly in trauma centers with specialized capabilities. Microfluidics now allows small volumes of whole blood (<1 mL) to be tested under venous or arterial shear rates with multi-color readouts to follow platelet function, thrombin generation, fibrin production, and clot stability. Injection molded chips containing pre-patterned fibrillar collagen and lipidated tissue factor can be stored dry for 6 months at 4C, thus allowing rapid blood testing on single-use disposable chips. Using only a small imaging microscope and micropump, these microfluidic devices can detect platelet inhibitors, direct oral anticoagulants (DOACs) and their reversal agents. POC microfluidics are ideal for neonatal surgical applications that involve small blood samples, rapid DOAC testing in stroke or bleeding or emergency surgery situations with patients presenting high risk cofactors for either bleeding or thrombosis.

[Applications of separation technology in novel coronavirus research, epidemic prevention and detection]

新型冠状病毒肺炎(COVID-19)疫情的爆发给世界公共卫生安全带来前所未有的挑战。随着新型冠状病毒(SARS-CoV-2)相关研究的不断深入,众多分析检测技术相继被应用,推动了病毒检测、疫苗和创新疗法的研发,从而使疫情早日得到控制。分离技术作为生命科学、医学、药学领域的关键技术,操作简单,分离效率高,选择性强,在新型冠状病毒的分离、检测、诊疗及防疫中起到不可替代的作用。该文以SARS-CoV-2或COVID-19为关键词在ISI Web of Science中进行主题检索,归纳了2020年度新型冠状病毒相关的研究论文,简要介绍主要的研究方向,并对国际顶级学术期刊Nature, Science, Cell的论文发表情况进行了统计。通过检索影响因子较高的期刊,综述了新型冠状病毒研究中主要应用的分离技术,并从亲和色谱和尺寸排阻色谱、液相色谱、磁珠分离、离心、微纳分离以及电泳6个方面进行说明。综述统计了亲和色谱和尺寸排阻色谱纯化的病毒相关蛋白,并介绍了其在新型冠状病毒传播、感染机制以及药物筛选中的应用;介绍了液相色谱对病毒候选药物评估以及复杂基质中单一成分的鉴定;介绍了磁珠分离在细胞分离、核酸提取和免疫学检测中的应用;介绍了离心对病毒颗粒、细胞以及血清的分离;介绍了微纳分离结合其他技术以实现病毒蛋白的高灵敏检测;简要介绍了电泳在聚合酶链式反应(PCR)产物分析中的应用。该文综述了2020年度新型冠状病毒研究和防疫检测中分离技术的应用情况,分析了分离技术在新型冠状病毒检测中发挥的作用,旨在为从事分离研究的科研工作者提供一些参考。