A novel automated microchip flow-chamber system to quantitatively evaluate thrombus formation and antithrombotic agents under blood flow conditions

SummaryFactors determining thrombus formation on a foreign surface were studied with the use of plastic flow chambers introduced into extracorporeal shunts. Silicone rubber shunts, joining the carotid artery and jugular vein, were implanted in dogs and remained patent for several weeks. The flow chamber geometry consisted of a 4.8 mm diameter straight tube having a 3.2 × 3.2 mm circumferential cavity in the wall. Chambers were introduced sequentially into the shunts for exposure times of 10 to 30 minutes and regulated blood flow rates of 100 to 400 ml/min. The dry weight of thrombus accumulated in the chamber (5 to 50 mg) was found to increase with exposure time up to 20 minutes and to decrease with increasing flow rate. Various components of the process of thrombus formation were altered by the administration of acetylsalicylic acid, heparin and lysozyme, used alone and in pairs. Heparin was found to be the most effective antithrombotic agent, dry weights of accumulated thrombus being on the order of 50 percent lower when compared to control values. The efficacy of heparin was found to be unaffected by the presence of aspirin and lysozyme, which themselves were not effective antithrombotic agents under the conditions of these experiments. The technique described here may provide a useful animal model for studying the influence of blood flow and different biomaterials on thrombus formation.

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Understanding the Mechanism of Platelet Thrombus Formation under Blood Flow Conditions and the Effect of New Antiplatelet Agents

Current Vascular Pharmacology ◽

10.2174/1570161043476456 ◽

2004 ◽

Vol 2 (1) ◽

pp. 23-32 ◽

Cited By ~ 17

Author(s):

Shinya Goto

Keyword(s):

Blood Flow ◽

Thrombus Formation ◽

Antiplatelet Agents ◽

Flow Conditions ◽

Platelet Thrombus

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Platelets, circulating tissue factor, and fibrin colocalize in ex vivo thrombi: real-time fluorescence images of thrombus formation and propagation under defined flow conditions

Blood ◽

10.1182/blood-2002-03-0902 ◽

2002 ◽

Vol 100 (8) ◽

pp. 2787-2792 ◽

Cited By ~ 95

Author(s):

Viji Balasubramanian ◽

Eric Grabowski ◽

Alessandra Bini ◽

Yale Nemerson

Keyword(s):

Real Time ◽

Tissue Factor ◽

Ex Vivo ◽

Thrombus Formation ◽

High Sensitivity ◽

Flow Chamber ◽

Flow Conditions ◽

Coated Glass ◽

Relative Contribution ◽

Fluorescent Markers

Although it is generally accepted that the initial event in coagulation and intravascular thrombus formation is the exposure of tissue factor (TF) to blood, there is still little agreement about the mechanisms of thrombus propagation and the identities of the molecular species participating in this process. In this study, we characterized the thrombotic process in real-time and under defined flow conditions to determine the relative contribution and spatial distribution of 3 components of the thrombi: circulating or blood-borne TF (cTF), fibrin, and platelets. For this purpose, we used high-sensitivity, multicolor immunofluorescence microscopy coupled with a laminar flow chamber. Freshly drawn blood, labeled with mepacrine (marker for platelets and white cells), anti-hTF1Alexa.568 (marker for tissue factor), and anti-T2G1Cy5 (marker for fibrin) was perfused over collagen-coated glass slides at wall shear rates of 100 and 650 s−1. A motorized filter cube selector facilitated imaging every 5 seconds at 1 of 3 different wavelengths, corresponding to optimal wavelengths for the 3 markers above. Real-time video recordings obtained during each of 10 discrete experiments show rapid deposition of platelets and fibrin onto collagen-coated glass. Overlay images of fluorescent markers corresponding to platelets, fibrin, and cTF clearly demonstrate colocalization of these 3 components in growing thrombi. These data further support our earlier observations that, in addition to TF present in the vessel wall, there is a pool of TF in circulating blood that contributes to the propagation of thrombosis at a site of vascular injury.

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A modified microchip-based flow chamber system for evaluating thrombogenicity in patients with thrombocytopenia

Thrombosis Journal ◽

10.1186/s12959-020-00244-9 ◽

2020 ◽

Vol 18 (1) ◽

Author(s):

Bengo Atari ◽

Takashi Ito ◽

Tomoka Nagasato ◽

Tomoko Ohnishi ◽

Kazuya Hosokawa ◽

...

Keyword(s):

Major Bleeding ◽

Platelet Transfusion ◽

Thrombus Formation ◽

Flow Chamber ◽

University Hospital ◽

Minor Bleeding ◽

Chamber System ◽

Occlusion Time ◽

Function Tests ◽

Thrombogenic Potential

Abstract Background In the intensive care unit (ICU), patients with thrombocytopenia are at high risk for bleeding and should be assessed for their thrombogenic potential. However, the analytical conditions of conventional hemostatic tests are unsuitable for the evaluation of low-platelet samples. Here we aimed to establish suitable analytical conditions with the Total Thrombus-formation Analysis System (T-TAS) for quantitative assessment of thrombogenic potential in patients with thrombocytopenia and to investigate how T-TAS values relate to bleeding symptoms and the effects of platelet transfusion. Methods Modified chips with a different chamber depth were developed for the analysis of low-platelet samples in the T-TAS. We included 10 adult patients admitted to the ICU of Kagoshima University Hospital who required platelet transfusion. Patients were divided into major and minor bleeding groups according to their bleeding scale before platelet transfusion. The thrombogenic potential of these patients before and after platelet transfusion was assessed with hemostatic function tests, including rotational thromboelastometry, multiplate aggregometry, and the T-TAS. Results Analysis of low-platelet samples revealed that, compared with the conventional chip (80-μm-deep chamber), the modified chip (50-μm-deep chamber) achieved higher sensitivity in detecting elevation of flow pressure caused by growth of an occlusive thrombus in the T-TAS analytical chamber. All patients in the minor bleeding group retained thrombogenic potential that occluded the modified chip (occlusion time 16.3 ± 3.3 min), whereas most patients in the major bleeding group were unable to occlude the modified chip during the 30-min measurement (P < 0.01). The recovery of thrombogenic potential after platelet transfusion was confirmed with the T-TAS and correlated with the function, rather than the count, of transfused platelets. Among all evaluated parameters in hemostatic function tests, only the T-TAS showed significant differences in occlusion time and area under the curve both between the minor and major bleeding groups and between pre- and post-platelet transfusion. Conclusions We developed a modified microchip-based flow chamber system that reflects the hemostatic function of patients with thrombocytopenia.

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Tissue factor-induced coagulation triggers platelet thrombus formation as efficiently as fibrillar collagen at arterial blood flow conditions.

Arteriosclerosis and Thrombosis A Journal of Vascular Biology ◽

10.1161/01.atv.14.12.1976 ◽

1994 ◽

Vol 14 (12) ◽

pp. 1976-1983 ◽

Cited By ~ 29

Author(s):

U Orvim ◽

H E Roald ◽

R W Stephens ◽

N Roos ◽

K S Sakariassen

Keyword(s):

Blood Flow ◽

Tissue Factor ◽

Thrombus Formation ◽

Arterial Blood Flow ◽

Fibrillar Collagen ◽

Flow Conditions ◽

Arterial Blood ◽

Platelet Thrombus

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Distinct Localization of Coagulation Factor VIII, Von Willebrand Factor and Factor VIIIa-Mimetic Bispecific Antibody Contributing to Thrombus Formation Under Whole Blood Flow Conditions

Blood ◽

10.1182/blood.v124.21.1483.1483 ◽

2014 ◽

Vol 124 (21) ◽

pp. 1483-1483

Author(s):

Yasuaki Shida ◽

Keiji Nogami ◽

Hiroaki Minami ◽

Hiroaki Yaoi ◽

Tomoko Matsumoto ◽

...

Keyword(s):

Shear Flow ◽

Research Funding ◽

Hemophilia A ◽

Thrombus Formation ◽

Flow Chamber ◽

High Shear ◽

Flow Conditions ◽

Von Willebrand ◽

Low Shear

Abstract Background Factor VIII (FVIII) is an essential factor for coagulation system in the intrinsic pathway. Due to the short survival of FVIII in the plasma circulation, it requires von Willebrand factor (VWF) as a carrier protein to maintain the optimal level for hemostasis. VWF also plays an important role in primary hemostasis by bridging platelets to exposed subendothelial collagens, especially under high shear flow environment. Since VWF carries FVIII, it is conceivable that VWF takes FVIII to the sites of vascular injury. However, the role of FVIII at the local sites under flow conditions is not fully understood despite of the fact that increased level of FVIII is associated with the risk of venous thrombosis and the deficiency of FVIII is the pathology of the bleeding disorder, hemophilia A. The treatment of hemophilia A largely depends on the infusion of FVIII concentrates, which is often complicated by the development of the inhibitor. Recently, bispecific antibody（ACE910）that mimics the role of FVIIIa by recognizing FIXa and FX has been developed and is currently under clinical trial. This antibody theoretically works regardless of the presence of devastating inhibitors against FVIII. Furthermore, it could also improve the clinical outcome of the other bleeding disorders, such as von Willebrand disease (VWD). Aim To analyze the role of FVIII and VWF, and impact of ACE910 at the sites of vascular injury under various shear conditions, we have developed the flow-mediated thrombosis model using flow chamber system. Method Whole blood obtained from healthy donors, hemophilia A and VWD patients were perfused into the collagen coated flow chamber under high (2,500s-1) or low shear (50s-1) flow conditions with/without FVIII concentrate, FVIII/VWF concentrate and ACE910. Formed thrombus was fixed and immunostaining was performed with phalloidin (Platelet), anti-FVIII antibody (FVIII) and anti-thrombin antibody (Thrombin). For the detection of ACE910, anti-human IgG or anti-ACE antibody (rAQ8 or rAJ540) were used. Size of thrombi and distribution of platelet, FVIII, thrombin and ACE910 were analyzed. Result 1) Under high shear flow, thrombus formation of VWD blood was significantly impaired while blood from Hemophilia A demonstrated nearly normal thrombus formation. Addition of FVIII/VWF but not FVIII concentrate to the blood of these patients rescued the impaired thrombus formation. ACE910 enhanced the thrombus formation of blood from both VWD and hemophilia A. Under low shear flow, blood from both hemophilia A and VWD demonstrated decreased thrombus formation. FVIII, FVIII/VWF concentrates and ACE910 improved the size of thrombus. 2) Localization of FVIII was evaluated with thrombin as a marker for the activation of coagulation. Platelets and thrombin demonstrated complete co-localization and intensity of thrombin staining was associated with thrombus size. VWF localized mainly outer layer of thrombus and FVIII localized in and around thrombus. At high shear condition, FVIII and VWF mostly existed with platelets. By contrast, FVIII and VWF demonstrated less co-localization with platelets under low shear condition. ACE910 demonstrated similar tendency to FVIII localization although ACE910 did not appear around thrombus. Conclusion We have developed the flow chamber system to evaluate the extent of thrombogenesis under various shear environment. VWF showed dominant role under high shear conditions while FVIII plays a key role under low shear conditions. FVIII, VWF and ACE910 demonstrated distinct localization. Interestingly, the distribution of FVIII was broader than VWF and platelet. FVIII localized to platelets presumably prior to its activation and contributed for the subsequent thrombin generation at local sites. Finally, ACE910 demonstrated consistent enhancement of thrombus formation of blood from both hemophilia A and VWD and, therefore, is prompted for the treatment of these bleeding disorders. Disclosures Shida: Chugai Pharmaceutical Co., Ltd.: Research Funding. Nogami:Chugai Pharmaceutical Co., Ltd.: Membership on an entity's Board of Directors or advisory committees, Research Funding. Minami:Chugai Pharmaceutical Co., Ltd.: Research Funding. Yaoi:Chugai Pharmaceutical Co., Ltd.: Research Funding. Matsumoto:Chugai Pharmaceutical Co., Ltd.: Research Funding. Kitazawa:Chugai Pharmaceutical Co., Ltd.: Employment, Equity Ownership, Patents & Royalties. Hattori:Chugai Pharmaceutical Co., Ltd.: Employment, Equity Ownership, Patents & Royalties. Shima:Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Functional imaging of shear-dependent activity of ADAMTS13 in regulating mural thrombus growth under whole blood flow conditions

Blood ◽

10.1182/blood-2007-09-110700 ◽

2008 ◽

Vol 111 (3) ◽

pp. 1295-1298 ◽

Cited By ~ 48

Author(s):

Yasuaki Shida ◽

Kenji Nishio ◽

Mitsuhiko Sugimoto ◽

Tomohiro Mizuno ◽

Masaaki Hamada ◽

...

Keyword(s):

Blood Flow ◽

Shear Rate ◽

Whole Blood ◽

Thrombus Formation ◽

Arterial Occlusion ◽

Generation Process ◽

Flow Conditions ◽

Normal Hemostasis

Abstract The metalloprotease ADAMTS13 is assumed to regulate the functional levels of von Willebrand factor (VWF) appropriate for normal hemostasis in vivo by reducing VWF multimer size, which directly represents the thrombogenic activity of this factor. Using an in vitro perfusion chamber system, we studied the mechanisms of ADAMTS13 action during platelet thrombus formation on a collagen surface under whole blood flow conditions. Inhibition studies with a function-blocking anti-ADAMTS13 antibody, combined with immunostaining of thrombi with an anti-VWF monoclonal antibody that specifically reflects the VWF-cleaving activity of ADAMTS13, provided visual evidence for a shear rate–dependent action of ADAMTS13 that limits thrombus growth directly at the site of the ongoing thrombus generation process. Our results identify an exquisitely specific regulatory mechanism that prevents arterial occlusion under high shear rate conditions during mural thrombogenesis.

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A microchip flow-chamber system for quantitative assessment of the platelet thrombus formation process

Microvascular Research ◽

10.1016/j.mvr.2011.11.007 ◽

2012 ◽

Vol 83 (2) ◽

pp. 154-161 ◽

Cited By ~ 59

Author(s):

Kazuya Hosokawa ◽

Tomoko Ohnishi ◽

Masashi Fukasawa ◽

Taro Kondo ◽

Hisayo Sameshima ◽

...

Keyword(s):

Formation Process ◽

Quantitative Assessment ◽

Thrombus Formation ◽

Flow Chamber ◽

Chamber System ◽

Platelet Thrombus

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Combined Dabigatran and Antiplatelet Agents Assessed by the Novel Microchip-Based Flow Chamber System

Blood ◽

10.1182/blood.v120.21.1167.1167 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1167-1167

Author(s):

Kenichi Tanaka ◽

Kazuya Hosokawa ◽

Tomoko Ohnishi ◽

Hisayo Sameshima ◽

Takehiko Koide ◽

...

Keyword(s):

Whole Blood ◽

Platelet Rich Plasma ◽

Thrombus Formation ◽

Antiplatelet Agents ◽

Lag Time ◽

Flow Chamber ◽

Chamber System ◽

Shear Rates ◽

Antithrombotic Effects ◽

Flow Pressure

Abstract Abstract 1167 Evaluation of the overall antithrombotic activity of dabigatran in combination with antiplatelet agents is difficult because plasma-based clotting for dabigatran, and platelet aggregometry in anticoagulated blood are two separate tests which do not reflect physiological interactions between soluble factors and platelets. The use of a flow chamber could be more suitable in evaluating a flow-dependent platelet activation and coagulation responses. The aim of the current study was to comparatively evaluate antithrombotic effects of dabigatran in combination with dual antiplatelet therapy (aspirin plus P2Y12 blockade) using the microchip-based flow chamber (T-TAS, Fujimori Kogyo, Japan)(1), and thrombin generation (TG) assay (Thrombinoscope, Maastricht, the Netherlands)(2). After the local ethics committee approval, blood samples were obtained from consented 5 healthy volunteers in the tubes containing 3.2% sodium citrate. Whole blood samples were mixed with dabigatran (250, 500, 1000 nM), aspirin (100 nM) plus ARC-66096 (P2Y12 inhibitor, 1000 nM) at 25¡C for 10 min. Corn trypsin inhibitor (50 μg/ml) was used to prevent contact activation. The whole blood sample was perfused in the capillary pre-coated with collagen and thromboplastin at the shear rate of 240 or 600 s−1. The process of thrombus formation was monitored by flow pressure increases inside the capillary; (i) lag time before it reaches 10 kPa (T10), (ii) occlusion time (OT) is the lag time before it reaches 80 kPa as thrombus completely occludes the capillary, and (iii) AUC30 is an area under the flow pressure curve (under 80 kPa) after 30 min of perfusion. For TG assay, platelet-rich plasma (platelet count 150 × 103/μl) was prepared from citrated whole blood. TG was triggered by adding 20 μl of CaCl2-fluorogenic substrate buffer to 80 μl of the sample mixed with tissue factor (1 pM) in each well. The lag time (min), and peak thrombin concentration (nM) were evaluated. In the flow chamber, dabigatran inhibited white thrombus formation in a concentration dependent manner at shear rates of 240 and 600 s−1(Fig. 1). At 500 nM of dabigatran, OT was prolonged by ∼2-fold from the (non-treated) control at both shear rates. The combination of aspirin and AR-C66096 only weakly suppressed thrombus formation, but it enhanced the antithrombotic efficacy of dabigatran at both shear rates (Fig. 1). In TG measurements using platelet-rich plasma, dabigatran at 500 nM prolonged the by 3.17-fold, and reduced the peak by 57.6% compared to the untreated control (Table 1). Aspirin and AR-C66096 weakly prolonged the lag time without affecting the peak height. There were relatively small changes in these parameters when antiplatelet agents were combined with dabigatran (Table 1). Our results suggest that combined antithrombotic effects of dabigatran, aspirin, and P2Y12inhibition can be demonstrated in the whole blood using the flow chamber system compared without additional plasma preparation required for TG assay. The re-calcified whole blood was perfused at the shear rate of 240 s−1 or 600 s−1. Asp/AR-C=aspirin and AR-C66096 Table 1. Lag time (min) Peak (nM) Native Asp/AR-C Native Asp/AR-C Control 6.8 ± 0.8 9.4 ± 3.2 92.1 ± 23.7 91.2 ± 29.5 Dabi 250 nM 18.6 ± 5.4 21.1 ± 4.5 69.3 ± 20.6 52.2 ± 13.6 Dabi 500 nM 21.6 ± 5.3 26.2 ± 10.2 53.0 ± 5.8 47.8 ± 9.1 Dabi 1000 nM 30.2 ± 5.6 35.1 ± 6.3 23.0 ± 6.9 22.0 ± 8.4 Dabi=dabigatran, Native=no antiplatelet agents, Asp/AR-C=aspirin and AR-C66096 Disclosures: Hosokawa: Fujimori Kogyo: Employment. Ohnishi:Fujimori Kogyo: Employment. Sameshima:Fujimori Kogyo: Employment.

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