In Vitro Thrombogenicity Testing of Artificial Organs

1998 ◽  
Vol 21 (9) ◽  
pp. 548-552 ◽  
Author(s):  
R. Paul ◽  
O. Marseille ◽  
E. Hintze ◽  
L. Huber ◽  
H. Schima ◽  
...  
Keyword(s):  
Heart Valves ◽  
Early Stage ◽  
Thrombus Formation ◽  
Testing Procedure ◽  
Artificial Organs ◽  
Coagulation System ◽  
In Vitro Testing ◽  
Animal Testing ◽  
Thrombogenic Potential

Thromboembolic complications remain as one of the main problems for blood contacting artificial organs such as heart valves, bloodpumps and others. In vitro evaluation of thrombogenesis in prototypes has not previously been part of the standard evaluation of these devices. In comparison to hemolysis testing, evaluation of the thrombogenic potential is more difficult to perform because of the complexity of the blood coagulation system. We present an in vitro testing procedure that allows the accelerated examination of the thrombogenic potential of different types of blood pumps. Additionally, first results are presented that indicate the reliability of the accelerated clotting test for mechanical heart valves. Results for the centrifugal pump BioMedicus and two microaxial pumps have shown typical thrombus formation at locations such as bearings. The results indicate that the accelerated clotting test is an excellent addition to the much more expensive animal testing of artificial organs or assist devices. In vitro testing permits studies of thrombus formation to be performed at an early stage and at low costs and also facilitates a more precise investigation of device areas known to be potential hot spots for thrombus formation.

A Comparison of the in Vitro and in Vivo Thrombogenic Activity of Factor IX Concentrates Using Stasis (Wessler) and Non-Stasis Rabbit Models

1980 ◽  
Vol 44 (02) ◽  
pp. 081-086 ◽  
Author(s):  
C V Prowse ◽  
A E Williams
Keyword(s):  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Factor Ix ◽  
Coagulation System ◽  
In Vitro Tests ◽  
Clinical Use ◽  
Low Activity

SummaryThe thrombogenic effects of selected factor IX concentrates were evaluated in two rabbit models; the Wessler stasis model and a novel non-stasis model. Concentrates active in either the NAPTT or TGt50 in vitro tests of potential thrombogenicity, or both, caused thrombus formation in the Wessler technique and activation of the coagulation system in the non-stasis model. A concentrate with low activity in both in vitro tests did not have thrombogenic effects in vivo, at the chosen dose. Results in the non-stasis model suggested that the thrombogenic effects of factor IX concentrates may occur by at least two mechanisms. A concentrate prepared from platelet-rich plasma and a pyrogenic concentrate were also tested and found to have no thrombogenic effect in vivo.These studies justify the use of the NAPTT and TGt50 in vitro tests for the screening of factor IX concentrates prior to clinical use.

scholarly journals Heparin is more effective than apixaban in inhibiting in vitro contact activated coagulation

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M.M Engelen ◽  
C Van Laer ◽  
M Jacquemin ◽  
C Vandenbriele ◽  
K Peerlinck ◽  
...  
Keyword(s):  
Thrombin Generation ◽  
Heart Valves ◽  
Thrombus Formation ◽  
Oral Anticoagulants ◽  
Direct Oral Anticoagulants ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Mechanical Heart Valves ◽  
Contact Activation

Abstract Introduction Contact of blood with artificial surfaces such as mechanical support devices, catheters, and mechanical heart valves activates the contact activation (CA) pathway of coagulation. Furthermore, recent animal data and clinical studies suggest a more important contribution of CA in pathological thrombus formation in other cardiovascular diseases. Direct oral anticoagulants (DOACs) are recommended as first-line treatment in most patients who require long-term anticoagulation. However, because DOACs directly inhibit a single downstream coagulation factor (thrombin (fXIIa) or factor Xa (fXa)), it has been suggested that their efficacy could be reduced in the presence of strong activation of the CA pathway as compared to anticoagulants that target multiple, more upstream located coagulation factors. Purpose To compare the efficacy of a DOAC (apixaban) and heparin to suppress thrombin generation in the presence of strong CA pathway activation. Methods Pooled platelet-poor plasma was spiked with either apixaban (dissolved in DMSO and PBS) or unfractionated heparin to achieve therapeutic plasma levels. SynthASil, a commercially available mixture of phospholipids and silica, was used to stimulate the CA pathway in two different dilutions (1–80 and 5–80). Downstream coagulation was accessed by Thrombin Generation Test using Thrombinoscope by Stago and associated Thrombin Calibrator (activity 640 nM). The endogenous thrombin potential (area under the thrombin generation curve; ETP), peak thrombin generation (PTG), time to peak (ttPeak) and time to start (ttStart) were accessed. Results With decreasing concentrations of apixaban, stimulation with the lower dose SynthASil reveals an increasing ETP and PTG. As expected, ttPeak and ttStart decreased. Even supratherapeutic levels of apixaban (i.e. 1120 ng/mL) could not inhibit thrombin from being generated, in striking contrast with UFH where no thrombin was formed. Using a five times higher dose of SynthASil showed comparable ETP for all concentrations of apixaban, allocated around the control value. PTG, however, slightly increased with decreasing concentrations of apixaban. ttPeak and ttStart slightly decreased. Except for the subtherapeutic UFH concentration of 0,114 IU/mL, no thrombin was generated with UFH. Conclusion UFH is more effective in inhibiting downstream thrombin generation compared to apixaban as a response to activation of the CA pathway in vitro. These findings could help explain why direct inhibitors were not able to show non-inferiority in patients with mechanical heart valves and support the development of specific CA pathway inhibitors for patients with conditions that activate the CA pathway. Thrombin generation curves Funding Acknowledgement Type of funding source: None

Argatroban and bivalirudin compared to unfractionated heparin in preventing thrombus formation on mechanical heart valves

2009 ◽  
Vol 101 (06) ◽  
pp. 1163-1169 ◽  
Author(s):  
Torsten Linde ◽  
Thomas Michel ◽  
Kathrin Hamilton ◽  
Ulrich Steinseifer ◽  
Ivar Friedrich ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Unfractionated Heparin ◽  
Continuous Infusion ◽  
Valve Replacement ◽  
Heart Valves ◽  
Thrombus Formation ◽  
Mechanical Heart Valve ◽  
Mechanical Heart Valves ◽  
Valve Prostheses

SummaryPrevention of valve thrombosis in patients after prosthetic mechanical heart valve replacement and heparin-induced thrombocytopenia (HIT) is still an open issue. The aim of the present in-vitro study was to investigate the efficacy of argatroban and bivalirudin in comparison to unfractionated heparin (UFH) in preventing thrombus formation on mechanical heart valves. Blood (230 ml) from healthy young male volunteers was anticoagulated either by UFH, argatroban bolus, argatroban bolus plus continuous infusion, bivalirudin bolus, or bivalirudin bolus plus continuous infusion. Valve prostheses were placed in a newly developed in-vitro thrombosis tester and exposed to the anticoagulated blood samples. To quantify the thrombi, electron microscopy was performed, and each valve was weighed before and after the experiment. Mean thrombus weight in group 1 (UFH) was 117 + 93 mg, in group 2 (argatroban bolus) 722 + 428 mg, in group 3 (bivalirudin bolus) 758 + 323 mg, in group 4 (argatroban bolus plus continuous infusion) 162 + 98 mg, and in group 5 (bivalirudin bolus plus continuous infusion) 166 + 141 mg (p-value <0.001). Electron microscopy showed increased rates of thrombus formation in groups 2 and 3. Argatroban and bivalirudin were as effective as UFH in preventing thrombus formation on valve prostheses in our in-vitro investigation when they were administered continuously. We hypothesise that continuous infusion of argatroban or bivalirudin are optimal treatment options for patients with HIT after mechanical heart valve replacement for adapting oral to parenteral anticoagulation or vice versa.

scholarly journals Decellularized tissue-engineered heart valves calcification: what do animal and clinical studies tell us?

2020 ◽  
Vol 31 (12) ◽  
Author(s):  
Adel F. Badria ◽  
Petros G. Koutsoukos ◽  
Dimosthenis Mavrilas
Keyword(s):  
Heart Valve ◽  
Clinical Studies ◽  
Heart Valves ◽  
Early Stage ◽  
Anticoagulation Therapy ◽  
Complex Nature ◽  
In Silico Studies ◽  
Decellularized Tissue ◽  
Tissue Engineered Heart Valves

AbstractCardiovascular diseases are the first cause of death worldwide. Among different heart malfunctions, heart valve failure due to calcification is still a challenging problem. While drug-dependent treatment for the early stage calcification could slow down its progression, heart valve replacement is inevitable in the late stages. Currently, heart valve replacements involve mainly two types of substitutes: mechanical and biological heart valves. Despite their significant advantages in restoring the cardiac function, both types of valves suffered from serious drawbacks in the long term. On the one hand, the mechanical one showed non-physiological hemodynamics and the need for the chronic anticoagulation therapy. On the other hand, the biological one showed stenosis and/or regurgitation due to calcification. Nowadays, new promising heart valve substitutes have emerged, known as decellularized tissue-engineered heart valves (dTEHV). Decellularized tissues of different types have been widely tested in bioprosthetic and tissue-engineered valves because of their superior biomechanics, biocompatibility, and biomimetic material composition. Such advantages allow successful cell attachment, growth and function leading finally to a living regenerative valvular tissue in vivo. Yet, there are no comprehensive studies that are covering the performance of dTEHV scaffolds in terms of their efficiency for the calcification problem. In this review article, we sought to answer the question of whether decellularized heart valves calcify or not. Also, which factors make them calcify and which ones lower and/or prevent their calcification. In addition, the review discussed the possible mechanisms for dTEHV calcification in comparison to the calcification in the native and bioprosthetic heart valves. For this purpose, we did a retrospective study for all the published work of decellularized heart valves. Only animal and clinical studies were included in this review. Those animal and clinical studies were further subcategorized into 4 categories for each depending on the effect of decellularization on calcification. Due to the complex nature of calcification in heart valves, other in vitro and in silico studies were not included. Finally, we compared the different results and summed up all the solid findings of whether decellularized heart valves calcify or not. Based on our review, the selection of the proper heart valve tissue sources (no immunological provoking residues), decellularization technique (no damaged exposed residues of the decellularized tissues, no remnants of dead cells, no remnants of decellularizing agents) and implantation techniques (avoiding suturing during the surgical implantation) could provide a perfect anticalcification potential even without in vitro cell seeding or additional scaffold treatment.

Inhibition of restenosis by tissue factor pathway inhibitor: in vivo and in vitro evidence for suppressed monocyte chemoattraction and reduced gelatinolytic activity

Blood ◽  
2004 ◽  
Vol 103 (5) ◽  
pp. 1653-1661 ◽  
Author(s):  
Christoph W. Kopp ◽  
Thomas Hölzenbein ◽  
Sabine Steiner ◽  
Rodrig Marculescu ◽  
Helga Bergmeister ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Early Stage ◽  
Thrombus Formation ◽  
Matrix Metalloproteinase 2 ◽  
Monocyte Chemoattractant Protein 1 ◽  
Markers Of Inflammation ◽  
Tissue Factor Pathway

AbstractActivation of inflammatory and procoagulant mechanisms is thought to contribute significantly to the initiation of restenosis, a common complication after balloon angioplasty of obstructed arteries. During this process, expression of tissue factor (TF) represents one of the major physiologic triggers of coagulation that results in thrombus formation and the generation of additional signals leading to vascular smooth muscle cell (VSMC) proliferation and migration. In this study, we have investigated the mechanisms by which inhibition of coagulation at an early stage through overexpression of tissue factor pathway inhibitor (TFPI), an endogenous inhibitor of TF, might reduce restenosis. In a rabbit femoral artery model, percutaneous delivery of TFPI using a recombinant adenoviral vector resulted in a significant reduction of the intimamedia ratio 21 days after injury. Investigating several markers of inflammation and coagulation, we found reduced neointimal expression of monocyte chemoattractant protein-1 (MCP-1), lesional monocyte infiltration, and expression of vascular TF, matrix metalloproteinase-2 (MMP-2), and MMP-9. Moreover, overexpression of TFPI suppressed the autocrine release of platelet-derived growth factor BB (PDGF-BB), MCP-1, and MMP-2 in response to factors VIIa and Xa from VSMCs in vitro and inhibited monocyte TF activity. These results suggest that TFPI exerts its action in vivo through not only thrombotic, but also nonthrombotic mechanisms.

scholarly journals Commentary on ‘‘Toxicity Testing in the 21st Century: A vision and a Strategy’’

2010 ◽  
Vol 29 (1) ◽  
pp. 11-14 ◽  
Author(s):  
Robert F Phalen
Keyword(s):  
21St Century ◽  
Toxicity Testing ◽  
In Vitro Testing ◽  
Chemical Toxicity ◽  
Animal Testing ◽  
In Vitro Techniques ◽  
Human Monitoring ◽  
Animal Tests ◽  
In Silico Methods

Toxicity Testing in the 21st Century: A Vision and a Strategy (NRC, 2007) presents a bold plan for chemical toxicity testing that replaces whole-animal tests with cell-culture, genetic, other in-vitro techniques, computational methods, and human monitoring. Although the proposed vision is eloquently described, and recent advances in in-vitro and in-silico methods are impressive, it is difficult believe that replacing in-vitro testing is either practical or wise. It is not clear that the toxicity-related events that occur in whole animals can be adequately replicated using the proposed methods. Protecting public health is a serious endeavor that should not be limited by denying animal testing. Toxicologists and regulators are encouraged to read the report, carefully consider its implications, and share their thoughts. The vision is for too important to ignore.

Prevention of Intravascular Thrombus Formation on Plastic Catheters with Heparin-Benzalkonium Complex: in Vivo and in Vitro Studies

1979 ◽  
Vol 41 (03) ◽  
pp. 537-543
Author(s):  
Roger W Evans ◽  
Mark W Pasmantier ◽  
Morton Coleman ◽  
Franklin S Wagner ◽  
Robert C Flair
Keyword(s):  
Organic Solvent ◽  
Thrombus Formation ◽  
Anticoagulant Activity ◽  
Model System ◽  
Quaternary Ammonium Compound ◽  
Ammonium Compound ◽  
In Vitro Testing ◽  
In Vivo Animal Model

SummaryA complex of heparin and a quaternary ammonium compound dissolved in an organic solvent was investigated for its potential ability to prevent clotting on the surface of plastic catheters. Despite the complexing of heparin to ammonium, anticoagulant activity remained on in vitro testing. Both the heparin complex and its organic solvent alone partially prevented catheter thrombus formation when tested in an in vivo animal model system. Neither, however, was totally effective in preventing thrombosis.

scholarly journals Custom tissue engineered aneurysm models with varying neck size and height for early stage in vitro testing of flow diverters

2020 ◽  
Vol 31 (3) ◽  
Author(s):  
Camille Villadolid ◽  
Brandon Puccini ◽  
Benjamin Dennis ◽  
Tessa Gunnin ◽  
Conor Hedigan ◽  
...  
Keyword(s):  
Early Stage ◽  
In Vitro Testing ◽  
Neck Size ◽  
Flow Diverters

scholarly journals Platelet interaction with activated endothelium: mechanistic insights from microfluidics

Blood ◽  
2017 ◽  
Vol 130 (26) ◽  
pp. 2819-2828 ◽  
Author(s):  
Daniëlle M. Coenen ◽  
Tom G. Mastenbroek ◽  
Judith M. E. M. Cosemans
Keyword(s):  
Molecular Mechanisms ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
Coagulation System ◽  
Intercellular Adhesion Molecule ◽  
Platelet Glycoprotein ◽  
Intercellular Adhesion Molecule 1 ◽  
Chamber Studies

Abstract Traditionally, in vitro flow chamber experiments and in vivo arterial thrombosis studies have been proved to be of vital importance to elucidate the mechanisms of platelet thrombus formation after vessel wall injury. In recent years, it has become clear that platelets also act as modulators of inflammatory processes, such as atherosclerosis. A key element herein is the complex cross talk between platelets, the coagulation system, leukocytes, and the activated endothelium. This review provides insight into the platelet-endothelial interface, based on in vitro flow chamber studies and cross referenced with in vivo thrombosis studies. The main mechanisms of platelet interaction with the activated endothelium encompass (1) platelet rolling via interaction of platelet glycoprotein Ib-IX-V with endothelial-released von Willebrand factor with a supporting role for the P-selectin/P-selectin glycoprotein ligand 1 axis, followed by (2) firm platelet adhesion to the endothelium via interaction of platelet αIIbβ3 with endothelial αvβ3 and intercellular adhesion molecule 1, and (3) a stimulatory role for thrombin, the thrombospondin-1/CD36 axis and cyclooxygenase 1 in subsequent platelet activation and stable thrombus formation. In addition, the molecular mechanisms underlying the stimulatory effect of platelets on leukocyte transendothelial migration, a key mediator of atheroprogression, are discussed. Throughout the review, emphasis is placed on recommendations for setting up, reporting, interpreting, and comparing endothelial-lined flow chamber studies and suggestions for future studies.

Sign in / Sign up

Export Citation Format

Share Document