Abstract
Abstract Newly developed materials for blood-contacting devices need to undergo hemocompatibility testing to prove compliance with clinical requirements. However, many current in vitro models disregard the influence of flow conditions and blood exchange as it occurs in vivo. Here, we present a flow model which allows testing of blood-surface interactions under more physiological conditions. This modular platform consists of a triple-pump-chip and a microchannel-chip with a customizable surface. Flow conditions can be adjusted individually within the physiological range. A performance test with whole blood confirmed the hemocompatibility of our modular platform. Hemolysis was negligible, inflammation and hemostasis parameters were comparable to those detected in a previously established quasi-static whole blood screening chamber. The steady supply of fresh blood avoids secondary effects by nonphysiological accumulation of activation products. Experiments with three subsequently tested biomaterials showed results similar to literature and our own experience. The reported results suggest that our developed flow model allows the evaluation of blood-contacting materials under physiological flow conditions. By adjusting the occurring wall shear stress, the model can be adapted for selected test conditions.
Highlights
The peak wall shear stress can be varied by adjusting the signal actuating the triple-pump-chip with the pneumatic damper “MPShemodyn”. This offers the possibility to independently vary flow conditions within the system mimicking hemodynamic conditions as they occur in different parts of the vascular system
Hemocompatibility was assessed according to hemolysis (Drabkin’s Reagent, Sigma-Aldrich, USA), pH stability and blood gases, activation of the complement cascade, cytokine MIP1-β (ProcartaPlex Immunoassay, Thermofisher Scientific, USA), and the leukocyte activation marker CD11b [8], as well as the adhesion of leukocytes and platelets to the test surface
Statistical analysis was performed by one-way analysis of variance (ANOVA) and subsequent Holm-Sidak multiple comparisons
Summary
The rapidly growing need for cardiovascular implants and other blood-contacting devices necessitates the development of new hemocompatible materials. Though ISO standard 10993-4 provides a guideline with specific testing categories, it does not define a specific measurement setup. [1,2] most described blood flow chambers do not consider the physiological exchange and continued replacement of blood. Such steady pool systems impede kinetic analysis and can cause exhaustion of source factors and accumulation of activation products. This may lead to the cross-activation of pathways to a non-physiological extent. The continuous blood exchange avoids disadvantages of steady pool systems, providing adjustable shear forces in a physiological range and allowing continuous sampling for the kinetic analysis of activation processes.
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