Microvascular flow model to study clot formation in real-time

L. Jenny1, J. Dobó2, P. Gál2, W. Lam3, V. Schroeder1 (1Bern, Switzerland, 2Budapest, Hungary, 3Atlanta, Unites States)

Innovation and Novelty
Date: 16.02.2017,
Time: 14:00 - 15:15

Objective: Microvascular occlusion and thrombosis is a process involving several components as coagulation factors, endothelial cells, hemodynamic forces and the vessel geometry and is further affected by the complement system. So far most experiments examining the course of vessel occlusion have been performed in either animal models or isolated in vitro systems, which are either difficult to interpret and to transfer to human physiology or only focus on certain aspects in a non-physiological environment. A recently developed so-called “microvasculature-on-a-chip” model (CHIP) combines the physiological environment of animal models with the reproducibility and easy-handling of in vitro systems.

Methods: This microvascular flow model features channels in the micrometer range coated by a confluent monolayer of endothelial cells which can be perfused with whole blood (WB) at a physiological flow rate. The transparent character of the device (poly-dimethyl-siloxane) allows for real-time observation of the blood flow, thrombus formation and subsequent vessel occlusion by confocal microscopy.

Results: Here we visualize the crosslinking actions of FXIII in clot formation and study the effect of the complement enzyme mannan-binding-lectin-associated serine protease-1 (MASP-1) on clot formation in whole blood. MASP-1 resembles thrombin in terms of its structural features and substrate specificity and has been shown to be involved in fibrin clot formation in a prothrombin-dependent manner. Perfusion of a CHIP with freshly drawn recalcified WB in presence or absence of physiological concentrations of a recombinant form of MASP-1 confirmed that rMASP-1 is able to significantly enhance clot formation in WB. We visualized the action of FXIII in WB by staining the crosslinks of forming fibrin clots with a specific antibody, by observing the incorporation of specific FXIII substrates and by the use of FXIII inhibitors. The model further allows to examine the dissolution of the clot in real-time.

Conclusion: Taken together, this microvascular flow model allows to study the effect of various enzymes on the process of vascular occlusion and thrombogenesis in a close-to-physiological environment in real-time.