PB1273 - Mechanical Injury of a tissue-engineered human arterial construct replicates the thrombotic and pharmacological properties of the native artery.

Background: Intravital microscopy in mice is widely used to study in vivo thrombus formation – however the relevance of these studies to human physiology is unclear. Previously we have developed a 3D, tissue-engineered human arterial construct (TEAC) that replicates the primary [1] and secondary haemostatic properties of the native artery, which could be used as an alternative to current in vivo experiments.

Aims: The aim of this study was to identify whether our model was able to replicate thrombus formation in response to mechanical and FeCl3 injury, as well as its sensitivity to clinically-relevant anti-thrombotic drugs.

Methods: Our TEAC was incorporated into a novel 3D printed microfluidic chamber and perfused recalcified citrated blood under arterial shear conditions. Platelets were fluorescently-labelled with CSFE. Thrombus formation was monitored by fluorescence microscopy for up to 13 minutes after perfusion onset in either intact channels, or those subjected to mechanical or FeCl3 injury.

Results: Both mechanical and FeCl3 injury models induced a reproducible thrombotic response, whilst there was limited thrombus formation seen in the uninjured channels. Under physiological flow with human blood, thrombus formation was faster and more extensive in TEACs subject to mechanical injury (average fluorescence = 11.7 ± 2.4 arbitrary units) compared to those injured with FeCl3 Injury (2.7 ± 0.4; P < 0.05; n=10). Mechanically-injured arterial constructs also had enhanced tissue factor activity and shorter prothrombin times compared to those subjected to FeCl3 injury in static assays. Pre-treatment of whole blood with ticagrelor or rivaroxaban before perfusion over mechanically-injured TEACs significantly reduced the thrombus formation when compared to the untreated control (P < 0.05, n=8 and 6 respectively).

Conclusion(s): Our study demonstrates that tissue-engineered human arterial constructs are a viable replacement to current murine thrombosis models, as they can replicate the haemostatic processes of the native artery, and are sensitive to clinically-relevant anti-platelet and anti-coagulant therapies.