A humanised thrombus-on-a-chip model utilising tissue-engineered arterial constructs: A method to reduce and replace mice used in thrombosis and haemostasis research.

Abstract

The study of in vivo thrombus formation has principally been performed using intravital microscopy in mice and other species. These have allowed us to visualise the molecular and cellular processes that regulate thrombus formation inside the body. However current in vivo arterial thrombosis models are difficult to standardise between labs and frequently produce results that do not reliably translate successfully in human clinical trials. Here we provide a step-by-step description with accompanying video tutorials to demonstrate how to produce a 3D humanised thrombus-on-a-chip model, which uses perfusion of fluorescently-labelled human blood over a mechanically-injured human tissue engineered arterial construct (TEAC) within a 3D printed microfluidic flow chamber to replicate thrombus formation within a healthy artery. We also provide a written methodology on how to use 3D printing to produce a mechanical injury press that can reproducibly damage the TEAC as a stimulus for thrombus formation as part of a mechanical injury model. Perfusion of the uninjured TEAC with whole human blood containing DiOC6-labelled platelets without initiating notable thrombus formation. The mechanical injury press was shown to induce a reproducible puncture wound in the TEAC. Fluorescence microscopy was used to demonstrate that thrombus formation could be observed reproducibly around sites of injury. This humanised thrombosis-on-a-chip model can replace the use of animals in in vivo thrombosis models for preclinical assessment of anti-thrombotic therapies. This method also offers multiple scientific advantages: allowing new drugs to be directly tested on human blood from a diverse array of donors, facilitating use of a realistic and reproducible injury modality as well as removing the potential confounding effects of general anaesthetics in animal studies. The use of human thrombus-on-a-chip models combining TEACs offers a new methodology to reduce animal use whilst improving the predictive capabilities of preclinical trials of anti-thrombotic therapies.