In Vivo Models for the Evaluation of Antithrombotics and Thrombolytics

Abstract

The development and application of animal models of thrombosis have played a crucial role in the discovery and validation of novel drug targets and the selection of new agents for clinical evaluation, and have informed dosing and safety information for clinical trials. These models also provide valuable information about the mechanisms of action/interaction of new antithrombotic agents. Small and large animal models of thrombosis and their role in the discovery and development of novel agents are described. Methods and major issues regarding the use of animal models of thrombosis, such as positive controls, appropriate pharmacodynamic markers of activity, safety evaluation, species specificity, and pharmacokinetics, are highlighted. Finally, the use of genetic models of thrombosis/hemostasis and how these models have aided in the development of therapies that are presently being evaluated clinically are presented.

Overexpression of the Cell Cycle Inhibitor p16 INK4a Promotes a Prothrombotic Phenotype Following Vascular Injury in Mice

“…Exposure of the vessel to FeCl 3 is a type of biochemical injury that results in endothelial denudation and exposure of the subendothelium following lipid peroxidation 37 . This type of oxidative damage produces thrombi that are rich in platelets, but also contain red blood cells both encased in a dense fibrin meshwork indicating a role for soluble plasma factors driving thrombus formation 38–40 . Rose Bengal is a fluorescein-based chemical that is excited to produce reactive oxygen species when exposed to green light at 540 nm.…”

“…This results in endothelial activation, although there is very little denudation, and is accompanied by rapid platelet adhesion. Thrombi in this model are primarily composed of platelets and contain less fibrin implying this process is mostly platelet driven 38 . The observation that p16 INK4a transgenic mice exhibit faster occlusion times in both of these models suggests there is likely a contribution by both soluble plasma factors and circulating cells.…”

Regulatory acceptance of animal models of disease to support clinical trials of medicines and advanced therapy medicinal products

“…These models are of pivotal value in development of antithrombotic drugs and provide extremely useful data on the safety and efficacy of new medicines developed for human use. (Mousa, 2010) …”

Sonothrombolysis

“…These studies are required prior to U.S. Food and Drug Administration approval for new clinical devices (Harris 2009). A variety of in-vivo thrombosis models have been developed and are summarized by Hossmann (1998), Verbeuren (2006), and Mousa (2010). Small animal models, such as rodent (Daffertshofer et al 2004) and rabbit (Hölscher et al 2012), are used in sonothrombolysis due to their low cost, ease of handling, and accumulation of data from previous studies.…”