Pulmonary embolism (PE) occurs when a pulmonary vessel becomes blocked with a blood clot, usually as a result of a dislodged deep vein thrombosis. Clinically PE is defined as massive or submassive which dictates treatment strategy and is dependent on cardiac output and blood pressure. Better treatment strategies, and improved survival, rely on a greater understanding of the cellular and molecular mechanisms leading to and resulting from PE. The most common mouse model of PE relies on non-specific endpoints of paralysis/death which do not relate exclusively to thrombosis. The model also cannot be used to determine factors affecting submassive PE or the progression from submassive to massive PE.
Why we funded it
This Project Grant aims to develop a refined mouse model of PE.
The traditional PE mouse model typically uses 200 mice per study. The mouse receives an intravenous injection of thrombogenic agents and the effects of genetic modifications/drug treatments are measured by their ability to significantly change the proportions of mice that are killed or paralysed. This procedure is defined as severe under the Animals (Scientific Procedures) Act 1986 but the refined procedure developed in this project has an unclassified severity. The refined model also has the potential to reduce the mice needed per study from 200 to 30, a reduction of 85% per study.
The refined mouse model proposed in this project administers sub-lethal doses of thrombogenic agents to anaesthetised mice. Blood is previously collected from the donor mouse, and the platelets isolated, radiolabelled and infused into a recipient animal. Platelet accumulation in the lung is then measured as an index of thrombotic occlusion. This system will measure platelet aggregation and disaggregation directly in real time and platelet activity can be measured in specific sites, such as the pulmonary vasculature. Platelet accumulation is reversible so procedures will be determined to allow repeated experiments in an individual mouse, providing a further opportunity to reduce the mice needed for these studies.
Moore C and Emerson M (2012) Assessment of platelet aggregation responses in vivo in the mouse. Methods in Molecular Biology 788: 21-28 doi:10.1007/978-1-61779-307-3_2
Emerson M et al. (2010) Distinct role and location of the endothelial isoform of nitric oxide synthase in regulating platelet aggregation in males and females in vivo. European Journal of Pharmacology 651: 152-58. doi:10.1016/j.ejphar.2010.11.011
Emerson M et al. (2010) Functional regulation of platelet and vascular activity during thrombosis by nitric oxide and endothelial nitric oxide synthase. Journal of Thrombosis and Haemostasis 104: 342-9. doi:10.1160/TH09-11-0764
Emerson M et al. (2010) The plasma membrane calcium ATPase (PMCA) modulates calcium homeostasis, intracellular signalling events and function in platelets. Journal of Thrombosis and Haemostasis 8: 2766-74. doi:10.1111/j.1538-7836.2010.04076.x
Tymvios C et al. (2009) Platelet aggregation responses are critically regulated in vivo by endogenous nitric oxide but not endothelial nitric oxide synthase. British Journal of Pharmacology 158 (7): 1735-42 doi:10.1111/j.1476-5381.2009.00408.x
Tymvios C et al. (2008) Real-time measurement of non-lethal platelet thromboembolic responses in the anaesthetized mouse. Thrombosis and Haemotosis 99 (2): 435-40. doi:10.1160/TH07-07-0479
Jones S et al. (2008) Peripheral tachykinins and the neurokinin receptor NK1 are required for platelet thrombus formation. Blood 111(2): 605-612. doi:10.1182/blood-2007-07-103424
Research Review 2011: Refinement of a mouse model of pulmonary embolism
Awards and Prizes: NC3Rs 3Rs Prize 2008 Highly commended
Further Funding: NC3Rs Project Grant, Real-time monitoring techniques and simplistic platelet assays to reduce and refine animal use in cardiovascular and respiratory biomedical research, November 2014, £232,737
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