The aim of this project was to reduce animal use in a model of pulmonary embolism involving infusion of radiolabelled platelets by characterising and validating the use of human rather than mouse platelets.
Until recently, research into platelet thromboembolism was carried out in mice by injection of thrombogenic substances which can result in paralysis and death of the animals. A previous NC3Rs award enabled this model to be refined so that the procedure was performed under general anaesthesia. The model involved monitoring radiolabelled platelets infused into the mouse, with mice also used as platelet donors. The use of human instead of mouse platelets would reduce the numbers of animals used in this research by 50%.
Research details and methods
This project comprised experiments to confirm that radiolabelled human platelets administered to NOD-SCID mice showed normal platelet responsiveness. It also investigated whether experiments on drugs such as aspirin can be evaluated in the mouse by giving the drug to human volunteers rather than administering it by gavage to the mice.
Key impacts and findings
Development of this human–mouse model has further reduced the use of mice by 50%. The traditional model of mouse pulmonary embolism used 200 animals per study. Mouse platelet infusion reduced this to 30 and with human platelets to 15 animals per study.
- Further Funding: NC3Rs Project Grant, Refinement of a mouse model of pulmonary embolism, February 2007, £149,171
- 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
Until recently, assessing platelet thromboembolism in mice involved the injection of thrombogenic substances into conscious animals to induce death or paralysis. This procedure inflicted considerable pain and suffering and was scientifically limited since it only modelled one extreme end-point of a disease with a broad spectrum. An NC3Rs research grant awarded in 2006 allowed us to refine this methodology so that we recorded non-lethal responses in anaesthetised mice by monitoring radiolabelled platelets in real-time. As well as refining a procedure from a severe to unclassified level, we were able to reduce mouse use by recording multiple responses within an individual animal. Our refined model involves the death of large numbers of donor mice that are bled for platelets which are radiolabelled and subsequently reinfused into recipient animals. We will now show that human donors can be used instead of mice to reduce mouse use by 50% and reduce the numbers of mice subjected to drug administration procedures. To achieve this we shall infuse radiolabelled human platelets into mice to create a humanised-mouse model. We intend to fully characterise the humanised-mouse as a model of thrombosis by extending our preliminary data by conducting experiments confirming normal physiological platelet responsiveness in our model together with supporting histological analysis. Additionally, we shall demonstrate that in vivo pharmacological experiments with agents such as aspirin can be conducted by giving aspirin to human volunteers rather than gavaging donor mice. In addition to the 3Rs benefits, the development of humanised-mouse models has scientific advantages in enabling us to investigate human rather than animal cells in a controlled, potentially genetically modified, in vivo environment. We intend publishing our work in a high quality peer reviewed journal and participating in stakeholder, scientific and public dissemination events. The 3Rs impact of our work will occur not only within our own group but with groups already collaborating with us by applying our refined methodology to their own research.
Holbrook L et al (2012) A NOD/SCID mouse model for the assessment of human platelet aggregation in vivo. J Thromb Haemost 10(3):490-2. doi: 10.1111/j.1538-7836.2011.04595.x
Emerson M (2010) Refinement, reduction and replacement approaches to in vivo cardiovascular research. Brit J Pharmacol 161 (4): 749–754. doi:10.1111/j.1476-5381.2010.00959.x