Thrombosis formation in rodents
Real-time monitoring and even direct visualization of thrombus formation in mice makes it possible to evaluate genetic and pharmacological interventions. Genetic studies, for which the mouse is the favoured species, have yielded valuable insights into the mechanisms underlying thrombus formation. Pharmacological interventions allow the assessment of fibrinolytic and thrombolytic properties of drugs.
Methods for inducing arterial thrombosis include both mechanical and chemically-induced injury, among others. In the latter category, two of the most widely used techniques are:
(1) application of ferric chloride (FeCl3) directly to the outside covering of the artery
(2) intravenous injection of a substance called Rose Bengal, which subsequently accumulates in membranes of endothelial cells. Segments of arteries exposed to green light trigger a reaction that leads to the formation of substances harmful to the epithelium.
In anesthetized subjects applications, thrombus formation is monitored by measuring flow.
If, for example, the thrombus is to be induced in the carotid artery:
• The flow probe (model MA0.5PSB) by Transonic Systems Inc. available from emka TECHNOLOGIES) is placed around the mouse carotid artery downstream of the thrombus site. The probe is connected to a control unit (model T420 from Transonic).
• The pressure catheter (model SPR 671 Ultra-Miniature Mikro-Tip cathether by Millar Inc, available from emka TECHNOLOGIES) is inserted into the aorta. This catheter is connected to a control unit (model TC510), then to an usb amplifier.
amplifier is directly connected to the computer running emka TECHNOLOGIES’ iox2 acquisition software.
Data acquisition is performed by iox2, with simultaneous analysis made feasible with a variety of add-on BP or BF analyzer modules.
• BP analyzer (blood pressure)
Systolic and diastolic pressures, amplitude, mean pressure, heart rate
• BF analyzer (blood flow)
Systolic & diastolic flows, mean flow, stroke volume, cardiac output, heart rate, mean blood pressure, total peripheral resistance
• compatible with Microsoft® Windows® XP or 7 environment
• setup for rats differs slightly (transducers and control units)
Westrick RJ Winn ME, Eitzman DT (2007) Murine models of vascular thrombosis (Eitzman series). Arterioscler Thromb Vasc Biol 27(10):2079-93.
This review article highlights developments in the field of thrombosis using mouse models and how studies using these models are expanding knowledge of thrombotic disease.
FeCl3-induced model of thrombosis in mice
Eslin ED et al (2004) Transgenic mice studies demonstrate a role for platelet factor 4 in thrombosis: dissociation between anticoagulant and antithrombotic effect of heparin. Blood 104(10):3173-3180.
The study, involving genetically modified mice (knock-out and transgenic mice), demonstrates that platelet-specific chemokine platelet factor 4 (PF4) plays a major role in thrombosis.
Konstantinides S, Schäfer K, Thinnes T, Loskutoff DJ (2001) Plasminogen activator inhibitor-1 and its cofactor vitronectin stabilize arterial thrombi after vascular injury in mice. Circulation 103:576-83.
The methodology section describes, in detail and with the aid of photographs, induction of the injury and application of an ultrasound flow probe (Transonic) in the carotid artery.
Rose Bengal/photochemical technique in mice
Wilson KM, McCaw RB, Leo L et al (2007) Prothrombotic effects of hyperhomocysteinemia and hypercholesterolemia in ApoE-deficient mice. Arterioscler Thromb Vasc Biol 27:233-40.
Report of a study demonstrating that hyperhomocysteinemia and hypercholesterolemia, alone or in combination, produce endothelial dysfunction and increased susceptibility to thrombosis in ApoE-deficient mice.
Wilson KM, Lynch CM, Faraci FM, Lentz SR (2003) Effect of mechanical ventilation on carotid artery thrombosis induced by photochemical injury in mice. J Thromb and Haemost 1:2669-74.
Report of a study demonstrating that hypoventilation in anesthetized mice may cause hypercapnia, increased carotid artery blood flow, and altered thrombotic responses. The upshot of this finding is that in studies of experimental thrombosis in vivo, general anesthesia performed without mechanical ventilation may confound results.