Basic NeuroscienceA novel atherothrombotic model of ischemic stroke induced by injection of collagen into the cerebral vasculature

- We developed a stroke model similar in pathophysiology to atherothrombotic stroke.
- Collagen was injected directly into the cerebral circulation of mice and rats.
- Cerebral blood flow remained depressed for at least 1 h after collagen injection.
- Platelet and fibrin rich thrombi formed in macro- and microvascular cerebral arteries.
- Cerebral infarcts and neurobehavioral deficits were observed after 48 h.

BackgroundMost ischemic strokes in humans are caused by ruptured arterial atheroma, which activate platelets and produce thrombi that occlude cerebral vessels.MethodsTo simulate these events, we threaded a catheter through the internal carotid artery toward the middle cerebral artery (MCA) orifice and injected collagen directly into the cerebral circulation of male C57Bl/6 mice and Wistar rats.ResultsLaser-Doppler flowmetry demonstrated reductions in cerebral blood flow (CBF) of ∼80% in mice and ∼60% in rats. CBF spontaneously increased but remained depressed after catheter withdrawal. Magnetic resonance imaging showed that ipsilateral CBF was reduced at 3 h after collagen injection and markedly improved at 48 h. Micro-computed tomography revealed reduced blood vessel density in the ipsilateral MCA territory at 3 h. Gross examination of excised brains revealed thrombi within ipsilateral cerebral arteries at 3 h, but not 24 h, after collagen injection. Immunofluorescence microscopy confirmed that platelets and fibrinogen/fibrin were major components of these thrombi at both macrovascular and microvascular levels. Cerebral infarcts comprising ∼30% of hemispheric volume and neurobehavioral deficits were observed 48 h after ischemic injury in both mice and rats.Comparison with existing methodsCollagen injection caused brain injury that was similar in magnitude and variability to mechanical MCA occlusion or injection of a pre-formed clot; however, alterations in CBF and the mechanism of vascular occlusion were more consistent with clinical ischemic stroke.ConclusionThis novel rodent model of ischemic stroke has pathophysiologic characteristics consistent with clinical atherothrombotic stroke, is technically feasible, and creates reproducible brain injury.