Characterization of a thromboembolic photochemical model of repeated stroke in mice

Abstract

Many stroke research groups utilize the model of middle cerebral artery occlusion induced by insertion of an intraluminal thread, owing to its pragmatism and reliability of cerebral infarct generation. However, 75% of stroke cases result from a thromboembolic event and 10% from occlusive atherothrombosis in situ. Here, we characterize a mouse model of repeated thromboembolic stroke, which closely mimics the intravascular pathophysiology of arterial thrombus generation from an atherosclerotic plaque, and subsequent release of a thrombus into the cerebral circulation as an embolus. Common carotid artery thrombosis (CCAT) was induced photochemically leading to non-occlusive platelet aggregation in C57/BL6 male mice (n=35), and was followed by mechanical assistance to facilitate release of the thrombus (MRT) and thus promote embolism. Six experimental groups, differing by changes in the surgical protocol, were used for the purpose of determining which such procedure yielded the most reliable and consistent brain infarct volumes with the lowest mortality at 3 days after surgery. The group which best satisfied these conditions was a double insult group which consisted of animals that underwent CCAT for 2 min by means of argon laser irradiation (514.5 nm) at an intensity of ca. 130 W/cm(2), with concomitant injection of erythrosin B (EB) (35 mg/kg infused over those same 2 min), followed by MRT 1 min later; the entire procedure was repeated 24h later. This group showed a percent of brain lesion volume of 15+/-4% (mean+/-S.D.) with no associated 3-day mortality. Compared to a single insult group which sustained a percent brain lesion volume of 7+/-3%, there was a statistically significant (p<0.05) increase in the volume of infarction in the double-insult group.

Potential Animal Models of Lacunar Stroke

“…23 Some models irradiated the internal/common carotid arteries in the presence of a photosensitive dye to produce an embolic source said to mimic thrombus generation on an atherosclerotic carotid artery plaque. 22 This produced multiple infarcts, mostly cortical with a few in the basal ganglia and the caudate nucleus, but the subcortical lesions were poorly documented making their relevance to lacunar infarction uncertain.…”

A Stable Focal Cerebral Ischemia Injury Model in Adult Mice: Assessment Using 7T MR Imaging

“…The mouse is the most appropriate animal on which to apply genetic modifications, 7 and transgenetic mice are now increasingly used to elucidate complex sequences of molecular events involved in ischemic injury. 16 Intraluminal thread occlusion of the MCA (intraluminal occlusion model) and thromboembolic occlusion of the MCA either by infusing clots into the cerebral circulation (thromboembolic model) 17 or by photochemically inducing thrombus 16 are now 2 principal procedures used for mouse MCAO models. The intraluminal suture MCAO is the most frequently used model.…”

“…This procedure yielded a reliable and consistent brain infarct volume, with the lowest mortality at 3 days after surgery. 16 Cerebral hypoxic-ischemic injury induced by unilateral ligation of the CCA, followed by a hypoxic exposure, could result in a stable cortical lesion and a high survival rate in neonatal rats. 23,24 In our study, a hypoxic-ischemic injury was used on adult mice.…”

Rodent Stroke Model Guidelines for Pre-clinical Stroke Trials (1st edition).

“…(Chen et al 2004;De Ryck et al 1996;De Ryck et al 1989;De Ryck et al 2000;Eichenbaum et al 2002;Futrell et al 1988;Lozano et al 2007;Ostrovskaya et al 1999) Autologous clot model Clot-related protection mechanisms. (Beech et al 2001;Busch et al 1997;Harada et al 2005;Kano et al 2003;Kano et al 2005;Kilic et al 1998;Krueger and Busch 2002;Orset et al 2007;Romanos et al 2007;Tejima et al 2001;Toomey et al 2002;Vosko et al 2003) Endothelin-1 model Transient to semi-permanent focal cerebral ischemia that need outcome measurements of both histology and neurofunctions (Biernaskie et al 2001;Horie et al 2008;Nikolova et al 2009;Windle et al 2006) Tamura model Permanent focal cerebral ischemia.…”