silicon and Brain-Ischemia

Stroke is among the most frequent causes of death and adult disability, especially in highly developed countries. However, treatment options to date are very limited. To meet the need for novel therapeutic approaches, experimental stroke research frequently employs rodent models of focal cerebral ischaemia. Most researchers use permanent or transient occlusion of the middle cerebral artery (MCA) in mice or rats. Proximal occlusion of the middle cerebral artery (MCA) via the intraluminal suture technique (so called filament or suture model) is probably the most frequently used model in experimental stroke research. The intraluminal MCAO model offers the advantage of inducing reproducible transient or permanent ischaemia of the MCA territory in a relatively non-invasive manner. Intraluminal approaches interrupt the blood flow of the entire territory of this artery. Filament occlusion thus arrests flow proximal to the lenticulo-striate arteries, which supply the basal ganglia. Filament occlusion of the MCA results in reproducible lesions in the cortex and striatum and can be either permanent or transient. In contrast, models inducing distal (to the branching of the lenticulo-striate arteries) MCA occlusion typically spare the striatum and primarily involve the neocortex. In addition these models do require craniectomy. In the model demonstrated in this article, a silicon coated filament is introduced into the common carotid artery and advanced along the internal carotid artery into the Circle of Willis, where it blocks the origin of the middle cerebral artery. In patients, occlusions of the middle cerebral artery are among the most common causes of ischaemic stroke. Since varying ischemic intervals can be chosen freely in this model depending on the time point of reperfusion, ischaemic lesions with varying degrees of severity can be produced. Reperfusion by removal of the occluding filament at least partially models the restoration of blood flow after spontaneous or therapeutic (tPA) lysis of a thromboembolic clot in humans. In this video we will present the basic technique as well as the major pitfalls and confounders which may limit the predictive value of this model.

Topics: Animals; Brain Ischemia; Disease Models, Animal; Infarction, Middle Cerebral Artery; Mice; Middle Cerebral Artery; Silicon

A variety of intraluminal sutures have been used in the middle cerebral artery occlusion model (MCAO) of focal ischemia. In the present study we tested commercially available silicon-coated nylon suture in the MCAO model and compared the results to traditional monofilament nylon suture occlusion. Twelve Sprague-Dawley male rats were randomly divided two groups, MCAO with 4-0 nylon suture (Group N, n=6) and MCAO with silicone-coated 4-0 nylon suture (Group S, n=6). Rats were sacrificed 24 h after reperfusion. Assessment included mortality rates, neurological evaluation, and infarct volume. One rat died in each group from subarachanoid hemorrhage. Neurological evaluation demonstrated that Group S tended to have worse neurological outcomes than Group N, although this difference was not statistically significant. On TTC stain Group S had significantly larger infarct volumes than Group N. We conclude that the commercially available silicone-coated occlusion suture provides better occlusion of the middle cerebral artery than the traditional uncoated nylon suture.. Disease-related neuroscience (Section 6).

Topics: Animals; Behavior, Animal; Brain; Brain Ischemia; Infarction, Middle Cerebral Artery; Ligation; Male; Middle Cerebral Artery; Nylons; Rats; Rats, Sprague-Dawley; Silicon; Sutures