Ideal suture diameter is critical for consistent middle cerebral artery occlusion in mice.

OBJECTIVE: The use of transgenic and knockout mice has led to a need for a consistent model of mouse transient focal cerebral ischemia. In a great majority of the published mouse middle cerebral artery (MCA) occlusion studies, the methods indicated the type of intraluminal suture used without indicating the actual suture diameter after modification. We attempted to determine the ideal suture diameter to produce consistent occlusion in the MCA of adult male C57BL/6 mice.
METHODS: Suture tips were coated to a depth 4 mm with glue, and 6-0 sutures of eight different, precisely measured diameters were produced. The coated 6-0 sutures in different diameters were introduced 10 mm into the internal carotid artery via the external carotid artery of the mice to produce MCA occlusion (n = 40; five animals for each diameter), and the mice (22-24 g) were transaortically perfused with saline. The base of the brain was exposed, and photographs of the vessels were obtained before and after transaortic injection of Evans blue dye to determine the consistency of MCA occlusion for each suture diameter. Cerebral blood flow was measured 10 minutes before occlusion and 20 minutes after reperfusion, and 2,3,5-triphenyltetrazolium chloride staining was performed to demonstrate the ischemic damage in additional animals with 110-microm (n = 5) and 180-microm (n = 8) diameter sutures.
RESULTS: Sutures measuring 170 microm and 180 microm in diameter consistently occluded the MCA of C57BL/6 mice. In addition, 2,3,5-triphenyltetrazolium chloride staining demonstrated consistent infarction with 180-microm diameter sutures. The infarct volume was 36.3 +/- 4.2 mm3.
CONCLUSION: Small changes in the diameter of the occlusion suture tip affect consistency in the mouse MCA occlusion model.