Effectiveness of a new modified intraluminal suture for temporary middle cerebral artery occlusion in rats of various weight.

Intraluminal temporary middle cerebral artery occlusion (MCAO) is a common model of ischemic stroke in the rat with significant, suture and weight-dependent variability along with increased risk of subarachnoid haemorrhage (SAH). Our purpose was to increase reproducibility and decrease SAH using a modification of the Koizumi suture. We compared a Koizumi 5/0 Ethilon poly-l-lysine-coated suture (s-2, group B) to an identical, uncoated one (s-1, group A) and the Belayev's 3/0 suture (s-3, group C), in the 2-h MCAO model in Wistar rats of varying weight (310-527 g). Assessment included successful infarction rates, the modified neurological stroke scale (mNSS), a modified Bederson's scale (mBS), the grid-walking test (GWT), infarction volume (with rostrocaudal subanalysis and analysis of cortical/striatal involvement) and hemispheric edema. The s-2 suture increased the successful MCAO from 61.1% and 66.6% (groups A and C) to 97.5% in group B and induced a more severe clinical stroke (P<0.05) irrespective of animal's weight, with no incidence of SAH. Infarction volume and ipsilateral hemispheric edema significantly (P<0.05) increased and well correlated with the mNSS (P<or=0.005), the mBS (P<or=0.01) and GWT outcomes. Our data suggest that the new modified suture induces a more reproducible ischemic stroke in Wistar rats for temporary-MCAO experiments, overcoming the variability of weight and the risk of SAH.