Effect of Suture Properties on Stability of Middle Cerebral Artery Occlusion Evaluated by Synchrotron Radiation Angiography

Abstract

Background and Purpose-The intraluminal suture technique for producing middle cerebral artery occlusion in rodents is the most commonly used method for modeling focal cerebral ischemia associated with clinical ischemic stroke. Synchrotron radiation angiography may provide a novel solution to directly monitor the success of middle cerebral artery occlusion. Methods-Twenty adult Sprague-Dawley rats for middle cerebral artery occlusion models were prepared randomly with different suture head silicone coating. In vivo imaging was performed at beam line BL13W1, Shanghai Synchrotron Radiation Facility, Shanghai, China. Results-Silicone-coated suture was superior to uncoated suture for producing consistent brain infarction. Additionally, silicone coating length was an important variable controlling the extent of the ischemic lesion: infarcts affected predominantly the caudate-putamen with large variability (Ͻ2 mm), both the cortex and caudate-putamen (2-3.3 mm), and most of the hemisphere, including the hypothalamus (Ͼ3.3 mm). Conclusions-Synchrotron radiation angiography provides a useful tool to observe hemodynamic changes after middle cerebral artery occlusion, and the physical properties of suture are critical to the success of the middle cerebral artery occlusion model. (Stroke. 2012;43:888-891.)Key Words: angiography Ⅲ middle cerebral artery occlusion Ⅲ synchrotron radiation T he focal cerebral ischemia model involves the occlusion of the middle cerebral artery (MCAO) and typically results in localized brain infarction, which recapitulates many of the pathophysiological and histopathologic features of stroke. The most common technique for MCAO is the intraluminal filament model. 1 However, 1 limitation of the suture model is its high variability in infarct size. 2 Factors that contribute to such variation include differences in animal strain and weight, method of anesthesia, blood pressure, brain and body temperature, brain vascular anatomy, suture material, duration, and site of occlusion. Physical properties of the filament are important because it is the key factor that affects lesion volume 3 ; however, there is no direct evidence to confirm this principle. 4,5 Regional cerebral blood flow can be measured using autoradiography and laser Doppler flowmetry to confirm successful MCAO, but neither method can dynamically monitor changes of cerebral blood flow in deeper tissue during ischemia-reperfusion. 6,7 Synchrotron radiation angiography (SRA) may represent a novel solution to directly and dynamically monitor MCAO. 8 In the present study, we used SRA to examine if the coating length was critical for producing a highly reproducible stroke model. Materials and Methods Experimental GroupsAnimal procedures were approved by the Institutional Animal Care and Use Committee of Shanghai Jiao Tong University, Shanghai, China. Twenty male Sprague-Dawley rats (SLAC, Shanghai, China) weighing 270 to 350 g were divided into 4 groups randomly (nϭ5/group). The sutures with different physical properties were used in 4 groups t...

Synchrotron Radiation Imaging for Advancing Our Understanding of Cardiovascular Function

“…43 Early experiments aimed to validate SR as an effective approach for measuring the diameter of small cerebral microvessels (≈240 μm) in the circle of Willis of dogs. 44 Since then, numerous studies have studied the microstructure and function of much smaller cerebral vessels, primarily in rats 24,42,[45][46][47] and mice. 23,48,49 Again, the advantage of SR is that it can simultaneously image both pial (surface) and penetrating perforating vessels 23,42,45 because there is no single focal plane ( Figure 5).…”

“…However, cerebral aneurysms of such traditional animal models are usually too small to be imaged in vivo with conventional CT. 50 SR microangiography has provided a novel means of identifying localized cerebral aneurysms 50 and differences in vascular reactivity after cerebral ischemia. 45,51 Moreover, the less invasive approach and detailed visualization of the cerebral arterioles mean SR can be used to confirm high reproducibility of experimentally induced cerebral vessel occlusion 47,49 and to repeatedly assess the morphological and functional changes of the cerebral vessels in vivo at regular intervals (eg, monthly) after induction of cerebral aneurysms or subarachnoid hemorrhage. As mentioned, spatial resolution is determined in part by the iodine concentration.…”

Permanent flame-blunted monofilament of middle cerebral artery occlusion technique for ischemia stroke induction in animal models

“…Furthermore, tips of flame-blunted monofilament would be coated approximately 1-1,5 mm in length to prevent the occlusion of the hypothalamic artery and decrease the mortality rate. 13 Pterygopalatine artery was identified to avoid misplacement of filament. Once filament insertion into the middle cerebral artery ( MCA) was confirmed, the midline neck incision was sewed using surgical suture.…”

“…Furthermore, mortality can be reduced since HTA supply thalamus where thermoregulation are controlled. 13 When the coating is more than 2 mm in length, blockage of HTA occurred and mortality is higher. Therefore, this method is suitable when permanent occlusion is needed for the study.…”

“…Nevertheless, the complication of this filament may have subarachnoid bleeding (40%) 22 and infarct size is not as wide as where the coating length of filament's tip more than 2 mm. 13 Another disadvantage of this technique is that the confirmation of MCAO cannot be visualized. Successful occlusion is confirmed by the evidence of motor neurological deficit (supplementary video).…”