An Optimized Mouse Model for Transient Ischemic Attack Pedrono E, Durukan A, Strbian D, Marinkovic I, Shekhar S, Pitkonen M, Abo-Ramadan U, Tatlisumak T. J Neuropathol Exp Neurol Feb; 69(2): 學生 : 黃怡靜 專討指導教授 : 鄭伯智老師 林宏榮老師

Introduction

A transient ischemic attack (TIA) is a brief episode of neurologic dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of acute infarction. N Engl J Med 2002; 347: A transient ischemic attack (TIA) is a sudden focal neurologic deficit of cerebrovascular origin lasting less than 24 hours and resolving without any residual symptoms or signs. “MRI-negative” Stroke 2008; 39:

TIA  Stroke (1/3) Histopatholog y Therapy Animal model Intraluminal suture MCAo (well-controlled reperfusion) 1. Ensures cerebral arterial occlusion and reperfusion (LDF) 2. No permanent neurological deficit at 24 hrs 3. No lesion on MRI (DWI, T2-WI) at 24 hrs

Materials and Methods

Adult male NMRI mice, g. Suture occlusion model (MCAo). CBF - laser Doppler flowmetry (LDF). MR imaging: 1) 4.7 T scanner, linear birdcage RF coil. 2) 7 coronal images, 1mm slice thickness. 3) DWI, T2-WI. Neurological evaluation (6-point scale of sensorimotor skills) : Score 0no deficit 1failure to fully extend the left forepaw 2circling to the left 3decreased resistance to lateral push 4no spontaneous walking with a depressed level of consciousness 5dead

Journal of Cerebral Blood Flow & Metabolism (2004) 24, 668–676. Bregma (LDF) Doppler shift

Histopathology: - hippocampus, caudoputamen, and frontoparietal cortex of both hemispheres 1) H&E stain 2) TUNEL stain (* TUNEL positivity index) Score 0no change 1 scattered neuronal changes 2selective neuronal necrosis (necrotic findings limited mainly to specific neuron populations) 3infarction (pan-necrosis characterized as the loss of affinity for hematoxylin in all cell types)

Middle cerebral artery occlusion induced brain ischemic injury Sham operation control group (sham) (n=4) Ischemia-Reperfusion group (I/R) (n=6) Physiology parameterHistologyMRI assay CBF, Tco, BWH&E stain TUNEL stain 20min15min10min7.5min5min2.5min*12.5min Reperfusion 24hrs T2-WI DWI Sensorimotor function * 3 day (72 hrs) follow-up

1. Sham group 2. I/R group 0 min StabilizedMCAo Ischemia- reperfusion Physiology parameters: CBF, Tco 24 hr* 72 hr 1. Sensorimotor function 2. MRI assay 3. Ischemic change 20 min, 15 min, *12.5 min, 10 min, 7.5 min, 5 min, 2.5 min

Statistical analysis: 1) Parametric data - means (± SD), unpaired t-test, 1-way analysis of variance. 2) Nonparametric data - medians, Mann-Whitney U test, Kruskal-Wallis test. 3) Spearman correlation coefficient (r). 4) p < 0.05.

Results

Fig 1. Cortical cerebral blood flow (CBF) monitoring by laser Doppler flowmetry.  85% 83%96%  Successful occlusion - decrease ≧ 75% CBF values from the baseline.  Adequate reperfusion - recovery ≧ 50% CBF values from the baseline after suture withdrawal.

Fig 2. T2-weighted images at 24 hours after reperfusion. optic chiasm levelhippocampal leveloptic chiasm levelhippocampal level

Neurological deficitPositive MRI 20 min15 ‛ 15 min14 " 12.5 min01 ª 10 min min00 5 min min00 ‛ : 1 small hippocampal infarct, 2 medium-sized subcortical infarcts, 2 large confluent infarcts " : 1 small cortical infarct, 3 medium-sized cortical and subcortical infarcts ª : 1 small cortical infarct 3-day follow-up group (12.5min): no delayed change.

Fig 3. Postmortem assessments at 24 hours postreperfusion. Ischemic change Duration of MCAo selective neuronal necrosis pan-necrosis (r = 0.95) lateral caudoputamen

Fig 4. Ischemic injury parameters. (A) Assessment with H&E. ** p = versus control. 3-day follow-up group (12.5min): no delayed injury.  Selective neuronal necrosis (score 2) was a consistent feature in the ischemic frontoparietal cortex starting at 5 minutes of MCAo.

Fig 4. Ischemic injury parameters. (B) Total TUNEL-positive cell counts of the right (ischemic) and left (contralateral) hemispheres. (C) Regional TUNEL counts. ** p = versus control. p < day follow-up group (12.5min): no delayed injury. Duration of MCAo TUNEL positivity index (r = 0.92) Ann Neurol 1999;46:

Conclusion

MCAo of 10 minutes or less induced by the intraluminal suture method is a reliable method of inducing a mouse model of TIA.  Animal species difference ?

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