A novel mouse model of ischemic carotid artery disease

Abstract

Background: Carotid artery occlusive disease gradually develops over time, eventually leading to cerebral infarction and high mortality rate. Animal models replicating cerebral infarction resulting from carotid artery occlusive disease have thus been developed to test potential novel treatments, which could be subsequently administered clinically.

Methods: Adult C57BL/6J male mice were subjected to ameroid constrictor (AC) placement to gradually narrow the bilateral common carotid arteries. Cerebral blood flow (CBF) was measured at several time points. At 7 and 28 days post-operation, post-mortem brain samples were analyzed for ischemic changes.

Results: The mortality rate was 58.8% at 28 days post-operation. Surviving mice with AC showed continuous reduction of CBF by up to 70% of the baseline level at 28 days. Most of the mice (75%) showed multiple cerebral infarctions in the gray and white matter. Non-surviving mice showed critical CBF reduction below 20-30% of the baseline level before death.

Conclusion: The application of the AC on the bilateral common carotid arteries in mice could offer a reliable model of severe cerebrovascular insufficiency due to carotid artery occlusive disease and may thus be useful in exploring pharmacological intervention in stroke through monitoring survival rate, infarct formation, and CBF profile.

Figure 1. Cerebral blood flow (CBF) was gradually decreased in mice with the ameroid constrictors (ACs).

(A) Representative CBF images of AC-implanted mice and bilateral common carotid artery stenosis (BCAS)-operated mice as assessed by laser speckle flowmetry at indicated time points. (B) Temporal profiles of CBF of the AC-implanted mice (n = 8) and BCAS-operated mice (n = 7) pre- and post-operation (2-way repeated-measures ANOVA, p<0.05; unpaired t-test, #p<0.01 vs. BCAS group). (C) Representative images of ACs at indicated time points.

Figure 2. Multiple cerebral infarcts in mice with ACs.

Hematoxylin and eosin staining showed multiple infarcts in the cerebral cortex, the corpus callosum, the caudoputamen, the anterior commissure, the hippocampal fimbria, and the hippocampus of the mice in the AC group at 28-operation. Arrows indicate infarct changes. Scale bars indicate 200 µm.

Figure 3. Percentage of AC-implanted mice with cerebral infarctions.

The histogram shows the number and percentage of AC-implanted mice (n = 8) that developed cerebral infarctions in cortex, corpus callosum, caudoputamen, anterior commissure, hippocampal fimbria, and hippocampus.

Figure 4. Hippocampal neuronal loss in AC-implanted mice.

Hematoxylin and eosin staining showed intact hippocampus of the BCAS-operated mouse (left panel) and hippocampal neuronal loss of the AC-implanted mouse (right panel) at 28 days post-operation. The inset shows a magnified image of the indicated area. Scale bar indicates 200 µm.

Figure 5. Survival rate in the AC group.

(A) Kaplan-Meier method indicates survival rate of mice in the AC group (n = 29). (B) CBF images of the 4 non-surviving mice in the AC group which died during the second week. These mice died on the next day of last CBF measurement.