Related Experiment Video
Updated: May 17, 2026
Subcutaneous Angiotensin II Infusion using Osmotic Pumps Induces Aortic Aneurysms in Mice
Published on: September 28, 2015
Aneurysm formation in proinflammatory, transgenic haptoglobin 2-2 mice
Jacob Ruzevick1, Christopher Jackson, Gustavo Pradilla
1Department of Neurological Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
Background:
Inflammation and macrophages in particular are believed to play a role in aneurysm formation. The haptoglobin (Hp) 2-2 genotype is associated with a proinflammatory state.
Objective:
To investigate the role of inflammation in the formation of aneurysms using a murine model of aneurysm formation in transgenic, proinflammatory Hp2-2 mice and wild-type Hp1-1 mice.
Methods:
Carotid artery aneurysms were induced in the left common carotid artery of wild-type Hp1-1 mice and transgenic Hp2-2 mice using elastase to degrade the arterial wall of the common carotid artery and angiotensin II to induce hypertension. There were 4 experimental groups: (1) sham surgery (n = 11); (2) angiotensin II only (n = 10); (3) elastase only (n = 20); and (4) elastase + angiotensin II (n = 20). Aneurysm size was determined by measuring the outer circumference and luminal circumference of the blood vessel. Macrophages that infiltrated the aneurysm wall were quantified by immunohistochemistry. Results were analyzed using 2-way analysis of variance with a Bonferroni post-test.
Results:
Aneurysms in Hp2-2 mice were significantly larger than aneurysms in Hp1-1 mice in the setting of vessel wall degradation and hypertension (P = .02 for outer circumference, P = .01 for luminal circumference). Furthermore, the number of macrophages infiltrating the aneurysm wall was significantly increased in Hp2-2 mice (P < .001).
Conclusion:
Hp2-2 mice formed aneurysms that were significantly larger and had a significantly greater number of macrophages in the aneurysm wall compared with Hp1-1 mice. This suggests that the proinflammatory state associated with the Hp2-2 protein is involved in aneurysm formation and that the Hp genotype may be a useful biomarker in predicting aneurysm progression.
Insights
The haptoglobin (Hp) 2-2 genotype, linked to inflammation, resulted in larger aneurysms and more macrophages in mice. This suggests Hp genotype may predict aneurysm progression.
Area of Science:
- Vascular Biology
- Immunology
- Genetics
Background:
- Inflammation, particularly involving macrophages, is implicated in aneurysm development.
- The haptoglobin (Hp) 2-2 genotype is associated with a proinflammatory state, potentially influencing aneurysm formation.
Purpose of the Study:
- To investigate the role of inflammation in aneurysm formation using a murine model.
- To compare aneurysm development in transgenic, proinflammatory Hp2-2 mice versus wild-type Hp1-1 mice.
Main Methods:
- Carotid artery aneurysms were induced in Hp1-1 and Hp2-2 mice using elastase and angiotensin II.
- Aneurysm size was measured by outer and luminal circumference.
- Macrophage infiltration was quantified via immunohistochemistry.
Main Results:
- Aneurysms were significantly larger in Hp2-2 mice compared to Hp1-1 mice (P = .02 outer, P = .01 luminal circumference).
- Macrophage infiltration into the aneurysm wall was significantly higher in Hp2-2 mice (P < .001).
Conclusions:
- The proinflammatory Hp2-2 genotype is associated with increased aneurysm size and macrophage infiltration.
- Hp genotype may serve as a biomarker for predicting aneurysm progression.
More Related Videos
09:35Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection
Published on: February 2, 2018
09:37A Phenotyping Regimen for Genetically Modified Mice Used to Study Genes Implicated in Human Diseases of Aging
Published on: July 14, 2016