The role of type I collagen in aortic wall strength with a homotrimeric.

Abstract

PURPOSE:

Elastin and collagen (types I and III) are the primary load-bearing elements in aortic tissue. Deficiencies and derangements in elastin and type III collagen have been associated with the development of aneurysmal disease. However, the role of type I collagen is less well defined. The purpose of this study was to define the role of type I collagen in maintaining biomechanical integrity in the thoracic aorta, with a mouse model that produces homotrimeric type I collagen [alpha1(I)]3, rather than the normally present heterotrimeric [alpha1(I)]2 alpha2(I) type I collagen isotype.

METHODS:

Ascending and descending thoracic aortas from homozygous (oim/oim ), heterozygous (oim /+), and wildtype (+/+) mice were harvested. Circumferential and longitudinal load-extension curves were used as a means of determining maximum breaking strength (Fmax) and incremental elastic modulus (IEM). Histologic analyses and hydroxyproline assays were performed as a means of determining collagen organization and content.

RESULTS:

Circumferentially, the ascending and descending aortas of oim /oim mice demonstrated significantly reduced Fmax, with an Fmax of only 60% and 23%, respectively, of wildtype mice aortas. Oim/oim descending aortas demonstrated significantly greater compliance (decreased IEM), and the ascending aortas also exhibited a trend toward increased compliance. Reduced breaking strength was also demonstrated with longitudinal extension of the descending aorta.

CONCLUSION:

The presence of homotrimeric type I collagen isotype (absence of alpha2(I) collagen) significantly weakens the aorta. This study demonstrates the integral role of type I collagen in the biomechanical and functional properties of the aorta and may help to elucidate the role of collagen in the development of aneurysmal aortic disease or dissection.

• Authors: A G Vouyouka, B J Pfeiffer, T K Liem, T A Taylor, J Mudaliar, C L Phillips
• Journal: Journal of vascular surgery (J Vasc Surg) Vol. 33 Issue 6 Pg. 1263-70 (Jun 2001) ISSN: 0741-5214 [Print] United States
• PMID: 11389427 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Collagen
• Hydroxyproline

Topics

• Analysis of Variance
• Animals
• Aorta (cytology, physiology)
• Biomechanical Phenomena
• Collagen (metabolism)
• Culture Techniques
• Hydroxyproline (analysis)
• Mice
• Mice, Inbred Strains
• Mice, Transgenic
• Models, Animal
• Probability
• Sensitivity and Specificity
• Species Specificity
• Tensile Strength