Basal lamina structural alterations in human asymmetric aneurismatic aorta

Area of Science:

• Vascular Biology
• Extracellular Matrix Research
• Aortic Disease Pathophysiology

Background:

• The basal lamina (BL) is vital for blood vessel structure and function, sensing the microenvironment for endothelial cells and pericytes.
• Abnormal remodeling of the extracellular matrix (ECM) is implicated in aortic dilation.
• Understanding BL composition changes is crucial for elucidating aortic aneurysm mechanisms.

Purpose of the Study:

• To investigate alterations in the composition and organization of the basal lamina (BL) in patients with aortic root aneurysm.
• To compare BL components between pathological aortic samples and healthy controls.
• To analyze regional differences in BL composition between the convexity and concavity of the aorta.

Main Methods:

• Surgical aortic wall specimens from 27 patients with aortic root aneurysm and 5 healthy controls were analyzed.
• Immunohistochemistry was used to examine BL organization.
• Molecular biology techniques (RT-PCR and Western Blot) assessed mRNA synthesis and protein levels of ECM components.

Main Results:

• Pathological aortic walls were thinner than normal controls.
• Significant changes in the three-dimensional arrangement of BL components were observed in aneurysmal samples.
• Collagen I, Laminin alpha2 chain, and Fibronectin levels decreased, while Collagen IV and Tenascin levels increased in pathological samples.
• Collagen IV was more abundant in the concavity, and Tenascin in the convexity of diseased aortas.

Conclusions:

• Aortic dilation is associated with significant remodeling of the basal lamina (BL) ECM.
• Specific changes in Collagen IV, Tenascin, Collagen I, Laminin alpha2, and Fibronectin contribute to aortic wall pathology.
• Asymmetrical distribution of Collagen IV and Tenascin correlates with the asymmetric nature of aortic dilation.