Angiogenesis and remodelling in human thoracic aortic aneurysms

Area of Science:

• Cardiovascular Biology
• Vascular Biology
• Pathology

Background:

• Thoracic aortic aneurysm (TAA) is a serious condition involving aortic wall dilation, potentially leading to dissection or rupture.
• All forms of TAA share common features, including significant tissue remodeling.
• Understanding the angiogenic processes in TAA is crucial for comprehending its pathogenesis.

Purpose of the Study:

• To investigate and characterize the angiogenic process in human thoracic aortic aneurysm (TAA).
• To determine the relationship between neo-angiogenesis and aortic wall remodeling in TAA.
• To analyze the expression profiles of angiogenic factors in TAA tissues.

Main Methods:

• Immunostaining to assess microvessel density and neovessel structure.
• Proteomic array analysis and ELISA to quantify angiogenic factors.
• Quantitative RT-PCR to determine gene expression levels of angiopoietins.
• Electron microscopy to examine endothelial cell junctions and mural cell coverage.

Main Results:

• Increased microvessel density was observed in the medial layer of TAA compared to healthy aortas.
• TAA tissues exhibited altered expression profiles of multiple pro- and anti-angiogenic factors.
• Neovessels in TAA showed defective endothelial junctions and poor mural cell coverage, leading to leaky vessels.
• Accumulation of plasminogen and albumin was noted in the media of TAA, associated with neovascularization.

Conclusions:

• This study reveals leaky neovessel formation in TAA media, associated with an imbalance of angiogenic factors.
• Neo-angiogenesis may play a role in TAA wall remodeling and weakening.
• The findings suggest that blood-borne zymogens deposited via leaky neovessels contribute to aortic wall pathology.