Fiber micro-architecture in the longitudinal-radial and circumferential-radial planes of ascending thoracic aortic aneurysm media.
It was recently demonstrated by our group that the delamination strength of ascending thoracic aortic aneurysms (ATAA) was lower than that of control (CTRL, non-aneurysmal) ascending thoracic aorta (ATA), and the reduced strength was more pronounced among bicuspid (BAV) vs. tricuspid aortic valve (TAV) patients, suggesting a different risk of aortic dissection for BAV patients. We hypothesized that aortic valve morphologic phenotype predicts fiber micro-architectural anomalies in ATA. To test the hypothesis, we characterized the micro-architecture in the longitudinal-radial (Z-RAD) and circumferential-radial (Θ-RAD) planes of human ATA tissue that was artificially dissected medially. The outer and inner-media of CTRL-ATA, BAV-ATAA and TAV-ATAA were imaged using multi-photon microscopy in the Z-RAD and Θ-RAD planes to observe collagen and elastin. Micrographs were processed using an image-based tool to quantify several micro-architectural characteristics. In the outer-media of BAV-ATAA, elastin was more undulated and less aligned about the Θ-axis when compared with CTRL-ATA, which is consistent with increased tensile stretch at inflection point of Θ-strips of adventitial-medial half of BAV-ATAA (1.28) when compared with CTRL-ATA (1.13). With increasing age, collagen became more undulated about the Z-axis within the outer-media of TAV-ATAA, and elastin became more oriented in the Z-axis and collagen less radially-oriented within the inner-media of TAV-ATAA. This discrepancy in the micro-architecture with fibers in the inner layers being more stretched and with disrupted radially-oriented components than fibers in the outer layers may be associated with the development, progression and vascular remodeling in aneurysms arising in TAV patients.
Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA, United States; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, United States.
Alkiviadis
A
Tsamis
Julie A
JA
Phillippi
Ryan G
RG
Koch
Salvatore
S
Pasta
Antonio
A
D'Amore
Simon C
SC
Watkins
William R
WR
Wagner
Thomas G
TG
Gleason
David A
DA
Vorp
D000704:Analysis of Variance; D000784:Aortic Dissection / Q000473:pathology* / Q000503:physiopathology; D017545:Aortic Aneurysm, Thoracic / Q000473:pathology* / Q000503:physiopathology; D001019:Aortic Rupture / Q000473:pathology / Q000503:physiopathology; D001021:Aortic Valve / Q000473:pathology* / Q000503:physiopathology; D001696:Biomechanical Phenomena; D003094:Collagen / Q000032:analysis*; D004549:Elastin / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D036641:Microscopy, Fluorescence, Multiphoton; D008875:Middle Aged; D019800:Phenol; D017539:Tunica Intima / Q000737:chemistry / Q000473:pathology*; D017540:Tunica Media / Q000737:chemistry / Q000473:pathology*
D019800:Phenol; D003094:Collagen; D004549:Elastin
Collagen; Dissection; Elastin; Human ascending thoracic aortic aneurysm; Micro-architecture; Multi-photon microscopy