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.
J Biomech. 2013 Nov 15;46(16):2787-94. doi: 10.1016/j.jbiomech.2013.09.003. Epub 2013 Sep 11.
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.
我们小组最近的研究表明，升主动脉夹层动脉瘤（ATAA）的分层强度低于对照（CTRL，非夹层升主动脉（ATA）），并且二叶式主动脉瓣（BAV）患者比三叶式主动脉瓣（TAV）患者的强度降低更为明显，表明 BAV 患者发生主动脉夹层的风险不同。我们假设主动脉瓣形态表型预测 ATA 中的纤维微观结构异常。为了验证这一假设，我们对人工解剖后 ATA 的纵向-径向（Z-RAD）和周向-径向（Θ-RAD）平面中的纤维微观结构进行了特征描述。使用多光子显微镜在 Z-RAD 和 Θ-RAD 平面上对 CTRL-ATA、BAV-ATAA 和 TAV-ATAA 的外-中膜和内-中膜进行成像，以观察胶原和弹性蛋白。使用基于图像的工具处理显微照片，以定量几种微观结构特征。在 BAV-ATAA 的外-中膜中，与 CTRL-ATA 相比，弹性蛋白在 Θ 轴周围更加波动，排列也不整齐，这与 BAV-ATAA 的心外膜-中膜半的 Θ 带拐点处的拉伸拉伸增加（1.28）相比，CTRL-ATA（1.13）。随着年龄的增长，TAV-ATAA 的外-中膜中胶原围绕 Z 轴变得更加波动，而弹性蛋白在 Z 轴上更加定向，胶原在 TAV-ATAA 的内-中膜中径向定向减少。这种内层纤维的微观结构差异，内层纤维的拉伸程度更大，而径向定向成分的破坏程度更大，可能与 TAV 患者的动脉瘤的发展、进展和血管重塑有关。
