Dingemans K P, Teeling P, Lagendijk J H, Becker A E
Department of Cardiovascular Pathology, University of Amsterdam, Academic Medical Center, 1105 AZ Amsterdam, The Netherlands.
Anat Rec. 2000 Jan 1;258(1):1-14. doi: 10.1002/(SICI)1097-0185(20000101)258:1<1::AID-AR1>3.0.CO;2-7.
Aortic distensability is the key to normal aortic function and relates to the lamellar unit in the media. However, the organization of the extracellular matrix components in these lamellar units, which are largely responsible for the distensability, is insufficiently known, especially in the human. We therefore performed a detailed ultrastructural analysis of these components. Thoracic aortas of 56 individuals (age 45-74 years), none of whom suffered from aortic disease, were studied by immunoelectron microscopy of elastin, collagen types I, III, IV, V, and VI, fibronectin, and fibrillin-1, and by ultrastructural histochemistry of proteoglycans, which were further characterized by enzymatic digestion. The elastic lamellae were closely associated with thick collagen fibers containing types I, III, and V collagen. Between these collagen fibers, numerous complex, circumferentially oriented streaks of elastin protruded from the lamellae. In contrast to what is usually reported in the aortas of experimental animals, the smooth muscle cells preferentially adhered to these ill-defined streaks rather than directly to the solid lamellae. Fibrillin-1- and type VI collagen-containing bundles of microfibrils (oxytalan fibers) were also involved in the smooth muscle cell-elastin contact. The smooth muscle cells were invested by basal lamina-like layers connecting them to each other as well as to the oxytalan fibers. Unexpectedly, these layers were abundantly labeled by anti-fibronectin, whereas type IV collagen, a specific basement membrane component, was mainly found in larger, flocculent deposits. The proteoglycans present were collagen-associated dermatan sulfate proteoglycan, cell-associated heparan sulfate proteoglycan, and interstitial chondroitin sulfate proteoglycan. Our observations demonstrate that the extracellular matrix in the human aorta is extremely complex and therefore differs from most descriptions based on experimental animals. They serve as reference for future studies on aortic diseases, such as aneurysmas and dissections.
主动脉扩张性是主动脉正常功能的关键，且与中膜的板层单元相关。然而，这些在很大程度上决定扩张性的板层单元中细胞外基质成分的组织情况，尤其是在人体中，还了解不足。因此，我们对这些成分进行了详细的超微结构分析。通过对弹性蛋白、I、III、IV、V和VI型胶原蛋白、纤连蛋白和原纤蛋白-1进行免疫电子显微镜检查，以及对蛋白聚糖进行超微结构组织化学分析（通过酶消化进一步表征），研究了56名个体（年龄45 - 74岁）的胸主动脉，这些个体均无主动脉疾病。弹性板层与含有I、III和V型胶原蛋白的粗胶原纤维紧密相连。在这些胶原纤维之间，大量复杂的、周向排列的弹性蛋白条纹从板层中突出。与实验动物主动脉中通常报道的情况不同，平滑肌细胞优先附着于这些界限不清的条纹，而非直接附着于坚实的板层。含有原纤蛋白-1和VI型胶原蛋白的微原纤维束（氧化弹力纤维）也参与了平滑肌细胞与弹性蛋白的接触。平滑肌细胞被类似基底膜的层所包裹，这些层将它们彼此连接以及与氧化弹力纤维连接。出乎意料的是，这些层被抗纤连蛋白大量标记，而IV型胶原蛋白，一种特定的基底膜成分，主要存在于较大的絮状沉积物中。存在的蛋白聚糖有胶原相关的硫酸皮肤素蛋白聚糖、细胞相关的硫酸乙酰肝素蛋白聚糖和间质硫酸软骨素蛋白聚糖。我们的观察表明，人类主动脉中的细胞外基质极其复杂，因此与基于实验动物的大多数描述不同。它们为未来关于主动脉疾病（如动脉瘤和夹层）的研究提供了参考。
