Kockx M M, Herman A G
Department of Pathology, AZ-Middleheim, Antwerp, Belgium.
Eur Heart J. 1998 Jul;19 Suppl G:G23-8.
Atherosclerotic plaques in coronary arteries are composed of a crescent-shaped mass of lipids separated from the lumen by a fibrous cap. Loss of smooth muscle cells (SMCs) in the fibrous cap could have serious consequences, since SMCs are the only cells in the cap that can synthesize collagen fibres type I and III. These fibres maintain the tensile strength of the fibrous cap. The role of cell loss and apoptotic cell death in the progression of atherosclerosis has received renewed attention recently in the literature. The large variability in the reported values for the percentage of apoptotic cells in plaques can be explained by the aspecificity of the TUNEL technique used to detect apoptosis. Despite this variability, there is no doubt that both SMCs and macrophages can die in plaques through apoptosis. The significance of macrophage apoptosis is very different from that of SMC apoptosis. Increased apoptosis of SMCs in the vulnerable regions of the plaque can result in weakening of the fibrous cap, whereas increased macrophage apoptosis can lead to plaque stabilization through decreased breakdown of collagen. Cytoplasmic remnants of apoptotic SMCs often remain in the plaque as matrix vesicles. These small calcium-containing vesicles could initiate plaque calcification.
冠状动脉粥样硬化斑块由新月形脂质团块组成，脂质团块与管腔之间由纤维帽分隔。纤维帽中平滑肌细胞（SMC）的丧失可能会产生严重后果，因为SMC是帽中唯一能够合成I型和III型胶原纤维的细胞。这些纤维维持着纤维帽的抗张强度。细胞丢失和凋亡性细胞死亡在动脉粥样硬化进展中的作用最近在文献中再次受到关注。报道的斑块中凋亡细胞百分比数值的巨大差异可以用用于检测凋亡的TUNEL技术的非特异性来解释。尽管存在这种差异，但毫无疑问，SMC和巨噬细胞都可以通过凋亡在斑块中死亡。巨噬细胞凋亡的意义与SMC凋亡的意义非常不同。斑块易损区域中SMC凋亡增加可导致纤维帽变薄，而巨噬细胞凋亡增加可通过减少胶原分解导致斑块稳定。凋亡SMC的细胞质残余物通常作为基质小泡留在斑块中。这些含小钙的小泡可引发斑块钙化。
