Lupu F, Danaricu I, Simionescu N
Institute of Cellular Biology and Pathology, Bucharest, Romania.
Atherosclerosis. 1987 Oct;67(2-3):127-42. doi: 10.1016/0021-9150(87)90273-5.
In atherosclerotic lesions of rabbits fed a cholesterol-rich diet, the lipid deposits of foam cells derived from monocytes, smooth muscle and endothelial cells were studied by physical, cytochemical and ultrastructural methods. Beginning with the third week of diet, the lipid material that could be visualized at the light microscope level by Oil red O and Nile red staining was progressively accumulated in the intimal cells of the atherosclerotic lesions. In the early stages of foam cell formation, the deposits occurred especially as intracytoplasmic non-membrane bound lipid inclusions (lipid droplets). In polarizing microscopy these appeared as a mixture of iso-, and anisotropic material. The latter were birefringent and showed an axial symmetry with a black cross image, suggesting that the lipids were in a liquid crystalline state. In chemically-fixed specimens, the content of lipid inclusions was preserved in various degrees. In freeze-fractured preparations they displayed a layered onion-like arrangement with smooth cleavage faces surrounding an amorphous core. Upon incubation with filipin, that specifically binds to 3 beta-hydroxysterols, the peripheral layers of the inclusions were labeled, revealing the existence of unesterified cholesterol. In the advanced stages of foam cell formation, lipids were additionally accumulated in the lysosomal compartment as polymorphic multilamellar structures concentrically arranged, with cleavage faces devoid of intralamellar particles. The presence of acid phosphatase showed that these features were modified lysosomes and were tentatively named lysosomal lipid bodies. In the latest stages examined cholesterol crystals developed within lysosomal lipid bodies usually enclosed in multilamellar structures. This lipid coat may represent the place of crystal formation and presumably acts as barrier for the turnover of the crystalline cholesterol, thus impeding plaque regression.
在喂食富含胆固醇饮食的兔子的动脉粥样硬化病变中，通过物理、细胞化学和超微结构方法研究了源自单核细胞、平滑肌细胞和内皮细胞的泡沫细胞的脂质沉积。从饮食的第三周开始，通过油红O和尼罗红染色在光学显微镜水平可见的脂质物质逐渐在动脉粥样硬化病变的内膜细胞中积累。在泡沫细胞形成的早期阶段，沉积物尤其表现为胞质内非膜结合脂质包涵体（脂滴）。在偏光显微镜下，这些表现为各向同性和各向异性物质的混合物。后者具有双折射性，并显示出带有黑色十字图像的轴对称性，表明脂质处于液晶状态。在化学固定的标本中，脂质包涵体的内容物在不同程度上得以保留。在冷冻断裂的制剂中，它们呈现出分层的洋葱状排列，光滑的裂解面围绕着一个无定形核心。在用特异性结合3β-羟基甾醇的制霉菌素孵育后，包涵体的外周层被标记，揭示了未酯化胆固醇的存在。在泡沫细胞形成的晚期阶段，脂质作为多态性多层结构同心排列在溶酶体区室中额外积累，裂解面没有层内颗粒。酸性磷酸酶的存在表明这些特征是修饰的溶酶体，暂称为溶酶体脂质体。在所检查的最新阶段，胆固醇晶体在溶酶体脂质体内形成，通常被多层结构包围。这种脂质包膜可能代表晶体形成的部位，大概作为结晶胆固醇周转的屏障，从而阻碍斑块消退。
