Three-dimensional cytoarchitecture of normal and atherosclerotic intima of human aorta.

The three-dimensional cytoarchitecture of normal and atherosclerotic intima of human aorta was studied by light microscopy of consecutive en face preparations (Hautchen preparations) and by scanning electron microscopy. In unaffected intima, a three-dimensional network consisting of cells of variable shape and probably origin was demonstrated. Cellular shape changed from predominantly stellate in the luminal regions of the elastic-hyperplastic layer to elongated spindlelike cells in the musculoelastic layer of the intima. In the surface layers of the fatty streak, cellular contacts were severed, and lipid droplets were often seen between cellular processes. Along with stellate and elongated cells, the fatty streak also had a number of round monocytelike cells. Lipid inclusions were usually detected in stellate and ovoid cells. The integrity of the cellular network was preserved at the marginal zone of the atherosclerotic plaque, while at the slopes and in the central part of the plaque, cells practically lost all contact with each other. Giant stellate cells embedded in crude fibrillar connective tissue matrix were often found there. Disintegration of the cellular network during atherosclerosis is suggested to play an important role in the development of various lesions.     

Ultrastructural analysis and electron microscopic localization of Nox4 in healthy and atherosclerotic human aorta

During diverse pathological conditions, vascular smooth muscle cells (SMCs) characteristically change from a quiescent, contractile phenotype to a proliferative, synthetic state, migrate toward the intima, and synthesize excess extracellular matrix. Although reactive oxygen species (ROS) are generally considered to be toxic to cells, recent evidence suggests that they may also modulate multiple signaling pathways. The vascular system contains several sources of ROS, among which NADPH oxidases (NOXes) have been shown to take an important part in the regulation of cell function, with effects on growth and proliferation. In the present study, the authors investigate the ultrastructural features of SMCs and the expression profile of Nox4 in healthy and atherosclerotic human aorta to explore the possibility of a relationship between Nox4 and SMCs differentiation state. The data extend at the level of immunoelectron microscopy previous observations, demonstrating for the first time the precise distribution and the differential expression of Nox4 in the morphologically distinct SMC types of healthy and diseased human aorta.     

Lipid metabolism in cells of the atherosclerotic human aorta. Experiments in primary culture

Bulletin of Experimental Biology and Medicine -     

Histochromatographical determination of cholesteryl ester composition in the human atherosclerotic aorta

In 14 human aortas, the cholesteryl ester (CE) composition of fatty spots was investigated histochromatographically. By a special method the intracellular lipid (foam cells) lying in the inner intima could be separated from the extracellular lipid found in the depth of the intima in many cases. The fatty acid pattern of CE of the intracellular lipid differed from that of the extracellular lipid by a relative increase in monoenoic acids (M) and trienoic acids (Tr) as well as by a relative decrease in linoleic acid (D), tetraenoic acids (Ar), and saturated fatty acids (S). In every case, the sum of the polyunsaturated fatty acids (PU) of CE (with 2 to 6 double bonds) was lower in the intracellular than in the extracellular lipid (highest difference: 23,2%, lowest difference: 5,7%). High differences of the PU-values between intra- and extracellular CE were associated with high or low D-values and with low values for Tr, Ar, and HU (high unsaturated fatty acids with more than 4 double bonds) of intracellular CE. Low differences of the PU-values between intra- and extracellular CE were accompanied with high D-values and medium or high values for Tr, Ar, and HU of intracellular CE. The results suggest that the cholesteryl esters in the intracellular lipid lose polyunsaturated fatty acids by the processes of hydrolysis and reesterification which are possibly used for other metabolic processes.     

脂蛋白（a）在主动脉粥样硬化病变中的定位与定量研究

脂蛋白（ａ）［Ｌｉｐｏｐｒｏｔｅｉｎ（ａ），Ｌｐ（ａ）］是动脉粥样化中的独立危险因子，我们采用免疫组织化学技术、免疫电镜技术、酶联免疫吸附法及图像分析技术，研究了正常及不同程度动脉粥样硬化病变的尸检主动脉中Ｌｐ（ａ）分布的量及形式。结果显示：动脉粥样硬化血管壁Ｌｐ（ａ）含量显著增高，各不同病变区域Ｌｐ（ａ）有其独特的分布规律，Ｌｐ（ａ）主要位于细胞外基质中，只在少数泡沫细胞内才发现有Ｌｐ（ａ）。Ａ     

Lipids in cells of atherosclerotic and uninvolved human aorta. III. Lipid distribution in intimal sublayers

The distribution, content, and composition of tissue and cellular lipids in intimal layers of unaffected and atherosclerotic human aorta were studied. Aortic tissue was divided into medial and intimal layers; the intimal layer was further separated into elastic-hyperplastic and musculo-elastic sublayers. Cells were isolated from both intimal layers by enzyme digestion. The lipids extracted from whole tissue and cells were separated by TLC and analyzed by scanning densitometry. The highest content of phospholipids (PhL), triglycerides (TG), cholesterol (C), and cholesteryl esters (CE) was detected in the elastic-hyperplastic layer of atherosclerotic plaque. However, taking into account that the elastic-hyperplastic layer of intima in lesioned areas was thickened, the lipid content per volume unit of both sublayers in fatty streaks and in plaques was equal. In the media underlying an atherosclerotic plaque, an increase in CE rather than in other lipid classes occurred. In the intima, an overall increase in PhL, TG, C, and CE content was found to display a constant ratio between these lipid classes, similar to that of low density lipoproteins (LDL). Cells isolated from atherosclerotic lesions had a higher lipid content than cells from areas of unaffected intima. However, the increase in the content of different lipid classes was not proportional, compared with tissue lipids. The content of PhL was the same, while an increase in TG, C, and CE was observed. The major contribution to excess cellular lipid accumulation in cells from atherosclerotic lesions was made by CE.(ABSTRACT TRUNCATED AT 250 WORDS)     

Combined histochemical and histostereometric evaluation of the morphogenesis of human aortic atherosclerotic plaques

Histochemical examinations of lipids, proteins and carbohydrates in aortal preparations from necropsy cases (54 males and 66 females) were combined with histostereometric examinations of the principal structural components of plaques. The lipid portion in the plaques was shown to decrease from 85.6 +/- +/- 4.9% in the stage of lipoidosis to 8.2 +/- 0.9% in the stage of ulceration. The portion of fibrous tissue is the highest in liposclerosis and atheromatosis of plaques (42.0 +/- 3.1 and 46.2 +/- +/- 1.2%, respectively) and that of necrotic and calcified tissues in the stage of ulceration (47.4 +/- 5.2 and 21.4 +/- 17%, respectively). Cellular infiltrations decrease markedly during plaque disintegration only. Such assessment is recommended for comparative studies in atherosclerosis.     

Monocyte-macrophage infiltration in portions of atherosclerotic lesions of the human aorta]

Human thoracic aorta was taken from trauma victims aged from 6 to 40 years. Cell composition of the intimal layer was investigated in the lesion predisposed (LP) areas of the aorta and in the lesion resistant (LR) areas. By double immunofluorescent staining with mono and polyclonal antibodies to monocytes/macrophages (Mn/Mph) and smooth muscle cells (SMC) the presence of Mn/Mph was revealed in all aortas studied. The number of these cells was 2-6 fold higher in LP areas, compared to LR areas in all persons over 21 years of age. Scanning electron microscopy revealed Mn on the luminal surface of the vessel the number of which was frequently higher in LP areas. Mn/Mph in LP areas were heterogeneous in their structure depending on the depth of their localization in the intima. The revealed Mn/Mph infiltration in aortas of young subjects may be the earliest manifestation of the atherosclerotic lesion.     

Lipids in cells of atherosclerotic and uninvolved human aorta. II. Lipid metabolism in primary culture

[3H]Acetate and [3H]oleate were used to evaluate the rate of lipid synthesis in smooth muscle cells of human aorta. Experiments were carried out in primary cultures derived from the intima and media of unaffected and atherosclerotic vascular segments. The obtained results indicate that the rate of lipid synthesis in cells cultured from fatty streaks, atherosclerotic plaques, and underlying media is higher than in cells cultured from an uninvolved intima and media, respectively. The highest level of the label incorporation was observed in the fraction of phospholipids. In cultures obtained from fatty streaks and plaques, an increased incorporation of the labeled precursors into phospholipids, triglycerides, free sterols, and sterol esters was registered. The highest relative increase occurred in the fraction of sterol esters, the rate of acetate inclusion being five- to sixfold higher compared to the cell cultures derived from unaffected aortic segments. A direct and very close correlation was found between the rate of lipid synthesis and lipid levels in cells of normal and atherosclerotic aorta. The role of intracellular lipid metabolism disorders in the accumulation of excessive fat by "atherosclerotic" cells is discussed in this report.     

Acid esterase in the aorta of the hyperlipidemic rat: a histochemical study.

In rats maintained for about three weeks on a diet inducing hyperlipidemia E-600 resistant acid esterase activities were markedly reduced in the aorta in comparison with untreated animals. In rats which were maintained on an ordinary diet containing the same amount of thiouracil as given to the hyperlipidemic animals, only a slight reduction of acid esterase activities was noted. Another group of animals was fed an ordinary diet for three weeks after three weeks on a hyperlipidemic diet. In the aorta of these animals the acid esterase activities were almost normal. There was little fat deposition in the aortas of animals given the various diets. No such effects on esterase activities were observed in the liver and lung of animals of the various groups. Inhibition of acid esterase activity was also observed in rats kept on a hyperlipidemic diet for 65 days. In these animals patchy deposition of partly anisotropic lipid was observed in the intima and media.     

Apolipoprotein A-1-derived amyloid in atherosclerotic plaques of the human aorta

Previous studies have shown that the amyloid localized to the aortic intima may be a biochemical entity different from other forms of localized amyloid. The amyloid fibril protein in one patient studied consisted of an N-terminal fragment of apolipoprotein A-1 (apo A-1). Since this patient was later shown to carry a missense mutation in the apo A-1 gene, leading to a deletion at position 107 of the mature protein, the question remained whether wild-type apo A-1 is amyloidogenic. In autopsy specimens from the thoracic aorta from 69 individuals, intimal atherosclerotic plaque-related amyloid was present in 11 cases (16%) and amyloid outside plaques in 37 cases (54%). The immunoreactivity of amyloid localized to the aortic intima was evaluated with the aid of antisera against N-terminal segments of apo A-1. The amyloid in association with atherosclerotic plaques was positively labelled by immunohistochemistry. The amyloid fibril protein from one patient, previously shown not to carry any mutation in the apo A-1 gene, was purified and shown by amino acid sequence analysis to be of apo A-1 nature. The result shows that wild-type apo A-1 is amyloidogenic and gives rise to a common localized form of amyloid associated with atherosclerosis.     

Localization of collagen-producing cells in normal and atherosclerotic intima of human aorta

Cells containing type I procollagen (PCI-cells) are identified immunocytochemically in grossly normal and atherosclerotic human aortic intima. Lipid streaks have the greatest content of these cells. PCl-cells are unevenly distributed over the intimal sublayers. They concentrate predominantly in the proteoglycan sublayer adjacent to the lumen. It is hypothesized that lipid accumulation by intimal cells stimulates collagen synthesis. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 123, No. 1, pp. 95–97, January, 1997     

Photodynamic treatment for atherosclerotic plaques of the rabbit abdominal aorta by the laparoscopical approach using a pheophorbide derivative

A new photosensitizer, PH-1126, was administered intravenously into the ear veins of cholesterol-fed atherosclerotic rabbits at a dose of 1 mg/kg of body weight. At 24 hr after PH-1126 administration, the atherosclerotic abdominal aorta was irradiated with a krypton ion laser with a wavelength of 647 nm by 100 J/cm² by the laparoscopical approach. Twenty-four hours later, the abdominal aorta irradiated by the laser beam was excised for histological analysis. In the atherosclerotic plaques with photodynamic treatment, damaged foam cells were observed by scanning electron microscopy and transmission electron microscopy. Some of these cells were exposed to the aortic lumen. No significant changes were shown in the abdominal aorta either with plaques not injected with PH-1126 or without plaques after photodynamic treatment. These findings suggest that atherosclerotic plaques of the abdominal aorta could be selectively degraded by laparoscopical photodynamic treatment.     

Intercellular contacts in portions of early atherosclerotic lesions of the human aorta]

The ultrastructure of human thoracic aortas collected at autopsy from 16 trauma victims aged from 3 to 40 years was investigated. Intercellular contacts were found in all aortas examined. The contacting cells localized predominantly in aortic areas predisposed to atherosclerosis, i. e. in areas situated around the ostia of the intercostal arteries. Most of contacting cells were monocytes--macrophages (Mn/Mph) which interacted with foam cell and intimal smooth muscle cells (SMCs). Only occasional contacts were formed by lymphocytes and endothelial cells. All intimal contacting SMCs were of the synthetic phenotype, i. e. they did not contain myofilaments and had well developed endoplasmic reticulum and Golgi apparatus. In thickened aortic intima the contacting cells were seen with the signs of destruction. The data obtained suggest that the contacts between intimal cells may be the consequence of the immune reaction directed to the transfer of information, cell cytolysis and utilization of cell debris.     

Analysis of the intermediate and basement membrane collagens in fibrous atherosclerotic lesions of human aorta

The collagens of fibrous atherosclerotic lesions of human aortae obtained at post mortem examination were compared with those of normal intima-media preparations. Assessed quantitatively, pepsin-solubilized types IV, V and VI collagens decreased in relation to types I and III in preparations from lesions as compared to values for controls. The type V collagen in both tissues were composed of alpha 1 (V) and alpha 2 (V) chains in a 2:1 ratio. A novel ("V") collagen polypeptide identical in size to the alpha 1 (V) chain was identified in association with the interstitial collagen fraction in both tissue types. This chain had unique solubility characteristics and cyanogen bromide peptide composition. The exact relation of this polypeptide to the other collagens is not known, but it is possible that it accounts for the reported fluctuations in type V chains in aortic tissues.     

Age and fibroplasia as preconditions for atheronecrosis in the human thoracic aorta

The atheronecrotic core of an aortic plaque is an easily recognized structural feature when present in histologic sections. This feature tends to be associated with other characteristics of the aorta, chief among these being old age, marked intimal fibroplasia, and diminished numbers of intimal smooth-muscle cells. The statistical relationships among these aortic characteristics were examined in a series of 356 autopsies. Intimal fibroplasia tended to be directly proportional to age. The density of smooth-muscle cells tended to be inversely proportional to intimal fibroplasia. The total cellularity of the intima was almost constant without regard to age or intimal thickness. The probability of finding atheronecrosis in a randomly chosen sample from the lateral thoracic aorta was directly proportional to age and to intimal thickness after appropriate mathematical transformations. Against this background of what is usual, two atypical kinds of lesion were identified.