Thrombospondin deposition in rat carotid artery injury.

The balloon catheter injury model was used to determine the relative contributions of vascular smooth muscle cells (SMC) and platelets to thrombospondin (TSP) antigen deposition in the artery wall. Rat carotid arteries were denuded of endothelium, exposing the thrombogenic subendothelial extracellular matrix (ECM) to the circulation. Rats were killed after 1 hour, or 5, 10, or 20 days. Thrombospondin antigen deposition in the injured arteries was assessed using a specific polyclonal antiserum raised in rabbit against rat platelet TSP and a sensitive silver-enhanced immunogold staining method. Faint immunostaining for TSP antigen was detected, associated mostly with cells, in the media of the carotid artery of the nonoperated controls. One hour after balloon catheter injury, however, prominent cell-associated immunostaining was evident in the media; extracellular matrix staining was negligible. At this time, large foci of immunostaining were present on the lumenal surface of the vessel. Intimal proliferation was evident on most stained sections of tissue taken 5 days after balloon injury. Thrombospondin antigen immunostaining was markedly increased compared to nonoperated controls in all sections, regardless of the degree of intimal thickening. Thrombospondin immunostaining remained associated with cells in the neointima and media; extracellular matrix staining remained negligible. Ten days after endothelial injury, immunostaining for TSP antigen was detected in all layers of the artery, but was greater in the neointima and media. Reaction product was still associated only with cells. Thrombospondin antigen levels, as detected by this procedure, remained high in the injured tissue through 10 days of observation but appeared less prominent 20 days after injury. At this time extracellular matrix staining was obvious and cell-associated staining was reduced. These data support the hypotheses that thrombospondin (TSP) expression by vascular smooth muscle cells is an early response to injury and that the primary source of TSP antigen in injured artery is the vascular smooth muscle cells (SMC). These results support data derived from in vitro studies of TSP secretion.     

Protective effect of hydrogen sulfide on balloon injury-induced neointima hyperplasia in rat carotid arteries

Endogenous hydrogen sulfide (H(2)S), generated from homocysteine metabolism mainly catalyzed by cystathionine gamma-lyase (CSE), possesses important functions in the cardiovascular system. In this study, we investigated the role of H(2)S during the pathogenesis of neointimal formation induced by balloon injury in rats. CSE mRNA levels were reduced by 86.5% at 1 week and 64.0% at 4 weeks after balloon injury compared with the uninjured controls. CSE activity was also correspondingly reduced. Endogenous production of H(2)S in the injured carotid artery was significantly inhibited at 1 week and 4 weeks after balloon injury. Treatment with NaHS (a donor of H(2)S) enhanced methacholine-induced vasorelaxation of balloon-injured artery. More importantly, treatment with NaHS significantly inhibited neointima formation (0.15 +/- 0.01 mm(2) versus 0.21 +/- 0.01 mm(2), P < 0.001) of the balloon-injured carotid arteries and reduced the intima/media ratio (1.05 +/- 0.07 versus 1.43 +/- 0.06, P < 0.001). A significant decrease in vascular smooth muscle cell proliferation was demonstrated by bromodeoxyuridine incorporation at day 7 after injury. In conclusion, CSE expression and H(2)S production are reduced during the development of balloon injury-induced neointimal hyperplasia, and treatment with NaHS significantly reduces neointimal lesion formation.     

Fas ligand gene therapy for vascular intimal hyperplasia

Fas, a member of the tumor necrosis factor receptor super-family, is expressed in all cell types examined, while physiologic expression of Fas ligand (FasL) is found predominantly in activated T-lymphocytes, vascular endothelial cells, and "immune-privileged" tissues. Activation of Fas following FasL binding activates caspases, which results in apoptosis. In the vasculature, there may be a delicate balance between cell proliferation and apoptosis in vascular smooth muscle cells. Shifts in this balance could account for the accumulation of vascular smooth muscle cells in response to arterial injury, a major feature of vascular intimal hyperplasia. Intimal hyperplasia occurs in more than a third of patients receiving percutaneous transluminal balloon angioplasty. Stenting with or without coating significantly reduces the incidence rate of angiographic restenosis and that of target vessel revascularization. However, "in-stent" intimal hyperplasia/restenosis remains a challenge for clinical cardiologists. Although both the cell types and mechanisms that contribute to intimal hyperplasia in response to vascular injury remain controversial, vascular smooth muscle cell migration and proliferation appear to play an important role in the process. In animal models, cytotoxic and cytostatic gene therapy strategies targeted at the vascular smooth muscle cells have shown therapeutic potential for the treatment of vascular intimal hyperplasia. However, Fas ligand-based gene therapy appears to offer several advantages. In this review article, we will discuss the mode of FasL/Fas signaling in vascular smooth muscle cells and its therapeutic implications. We will also compare the relative merits of FasL with other cytotoxic and cytostatic gene therapy approaches for the treatment of intimal hyperplasia.     

Decorin inhibition of PDGF-stimulated vascular smooth muscle cell function: potential mechanism for inhibition of intimal hyperplasia after balloon angioplasty

Decorin is a small proteoglycan that binds to transforming growth factor-beta (TGF-beta) and inhibits its activity. However, its interaction with platelet-derived growth factor (PDGF), involved in arterial repair after injury, is not well characterized. The objectives of this study were to assess decorin-PDGF and decorin-PDGF receptor (PDGFR) interactions, the in vitro effects of decorin on PDGF-stimulated smooth muscle cell (SMC) functions and the in vivo effects of decorin overexpression on arterial repair in a rabbit carotid balloon-injury model. Decorin binding to PDGF was demonstrated by solid-phase binding and affinity cross-linking assays. Decorin potently inhibited PDGF-stimulated PDGFR phosphorylation. Pretreatment of rabbit aortic SMC with decorin significantly inhibited PDGF-stimulated cell migration, proliferation, and collagen synthesis. Decorin overexpression by adenoviral-mediated gene transfection in balloon-injured carotid arteries significantly decreased intimal cross-sectional area and collagen content by approximately 50% at 10 weeks compared to beta-galactosidase-transfected or balloon-injured, non-transfected controls. This study shows that decorin binds to PDGF and inhibits its stimulatory activity on SMCs by preventing PDGFR phosphorylation. Decorin overexpression reduces intimal hyperplasia and collagen content after arterial injury. Decorin may be an effective therapy for the prevention of intimal hyperplasia after balloon angioplasty.     

内皮型一氧化氮合酶基因转染对血管损伤后新生内膜增生的影响

背景：一氧化氮能够抑制血管平滑肌细胞的迁移和增殖,而一氧化氮合酶是其合成的关键酶,有关一氧化氮合酶基因体内转染对平滑肌细胞及动脉粥样硬化血管损伤后内膜增生影响少有报道。 目的：观察内皮型一氧化氮合酶 (endothelial nitric oxide synthase,eNOS)基因体内局部转染对动脉粥样硬化大鼠血管损伤后新生内膜增生的抑制作用。 方法：建立动脉粥样硬化Wistar大鼠颈动脉球囊损伤模型,建模后随机分成空白对照组、AdCMV-lacz对照组和AdCMV-eNOS组,分别将PBS,AdCMV-lacz和AdCMV-eNOS体内转染至以上3组大鼠的损伤血管壁。转染2周后培养并鉴定损伤局部平滑肌细胞,并用RT-PCR法检测各组损伤及转染后血管平滑肌细胞eNOS mRNA的表达,同时观察转染后不同时期新生内膜增生的影响。 结果与结论：AdCMV-eNOS组的颈总动脉血管平滑肌细胞可表达eNOS mRNA。3组大鼠转染后1和3个月,AdCMV-eNOS组内膜/中膜面积比值低于空白对照组和AdCMV-lacz对照组(P < 0.01)。结果显示,eNOS基因体内转染损伤后血管可以抑制血管新生内膜增生,减少再狭窄发生率。     

KLF4抑制球囊损伤诱导的新生内膜形成

目的： 通过腺病毒载体介导外源性KLF4在大鼠颈动脉球囊剥脱血管中进行表达,观察新生内膜增生情况,研究外源性KLF4对球囊损伤诱导的新生内膜形成的影响及初步探讨其机制。方法： 构建含有KLF4基因的重组腺病毒载体pAd-KLF4,将其导入内皮剥脱的血管壁。用HE染色观察血管新生内膜的厚度,免疫组织化学染色和RT-PCR分别检测外源性KLF4在血管中的表达以及与增殖和分化标志基因表达的关系。结果： 重组腺病毒pAd-KLF4可在血管壁中稳定表达KLF4。KLF4的过表达可显著抑制球囊损伤后血管新生内膜的增厚,转染pAd-KLF4的血管,其内膜/中膜比值（I/M）（0.52±0.15）明显小于pAd对照组（2.48±0.38）,P<0.05。pAd-KLF4组血管壁增殖标志蛋白PCNA和c-Jun表达也较pAd组明显降低（P<0.05）。结论： KLF4过表达可阻断损伤诱导的血管平滑肌细胞表型转化,进而抑制球囊剥脱后血管内膜的增生。     

Expression of cell cycle regulators during smooth muscle cell proliferation after balloon catheter injury of rat artery

Intimal hyperplasia is defined as the abnormal migration and proliferation of vascular smooth muscle cells (VSMCs) with deposition of extracellular matrix. However, the cell cycle regulatory mechanisms of injury-induced VSMC proliferation are largely unknown. To examine the expression kinetics of cell cycle regulatory factors which is known to be worked positively or negatively, we used rat balloon injury model. Marked induction of proliferating cell nuclear antigen (PCNA), G1/S cyclin-dependent kinase (cdk2), and its regulatory subunit (cyclin E) occurred between 1 and 3 days after balloon arterial injury, and this was sustained for up to 7 days and then declined. However, the induction of the negative regulators, p21 and p27, occurred between 3 and 5 days of injury, peaked after 7 and 14 days and was then sustained. VSMC proliferation after balloon catheter injury of the rat iliac artery is associated with coordinated expression of positive (cdk2, cyclin E and PCNA) and negative (p21, p27) regulators. Cell cycle regulators such as cdk2, cyclin E, p21, p27 may be suitable targets for the control of intimal hyperplasia.     

动脉粥样硬化大鼠血管损伤后局部组织学结构的变化

目的建立大鼠颈总动脉球囊损伤模型，了解血管成形术后再狭窄的发生规律及病理机制。方法在大鼠动脉粥样硬化病变的基础上，使用2F球囊导管损伤大鼠左侧颈总动脉，观察术后不同时期内膜、中膜增生的动态改变；对血管壁增殖的细胞进行鉴定；观察血管壁平滑肌细胞表型标志物SMα—actin表达的变化。结果损伤后7天薪生内膜开始形成，至3月时内膜增厚达最大，管腔明显狭窄，损伤动脉壁可见细胞大量增殖，大部分为平滑肌细胞。损伤早期血管壁表达SMα—actin减少，至损伤后期逐渐恢复至原有水平。结论应用球囊导管可以成功建立大鼠血管损伤动物模型，损伤后新生内膜增生导致管腔狭窄，平滑肌细胞的表型改变、迁移及增殖是内膜过度增生的病理基础。     

CD4+ mononuclear cells induce cytokine expression, vascular smooth muscle cell proliferation, and arterial occlusion after endothelial injury.

Studies of T cell-deficient or immunosuppressed animals undergoing arterial endothelial denudation have yielded conflicting results as to the contribution of the immune system to neointimal vascular smooth muscle cell accumulation and proliferation. We investigated the cell types and cytokine expression associated with intimal hyperplasia occurring 14 days after balloon angioplasty of the carotid artery in Sprague-Dawley rats. Immunohistological studies using monoclonal antibodies showed that the carotid luminal occlusion observed was associated with smooth muscle cell proliferation and neointimal accumulation of large numbers of CD4+, ED1+ mononuclear cells but no T cells. There was also wide-spread staining for the inflammatory cytokine interleukin-1B (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and IL-8, as well as dense expression of the potent smooth muscle mitogens platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), and protein S. The relationship of smooth muscle cell proliferation to monocyte/macrophage accumulation and cytokine expression was tested by daily intraperitoneal administration for 14 days of a rat CD4-specific monoclonal antibody, BWH-4 (500 micrograms/day). Morphometric analysis at day 14 showed that the intimal area of animals treated with CD4 monoclonal antibody comprised 7% +/- 4% of the arterial wall compared with 50% +/- 6% in control animals (n = 6/group, P < 0.001). In addition, immunohistological studies showed that CD4 monoclonal antibody treatment markedly reduced the intimal accumulation of mononuclear and smooth muscle cells and essentially abrogated expression of the cytokines PDGF-BB, TGF-beta, IL-1 beta, TNF-alpha, and IL-8, plus the anticoagulant molecule, protein S. Our results document the extensive expression in vivo of cytokines that in vitro promote vascular smooth muscle cell proliferation, and suggest that CD4+ mononuclear cells or their secreted products play a key role in the pathogenesis of intimal hyperplasia after endothelial injury. Furthermore, these observations may have clinical relevance in the development of novel strategies to prevent arteriosclerosis.     

Phenotypic features of smooth muscle cells during the evolution of experimental carotid artery intimal thickening. Biochemical and morphologic studies

Balloon catheter denudation of rat carotid artery that results in significant medial damage is followed by marked intimal smooth muscle cell (SMC) proliferation associated with limited endothelial regrowth. In this report we demonstrate that: (a) SMC of the carotid media, preceding their intimal proliferation, develop a cytoskeletal profile and morphology consistent with a de-differentiated SMC phenotype; and (b) both medial and intimal SMC subsequently revert to a cytoskeletal profile and morphology reflecting incomplete but significant re-differentiation toward normal SMC phenotype. Specifically, early after balloon injury, SMC of the media and those that have migrated into the intima contain decreased amounts of actin, desmin, and tropomyosin and increased amounts of vimentin; moreover, beta-actin becomes the dominant actin isoform, whereas alpha-actin decreases as compared with that found in normal medial SMC. Late after balloon injury, actin is still less abundant, however, desmin, tropomyosin, and vimentin return toward normal values and both medial and intimal SMC again show a predominance of alpha-actin, although the endothelium does not regenerate over the central surface of intimal thickening in this model. The SMC surface to volume ratio significantly decreases early after balloon injury, whereas it is not significantly different late after balloon injury as compared with that of SMC of the normal carotid media. We demonstrate, furthermore that: (c) adjacent luminal SMC are interconnected by gap junctions and develop focal tight junctions, a feature not reported previously to occur in smooth muscle; these cells however do not form any well defined membrane specialization with the leading edge of endothelium, supporting the view that presence of modified SMC on the luminal surface of chronically denuded vessels is not responsible for the cessation of endothelial regrowth.     

Intimal smooth muscle cell proliferation after balloon catheter injury. The role of basic fibroblast growth factor.

The localization and synthesis of basic fibroblast growth factor (bFGF) in the rat carotid artery were investigated at times of chronic smooth muscle cell proliferation. Immunocytochemical staining showed the presence of bFGF in the uninjured arterial wall, and after balloon injury, this cellular staining was decreased. Western and northern blot analyses likewise showed that the amount of bFGF protein and mRNA decreased after injury. A neutralizing antibody to bFGF was administered 4 and 5 days after injury and was found to have no effect on intimal smooth muscle cell proliferation. These data suggest that an increase in the expression of bFGF is not necessary for chronic smooth muscle cell proliferation observed after balloon catheter injury and that bFGF is not the major mitogen responsible for intimal smooth muscle cell proliferation.     

Basic fibroblast growth factor: its role in the control of smooth muscle cell migration.

The formation of an intimal lesion in an injured artery is the consequence of the replication and migration of smooth muscle cells. Recent studies have implicated basic fibroblast growth factor (bFGF) as an important mediator of replication in the arterial media, and platelet-derived growth factor as an important mediator of migration. However, the degree of arterial trauma produced during injury has a significant influence on the time of onset of intimal thickening, suggesting that factors released from damaged smooth muscle cells may affect migration. We have investigated the role of one of these factors, bFGF, in smooth muscle cell migration in vivo. We found that 1) deendothelialization of the rat carotid artery results in significantly more migration when it is accompanied by traumatic injury to the underlying smooth muscle; 2) the rate of migration in arteries that have been gently deendothelialized is significantly stimulated by systemic injection of bFGF; and 3) inhibition of bFGF with a blocking antibody significantly reduces the amount of migration after traumatic deendothelializing injury with a balloon catheter. These findings suggest that bFGF plays an important role in the mediation of smooth muscle cell migration after arterial injury.     

强力霉素影响基质金属蛋白酶活性和血管重构的实验研究

目的：观察强力霉素对损伤动脉组织中基质金属蛋白酶（MMP）活性的抑制作用，并探讨强力霉素对血管平滑肌细胞增殖、动脉内膜增生、管腔重构的影响。方法:球囊导管扩张动脉的方法建立大鼠颈总动脉损伤模型。治疗组用强力霉素30 mg·kg^-1·d^-1干预。明胶酶谱法测定损伤动脉组织中MMPs的活性。用HE染色、VVG染色、免疫组化标记α-actin和增殖细胞核抗原的方法观察损伤动脉内膜厚度、管腔重构及平滑肌细胞增殖的情况。结果:①强力霉素治疗组MMP-9活性在术后24 h、3 d分别比对照组低26.3％、34.5％（P<0.01）；MMP-2活性在术后7 d比对照组低40.0％（P<0.01）。②强力霉素治疗使术后7 d内膜平滑肌细胞增殖率（43.23％±1.06％）显著低于对照组（62.76％±1.02％）（P<0.01）；使术后14 d、28 d新生内膜厚度比对照组分别少32.0％、38.8％（P<0.01），而管腔面积比对照组多58.0％、90.4％（P<0.01） 。结论：强力霉素可以显著降低血管损伤后MMPs活性，抑制内膜平滑肌细胞的增殖、新生内膜增生以及管腔重构，提示它可能具有防治PTCA术后再狭窄的作用。     

氟伐他汀抑制球囊损伤后兔的血管内膜增殖

目的：探讨兔髂动脉急性损伤后，氟伐他汀对血管内膜增殖的抑制作用及机制。 方法： 给新西兰大耳白兔行右髂动脉球囊导管内膜剥脱术，术后灌胃予氟伐他汀（8 mg·kg-1·d-1）治疗28 d，术前、术后3 h及3 d用放射免疫法测定血清中内皮素-1、血栓素A2和前列环素浓度；28 d后HE染色观察血管内膜增生情况，免疫组织化学方法检测细胞外基质的变化。结果： ① 兔髂动脉急性损伤后血清内皮素-1及血栓素A2浓度即明显增加，前列环素水平则显著下降；氟伐他汀治疗显著抑制内皮素-1和血栓素A2的升高；提高血清前列环素的水平；② 氟伐他汀治疗减轻了内膜TGF-β1的过度表达及细胞外基质（FN、LN）的沉积；③ 氟伐他汀显著抑制了内膜的增殖和肥厚。结论：氟伐他汀治疗抑制血管损伤后血栓的形成，减轻了内膜的增殖及内膜中细胞外基质的沉积。     

Wound healing in the media of the normolipemic rabbit carotid artery injured by air drying or by balloon catheter de-endothelialization.

The response to air-dry injury to the carotid artery of the normolipemic rabbit was compared with the response to de-endothelialization with a balloon catheter. Air drying induced an inflammatory response that resembled arteritis rather than atherosclerosis. There was medial damage, neutrophil but not macrophage infiltration, and fibrin formation, limited smooth muscle proliferation, which regressed after 3 months, and no lipid deposition. Within 1 week the smooth muscle cells were mainly of the secretory phenotype, and a neointima had formed. At 4 weeks the neointimal proliferation continued, but most cells showed a contractile phenotype. By 3 months, the lesion consisted of fibromuscular thickening with few small smooth muscle cells. Balloon injury induced minimal medial damage and continuing intimal proliferation with no evidence of regression by 3 months. It is concluded that air drying the carotid artery induces smooth muscle damage as well as endothelial cell loss, and this stimulates a wound-healing mechanism that is different from the response to selective intimal injury.     

瑞舒伐他汀对大鼠颈动脉球囊损伤后细胞凋亡的影响

目的观察瑞舒伐他汀对大鼠颈动脉球囊损伤后细胞凋亡的影响。方法36只雄性SD大鼠随机分为对照组、损伤组和治疗组,每组12只。损伤组和治疗组分别建立大鼠左侧颈动脉球囊损伤模型,右侧颈动脉未予球囊损伤。治疗组于损伤前3d始连续每天给予瑞舒伐他汀5mg／（kg·d）灌胃,对照组和损伤组予9g／L氯化钠溶液灌胃。术后14d取左侧颈总动脉,进行HE染色和末端脱氧核苷酸转移酶介导的生物素-dUTP缺口标记技术（Terminal deoxynucleotidyl transferase biotin—dUTP nick end labeling,TUNEL）的凋亡检测。结果共30只大鼠成功完成本次实验。①血管损伤14d,可见明显的新生内膜;损伤组和治疗组的内膜面积、内膜／中膜面积的比值较对照组增大（P〈0．05）;与损伤组比较,治疗组内膜／中膜面积的比值减少,管腔面积增加26％（P〈0．05）。②对照组血管偶可见单个散在的凋亡细胞;损伤组凋亡细胞阳性率为（12．3±1．8）％,与对照组比较,差异有统计学意义（P〈0．05）;治疗组凋亡细胞数目增多,凋亡细胞阳性率达（26．8±3．2）％,与损伤组比较,差异有统计学意义（P〈0．05）。凋亡细胞主要位于新生内膜。结论瑞舒伐他汀可抑制大鼠颈动脉球囊损伤后的内膜增生,可促进大鼠颈动脉球囊损伤后的细胞凋亡。瑞舒伐他汀促进细胞凋亡的作用可能与其抑制内膜增生有关。     

藏红花素促进颈动脉损伤小鼠体内EPCs动员及损伤血管的再内皮化

目的:研究藏红花素对颈动脉损伤小鼠外周血中内皮祖细胞(endothelial progenitor cells,EPCs)动员的影响及其作用机制。方法:利用导丝损伤的方法构建C57BL/6小鼠颈动脉损伤模型,动物分为假手术组(sham组)、生理盐水处理模型组(model组)和藏红花素低、中、高剂量(10、50和100μmol·kg~(-1)·L~(-1))处理组。在3 d时,利用流式细胞术检测各组颈动脉损伤小鼠体内外周血中EPCs动员情况;7 d时,利用酶联免疫吸附法检测各组颈动脉损伤小鼠外周血血清中促血管修复因子——血管内皮生长因子(vascular endothelial growth factor,VEGF)、基质细胞衍生因子1(stromal-derived factor-1,SDF-1)、碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)、表皮生长因子(epidermal growth factor,EGF)和基质金属蛋白酶9(matrix metalloproteinase-9,MMP-9)的含量变化;14 d时,利用依文思蓝和苏木精-伊红染色分别检测各组颈动脉损伤小鼠损伤血管再内皮化和内膜增生情况;同时采用real-time PCR检测各组颈动脉损伤小鼠损伤段血管中促修复因子相关受体——血管内皮生长因子受体2(vascular endothelial growth factor receptor 2,VEGFR-2)、CXC趋化因子受体4(CXC chemokine receptor-4,CXCR4)、碱性成纤维细胞生长因子受体(basic fibroblast growth factor receptor,bFGFR)和表皮生长因子受体(epidermal growth factor receptor,EGFR)的mRNA表达水平。结果:与sham组相比,model组颈动脉损伤小鼠外周血中EPCs动员量和促血管修复因子VEGF、SDF-1、bFGF、EGF、MMP-9的含量上升(P0.05);损伤血管再内皮化面积下降而增生内膜面积和增生内膜与中层膜面积比显著升高(P0.05);损伤段血管中促修复因子相关受体VEGFR-2、CXCR4、bFGFR和EGFR的表达水平亦上升(P0.05)。而与model组相比,不同浓度藏红花素处理组颈动脉损伤小鼠外周血中EPCs动员量和促血管修复因子VEGF、SDF-1、bFGF、EGF、MMP-9含量均显著上升(P0.05);损伤血管再内皮化面积逐渐上升而增生内膜面积和增生内膜与中层膜面积比逐渐下降(P0.05);损伤段血管中促修复因子相关受体基因VEGFR-2、CXCR4、bFGF-R和EGFR的表达水平随之逐渐上升(P0.05)。结论:藏红花素能够促进颈动脉损伤小鼠体内EPCs细胞动员及损伤血管的再内皮化,从而对损伤血管发挥修复作用。     

Long-term engraftment of bone marrow-derived cells in the intimal hyperplasia lesion of autologous vein grafts

Intimal hyperplasia of autologous vein grafts is a critical problem affecting the long-term patency of many types of vascular reconstruction. Within intimal hyperplasia lesions, smooth muscle cells are a major component, playing an essential role in the pathological process. Given that bone marrow-derived cells may differentiate into smooth muscle cells in the neointima of injured arteries, we hypothesized that the bone marrow may serve as a source for some of the smooth muscle cells within intimal hyperplasia lesions of vein grafts. To test this hypothesis, we used an established mouse model for intimal hyperplasia in wild-type mice that had been transplanted with bone marrow from a green fluorescent protein (GFP+/+) transgenic mouse. High-resolution confocal microscopy analysis performed 2 and 8 weeks after grafting demonstrated expression of GFP in 5.4 +/- 0.8% and 11.9 +/- 2.3%, respectively, of smooth muscle cells within intimal hyperplasia lesions. By 16 weeks, GFP expression in smooth muscle cells was not detected by immunohistochemistry; however, real-time PCR revealed that 20.2 +/- 1.7% of the smooth muscle cells captured from the neointima lesion by laser capture microdissection at 16 weeks contained GFP DNA. Our results suggest that bone marrow-derived cells differentiated into smooth muscle cells within the intimal lesion and may provide a novel clinical approach for decreasing intimal hyperplasia in vein grafts.     

Coronary and thyroid arteriopathy induced by allylamine and β-aminopropionitrile

Broad breasted white male turkeys were fed four different diets: allylamine fumarate (AL), AL plus β-aminopropionitrile (BAPN), BAPN alone, and a control diet. Twice as many turkeys died of internal hemorrhage when fed BAPN and AL, as compared to those fed only BAPN. None fed AL alone or the control diet died. Arterial blood pressure was highest in turkeys fed BAPN or the control diet. Light microscopic lesions of the coronary and thyroid arteries were seen only in turkeys fed BAPN and AL, or AL alone. There was intimal hyperplasia, hypertrophy of medial smooth muscle cells, and hyalinization of vascular walls which did not exhibit intimal hyperplasia. Lesions were more prominent in turkeys fed BAPN and AL. Electron microscopic lesions of the coronary artery also were seen only in turkeys fed BAPN and AL, or AL alone. Intimal hyperplasia was manifested as several rows of smooth muscle cells above the internal elastic membrane. Smooth muscle cells in both the hyperplastic intima and also the tunica media contained closely packed myofilaments and prominent attachment points. Rare medial smooth muscle cells were electron lucent due to mitosis, while others were infrequently electron-opaque because of necrosis. Small arterioles without intimal thickenings had lumens which were almost occluded and their medial smooth muscle cells were edematous. The walls of hyalinized arterioles contained intertwined bundles of striated fibers.