兔颈动、静脉移植桥血管狭窄模型的建立及其电镜观察

目的:建立兔颈动、静脉移植血管桥动物模型,观察移植桥血管内膜增生和狭窄的电镜下表现。方法:通过兔双侧颈动脉进行动脉桥和静脉桥的移植,形成双侧移植血管桥再狭窄动物模型。在第8周施行血管桥移植手术的同时留取右侧颈动静脉标本作为对照血管,再分别于第12周、16周和第20周分别处死模型兔,采集移植桥血管标本,在光镜下测量其内膜厚度、面积、狭窄度,并进行电镜观察。结果:颈动脉和颈静脉桥移植后,随着时间的延长,桥血管的出现平滑肌迁移,脂质沉积,内膜增生,血管狭窄等改变,且以静脉桥血管的病理改变更为明显。结论:在兔形成动脉粥样硬化病变基础上,进行双侧颈动脉血管桥的移植,建立兔双侧颈动脉移植血管桥再狭窄动物模型,有利于设立自身对照,研究术后动静脉桥再狭窄差异机制;建立动、静脉桥后,位于血管中膜的平滑肌细胞出现向血管内膜迁移现象,说明中膜平滑肌细胞迁移进入内膜导致新内膜形成是血管再狭窄的重要环节。     

球囊拉伤兔髂动脉内膜的组织形态变化的研究

球囊拉伤血管内膜是目前研究血管内膜增厚,管腔狭窄的方便而切实的模型。因此,对其演变过程的形态学研究是必要的。方法：应用ＰＴＣＡ球囊导管拉伤兔髂动脉,用光镜、电镜和扫描电镜观察拉伤后不同时间的动态变化。结果：拉伤后各期变化不同,拉伤后１周内,以血细胞沉积为主,１周后,内膜开始增生,２至４周增生最快。增生活跃的内膜平滑肌细胞来自活化的中膜平滑肌细胞。内皮细胞增生极慢,４周内未见内膜内皮化,呈虫食样改变。结论：球囊拉伤兔髂动脉内膜,可引起血栓形成,炎症反应,平滑肌细胞增生和细胞外基质堆积,导致血管腔狭窄。此研究为今后的工作提供一定的客观依据     

静脉桥狭窄家兔动物模型的建立

目的建立冠心病冠状动脉旁路移植术后移植静脉桥狭窄的动物模型。方法取3.0～3.5 kg普通新西兰兔8只,取同侧颈外静脉与颈总动脉进行端端吻合,吻合时采用间断缝合的方法。结果术后2周、4周取下静脉桥及对侧颈外静脉,光镜下见静脉桥新生内膜形成,中膜增厚,弹力纤维减少;胶原纤维不均匀性增厚。结论本模型能反映冠状动脉旁路移植术后静脉桥狭窄的情况,可满意模拟人冠状动脉旁路移植术后大隐静脉桥的病理变化。     

炎性因子IL-1βIL-18对静脉移植血管再狭窄影响的动物实验研究

目的：通过观察炎性因子白细胞介素-1β、白细胞介素-18在小鼠静脉移植后再狭窄血管中的表达,为临床冠脉搭桥术后血管再狭窄的早期诊断和药物治疗提供潜在靶点。方法：48只雄性小鼠,其中24只小鼠取出下腔静脉作为供体,采用套管法移植至另外24只小鼠的右颈动脉。建立颈动静脉血管移植模型,成活后随机分成三组每组8只,分别在一周、四周、八周处死,取移植血管,观察移植血管的通畅情况、血管内膜、中膜的增殖情况及炎性因子IL-1β、IL-18的表达;以供体血管作为对照组。结果：24只模型小鼠均存活,移植静脉血管内膜、中膜不同程度增生,免疫组化结果显示,正常静脉无明显炎症细胞侵润,移植静脉在一周时组织中大量MAC-2阳性单核巨噬细胞侵润,细胞因子IL-1β、IL-18的表达与正常静脉相比明显增加,、IL-18的表达分别为（9.52±1.81）%VS（0.82±0.12）%;（7.51±1.31）%VS（0.69±0.06）%,均为P〈0.05）。在四周、八周仍有大量巨噬细胞侵润,细胞因子IL-1β高表达,四周、八周IL-1β表达分别为（7.01±1.21）%、（2.48±0.62）%。移植静脉管壁逐渐增厚,管腔逐渐狭窄;与对照组静脉比较（56.15μm±4.65μm）,一周、四周、八周血管内膜厚度显著增厚分别为（204.26μm±24.29μm 551.83μm±35.00μm 723.90μm±127.42μm,均为P〈0.05）。结论：炎性因子IL-1β、IL-18在静脉移植血管再狭窄中的表达增加,参与静脉移植后血管再狭窄的发生,因此可通过抑制炎性因子IL-1β、IL-18来治疗冠脉搭桥后静脉再狭窄。     

血管内皮生长因子基因对兔髂动脉内膜损伤的组织形态变化过程的影响

探讨血管内皮细胞的特异丝裂原－血管内皮生长因子（VEGF）基因阻止血管内膜损伤后形成再狭窄的组织变化过程。建立球囊拉伤血管内膜的兔髂动脉模型,将携带VEGF目的基因的真核表达载体pcDNA3/VEGF经多聚赖氨酸处理的PTCA球囊导管导入拉伤的血管内膜。VEGF基因组拉伤2周时血管内壁有VEGF mRNA和蛋白的高表达。血管内膜内皮化较快。2周时即有许多血管内皮细胞呈岛状分布。4周时内膜基本恢复光滑。内膜平滑肌细胞增生明显减少,而对照组2周时血管内膜粗糙,基底膜暴露,拉伤后4周仍无内皮细胞再生,最后形成虫蚀样改变。血管中膜平滑肌细胞穿过内弹性膜进入内膜并大量增生,内膜增厚。VEGF基因定位导入血管内壁后。VEGF mRNA和蛋白高表达且发挥其生物学效应,内皮细胞岛状增生,加快内膜内皮化,减轻内膜增厚。     

家兔新型动脉粥样硬化狭窄模型的建立及其动态观察

目的　为血管成形术后再狭窄的研究提供非球囊扩张和动脉造影的简单易行的新型动脉粥样硬化斑块狭窄动物模型。方法　选择日本大耳白兔 18只 (含正常组 6只 ) ,用电刺激血栓形成仪刺激颈总动脉并在术后高脂饲料喂养 6周 ,模型分别于术后 3天、1周、3周、6周处死颈总动脉取材 ,常规病理切片行HE、弹力V G染色 ,光学显微镜观察病理变化。结果　术后 1周内动脉有血栓形成 ,内皮剥脱和部分内弹力板断裂 ,内皮细胞增生 ,中膜局部平滑肌细胞有少量水肿、消失 ,外膜有中性粒细胞浸润 ;术后 3周以上则内膜明显增生 ,内膜下脂质沉积 ,中膜平滑肌细胞核有轻度减少 ,纤维组织及基质增生 ,以损伤部位更明显 ,外膜刺激部位有轻度增厚。术后 6周 6只动物颈总动脉均形成管腔狭窄。结论　用电刺激加高脂饲料喂养的方法可成功建立动脉粥样硬化狭窄的动物模型 ;该模型的病理表现与人类动脉粥样硬化的病理过程相似 ,且避免了二次球囊造模法形成的血管盲端     

大鼠颈部自体静脉移植模型两种吻合方法的比较

目的比较间断吻合和连续吻合法建立静脉桥狭窄动物模型的优劣。方法SD大鼠20只,分成两组（间断吻合组和连续吻合组）,取颈外静脉与颈总动脉行端端吻合。术后4周取下静脉桥,观察桥管通畅性,分析新生内膜与中膜的厚度、面积比。结果连续组与间断组相比手术时间更短,出血更少,但桥管通畅率低,两组内膜增生程度没有显著差异。结论连续吻合用时短,出血少,对术者要求更高,较易形成吻合口狭窄。两者造模效果一样。     

冠状动脉旁路移植术桡动脉桥家兔模型的建立

目的建立一个能模拟冠状动脉旁路移植术桡动脉桥情况的模型。方法50只新西兰兔,股动脉与颈总动脉行端侧吻合,两吻合口之间的颈总动脉予以结扎。术后1、3、7、14、56d分别取完整动脉桥,进行肉眼观察,HE染色观察病理变化,弹力纤维染色,计算机测算血管内膜厚度、新生内膜中膜比指数;电镜观察血管内皮细胞变化。结果50只兔成功建立动脉桥,无手术及围手术期死亡,桥血管总通畅率为86％,对通畅的桥血管作形态学观测发现血管移植后7d起至56d内膜增厚有统计学差异。结论本动物模型可以较好地模拟冠状动脉旁路移植术桡动脉桥的情况。     

高压氧治疗对早期兔动静脉瘘模型中静脉血管平滑肌细胞增殖和迁移的影响

该文探讨了高压氧治疗对早期兔动静脉瘘模型中静脉血管平滑肌细胞增殖和迁移的影响。通过腺嘌呤诱导36只成年新西兰兔建立慢性肾衰模型,然后将其随机分为3组(每组12只):假手术组;单纯动静脉瘘组;高压氧治疗和动静脉瘘组。应用Masson染色检测静脉内膜增生和血管重塑的情况;免疫组化染色和Western blot检测α-SMA、PCNA、PDGF-BB、VEGF-A、TNF-α和MMP-9表达情况; RT-PCR检测α-SMA、PDGF-BB和VEGF-A表达水平。结果显示,相较于假手术组,单纯动静脉瘘组的静脉管壁弹力纤维明显增生,中内膜增厚,血管明显重塑。与单纯动静脉瘘组相比较,高压氧治疗和动静脉瘘组的弹力纤维增生受到抑制,以及相关的各目的蛋白和mRNA的表达水平下降。这说明,动静脉瘘术后,高压氧治疗可明显抑制动静脉瘘静脉血管平滑肌细胞的增殖和迁移,改善血管重塑。     

整联蛋白调控血管新生内膜增生的研究进展

血管新生内膜增生是支架植入术、动静脉瘘术等血管手术以及动脉粥样硬化、高血压等心血管疾病的生理特征。整联蛋白介导的细胞黏附在新生内膜增生过程中起着重要作用。该文概述了整联蛋白在此过程中对白细胞黏附、平滑肌细胞迁移增殖、再内皮化的调控及目前用于研究新生内膜的相关动物模型。了解整联蛋白调节血管新生内膜增生的分子机制,为临床上防治新生内膜增生、解决术后血管再狭窄等相关研究提供参考。     

External-beam radiation therapy for improved dialysis access patency: feasibility and early safety.

Rectenwald, J. E., Pretus, H. A., Seeger, J. M., Huber, T. S., Mendenhall, N. P., Zlotecki, R. A., Palta, J. R., Li, Z. F., Hook, S. Y., Sarac, T. P., Welborn, M. B., Klingman, N. V., Abouhamze, Z. S. and Ozaki, C. K. External-Beam Radiation Therapy for Improved Dialysis Access Patency: Feasibility and Early Safety. Radiat. Res. 156, 53-60 (2001).Prosthetic dialysis access grafts fail secondary to neointimal hyperplasia at the venous anastomosis. We hypothesized that postoperative single-fraction external-beam radiation therapy to the venous anastomosis of hemodialysis grafts can be used safely in an effort to improve access patency. Dogs (n = 8) underwent placement of expanded polytetrafluoroethylene grafts from the right carotid artery to the left jugular vein. Five dogs received single-fraction external-beam photon irradiation (8 Gy) to the venous anastomosis after surgery. Controls were not irradiated. Shunt angiograms were completed 3 and 6 months postoperatively. Anastomoses, mid-graft, and the surrounding tissues were analyzed. Immunohistochemistry for smooth muscle cell alpha-actin, proliferating cellular nuclear antigen (PCNA), and apoptosis was performed. Incisions healed well, though all animals developed wound seromas. One control suffered graft thrombosis 4 months postoperatively. Angiography/histology confirmed severe neointimal hyperplasia at the venous anastomosis. The remaining seven dogs developed similar amounts of neointimal hyperplasia. PCNA studies showed no accelerated fibroproliferative response at irradiated anastomoses compared to controls. Skin incisions and soft tissues over irradiated anastomoses revealed no radiation-induced changes or increase in apoptosis. Thus we conclude that postoperative single-fraction external-beam irradiation of the venous anastomosis of a prosthetic arteriovenous graft that mimics the situation in humans is feasible and safe with regard to early wound healing.     

Experience of vein grafting in G?ttingen minipigs.

We experimented with vein grafting surgery on G?ttingen minipigs. Using the internal jugular vein for the tissue graft, we performed side-to-side anastomosis to the carotid artery, to which it runs parallel. One key point in this surgery was to prevent vasospasm of the carotid artery so as to keep the lumen sufficiently patent during anastomosis. The histopathological findings in the grafts which remained patent resembled those of vein grafts in humans. We therefore considered that this technique in minipigs can be applied for the study of coronary artery bypass surgery in humans.     

The geometry of unstented and stented pig common carotid artery bypass grafts

The long-term success of arterial bypass grafting with autologous saphenous veins is limited by neointimal hyperplasia (NIH), which seemingly develops preferentially at sites where hydrodynamic wall shear is low. Placement of a loose-fitting, porous stent around end-to-end, or end-to-side, autologous saphenous vein grafts on the porcine common carotid artery has been found significantly to reduce NIH, but the mechanism is unclear. In a preliminary study, we implanted autologous saphenous vein grafts bilaterally on the common carotid arteries of pigs, placing a stent around one graft and leaving the contralateral graft unstented. At sacrifice 1 month post implantation, the grafts were pressure fixed in situ and resin casts were made. Unstented graft geometry was highly irregular, with non-uniform dilatation, substantial axial lengthening, curvature, kinking, and possible long-pitch helical distortion. In contrast, stented grafts showed no major dilatation, lengthening or curvature, but there was commonly fine corrugation, occasional slight kinking or narrowing of segments, and possible long-pitch helical distortion. Axial growth of grafts against effectively tethered anastomoses could account for these changes. CFD studies are planned, using 3D MR reconstructions, on the effects of graft geometry on the flow. Abnormality of the flow could favour the development of vascular pathology, including NIH.     

Numbers of cells and cell proliferation in intima of different human arteries

Increased cell proliferation in early atherosclerotic lesions is recognized as an essential event of atherogenesis but the levels of cell proliferation in different stages of atherosclerotic plague formation in different types of human large arteries are still insufficiently studied. In the present work, we studied intima thickness and proliferation of newly "infiltrates" hematogenous and resident cells in atherosclerotic lesions of the carotid and coronary arteries and compared these parameters with those in the aorta, reported by us in earlier publication. Analysis of intima thickness and proliferation in grossly unaffected intima and in different types pf atherosclerotic lesions (initial lesions, fatty streaks, lipofibrous, plaques, and fibrous plaque) revealed that although there were similar tendencies in the change of the infiltration levels of hematogenous cells and proliferation in different types of arteries, there were significant quantitative differences between different types of arteries. Hematogenous cells in lipofibrous plaques of the coronary and carotid arteries were found to account for a third and almost for a half of the total cell population, respectively, while atherosclerotic lesions in the aorta, as it has been shown by us earlier, to contain no more than 15% ofhematogenous cells. This suggests that the contribution of hematogenous cells to the development of atherosclerosis in the carotid and the coronary artery appears to be more significant than that in the aorta. Despite the differences in numbers of accumulating hematogenous cells in the intima, a similar "bell-shaped" dependence of cell numbers on the lesion type, involved in the following sequence: unaffected intima-initial lesions-fatty streaks-lipofibrous plaques-fibrous plaques, was detected in the coronary and carotid arteries. The visualization of proliferating cells (PCNA-positive) in atherosclerotic and unaffected zones of the coronary and carotid arteries revealed similar patterns. The maximum numbers of PCNA-positive resident cells were identified in lipofibrous plaques. The changes in the total cell numbers were accompanied by the changes in the numbers of both proliferating resident cells and proliferating hematogenous cells.     

Mechanical remodeling of small-intestine submucosa small-diameter vascular grafts--a preliminary report

Small-intestine submucosa (SIS) is cell-free, 100-mu-thick collagen derived from the small intestine. It has been used as a vascular graft and has the highly desirable ability to be remodeled to become histologically indistinguishable from native adjacent artery. To date there has been limited reporting of its preimplantation and explant mechanical properties as a vascular graft. In this study, compliance, elastic modulus, and burst pressure were measured on preimplant-tested 5- and 8-mm SIS grafts and two 60-day remodeled grafts. Seven prefabricated grafts were implanted in the carotid (n = 7) in dogs, which were sacrificed after 55-63 days. The animals (n = 4) weighed from 22 to 27 kg. One dog received a unilateral carotid graft, and 3 dogs received bilateral carotid grafts. The fabrication technique employed hand-suturing with either nonresorbable or resorbable sutures. None of the grafts had a patency failure. Angiograms taken at 1 month and just before explantation showed uniform flow and no dilation. At the time of explantation, all carotid grafts were found to be encased in fibrous tissue. The grafts made with nonresorbable sutures showed thicker tissue growth at the suture line compared with those made with the resorbable sutures. Along the suture line, the grafts made with resorbable sutures exhibited a more natural color than those sutured with nonresorbable sutures. When the explanted carotid grafts were slit open, the lumen was white, shiny, and glistening. The grafts sutured with nonresorbable sutures exhibited small areas of fibrin and red blood cells when the suture was within the lumen. The resorbable-sutured grafts did not exhibit this response. The mean compliance (percent diameter increase for a pressure rise from 80 to 120 mm Hg) was on average 4.6% (range, 2.9%-8.6%) for the 5-mm preimplant-tested grafts. For the 8-mm preimplant-tested grafts, the increase in diameter for the same pressure rise was 8.7%, on average (range, 7.2% to 9.5%). For comparison, the small-diameter SIS graft at the time of implantation was about one half as compliant as the adjacent dog carotid artery, about 4 times more compliant than a typical vein graft, and more than 10 times more compliant than synthetic vascular grafts. The compliance measured on two 60-day carotid grafts was 10.5% and 7.2%, respectively. This is midway between the original compliance value and the compliance of a typical canine carotid artery (14%), indicating that mechanical remodeling occurred. The modulus of elasticity (E) increased exponentially with increasing pressure according to E = E0e alpha P, where E0 is the zero-pressure modulus and alpha is the exponent that describes the rate of increase in E with pressure; the unit of measure for variables E, E0, and P is g/cm2. The mean value for E0 was 4106 gm/cm2 (range, 1348-5601). The mean value for alpha was 0.0059 (range, 0.0028-0.0125). At 100 mm Hg, the mean value for E was 8.03 x 10(6) dynes/cm2 (range, 4.95-15.7 x 10(6)). For a 60-day SIS graft implant, the elastic modulus at 100 mm Hg decreased from a high value at implant time to twice that of a typical native canine carotid artery. The mean burst pressure for 5.5-mm grafts was 3517 mm Hg (range, 2069-4654). The burst pressure of the remodeled carotid grafts averaged 5660 mm Hg. The burst pressure for a typical carotid artery is about 5000 mm Hg. The results of this preliminary study complement those of previous SIS-vascular-graft studies and add a new factor, namely that the mechanical properties of the remodeled graft approach those of the vessel it replaces.     

Increased Expression of Phosphorylated Polo-Like Kinase 1 and Histone in Bypass Vein Graft and Coronary Arteries following Angioplasty

Interventional procedures, including percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass surgery (CABG) to re-vascularize occluded coronary arteries, injure the vascular wall and cause endothelial denudation and medial vascular smooth muscle cell (VSMCs) metaplasia. Proliferation of the phenotypically altered SMCs is the key event in the pathogenesis of intimal hyperplasia (IH). Several kinases and phosphatases regulate cell cycle in SMC proliferation. It is our hypothesis that increased expression and activity of polo-like kinase-1 (PLK1) in SMCs, following PTCA and CABG, contributes to greater SMC proliferation in the injured than uninjured blood vessels. Using immunofluorescence (IF), we assessed the expression of PLK1 and phosphorylated-PLK1 (pPLK1) in post-PTCA coronary arteries, and superficial epigastric vein grafts (SEV) and compared it with those in the corresponding uninjured vessels. We also compared the expressions of mitotic marker phospho-histone, synthetic-SMC marker, contractile SMC marker, IFN-γ and phosphorylated STAT-3 in the post-PTCA arteries, SEV-grafts, and the uninjured vessels. Immunostaining demonstrated an increase in the number of cells expressing PLK1 and pPLK1 in the neointima of post PTCA-coronary arteries and SEV-grafts compared to their uninjured counterparts. VSMCs in the neointima showed an increased expression of phospho-histone, synthetic and contractile SMC markers, IFN-γ and phosphorylated STAT-3. However, VSMCs of uninjured coronaries and SEV had no significant expression of the aforementioned proteins. These data suggest that PLK1 might play a critical role in VSMC mitosis in hyperplastic intima of the injured vessels. Thus, novel therapies to inhibit PLK1 could be developed to inhibit the mitogenesis of VSMCs and control neointimal hyperplasia.     

Gore-Tex small-vessel angioplasty: A suitable substitute for the use of autogenous saphenous vein grafts

Autogenous saphenous vein has been the material of choice for small-vessel angioplasty and for circulatory access graft reconstruction. In an effort to conserve autogenous saphenous vein, we used expanded polytetrafluoroethylene (PTFE) grafts in 45 patients over a 12-month period. We used Gore-Tex(*) to reconstruct 17 circulatory access grafts, 16 carotid arteries, two brachial arteries, seven femoral arteries, and three popliteal anterior or posterior tibial arteries. The indications for reconstruction were chronic occlusion of the access grafts, trauma to the brachial and anterior tibial arteries, and atherosclerotic disease of the carotid, femoral, and popliteal-tibial arteries. Of the reconstructed circulatory access grafts, one failed immediately because of technical problems in the conduit, and one failed 11 months after reconstruction. All other grafts have functioned well and have produced a marked improvement in flow. Of the 28 patients who underwent reconstruction of arteries measuring 3 mm or less, two had patent arteries but died shortly after operation. The remaining 26 have been followed for one to 43 months. All reconstructed arteries are patent, and there have been no instances of distal embolization or false aneurysm formation. From this brief experience, we conclude that Gore-Tex is a suitable short-term alternative to saphenous vein for small vessel arterioplasty; it also may be the material of choice for reconstructing the outflow tract of occluded access grafts.