新型可降解支架治疗食管吻合口瘘的疗效分析

目的:评价新型生物可降解支架治疗颈部食管吻合口瘘的效果,为治疗食管吻合口瘘提供理论依据。方法:将成年健康新西兰大白兔采用切开吻合置管造瘘法建立颈部食管吻合口瘘的动物模型,1周后,食管造影确定食管瘘口完成。完全随机分组,空白对照组(A组,n=5),对照组(B组,n=5)和实验组(C组,n=5)。实验组使用生物可降解支架封闭瘘口,而对照组应用同规格不可降解支架封堵食管瘘口。植入后每周行食管造影,观察支架及瘘口情况,植入后8周为实验终点。结果:本研究成功建立了兔颈部食管吻合口瘘的动物模型,至实验终点,普通支架组,支架覆盖瘘口,未发生支架移位及穿孔等现象。新型可分解支架组,3例支架分别在支架植入后5-8周分解,发生移位。实验组与对照组闭合率无统计学意义(4/5比3/5,P0.05)。结论:新型生物可降解支架支架是治疗食管吻合口瘘的一种有效方法。     

仿生技术构建小口径人造血管

目的：研究以改性猪小肠粘膜下层组织(SIS)为支架,利用仿生技术构建小口径人造血管的可行性。方法：自犬隐动脉分离出血管内皮细胞和平滑肌细胞,与胶原蛋白凝胶均匀混合,分别种植于改性SIS膜表面,制成3 mm 仿生三层人造血管为实验组;制成单层人造血管为对照组,分别植入修复15例犬双侧股动脉缺损,术后进行彩超、组织学检测和电镜检测鉴定。结果：植入12周,14个仿生人造血管保持通畅,通畅率93.3%,有血管样生物结构形成,管腔内壁有完整的内皮覆盖,管壁中层见大量平滑肌细胞;对照组通畅率60%,有少许内皮细胞覆盖。结论：仿生小口径人造血管具有良好的血液相容性,并能在体内保持良好通畅性, 修复动脉缺损效果满意。     

血管镜下原位下肢动脉旁路术

作者经对27条肢体行动脉重建术,证明血管镜直视下可完全切开静脉移植物瓣膜,可准确定位结扎静脉属支,从而避免了术后动静脉瘘,避免了全程游离大隐静脉所造成的热缺血损伤并发症。血管镜可在术中监控移植物和吻合口质量。作者所设计应用的”复合移植物”和“共同流出道”技术有效地提高了静脉移植物的使用率,扩大了流出道的吻合口径和血流量。本组肢体救治率为25/27肢,在2～13个月随访期间吻合口均通畅,踝压由术前25.5±1.2mmHg上升为术后40.2±0.4mmHg,趾压由16.0±0.3上升为28.3±1.1(均值±S)。表明本手术在下肢动脉重建中具有良好的实用价值和独特的优点。     

静脉移植物对下肢动脉旁路术疗效的影响

自体静脉的预存病变及术后内膜增生是影响下肢动脉旁路术中远期通畅率的主要因素。对上述病变的及时查出和剔除,是提高术后通畅率的关键措施。对静脉移植物进行质量检测的主要方法包括静脉造影、彩超及血管镜。其中血管镜是更为先进的检测手段。随着对静脉移植的精细检测和及时剔除病变,透彻理解内膜增生的病理过程并采取相应的防治措施,下肢动脉旁路术后的中远期通畅率必将明显提高。     

部分股骨移植:一个新的带血管的骨髓移植模型

目的:大鼠后肢移植是带血管的骨髓移植的主要模型,同时含有骨髓和骨髓微环境,有利于免疫耐受的诱导.但其成分复杂,为研究其中骨髓的作用,构建一个成分相对单一的带血管的骨髓移植模型.方法:以MHC不相符的近交系Lewis和BN大鼠分别作为供体或受体,将含血管蒂的供体2/3股骨移植到受体腹股沟区,显微吻合供受体间的股动静脉.实验分为3组:同基因移植组Lewis→Lewis;排斥组Lewis→BN;免疫抑制组Lewis→BN,术后给予环孢素A.通过大体和病理学检查观察各组移植物存活情况,外周血流式监测排斥组和免疫抑制组的嵌合水平.结果:术后7d,排斥组排斥反应显著,骨髓细胞明显减少、坏死,外周血嵌合水平几乎为0,而同基因移植组股骨存活良好,骨髓HE染色大致正常,可见髓腔内有大量的嗜碱性骨髓细胞;术后60 d,同系移植组和免疫抑制组的大体观察及组织病理学大致相同,均证实移植物存活良好,同时流式可见免疫抑制组术后7、28、60 d外周血中存在供体特异性的嵌合.结论:带血管蒂的部分股骨移植物是一个简便可靠的带血管的骨髓移植模型,嵌合分析表明其具有诱导耐受的潜能,有利于阐明异体复合组织中骨髓对免疫耐受诱导的作用和机制.     

不同移植物对兔前叉韧带重建术后血运变化的影响

目的：比较自体和同种异体半肌腱重建兔前叉韧带对血管生成的影响。方法：选择48 只骨骼发育成熟的新西兰种属兔作为 研究对象,将其随机分为自体组(A 组)和异体组(B 组),每组24 只,分别接受半肌腱重建前叉韧带手术。从手术日期开始,分别记 录手术后第3 周、第6 周、第12 周和第24 周重建韧带的血管生成情况同时对血管生成数量进行定量。结果：手术后两组实验兔 关节均无肿胀,关节囊无炎性反应发生。在手术后第3 周,两组血管生成无明显差异(P>0.05);术后第6 周和第12周,自体移植组 新生血管数量明显高于异体移植组(P<0.05);术后第24 周,异体组新生血管数量明显高于自体组(P<0.05)。结论：在兔前叉韧带的 重建过程中,异体移植物重建的血管生成速度和数量明显慢于自体移植物,提示在临床上选择自体移植物对术后恢复更理想.     

在心外科异种膜状移植物组织内种植人体活性细胞的方法

目前临床的应用的心外科膜状移植物主要有心脏瓣膜和血管两种移植物。由于现有的各种心外科膜状移植物尚无法令人满意,因此国外正在研究一种先清除异种膜状移植物组织内原有的细胞、再在已清除组织内原有细胞的异种膜状移植的人种植人体活性细胞的方法。将新鲜异种膜状移植物先经高、低渗溶液处理,然后用酶溶液处理,以清除异种膜状移植物组织内原有细胞。人体细胞经培养分离后,将成纤维细胞和平滑肌细胞植入已清除组织内原有细胞的异种膜状移植物组织内,再植入内皮细胞。种植人体活性细胞的异种膜状移植物不会促使受体产生有害的免疫反应,并具有再生能力。     

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。     

小型猪胰腺移植急性排斥反应模型的实验研究

目的　建立小型猪胰腺移植动物模型 ,探索早期诊断急性排斥反应的方法。方法　 4 0只猪随机配对行胰腺移植 2 0次 ,将供胰所带的血管与受体髂血管吻合 ,所带小段十二指肠与空肠吻合 ,术中监测平均动脉压、中心静脉压及血气。术后测定受体的血淀粉酶、血糖 ,监测外周血免疫指标 ,彩色多普勒检测供胰血流及超声引导下活检、组织病理检查。结果　移植手术成功率为 90 % ,受体平均动脉压在吻合血管开放后有明显下降 ,与血流开放前差异有显著性 (P <0 0 5 ) ,输血有助于手术成功 ,受体术后平均存活 (12 6± 2 3)d。外周血免疫学监测指标早于供胰的组织病理改变 ,两者的改变均早于急性排斥反应的临床表现。结论　小型猪适用于胰腺移植模型的建立 ,加强术中循环功能的管理、及时输血有利于受体成活 ;超声引导下穿刺活检供胰的组织病理学检查与监测外周血免疫指标均适于早期诊断急性排斥反应     

丹参对冻融入胎儿卵巢组织异种移植早期血管生成的影响

目的：研究冻融人胎儿卵巢组织移植早期血管生成过程中微血管形态和密度的改变以及血管生成相关基因mRNA的表达;探讨丹参注射液对移植物血管生成的影响。方法：冻融胎儿卵巢组织异种移植至裸鼠肾被膜下,按给药不同分为对照组（生理盐水）和丹参组（丹参注射液每只0．09g／d）,分别于移植后48h、7d和28d回收移植物。结果：移植后两组卵巢组织微血管密度均明显增多;对照组移植后7d血管密度达峰,丹参组血管密度在移植后48h即已显著上升,此后两个时间段保持相对平稳。Angiopoietin-2mRNA表达在移植后48h两组均显著升高,丹参组上升幅度大于对照组（P〈0．05）。结论：冻融人胎儿卵巢组织新血管生成开始于异种移植后48h内,移植后7d组织内微血管密度达峰。丹参在移植早期应用可以促进移植后血管生成,其机制可能与它增加了血管生成相关因子Ang-2mRNA的表达有关。     

Revascularized periosteal grafts--a new method to produce functional new bone without bone grafting

Rib periosteum was transplanted to the groins of 9 dogs. In half of the periosteal grafts, no microvascular anastomoses were done (free grafts); at 6 weeks after grafting they had become resorbed. The other periosteal grafts were revascularized by microvascular anastomoses of the intercostal vessels to local muscular vessels; at 6 weeks those with confirmed vascular patency had all formed substantial amounts of new bone. Five cm, full-thickness defects were created in the tibias of 10 dogs. The control animals (without grafting) did not heal in two months. However, the experimental dogs, with vascularized periosteal grafts in the defects regenerated their tibias with healthy new bone by 6 weeks--and were walking on them then.     

Comparison of lymphatic and venous interpositional autografts in experimental microsurgery of the canine lymphatics

In mongrel dogs, 56 autologous lymphatic and vein grafts were interpositioned to bridge a defect in the femoral collecting lymphatics. In one group, 26 lymphatic autografts were interpositioned with good results. No obstruction was observed over 6 months. In another group, 20 venous autografts were interpositioned after irrigation with heparinized saline and another 10 autografts were interpositioned without irrigation. After 1 week, four irrigated grafts were partially occluded with a red thrombus; after 6 months, all grafts were totally occluded. In a third group, 15 lymphaticolymphatic anastomoses were enveloped by a silicone sheet to provoke prolonged devascularization. None of the vessels was patent. Anastomotic patency was inspected in vivo postoperatively. The specimens were studied with light microscopy and scanning and transmission electron microscopy. Prolonged devascularization damaged the endothelial cells. The results show that the lymphatic vessel autograft is the best choice for an interpositional autografting to bridge a defect in lymphatic vessels.     

Development of Small Diameter Nanofiber Tissue Engineered Arterial Grafts

The surgical repair of heart and vascular disease often requires implanting synthetic grafts. While synthetic grafts have been successfully used for medium-to-large sized arteries, applications for small diameter arteries (<6 mm) is limited due to high rates of occlusion by thrombosis. Our objective was to develop a tissue engineered vascular graft (TEVG) for small diameter arteries. TEVGs composed of polylactic acid nanofibers with inner luminal diameter between 0.5 and 0.6 mm were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice. Twelve mice were given sham operations. Survival of mice with TEVG grafts was 91.6% at 12 months post-implantation (sham group: 83.3%). No instances of graft stenosis or aneurysmal dilatation were observed over 12 months post-implantation, assessed by Doppler ultrasound and microCT. Histologic analysis of explanted TEVG grafts showed presence of CD31-positive endothelial monolayer and F4/80-positive macrophages after 4, 8, and 12 months in vivo. Cells positive for α-smooth muscle actin were observed within TEVG, demonstrating presence of smooth muscle cells (SMCs). Neo-extracellular matrix consisting mostly of collagen types I and III were observed at 12 months post-implantation. PCR analysis supports histological observations. TEVG group showed significant increases in expressions of SMC marker, collagen-I and III, matrix metalloproteinases-2 and 9, and itgam (a macrophage marker), when compared to sham group. Overall, patency rates were excellent at 12 months after implantation, as structural integrity of these TEVG. Tissue analysis also demonstrated vessel remodeling by autologous cell.     

The use of cryopreserved arteries as arterial vascular prostheses]

The aim of the study is investigation of possibility to bypass small and medium-size arteries with cryopreserved artery allografts, storing 7-10 days at -196 degrees C under the protection of 15% dimethylsulfoxide. In experiments on 40 rabbits were placed a region of the left renal artery by cryopreserved bioprosthesis. Graft patency was 80% after observation up to 6 months. By angiography it was 8 cases of graft thrombosis (all during the 1st week after implantation) and 5 cases of moderate graft dilation (in 4 of them it was accompanied with stenosis of distal anastomosis). In 20 dogs we replaced a region of the femoral artery by cryostoring bioprosthesis. It was only one case of graft thrombosis which occurred on month 2 after the implantation during 1-year follow-up. After 3 months in 3 cases there developed 3 cases of diffuse narrowing of graft lumen without decreasing of blood flow through the prosthesis. Later, the graft lumen did not change. Histological investigations have revealed a viability of cryopreserved vessels, its almost complete de-endothelialization at 3 days and total re-endothelialization 2 weeks after implantation. During the first 2 weeks there were morphological events of graft rejection, which disappeared after 3 months.     

Remodeling of an acellular collagen graft into a physiologically responsive neovessel.

Surgical treatment of vascular disease has become common, creating the need for a readily available, small-diameter vascular graft. However, the use of synthetic materials is limited to grafts larger than 5-6 mm because of the frequency of occlusion observed with smaller-diameter prosthetics. An alternative to synthetic materials would be a biomaterial that could be used in the design of a tissue-engineered graft. We demonstrate that a small-diameter (4 mm) graft constructed from a collagen biomaterial derived from the submucosa of the small intestine and type I bovine collagen has the potential to integrate into the host tissue and provide a scaffold for remodeling into a functional blood vessel. The results obtained using a rabbit arterial bypass model have shown excellent hemostasis and patency. Furthermore, within three months after implantation, the collagen grafts were remodeled into cellularized vessels that exhibited physiological activity in response to vasoactive agents.     

Late results of aortocoronary bypass grafts in 100 patients with stable angina pectoris

From March 1969 to December 1972, 314 patients underwent elective aortocoronary saphenous vein bypass graft surgery at the Toronto General Hospital for the relief of stable disabling angina refractory to medical management. Inhospital mortality was 2.5%. Of these patients 100 agreed to return for follow-up hemodynamic and angiographic assessment at a mean interval of 19.7 months after operation. Seventy-four percent of patients were asymptomatic or had angina only with strenuous exertion at the time of follow-up. Seventy-five percent of the 142 grafts were patent, though a few had significant narrowings. Clinical improvement could be correlated with successful myocardial revascularization. Myocardial infarction was diagnosed by the presence of new Q waves after operation in 15% of patients. Many of these patients had patent grafts at follow-up and all were improved. Dyslipoproteinemia was not found to be a factor affecting late graft patency. Total left ventricular function was not shown to be improved by segmental revascularization. The trend toward improved survival in the intervening period for the total operated group is encouraging.     

In vivo study of a model tissue-engineered small-diameter vascular bypass graft

Conventionally used vascular grafts such as polyester (Dacron) or expanded polytetrafluoroethylene perform inadequately as small-diameter vascular bypass grafts (SDBGs). SDBGs, which can maintain long-term patency and those that could potentially evolve with the somatic growth, are highly desirable in vascular surgery and thus research into tissue-engineered blood vessels (TEBVs) is of keen interest. A TEBV was developed by seeding endothelial cells onto a collagen matrix that was cross-linked and contracted by smooth muscle cells (SMCs). A polyester graft served as a scaffold. Recovery studies (12 TEBVs and seven controls) were carried out to assess in vivo endothelialization and long-term patency of TEBVs. Hemodynamic observations indicated para-anastomotic turbulences and high shear stress at anastomosis. Recovery studies demonstrated confluent endothelialization, thrombus-free surfaces, and patent TEBVs in all cases. Graft incorporation and neovascularization of the scaffold occurred in both hybrid and control grafts. However, thickened neointima formation occurred in TEBV grafts, which was most likely caused by the rigidity of polyester scaffold. Significant perigraft inflammatory changes could be observed in both TEBVs and control grafts at 1, 4, and 8 weeks. In conclusion, the TEBVs demonstrated satisfactory performance as an infra-renal-aortic graft in a porcine model. The TEBV serves as a promising model and facilitates the development of a TEBV in a clinical setting, potentially with human stem cells and with more biocompatible, biodegradable scaffolds that are mechanically more compliant with natural vessels.     

The long-term fate of microvenous autografts

Changes in length, external diameter, wall thickness, and morphology were examined in 60 intraarterial vein grafts and 30 intravenous vein grafts inserted in rabbit femoral vessels. Half of each graft type was explored at 6 or 12 months, giving four experimental groups. The overall patency for intraarterial grafts at exploration was 98 percent and for intravenous grafts 100 percent. In comparison with the initial graft length resected, all four groups were significantly shorter at the completion of anastomosis, and three of the four groups also were significantly shorter at exploration. The overall loss in length of grafts varied between 26 and 30 percent of original length. External diameter was significantly increased (from between 133 and 201 percent) in all four groups at exploration compared to the normal femoral vein. Intravenous grafts maintained normal vein morphology to 12 months. Intraarterial grafts were modified by the ingrowth of smooth-muscle cells from the recipient artery, thereby creating a neointima that significantly thickened their walls at both 6 and 12 months.     

Functional small-diameter neovessels created using endothelial progenitor cells expanded ex vivo

Arterial conduits are increasingly preferred for surgical bypass because of inherent functional properties conferred by arterial endothelial cells, especially nitric oxide production in response to physiologic stimuli. Here we tested whether endothelial progenitor cells (EPCs) can replace arterial endothelial cells and promote patency in tissue-engineered small-diameter blood vessels (4 mm). We isolated EPCs from peripheral blood of sheep, expanded them ex vivo and then seeded them on decellularized porcine iliac vessels. EPC-seeded grafts remained patent for 130 days as a carotid interposition graft in sheep, whereas non-seeded grafts occluded within 15 days. The EPC-explanted grafts exhibited contractile activity and nitric-oxide-mediated vascular relaxation that were similar to native carotid arteries. These results indicate that EPCs can function similarly to arterial endothelial cells and thereby confer longer vascular-graft survival. Due to their unique properties, EPCs might have other general applications for tissue-engineered structures and in treating vascular diseases.