A novel flexible nerve guidance conduit promotes nerve regeneration while providing excellent mechanical properties

Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduits may be used.The ideal conduit should be flexible,resistant to kinks and lumen collapse,and provide physical cues to guide nerve regeneration.We designed a novel flexible conduit using electrospinning technology to create fibers on the innermost surface of the nerve guidance conduit and employed melt spinning to align them.Subsequently,we prepared disordered electrospun fibers outside the aligned fibers and helical melt-spun fibers on the outer wall of the electrospun fiber lumen.The presence of aligned fibers on the inner surface can promote the extension of nerve cells along the fibers.The helical melt-spun fibers on the outer surface can enhance resistance to kinking and compression and provide stability.Our novel conduit promoted nerve regeneration and functional recovery in a rat sciatic nerve defect model,suggesting that it has potential for clinical use in human nerve injuries.

Silk-based nerve guidance conduits with macroscopic holes modulate the vascularization of regenerating rat sciatic nerve

Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.

Human umbilical cord mesenchymal stem cell-derived exosomes loaded into a composite conduit promote functional recovery after peripheral nerve injury in rats

Complete transverse injury of peripheral nerves is challenging to treat.Exosomes secreted by human umbilical cord mesenchymal stem cells are considered to play an important role in intercellular communication and regulate tissue regeneration.In previous studies,a collagen/hyaluronic acid sponge was shown to provide a suitable regeneration environment for Schwann cell proliferation and to promote axonal regeneration.This three-dimensional(3D)composite conduit contains a collagen/hyaluronic acid inner sponge enclosed in an electrospun hollow poly(lactic-co-glycolic acid)tube.However,whether there is a synergy between the 3D composite conduit and exosomes in the repair of peripheral nerve injury remains unknown.In this study,we tested a comprehensive strategy for repairing long-gap(10 mm)peripheral nerve injury that combined the 3D composite conduit with human umbilical cord mesenchymal stem cell-derived exosomes.Repair effectiveness was evaluated by sciatic functional index,sciatic nerve compound muscle action potential recording,recovery of muscle mass,measuring the cross-sectional area of the muscle fiber,Masson trichrome staining,and transmission electron microscopy of the regenerated nerve in rats.The results showed that transplantation of the 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes promoted peripheral nerve regeneration and restoration of motor function,similar to autograft transplantation.More CD31-positive endothelial cells were observed in the regenerated nerve after transplantation of the loaded conduit than after transplantation of the conduit without exosomes,which may have contributed to the observed increase in axon regeneration and distal nerve reconnection.Therefore,the use of a 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes represents a promising cell-free therapeutic option for the treatment of peripheral nerve injury.

心瓣膜Gore-Tex人工腱索植入前后超微形态研究

目的:观察Gore Tex线的超微形态和结构。方法:采用CV 4Gore Tex线,在植入前及植入绵羊、病人体内(二尖瓣腱索替换)后,分别于71及626天进行扫描、透射电镜观察。结果:本材料由呈纵行排列的纤细纤维构成,线内有许多气泡样间隙。植入绵羊体内71天后,线表面有宿主内皮细胞层覆盖生长。植入人体626天,表面有少数内皮细胞覆盖,表层下有成纤维细胞长入。结论:Gore Tex线具有微孔结构,利于宿主内皮细胞覆盖及成纤维细胞长入,是人工腱索替换的适合材料。

Gore-tex防水透湿层压织物的概述

介绍了各类防水透湿织物的种类、性能及研究发展状况,着重叙述了商品名为Gore-tex的PTFE微孔膜层压织物,并提出了存在的问题.

Gore-Tex多线圈技术在心脏瓣膜腱索重建中的应用

目的评价使用Gore-Tex线圈技术在心脏瓣膜重建术中的疗效。方法比较11例使用Gore-Tex线圈技术治疗二尖瓣脱垂患者术前、术后心功能和二尖瓣反流程度的变化。结果术后心功能较术前明显改善,射血分数(EF)从术前的(0.52±0.03)提高至(0.62±0.07)(P<0.05)。术中超声检查无明显二尖瓣反流7例,二尖瓣轻微反流2例,轻度反流2例;术后1月均常规复查心脏彩超,二尖瓣无明显反流6例,轻微反流3例,轻度反流2例。结论 Gore-Tex线圈技术应用于心脏瓣膜腱索重建疗效满意,与传统腱索重建技术相比较更方便、安全。

Gore-Tex缝线四点式人工晶状体睫状沟固定术的临床疗效

目的评价Gore-Tex缝线四点式人工晶状体睫状沟固定术的临床疗效和安全性。方法回顾性分析行人工晶状体睫状沟缝线固定术的患者29例(30眼),其中20例(20眼)采用传统聚丙烯缝线人工晶状体睫状沟缝线固定术(对照组),9例(10眼)行Gore-Tex缝线四点式人工晶状体睫状沟缝线固定术(四点式组)。对术后裸眼视力、验光值、裂隙灯检查及眼压结果等进行统计分析,随访时间为12个月。结果四点式组于术后1个月开始裸眼视力明显提高(P<0.05),对照组于术后3个月开始裸眼视力明显提高(P<0.05)。术后1、3、6、12个月时,四点式组较术前裸眼视力提高量均优于对照组(P<0.05)。术后1周和1、3、6、12个月时,四点式组眼内残余散光值均小于对照组(P<0.05)。2组均未出现严重的眼部并发症。结论Gore-Tex缝线四点式人工晶状体睫状沟固定术通过四点固定,使术后人工晶状体不易发生旋转和偏斜,显著降低术后眼内残余散光,更早改善术后裸眼视力,手术安全有效。

应用Gore-Tex人造血管重建颈总动脉的实验研究

目的 观察人造血管移植后不同时间的通畅率和组织病理学变化 ,探讨人造血管移植失败的原因。方法 3只健康成年山羊作为实验对象 ,手术切除 2 cm颈总动脉 ,以口径 4m m的 Gore- Tex人造血管进行桥接。 3只动物的 6侧颈部随机分为 A、B两组 ,各含 3条动脉。A组的近、远心端均为端 -端吻合术 ,B组的近心端为端 -侧吻合术 ,远心端为端 -端吻合术。移植术后 1周 ,以激光多普勒血流仪监测移植血管通畅情况 ,并择例行颈动脉造影术。术后 2周、3月、6月分期切取标本 ,观察人造血管不同时间的通畅率。标本经处理后分别作光镜、透射电镜和扫描电镜检查。结果 A、B两组人造血管于术后 2周、3月和 6月时的通畅情况分别为 1/1,0 /1,0 /1和 0 /1,1/1,1/1,其差别无显著意义 (χ2 =0 .1414,P=1.0 )。组织病理学检查显示 ,植入后 2周 ,人造血管内壁有少量内皮细胞覆盖 ,结缔组织外膜形成。植入后 3月 ,吻合口处动脉内膜增生 ,向人造血管中段移行 ,延伸长度距吻合口约 6 mm。人造血管新内膜形成不均一 ,部分区域出现过度增生。吻合后 6月 ,扫描电镜显示内皮细胞覆盖不完全 ,延伸长度距吻合口8m m。结论 以人造血管修复颈动脉缺损是可行的 ,但自然内皮化相对有限 ,而且新内膜形成不均。血栓形成和新内膜过度增生 ,均?

Gore-Tex面料透湿性能对比测试

采用YG 601型织物透湿仪和被动式微气候仪,在3种标准试验条件和4种微气候仪条件下,对3种6块Gore-Tex试样和2块棉织物试样进行了透湿性能测试。在标准透湿杯条件下,各试样的透湿量差异相对较大,平均透湿量与透湿量差异与试样两侧所存在的蒸汽压差成正比,Gore-Tex试样平均透湿能力要小于普通棉织物。采用被动式微气候仪的透湿试验发现:试样的透湿量与模拟皮肤内的水温成正比,水温越高,皮肤出汗量越大,内外湿度差越大,试样的透湿量也越大,同时微气候室内的积水也越多;在稳态情况下,微气候室内的积水量随时间成正比;在相同条件下Gore-Tex试样及棉织物试样的透湿量相差很小,但前者在微气候室内的积水量要大一些,也说明不同Gore-Tex织物的透湿量接近但还是小于普通棉织物。虽然Gore-Tex织物的透湿量接近棉织物,但其透气性能要远低于普通织物。所以,Gore-Tex织物称作防风透湿织物是准确的,其主要性能取决于PTFE(聚四氟乙烯)微孔膜的性能。

聚氨酯材料修复周围神经的新思路与机遇

背景:聚氨酯材料因优异的理化性质在生物医学领域中具有广泛的应用前景,对基于聚氨酯材料构建的神经导管进行仿生设计和功能化修饰,有望进一步解决神经再生修复难题。目的:综述基于聚氨酯材料构建的神经导管在周围神经修复领域的应用现状及进展。方法:设置英文检索词为“polyurethane,PU,polyurethane material,polyurethane biomaterials,nerve regeneration,peripheral nerve injury,nerve repair,nerve scaffold,nerve guidance conduit,nerve conduits”,中文检索词为“聚氨酯,PU,聚氨酯材料,聚氨酯生物材料,神经再生,周围神经损伤,神经修复,神经支架,神经导管”,检索PubMed、Web of Science、中国知网和万方数据库中2014-2024年发表的文献,最终纳入61篇文献进行综述。结果与结论:成分仿生是提高聚氨酯神经导管生物活性的有效策略。通过结构仿生优化聚氨酯神经导管,能够为神经组织再生提供生物引导线索。生物力学仿生聚氨酯神经导管可能在免疫调节和促进轴突生长中发挥重要作用。通过优化聚氨酯材料的导电微环境,有助于重建神经电信号传导通路。聚氨酯神经导管可作为药物载体,发挥抗炎和神经保护作用。联合应用多种设计策略优化聚氨酯神经导管虽然可以在多方面改善受损神经的功能,但由于神经复杂的结构和动态变化的病理生理微环境,神经导管设计策略仍旧有待完善。未来进一步改进和创新神经仿生设计策略,有望为神经组织工程领域的发展提供新的思路和机遇。

Gore-Tex在耳郭部分缺损修复中的应用

目的:探索用于部分耳郭缺损再造的理想材料。方法:对13例外伤后导致的部分耳郭缺损的病人,采用Gore-Tex整形材料作为再造耳的支架,在耳后设计局部皮瓣覆盖进行修复,供瓣区直接缝合或另取皮片植皮。结果:本组共13例13耳,4例术后发生假体外露,经再次手术修整,随访1～2年,所有再造耳郭外形满意,与对侧正常耳外形基本一致。结论:Gore-Tex材料具有良好的组织相容性和可塑性,是部分耳郭再造的理想材料之一。

1例胸腔镜下Gore-Tex线圈腱索重建术的护理配合

[目的]总结1例全胸腔镜下Gore-Tex线圈腱索重建术的护理配合。[方法]回顾性分析1例全胸腔镜下Gore-Tex线圈腱索重建病例的手术过程。[结果]手术过程顺利,病人3个月后及6个月后分别进行心脏彩超复查,均报告二尖瓣关闭良好,未见反流。[结论]充分的术前准备工作、积极默契的医护配合、落实到位的安全护理是胸腔镜下Gore-Tex线圈腱索重建术顺利完成的保证。

腾冲火山壳幔过渡带分析及岩浆上涌通道初探

壳幔过渡带是地壳与地幔物质和能量的交换场所,其结构特征与该区的深部过程和构造演化密切相关。提取腾冲火山区31个地震台站下方的接收函数H-κ叠加获得的地壳厚度随频率变化特征和接收函数的Ps/P、PpPs/P振幅比,发现盈江断裂北部的黑空山-燃灯寺和南侧沙坝台区域具有比周边区域更低的振幅比,约有2 km地壳厚度差异。将该观测结果与前人获得的这两个区域相对薄的地壳厚度与高的V_(P)/V_(S)比值相结合,表明黑空山-燃灯寺和沙坝台区域具有厚的壳幔过渡带,推测其是地幔物质涌入地壳的通道。结合前人获得的该区上、中、下地壳都存在大片低速体的特征,推测来自地幔的岩浆很可能沿着腾冲火山区黑空山-燃灯寺和沙坝台这两个区域上涌到地壳,并依次在下、中和上地壳富集和横向展布,最终沿多个通道喷出地表。

Decellularized sciatic nerve matrix as a biodegradable conduit for peripheral nerve regeneration

The use of autologous nerve grafts remains the gold standard for treating nerve defects, but current nerve repair techniques are limited by donor tissue availability and morbidity associated with tissue loss. Recently, the use of conduits in nerve injury repair, made possible by tissue engineering, has shown therapeutic potential. We manufactured a biodegradable, collagen-based nerve conduit containing decellularized sciatic nerve matrix and compared this with a silicone conduit for peripheral nerve regeneration using a rat model. The collagen-based conduit contains nerve growth factor, brain-derived neurotrophic factor, and laminin, as demonstrated by enzyme-linked immunosorbent assay. Scanning electron microscopy images showed that the collagen-based conduit had an outer wall to prevent scar tissue infiltration and a porous inner structure to allow axonal growth. Rats that were implanted with the collagen-based conduit to bridge a sciatic nerve defect experienced significantly improved motor and sensory nerve functions and greatly enhanced nerve regeneration compared with rats in the sham control group and the silicone conduit group. Our results suggest that the biodegradable collagen-based nerve conduit is more effective for peripheral nerve regeneration than the silicone conduit.

Chitosan conduits combined with nerve growth factor microspheres repair facial nerve defects

Microspheres containing nerve growth factor for sustained release were prepared by a compound method, and implanted into chitosan conduits to repair 10-mm defects on the right buccal branches of the facial nerve in rabbits. In addition, chitosan conduits combined with nerve growth factor or normal saline, as well as autologous nerve, were used as controls. At 90 days post-surgery, the muscular atrophy on the right upper lip was more evident in the nerve growth factor and normal sa- line groups than in the nerve growth factor-microspheres and autologous nerve groups. Electro- physiological analysis revealed that the nerve conduction velocity and amplitude were significantly higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. Moreover, histological observation illustrated that the di- ameter, number, alignment and myelin sheath thickness of myelinated nerves derived from rabbits were higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. These findings indicate that chitosan nerve conduits com- bined with microspheres for sustained release of nerve growth factor can significantly improve facial nerve defect repair in rabbits.

Flow patterns and boundary conditions for inlet and outlet conduits of large pump system with low head

The flow patterns in the inlet and outlet conduits have a decisive effect on the safe, stable, and highly efficient operation of the pump in a large pumping station with low head. The numerical simulation of three-dimensional （3D） turbulence flow in conduits is an important method to study the hydraulic performance and conduct an optimum hydraulic design for the conduits. With the analyses of the flow patterns in the inlet and outlet conduits, the boundary conditions of the numerical simulation for them can be determined. The main obtained conclusions are as follows： （i） Under normal operation conditions, there is essentially no pre-swirl flow at the impeller chamber inlet of an axial-flow pump system, based on which the boundary condition at the inlet conduit may be defined. （ii） The circulation at the guide vane outlet of an axial-flow pump system has a great effect on the hydraulic performance of the outlet conduit, and there is optimum circulation for the performance. Therefore, it is strongly suggested to design the guide vane according to the optimum circulation. （iii） The residual circulation at the guide vane outlet needs to be considered for the inlet boundary condition of the outlet conduit, and the value of the circulation may be measured in a specially designed test model.

Therapeutic strategies for peripheral nerve injury: decellularized nerve conduits and Schwann cell transplantation

In recent years, the use of Schwann cell transplantation to repair peripheral nerve injury has attracted much attention. Animal-based studies show that the transplantation of Schwann cells in combination with nerve scaffolds promotes the repair of injured peripheral nerves. Autologous Schwann cell transplantation in humans has been reported recently. This article reviews current methods for removing the extracellular matrix and analyzes its composition and function. The development and secretory products of Schwann cells are also reviewed. The methods for the repair of peripheral nerve injuries that use myelin and Schwann cell transplantation are assessed. This survey of the literature data shows that using a decellularized nerve conduit combined with Schwann cells represents an effective strategy for the treatment of peripheral nerve injury. This analysis provides a comprehensive basis on which to make clinical decisions for the repair of peripheral nerve injury.

Biological conduit small gap sleeve bridging method for peripheral nerve injury: regeneration law of nerve fibers in the conduit

The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph- eral nerve injury are better than in the traditional epineurium suture, so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury. This study sought to identify the regeneration law of nerve fibers in the biological conduit. A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit. The results showed that the biological conduit had good his- tocompatibility. Tissue and cell apoptosis in the conduit apparently lessened, and regenerating nerve fibers were common. The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture. During the prime period for nerve fiber regeneration （2-8 weeks）, the number of Schwann cells and nerve fibers was higher in both proximal and distal ends, and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture. The above results provide an objec- tive and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.

Gastric conduit perforation

As patients with carcinoma of the esophagus live longer, complications associated with the use of a gastric conduit are increasing. Ulcers form in the gastric conduit in 6.6% to 19.4% of patients. There are a few reports of perforation of a gastric conduit in the English literature. Almost all of these were associated with serious complications. We report a patient who developed a tension pneumothorax consequent to spontaneous perforation of an ulcer in the gastric conduit 7 years after the index surgery in a patient with carcinoma of the gastroesophageal junction. He responded well to conservative management. Complications related to a gastric conduit can be because of multiple factors. Periodic endoscopic surveillance of gastric conduits should be considered as these are at a higher risk of ulcer formation than a normal stomach. Long term treatment with proton pump inhibitors may decrease complications. There are no guidelines for the treatment of a perforated gastric conduit ulcer and the management should be individualized.