Comparison of regeneration results of prefabricated nerve graft, autogenous nerve graft, and vein graft in repair of nerve defects

The purpose of this study was to evaluate the effectivity of prefabricated nerve grafts in the repairing nerve defect and to compare them with the autogenous nerve graft and vein graft. Four groups were created, each containing 10 rats. First, nerve prefabrication was carried out in groups I and II during 8 weeks. For this purpose, jugular vein graft was sutured to the epineural windows on the peroneal and tibial nerve at the right side in an end-to-side fashion. To create neurotrophic stimulus, partial incision was performed on the nerves in group I, and gene therapy was performed by plasmid injecting to the adjacent muscles in group II. At the end of the eighth week, prefabricated nerve grafts, jugular vein, and the axons passing through it were taken. Then, gap was created on the left peroneal nerve in all groups. Defect on the peroneal nerve was repaired by using the prefabricated nerve grafts in groups I and II, the autogenous nerve graft in group III, and the vein in group IV. Assessment of nerve regeneration was performed by using electromyography. Morphological assessment was performed after follow-up period. According to electrophysiological and morphological results, the results of first three groups were similar. There was no statistically significant difference between three groups. Prefabricated nerve graft is as effective as autogenous nerve graft, and it can be used in the repair of nerve defects as autogenous nerve graft as an alternative.     

几丁糖胶原复合膜及激活态雪旺细胞修复周围神经缺损的实验研究

目的研究几丁糖胶原复合膜、激活态雪旺细胞(activatedSchwanncell,ASC)促进周围神经再生的作用。方法将激活态雪旺细胞培养于几丁糖胶原复合膜后,将膜缝制成导管修复大鼠坐骨神经10mm的缺损(D组);并以自体神经移植(A组)、几丁糖胶原复合膜管(B组)及几丁糖胶原复合膜加脑源性神经营养因子[(brainderivedneurotrophicfactor,BDNF)C组]为对照。术后4、8、12周观察肢体运动,复合肌肉动作电位(CMAP)的波幅、潜伏期和运动神经传导速度(MNCV)。术后12周取材,样本染色观察神经轴突再生情况。结果几丁糖胶原复合膜加激活态雪旺细胞修复10mm神经缺损的效果优于几丁糖胶原复合膜加BDNF,与自体神经相似。结论几丁糖胶原复合膜加激活态雪旺细胞能有效地促进周围神经再生。     

Increased axonal regeneration over long nerve gaps using autologous nerve-muscle sandwich grafts

Poor recovery is seen after repair of long defects in peripheral nerves when denatured muscle grafts or regeneration chambers providing physical support alone are used. The presence of Schwann cells and neurotrophic factors is required for axons to migrate significant distances. In this study we have used immunohistochemical techniques and axon counts to quantify the regeneration seen when 5 cm defects in rabbit sciatic nerve were repaired with a composite graft consisting of 2–3 mm lengths of fresh autologous nerve sandwiched between 1 cm frozen-thawed muscle grafts. This technique led to a similar pattern of regeneration as that seen in autologous nerve grafts, used as controls, and a significantly (P<0.0001) greater axonal and Schwann cell regeneration compared with that seen in frozen-thawed muscle grafts of the same total length. In conclusion, we present a simple technique for incorporating a depot of Schwann cells and other essential components into a nerve conduit which has a marked effect on axonal regeneration across long defects. © 1995 Wiley-Liss, Inc.     

Reconstruction of ureteral defects with microvascular vein grafts in a rat model

This study was undertaken to test the performance of an autologous vein graft as a ureteral replacement in the rat model. Twenty-six rats were divided into three groups. In Group 1 (n = 10), the animals had a 3-mm segment of the ipsilateral ureter excised and the ureteral defect repaired, using a superficial epigastric vein graft. In Group 2 (n = 10), the same ureteral defect was created and again repaired, using a superficial epigastric vein graft, with the addition of a Silastic stent. The control, Group 3 (n = 6), had the ureter transected and repaired solely by means of primary anastomosis. Animals from each group underwent urography and were sacrificed for histology at three different postoperative intervals: 1, 4, and 12 weeks. Postoperative urography results showed normal renal function in the animals with ureteral reconstruction using vein grafting aided by a stent, as well as in those with primary ureteral anastomosis. No renal function return was seen in the animals with ureteral reconstruction by vein grafting alone, without stent support. Histologically, a progressive loss of the vascular endothelium, and replacement with the urothelium typical of the ureter, was seen in the stented vein grafts. Severe ureteral obstruction at the proximal site of the graft and hydronephrosis were seen in the vein-graft group without stenting. This study demonstrates that autologous vein grafts can be used successfully to correct a ureteral deficit, contingent on accurate microsurgical technique and immediate stenting.     

Nerve repair by means of vein filled with muscle grafts I. Clinical results

Peripheral nerve lesions with a long segment defect need a grafting conduit to heal. Although autogenous nerve grafting is still considered the best method for bridging nerve defects, several alternative types of conduits (biological and synthetic) have been studied. We have demonstrated in previous experimental research in rats that a graft made using a vein (providing a guide for nerve regeneration) filled with fresh skeletal muscle (to prevent vein collapse and support axon regeneration) gave similar results to traditional nerve grafts. On this basis, we decided to use the muscle-vein-combined grafts in clinical cases. From 1993 to 1997, this technique was applied for bridging both sensory and mixed nerve defects (21 cases). We report good results in 85% of our cases with a minimum follow-up of 14 months. These results, obtained on nerve defects ranging from 0.5 to 6 cm in length, seem to be superior to those reported with other kinds of artificial or biological conduits.     

Nerve repair using a vein graft filled with collagen gel

It has been shown that a vein graft provides a good environment for axon regeneration in short nerve gaps. But the use of a vein graft for long nerve gaps is controversial because veins may collapse, due to their thin walls, and the surrounding scar tissue can cause constriction. In an attempt to improve results using the vein graft, the authors conducted the reported experiment by filling the lumen of the vein with collagen gel. A 15-mm rabbit peroneal nerve defect was bridged with a collagen-filled vein graft. On the contralateral side, the defect was bridged with the vein alone. When the regenerated tissue was examined 4 weeks, 8 weeks, and 12 weeks after grafting, the number and diameter of myelinated fibers were significantly increased, compared with the control group without collagen gel. This study found that in order to increase the efficacy of a vein graft for axonal regeneration, collagen gel might be an appropriate matrix material with which to fill the vein graft.     

Regeneration through nerve allografts in the cynomolgus monkey (Macaca fascicularis)

With the use of ulnar nerves of cynomolgus monkeys, the present study examined whether basal laminae of Schwann cells can serve as conduits for regenerating axons in nerve allografts from non-human primates. A segment of ulnar nerve was transected distal to the elbow joint one week before grafting. In Group A, a distal segment of the transected nerve was transplanted, after freezing and thawing, into the ulnar nerve of another monkey, at a level that corresponded to that from which the graft was taken. In Group B (the control group), the segment of nerve was grafted in the same manner but without cryotreatment. Two weeks, five weeks, eight weeks, and five months after grafting, the graft and the host nerve were examined with light and electron microscopy. Within two weeks after grafting in Group A, after degradation of the cellular components of the Schwann cells, the basal laminae of the Schwann cells were intact in the form of tubes. Within five weeks, many regenerating axons grew out into these basal lamina tubes in the three-centimeter-long grafts and extended into the host nerve. As seen at the wrist (seven centimeters from the distal suture) five months after grafting, the axons exhibited fully mature myelination both in the graft and in the host nerve. In contrast, in Group B, in which the Schwann cells had not been disrupted by cryotreatment, cellular components and connective-tissue matrices, including basal laminae, had been degraded and had been replaced by invading cells, which filled the endoneurial spaces of the graft. Five months after grafting, axonal growth had been arrested in the graft one centimeter distal to the proximal suture. The beneficial effect in Group A appears to have been the result of the retention and preservation of intact basal laminae of Schwann cells after rapid removal of killed Schwann cells and myelin debris. Killing of Schwann cells by freezing before grafting may abolish the immune response to the Schwann cells in allografts and lead to fragmentation and disruption of myelin, which facilitates the rapid removal of myelin by macrophages.     

Inside-outl vein graft repair compared with nerve grafting for nerve regeneration in rats

The inside-out vein graft is a vein conduit pulled through itself to invert the normal orientation and place the adventitial layer within the lumen of the conduit. Our study compares regeneration of peripheral nerves in the rat through two conduits: inside-out graft of the jugular vein and autogenous nerve graft. In 10 rats, the right jugular vein was harvested, turned inside out, and used to bridge a 10 mm defect created in the right sciatic nerve. The 10 mm nerve segment from the right was then used as a standard nerve graft to bridge a 10 mm gap created in the left sciatic nerve. Rats were sacrificed at 8 and 12 weeks. Regeneration on the inside-out vein graft side showed superior functional results (faster conduction velocities) and improved histological results (greater axon counts) compared with the nerve grafted side. We feel the adventitial surface of the wall of the vein promotes nerve regeneration by providing an environment rich with collagen, laminin, and Schwann cells and promotes increased vascularization of the new nerve. © 1995 Wiley-Liss, Inc.     

Distal nerve elongation vs nerve grafting in repairing segmental nerve defects in rabbits

Segmental nerve defects have been repaired with nerve grafts. However, regenerating fibers must go through two coaptation sites, and donor site morbidities are inevitable. We elongated the distal nerve segment using a tissue expander and reconnected the nerve. We compared these results with those of nerve grafting. Nerve injury models were created in the median nerves of both forelimbs in 27 rabbits. The right nerve was repaired by elongation, and the left by tibial nerve grafting. The length of the elongation was the same as that of the graft in each animal. Eight rabbits had a 10-mm segment repaired, 9 had a 15-mm segment repaired, and 10 had a 20-mm segment repaired. Evaluated outcomes were nerve conduction velocity, contractile force of the flexor muscle, axons number, and fiber diameter. The elongated and grafted groups did not differ substantially on any outcome. Distal nerve elongation could be an alternative to nerve grafting for repairing large nerve defects.     

构建猕猴组织工程化周围神经的实验研究

目的评价组织工程化周围神经修复猕猴4cm尺神经缺损的实验效果,为临床研究提供资料。方法分别用6种移植物桥接4cm尺神经缺损。A组:自体BMSCs 去细胞同种异体神经支架;B组:自体SCs 去细胞同种异体神经支架;C组:自体BMSCs PLGA支架导管;D组:去细胞同种异体神经支架;E组:PLGA支架导管;F组:自体神经。通过功能学、神经电生理学及组织学研究评价各自的实验效果。结果A、B、C三种组织工程化神经实验组,术后6个月神经电生理和组织学检查,能引起小鱼际肌群产生复合动作电位的潜伏期、复合动作电位的最大振幅、神经传导速度和再生的神经纤维数目与自体神经移植组(F组)相比差异无显著性意义(P>0.05),但分别大于未加细胞的支架组(D、E组),差异有显著意义(P<0.05)。结论用自体源SCs或BMSCs作种子细胞与去细胞同种异体神经支架,或自体源BMSCs与PLGA支架导管构建不同的组织工程化周围神经,修复猕猴4cm尺神经缺损均取得较好的效果。     

The variation in vein graft flow velocity with luminal diameter and outflow level.

Duplex scanning has recently been used to monitor the patency of infrainguinal vein grafts. Empirically derived criteria that have been used for identifying the failing graft have never accounted for the effect of vein graft diameter or varying outflow resistance, despite the fact that they are major determinants of flow. We prospectively examined the variation in graft peak systolic flow velocity with graft diameter and outflow level in a consecutive series of 68 patients with 72 normally functioning vein grafts returning for routine follow-up. Images were obtained of vein grafts with a duplex scanner throughout their lengths, and the distal peak systolic flow velocity and intraluminal diameters were recorded. There were 15 popliteal, 26 tibial, and 21 inframalleolar grafts. The mean ankle-brachial index of inframalleolar grafts was 1.01 +/- 0.04 and did not differ significantly from tibial (0.96 +/- 0.03) or popliteal (0.93 +/- 0.06) grafts (p = 0.32). Grafts to the three outflow levels differed significantly in diameter, with inframalleolar grafts measuring 3.95 +/- 0.17 mm, tibial grafts 4.78 +/- 0.21 mm, and popliteal grafts 5.65 +/- 0.38 mm (p = 0.0001). In a similar manner inframalleolar grafts had significantly lower peak systolic flow velocities (59.1 +/- 3.4 cm/sec) than tibial (77.2 +/- 5.6 cm/sec) or popliteal (71.0 +/- 7.6 cm/sec) grafts (p = 0.04). Inframalleolar grafts did not demonstrate a significant correlation (r = -0.21, p = 0.29) between peak systolic flow velocity and graft diameter. Conversely, both tibial (r = -0.49, p = 0.005) and popliteal (r = -0.73, p = 0.002) grafts demonstrated significant inverse correlations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Autogenous standard versus inside-out vein graft to repair facial nerve in rabbits

Objective： To evaluate autogenous vein grafts and inside-out vein grafts as conduits for the defects repair in the rabbit facial nerves. Methods： The 10 nun segments of buccal division of facial nerve were transected for 48 rabbits in this study. Then the gaps were immediately repaired by autogenous vein grafts or inside-out vein grafts in different groups. All the animals underwent the whisker movement test and electrophysiologic test during the following 16 weeks at different time points postoperatively. Subsequently, the histological examination was performed to observe the facial nerve regeneration morphologically. Results： At 8 weeks after operation, the facial nerve regeneration has significant difference between the experimental group and the control group in electrophysiologic test and histological observation. However, at the end of this study, 16 weeks after operation, there was no signifi- cant difference between inside-out vein grafts and standard vein grafts in enhancing peripheral nerve regeneration. Conclusion： This study suggest that both kinds of vein grafts play positive roles in facial nerve regeneration after being repaired immediately, but the autogenous inside-out vein grafts might accelerate and facilitate axonal regeneration as compared with control.     

Neurotrophins and their receptors in early axonal regeneration along muscle-vein-combined grafts

Experimental and clinical studies have shown that a vein segment filled with skeletal muscle used to bridge a peripheral nerve defect (muscle-vein-combined graft) leads to good nerve repair. However, the molecular basis of the nerve fiber regeneration process along this type of graft still remains to be elucidated. The aim of this study was to verify the expression of two neurotrophins, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), as well as their receptors, trkA and p75, in an early stage of axonal regeneration in muscle-vein-combined grafts. Severed rat sciatic nerves were repaired by means of 1-cm-long muscle-vein-combined grafts and withdrawn immediately after surgery (control grafts) and 5 days after surgery. Longitudinal sections of grafts were immunostained by means of the following antibodies: anti-NGF, anti-BDNF, anti-trkA, and anti-p75. An anti-glial fibrillar acid protein (anti-GFAP) antibody was used to recognize Schwann cells. Results showed the presence of a number of GFAP-positive Schwann cells inside the muscle-vein grafts. Many of these cells reacted for NGF, BDNF, and p75, but not trkA. In control grafts, i.e., immediately after surgery, no immunostaining was detected for any of the antibodies used in this study. These observations suggest that, very early after surgery, the muscle-vein-combined graft offers to growing axons an environment particularly favorable for regeneration, providing us with a possible explanation for the efficacy of this grafting technique for peripheral nerve repair.     

A study of the mechanical strength of long bone defects treated with various bone autograft substitutes: an experimental investigation in the rabbit

This study was designed to determine which of several bone grafting materials would be the most efficacious substitute for autogenous bone graft in the treatment of segmental long bone defects. The experimental model was a 1-cm defect in the rabbit ulna. The control group had nothing implanted in the defect. The six grafts tested were: (a) autogenous iliac crest bone, (b) autogenous cortical bone (ulna), (c) hydroxylapatite, (d) hydroxylapatite-demineralized bone matrix (allograft) composite graft, (e) freeze-dried bone (allograft), and (f) demineralized bone matrix (allograft). At 6 weeks postoperatively, the ulnas were harvested, examined radiographically, and tested mechanically in torsion. The radiographic examination proved to be of little value because some materials were radiodense at the time of implantation. The rates (percentage) of union, torques at failure, and energy to failure values were statistically significantly higher than control for all groups except hydroxylapatite. We concluded that demineralized bone matrix and hydroxylapatite-demineralized bone matrix composite graft compare favorably with cortical replacement (autograft) in mechanical strength and rate of union and therefore may be satisfactory substitutes for bone grafting. Freeze-dried bone did not appear to be as satisfactory because of its low mean energy to failure, but statistical analysis failed to confirm this opinion. Hydroxylapatite graft, when used alone, does not appear to be a suitable material for grafting segmental bone defects.     

亲和素-生物素黏附系统修饰纳米纤维构建组织工程神经的实验研究

目的 观察亲和素-生物素黏附系统(avidin-biotin binding system,ABBS)快速黏附雪旺细胞(SCs)对组织工程神经促进神经再生的影响.方法 以坐骨神经缺损10 mm作为实验模型.取40只Wistar大鼠分成A、B、C、D4组,每组10只.A组:自体神经移植修复组;B组:空白对照组,用聚乳酸己内酮共聚物[ Poly(L-lactic acid-co-epsilon-caprolactone),P(LLA-CL)]支架修复神经缺损;C组:P(LLA-CL)支架上用普通方法黏附雪旺细胞修复神经缺损;D组:P(ILA-CL)支架上用ABBS法黏附雪旺细胞修复神经缺损.术后3个月,检测坐骨神经功能指数、神经传导速度、再生神经轴突及髓鞘厚度,评估ABBS对于促进神经再生的影响.结果 C组与D组的神经修复效果无差别.虽然修复效果不及A组,但是均明显好于没有雪旺细胞的B组.结论 ABBS在动物体内实验中未对组织工程神经促进神经再生造成不利影响,是一种可靠的细胞快速黏附方法.     

Repair of nerve defect with acellular nerve graft supplemented by bone marrow stromal cells in mice

The acellular nerve graft that can provide internal structure and extracellular matrix components of the nerve is an alternative for repair of peripheral nerve defects. However, results of the acellular nerve grafting for nerve repair still remain inconsistent. This study aimed to investigate if supplementing bone marrow mesenchymal stromal cells (MSCs) could improve the results of nerve repair with the acellular nerve graft in a 10-mm sciatic nerve defect model in mice. Eighteen mice were divided into three groups (n = 6 for each group) for nerve repairs with the nerve autograft, the acellular nerve graft, and the acellular nerve graft by supplemented with MSCs (5 × 10(5)) fibrin glue around the graft. The mouse static sciatic index was evaluated by walking-track testing every 2 weeks. The weight preservation of the triceps surae muscles and histomorphometric assessment of triceps surae muscles and repaired nerves were examined at week 8. The results showed that the nerve repair by the nerve autografting obtained the best functional recovery of limb. The nerve repair with the acellular nerve graft supplemented with MSCs achieved better functional recovery and higher axon number than that with the acellular nerve graft alone at week 8 postoperatively. The results indicated that supplementing MSCs might help to improve nerve regeneration and functional recovery in repair of the nerve defect with the acellular nerve graft.     

碱性成纤维细胞生长因子结合静脉套接法修复周围神经缺损的实验研究

目的 探讨碱性成纤维细胞生长因子（ｂＦＧＦ）与静脉套接法修复神经缺损的作用。方法 新西兰大白兔５４只,分成三组,切断兔一侧坐骨神经,用自体静脉桥接。Ａ组于静脉段内注入ｂＦＧＦ溶液０．２ｍｌ（浓度４０００Ｕ／ｍｌ）,Ｂ组注入等量的生理盐水,Ｃ组不注入任何物质。分别于术后１０、３０及１００天取标本行ＨＥ染色,光镜检查。其中１００天组先做传导速度测定,远端再生神经做髓鞘染色,轴突断面做图像分析并与健侧比     

去细胞异种神经复合神经生长因子修复神经缺损的实验研究

目的 应用含有神经生长因子(NGF)的去细胞异种神经基膜管作为神经移植替代物桥接大鼠坐骨神经缺损,观察其对神经再生的作用.方法 选用Wistar大鼠45只,随机分为3组,每组15只,于术制成右后肢坐骨神经长10 mm的神经缺损,取兔胫神经制成去细胞神经基膜管,电镜及HE染色观察神经基膜管超微结构,流式细胞仪检测去细胞前后神经主要组织相容性抗原Ⅱ(MHC Ⅱ)的变化情况.A组以含有NGF的去细胞异种神经基膜管桥接神经缺损,B组单纯采用去细胞异种神经基膜管桥接神经缺损,C组采用自体神经移植修复神经缺损.术后1个月行神经电生理检测即胫后肌群运动诱发电位,用HE染色、免疫组化染色、透射电镜等方法对移植体远端吻个口再生神经纤维进行形态学观察,并对再生有髓神经纤维的数量、密度、直径及雪旺细胞的密度进行量化分析.结果 移植前新鲜神经组MHC-Ⅱ检测值为72.14±19.88,去细胞组MHC-Ⅱ检测值为4.19±3.11,两组比较差异有统计学意义(t=3.817,P＜0.05);透射电镜观察显示为胶原性管道,无细胞成分.术后4周,处死前行运动诱发电位检测,神经传导速度A组为(21.16±2.31)m/s,B组为(13.37±1.89)m/s,C组为(21.43±2.18)m/s,A组与 C组比较差异无统计学意义(P＞0.05),A组与 B组比较差异有统计学意义(P＜0.05).组织学观察见3组移植体远端吻合口横切面再生神经纤维呈微束状,透射电镜观察再生神经纤维具有正常的形态和结构.A、C组再生神纤纤维数量及直径均优于B组,差异有统计学意义(P＜0.05).结论 经化学萃取的去细胞兔胫神经基膜管能够移植于大鼠,成功修复大鼠坐骨神经缺损,而且复合NGF的去细胞基膜管在神经修复质量上优于单纯的去细胞神经基膜管,更加接近自体神经移植的效果.     

多种移植体修复周围神经的比较实验研究

修复神经缺损的材料甚多，但至今尚未见各种材料的比较研究。为了比较自体神经、肌肉、静脉、肌腱及硅橡胶修复神经缺损的效果，选用ＳＤ大白鼠，切断腓总神经，制成０．６ｃｍ缺损，分别用不同移植物桥接缺损。于术后６周、１２周在电生理、胫前肌称重、远端轴突计数及组织学等方面进行综合分析评价。结果表明：自体神经移植在各方面均优于其它移植体，而静脉组又优于另外３组。对各种移植体中神经再生的特点及其成熟过程进行了讨论，并探讨了形成这种差别的有关神经再生微环境的影响。     

自体骨膜延迟游离移植修复成年后关节软骨缺损的实验研究

目的：研究年龄对自体骨膜游离移植修复关节软骨缺损的影响,探讨延迟游离移植能否提高成年后骨膜修复软骨能力。方法：选中国白兔,成年兔20只,幼兔10只,分3组。A组：成年兔左膝骨膜直接游离移植组;B组：成年兔右膝骨膜延迟游离移植组;C组：幼兔骨膜直接游离移植组,取骨膜或骨膜新生组织、行光镜、电镜组织学观察比较。结果：移植前B、C组骨膜厚度、细胞计数及细胞活跃程度均优于A组（均为P＜0．01）,移植后12周3组关节软骨缺损获得不同程度修复,C组优于A组（P＜0．01）及B组（P＜0．05）,B组优于A组（P＜0．01）。结论：自体骨膜局部剥离、原位激活,体内培养、延迟游离移植可提高成年骨膜成软骨能力,更好地修复成年后关节软骨缺损。