人工神经导管原材料选择与功能设计的研究进展

人工神经导管（nerve guidance conduits,NGCs）作为一种合成的神经移植物,为神经再生提供结构与营养支持。理想的神经导管对生物相容性、机械强度、拓扑结构和导电性等均有较高要求,因此需对神经导管的设计不断改进并建立更完善的周围神经再生策略,以期满足临床需求。虽然NGCs在周围神经损伤的治疗中已经取得一定进展,但其对长距离神经离断伤的结构与功能修复仍不理想。本文分别从原材料选择、结构设计、治疗因子搭载及自供电元件集成4个方面对神经导管的设计进行综述,归纳总结NGCs在周围神经损伤治疗中的研究进展,以期推动NGCs的迭代更新与临床转化。     

神经导管研究与进展

随着机械化程度的提高和交通事业的发展,周围神经损伤发生率大幅度的上升。虽然通过手术的方法可以进行端对端的缝合,但是神经恢复的效果仍然不理想,特别是存在神经短距离缺损时,神经导管可为神经的修复提供一个合适的微环境,使得神经纤维能够再生并顺利到达远端。本文介绍了受损神经恢复效果的评价标准,神经导管材料的研究进展,神经生长因子对神经再生的影响因素及作用机理,和神经导管的制备方法,且在总结前人研究的基础上,给出适合于神经导管支架所需的材料和结构要求。     

PLGA支架降解对血管化功能影响的体外研究

目的:研究聚乳酸-羟基乙酸(PLGA)支架材料降解产物对血管内皮细胞增殖、迁移和小管样结构形成的影响。方法:将PLGA支架材料放入磷酸盐缓冲液(PBS)中体外无菌降解1、2、4周。用降解液处理人脐静脉内皮细胞株HUVEC,采用Brdu ELISA法、Transwell小室法和小管形成实验检测PLGA支架材料降解液对血管内皮细胞增殖、迁移和小管样结构形成的影响。结果:PLGA支架材料1周降解液对内皮细胞的迁移和小管形成无明显影响,对内皮细胞增殖有一定的促进作用。随着降解时间的延长,2周降解液抑制内皮细胞的迁移和小管形成,4周的降解液对内皮细胞增殖、迁移和小管形成均有抑制作用。结论:PLGA支架材料降解初期有对血管内皮细胞的增殖有促进作用,降解后期可能由于降解过程中产生的酸性物质累积增多,影响了血管内皮细胞的生长和功能,从而抑制新生血管的形成。     

血管与导管选择对PICC置管引发并发症的影响

目的:通过比较PICC置管的血管与导管选择,探讨其对并发症发生率的影响。方法:2005年10月至2006年7月共336例恶性肿瘤病人应用B/BRAUN单腔导管,"可分裂"穿刺针355型173例,257型163例分别选择头静脉、贵要静脉、颈外静脉进行观察。结果:头静脉病人>50%出现并发症,其中30%出现中途拔管;贵要静脉<10%出现并发症,90%完成治疗计划;颈外静脉2例因固定不妥导致导管脱出。结论:在非高速度滴注的情况下,尽量选用小管径的导管;对血管的选择应当首选责要静脉,优选右侧,穿刺点最好过肘关节,其次选择颈外静脉优选右侧;选择PICC置管操作应慎重,操作之前做好详细的评估。     

聚己内酯/壳聚糖神经导管复合骨髓间充质干细胞促进大鼠坐骨神经损伤修复的研究

目的:观察聚己内酯/壳聚糖神经导管复合骨髓间充质干细胞修复大鼠坐骨神经缺损的效果。方法:将24只SD大鼠随机分为4组,制备右侧坐骨神经5mm缺损模型,A组聚己内酯/壳聚糖神经导管复合骨髓间充质干细胞移植组;B组聚己内酯神经导管复合骨髓间充质干细胞移植组;C组壳聚糖神经导管复合骨髓间充质干细胞移植组;D组自体神经移植组。术后每2周进行坐骨神经功能指数检测,12周时行电生理、腓肠肌湿重恢复率、组织学观察和免疫组织化学检测。结果:坐骨神经功能指数显示,A组运动功能恢复速度较B、C组快,但比D组慢。A组电生理和腓肠肌湿重恢复率的检测结果与C、D组相比无统计学意义(P0.05),但优于B组(P0.05)。组织学观察,A组再生神经纤维排列密集。S-100免疫组织化学结果表明A组有大量雪旺细胞增生。结论:聚己内酯/壳聚糖神经导管复合骨髓间充质干细胞能够促进周围神经损伤修复,效果与壳聚糖神经导管、自体神经相同,优于聚己内酯神经导管。     

木质部导管空穴化研究中的几个热点问题

 导管的空穴化和栓塞化现象是目前国际上水分生理生态研究的一个热点。该文对导管空穴化和栓塞化研究中出现的几个热点问题进行了概括和总结。1）在研究导管空穴化的实验手段上,超声波传感器探测法具有一定的局限性;目前至少存在4种可能的原因来解释木质部压力探针法（XPP）和压力室法所测得的导管水柱张力不一致的现象;近来出现的核磁共振成像法可以进行导管空穴化的无损伤检测。2）导管解剖学特征与形成空穴的可能性之间的关系可能与树种相关。3）导管空穴化引起气孔关闭的作用机制目前还不太清楚。4）植物防止空穴化产生的能力与适应干旱能力之间的关系还没有定论。5）单独用根压来解释空穴化导管的重新注水机制是不全面的,还存在其它重新注水机制。     

人造血管移植物自然内皮化的研究

人造血管移植作为自体血管代用品已被广泛使用了解内皮细胞的功能,来源,血管内皮化的过程,形成机理及影响内皮化的因素,对防治血栓形成,内膜增生,维持移植血管通畅率有重要意义。     

血管内皮生长因子的神经保护作用

血管内皮生长因子（vascular endothelial growth factor,VEGF）是内皮细胞特异性的生长因子,大多数关于VEGF的研究都是致力于其在血管生长方面的作用,而近年来有大量文献报道VEGF具有神经营养和促神经发生作用,它能够直接作用于神经元细胞和神经胶质细胞甚至是神经干细胞,促进其生长及存活。VEGF的多种功能使其和多种神经退行性疾病相关,如阿茨海默病,肌萎缩侧索硬化症,帕金森病等。导入VEGF基因能够改善肌萎缩侧索硬化症、帕金森病动物模型的病情。     

骨组织工程血管化的研究进展

血管化是组织工程骨成活的关键,组织工程骨的血管化过程与生理情况下的血管发生相似,但又有其独特性,并受多种因素影响。基于对组织工程骨血管化过程的认识,研究者通过联合细胞培养、促血管化生长因子、显微外科等方法重建血运。本文综述了当前骨组织工程的血管化研究进展。     

Lipid composition of the peripheral nerves in malnutrition: an experimental study in young rhesus monkeys

An experimental model of protein calorie malnutrition (PCM) was created in young rhesus monkeys. Ulnar and tibial nerves from six monkeys with PCM, six rehabilitated and 12 control monkeys were studied for lipid composition and activity of myelin marker enzyme. Total lipids, myelin marker lipids and activity of myelin marker enzyme, 2', 3'-cyclic nucleotide 3' - phosphohydrolase were decreased, while esterified cholesterol and free fatty acids were increased in PCM as compared to controls. There was partial recovery in myelin marker lipids and complete restoration of other lipids on nutritional rehabilitation.     

Laminin-incorporated nerve conduits made by plasma treatment for repairing spinal cord injury

To better direct the repair of damaged axons following spinal cord injury (SCI), we designed a nerve conduit (NC) modeled after the intact spinal cord, which would enable the axons to cross the lesioned area to rejoin on the other side. The NC consisted of a porous chitosan scaffold and was incorporated with laminin (LN) on the inner surface through oxygen plasma treatment. According to the BBB, CBS, and treadmill analyses, we found that following the implantation of the laminin-coated NC (LN-NC) the rats showed a tendency towards behavior improvement and functional recovery. Histology and immunocytochemical analyses indicated that the NC groups were capable of leading the damaged axons through the lesioned area without triggering inflammation or apoptosis. Together with the significantly enhanced expression of local GAP-43 in the LN-NC groups, as evidenced by western blot analysis, axon re-growth mediated by LN-NC was found to compare better than that by NC group. These results suggest a new possible approach to repairing SCI and, in general, a model which will be useful for other multidisciplinary procedures for complex neurological situations.     

Investigating the mechanical shear-plane between core and sheath elements of peripheral nerves

The mechanical architecture of rat sciatic nerve has been described as a central core surrounded by a sheath, although the way in which these structures contribute to the overall mechanical properties of the nerve is unknown. We have studied the retraction responses of the core and sheath following transection, together with their tensile properties and the interface between them. Nerves were harvested and maintained at their in situ tension and then either transected entirely, through the sheath only, or through an exposed section of the core. The retraction of each component was measured within 5 min and again after 45 min. Post mortem loss of retraction was tested 0 min or 60 min after excision. For fresh nerves, immediate retraction was 12.68% (whole nerve), 5.35% (sheath) and 4% (core), with a total retraction of 15%, 7.21% and 5.26% respectively. For stored nerves, immediate retraction was 5.33% (whole nerve) and 5.87% (sheath), with an extension of 0.78% for core, and a total retraction of 6.71% and 7.87% and an extension of 1.74%, respectively. Tensile extension and pullout force profiles were obtained for the sheath, the core and the interface between them. These showed a consistent hierarchy of break strengths that would, under increasing load, result in failure of the interface, then the core and finally the sheath. These data reflect the contributions of material tension and fluid swelling pressure to total retraction, and the involvement of an energy-dependent process that runs down rapidly post mortem. This study increases our understanding of the composite nature of peripheral nerve tissue architecture and quantifies the material properties of the distinct elements that contribute to overall mechanical function.Preliminary forms of this study were presented at: (1) British Matrix Biology Society Meeting, Manchester, March 2001; (2) Tissue and Cell Engineering Society Meeting, Keele, United Kingdom, September 2001.Financial support was provided by the EU framework 5 programme in neural tissue engineering (QLK3-CT-1999-00625).     

Non-thermal plasma application enhances the recovery of transected sciatic nerves in rats

This experimental research aimed to investigate the effects of non-thermal plasma on nerve regeneration after transected nerve damage using the sciatic nerve in Wistar albino (A) rats. The experiments were performed on 27 Wistar A rats. The rats underwent surgery for right sciatic nerve exposure and were divided into three groups (each group, n = 9) according to sciatic nerve transected injury (SNTI) and non-thermal plasma application: a non-nerve damage (non-ND) group, a only nerve damage without non-thermal plasma application (ND) group, and a nerve damage with non-thermal plasma application (ND + NTP) group. Subsequent to SNTI and immediate suture, non-thermal plasma was administered three times per week for eight weeks. Evaluation for functional recovery was performed using the static sciatic index measured over the full treatment period of eight weeks. The sciatic nerve specimens were obtained after euthanasia and third day from the last non-thermal plasma application. The sciatic nerve tissues were subjected to histological analysis. Behavior analysis presented that the ND + NTP group showed improved static sciatic index compared with the nerve damage group. Histopathological findings demonstrated that the ND + NTP group had more dense Schwann cells and well-established continuity of nerve fibers, greater than the nerve damage group. Immunohistochemistry showed that the ND + NTP group had increased levels of markers for microtubule-associated protein 2 (MAP2), tau, S100 calcium-binding protein B, and neurofilament-200 and regulated the overexpression of CD68 and MAP2. These results indicated that non-thermal plasma enhanced the motor function and restored the neuronal structure by accelerating myelination and axonal regeneration. Additionally, non-thermal plasma was confirmed to have a positive effect on the recovery of SNTI in rats.     

碱性成纤维细胞生长因子对大鼠晚期周围神经再生作用的实验研究

目的探讨外源性碱性成纤维细胞生长因子(bFGF)对晚期周围神经再生的作用.方法50只SD大鼠随机分治疗组、对照组各25只,切断右侧坐骨神经,12周后予以修复,修复术后每日分别给予bFGF和生理盐水,行神经电生理和组织学检查.结果治疗组和对照组修复处远段神经均有不同程度再生,4周时已可见到再生轴突,且治疗组多见.计量分析治疗组运动神经传导速度、神经肌肉动作电位幅值、髓鞘厚度、再生轴突直径和截面积明显优于对照组.治疗组与对照组相比,差异有显著性.结论bFGF能促进晚期周围神经再生.     

蛇毒神经生长因子促进周围神经再生的诱发电位观察

目的：研究蛇毒神经生长因子（sNGF)对大鼠坐骨神经损伤后诱发电位的影响,评价蛇毒神经生长因子在促进周围神经再生中的作用。方法：建立大鼠坐骨神经钳夹模型,局部滴加药物和术后肌注sNGF,通过脊髓诱发电位（SEP）,运动诱发电位（MEP）评定,观察坐骨神经修复情况。结果：sNGF治疗后可使伤后SEP,MEP提早出现,结论：蛇毒提取的NGF对大鼠坐骨神经损伤修复具有促进作用。     

Amniotic mesenchymal stem cells display neurovascular tropism and aid in the recovery of injured peripheral nerves

Recently, we reported that human amniotic membrane‐derived mesenchymal stem cells (AMMs) possess great angiogenic potential. In this study, we determined whether local injection of AMMs ameliorates peripheral neuropathy. AMMs were transplanted into injured sciatic nerves. AMM injection promoted significant recovery of motor nerve conduction velocity and voltage amplitude compared to human adipose‐derived mesenchymal stem cells. AMM implantation also augmented blood perfusion and increased intraneural vascularity. Whole‐mount fluorescent imaging analysis demonstrated that AMMs exhibited higher engraftment and endothelial incorporation abilities in the sciatic nerve. In addition, the higher expression of pro‐angiogenic factors was detected in AMMs injected into the peripheral nerve. Therefore, these data provide novel therapeutic and mechanistic insights into stem cell biology, and AMM transplantation may represent an alternative therapeutic option for treating peripheral neuropathy.     

骨髓间充质干细胞与施万细胞联合移植对大鼠周围神经 损伤端侧吻合的修复效果研究

目的:探究骨髓间充质干细胞(MSCs)与施万细胞(SCs)联合移植对大鼠周围神经损伤端侧吻合的修复效果。方法:选取SD雌性大鼠60只均制作成坐骨神经损伤端侧吻合模型,并将其随机分为联合移植组、MSCs组和SCs组,分别对吻合端进行骨髓间充质干细胞与SCs联合移植、MSCs移植、SCs移植。观察分析三组大鼠的神经电生理学指标和腓神经功能指数(PFI)和神经传导速度(NCV)。结果:三组大鼠的PFI和NCV均有所改善,且联合移植组的PFI和NCV均优于其他两组,并随着时间推移损伤坐骨神经功能恢复越来越好。结论:MSCs与SCs均具有促进大鼠周围神经身上修复的功能,且两种细胞联合移植效果更加明显。