Effects of local release of hepatocyte growth factor on peripheral nerve regeneration in acellular nerve grafts

Options for reconstructing peripheral nerve gaps after trauma are limited. The acellular nerve is a new kind of biomaterial used to reconstruct the peripheral nerve defect, but its use could be improved upon. We aimed to investigate the effect of adenoviral transfection with hepatocyte growth factor (HGF) on the functional recovery of transected sciatic nerves repaired by acellular nerve grafting. 30 Rats were divided into three groups (10/group) for autografting and acellular grafting, as well as acellular grafting with adenovirus transfection of HGF (1 × 10⁸ pfu) injected in muscles around the proximal and distal allograft coapation. Sciatic functional index (SFI) was evaluated every 4 weeks to week 16 by measuring rat footprints on walking-track testing. The three groups presented initial complete functional loss, followed by slow but steady recovery, with final similar SFIs. Weight of the gastrocnemius and soleus muscles, histologic and morphometric study and neovascularization in the nerve grafts were evaluated at week 16. Autografting gave the best functional recovery, but HGF-treated acellular grafting gave better recovery than acellular grafting alone. Neovascularization was greater with HGF-treated acellular grafting than with autografting and acellular grafting alone. Axonal regeneration distance of autografting on the 20th postoperative day was the longest in the three groups,while that of acellular grafting alone was the smallest. Acellular nerve grafting may be useful for functional peripheral nerve regeneration, and with human HGF gene transfection may improve on acellular grafting alone in functional recovery.     

Substrate-bound nerve growth factor promotes neurite growth in peripheral nerve

Nerve growth factor (NGF), in addition to its well-known effects as a soluble neurite growth-promoting factor, also appears to promote the elongation of neurites when it is adsorbed to tissue culture substrates. Peripheral nerve Schwann cells appear to possess a receptor for NGF on their surfaces which is induced substantially after axotomy. We have found that the adsorption of NGF onto cryostat sections of the distal stump of previously severed sciatic nerve enhances neurite growth over this tissue. This finding, coupled with the two previous observations, suggests that Schwann cell surface NGF receptors serve to bind to NGF-like growth factors so as to provide favorable surfaces for regenerating peripheral nerve axons.     

Vascular endothelial growth factor gene therapy improves nerve regeneration in a model of obstetric brachial plexus palsy

Abstract

The treatment of obstetric brachial plexus palsy has been limited to conservative therapies and surgical reconstruction of peripheral nerves. In addition to the damage of the brachial plexus itself, it also leads to a loss of the corresponding motoneurons in the spinal cord, which raises the need for supportive strategies that take the participation of the central nervous system into account. Based on the protective and regenerative effects of VEGF on neural tissue, our aim was to analyse the effect on nerve regeneration by adenoviral gene transfer of vascular endothelial growth factor (VEGF) in postpartum nerve injury of the brachial plexus in rats. In the present study, we induced a selective crush injury to the left spinal roots C5 and C6 in 18 rats within 24 hours after birth and examined the effect of VEGF-gene therapy on nerve regeneration. For gene transduction an adenoviral vector encoding for VEGF165 (AdCMV.VEGF165) was used. In a period of 11 weeks, starting 3 weeks post-operatively, functional regeneration was assessed weekly by behavioural analysis and force measurement of the upper limb. Morphometric evaluation was carried out 8 months post-operatively and consisted of a histological examination of the deltoid muscle and the brachial plexus according to defined criteria of degeneration. In addition, atrophy of the deltoid muscle was evaluated by weight determination comparing the left with the right side. VEGF expression in the brachial plexus was quantified by an enzyme-linked immunosorbent assay (ELISA). Furthermore the motoneurons of the spinal cord segment C5 were counted comparing the left with the right side. On the functional level, VEGF-treated animals showed faster nerve regeneration. It was found less degeneration and smaller mass reduction of the deltoid muscle in VEGF-treated animals. We observed significantly less degeneration of the brachial plexus and a greater number of surviving motoneurons (P < 0·05) in the VEGF group. The results of this study confirmed the positive effect of VEGF-gene therapy on regeneration and survival of nerve cells. We could demonstrate a significant improvement on the motor-functional as well as on the histomorphological level. However, increased vascularization of the nerve tissue caused by VEGF does not seem to be the major reason for these effects. The clinical use of adenoviral VEGF-gene therapy in the newborn cannot be justified so far.     

Does insulin-like growth factor I (IGF-1) trigger the cell body reaction in the rat sciatic nerve?

Regeneration was measured after the infliction of a crush lesion on rat sciatic nerves which 4 days earlier had been subjected to a distal conditioning transection. Such nerves exhibited an increased outgrowth of nerve fibers as compared to nerves subjected to a single crush lesion. This increased outgrowth could be prevented, if the nerve was locally perfused around the site of the transection during the 4 days conditioning interval, with cycloheximide, actinomycin D and vinblastine, inhibitors of protein-, RNA-synthesis and retrograde axonal transport, respectively. The inhibitory effect of cycloheximide could be overcome by simultaneous perfusion with insulin-like growth factor I (IGF-1). The results suggest that proteins including IGF-1 which are synthesised locally around a nerve lesion and then transported retrogradely could trigger regenerative events in the neuronal cell body.     

Schwann cells seeded in acellular nerve grafts improve functional recovery

Introduction: This study evaluated whether Schwann cells (SCs) from different nerve sources transplanted into cold‐preserved acellular nerve grafts (CP‐ANGs) would improve functional regeneration compared with nerve isografts. Methods: SCs isolated and expanded from motor and sensory branches of rat femoral and sciatic nerves were seeded into 14mm CP‐ANGs. Growth factor expression, axonal regeneration, and functional recovery were evaluated in a 14‐mm rat sciatic injury model and compared with isografts. Results: At 14 days, motor or sensory‐derived SCs increased expression of growth factors in CP‐ANGs versus isografts. After 42 days, histomorphometric analysis found CP‐ANGs with SCs and isografts had similar numbers of regenerating nerve fibers. At 84 days, muscle force generation was similar for CP‐ANGs with SCs and isografts. SC source did not affect nerve fiber counts or muscle force generation. Conclusions: SCs transplanted into CP‐ANGs increase functional regeneration to isograft levels; however SC nerve source did not have an effect. Muscle Nerve 49 : 267–276, 2014     

Pre-degenerated nerve grafts enhance regeneration by shortening the initial delay period

In the present study we tested how nerve grafts with different pre-degeneration periods (1–28 days) influenced the early regenerative response in the rat sciatic nerve. The sciatic nerve on the right side was crushed and after 1–28 days of pre-degeneration, a 10 mm segment was used as an autologous nerve graft and transposed to a freshly made 10 mm long nerve defect on the left side. The regeneration distance was measured by the sensory pinch test 2–10 days after nerve repair. A newly developed mathematical model was used to calculate regeneration rates and initial delay periods from the measured regeneration distances. Pre-degenerated nerve grafts improved nerve regeneration by decreasing the initial delay period as compared to fresh nerve grafts without affecting the regeneration rate. Only one day of pre-degeneration was sufficient to reduce the initial delay period from 3.6 days to 1.7 days. The maximal effect on the initial delay period was achieved after 3 days of pre-degeneration. The initial delay period at later pre-degeneration intervals (7–14 days) was about 1 day. The effect persisted for at least 28 days of pre-degeneration. The regeneration rate was 1.5 mm/day for fresh nerve grafts and between 1.8–2.1 mm/day for pre-degenerated grafts. The results suggest that the effects of pre-degeneration are not only due to the increased cell proliferation in the graft, but that also trophic and/or inflammatory mechanisms may be of importance. Grafts pre-degenerated by crush may have clinical implications since they are easy to perform if an elective nerve grafting procedure is planned.     

The influence of cultured Schwann cells on regeneration through acellular basal lamina grafts

Acellular basal lamina grafts have been shown to be less immunogenic in comparison to cellular grafts, but possess a limited potential for supporting axonal regeneration through them. The present study describes the effect of cultured Schwann cells on enhancing regeneration through acellular grafts. 2 cm long acellular grafts, and in vitro Schwann cell populated acellular grafts were used to repair a surgically created gap in the host peroneal nerve. The transplants were analyzed at 1, 2, 4 and 8 weeks to determine their ability to support axonal regeneration. Host axonal regeneration through Schwann cell cocultured acellular grafts occurred rapidly and was significantly better as compared to non-cultured acellular grafts. The results demonstrate a beneficial effect of Schwann cell culture pretreatment on regeneration through acellular grafts and an improved recovery of the target muscle. The procedure of first preparing acellular grafts with subsequent coculture with Schwann cells offers a novel approach for the repair of injured nervous tissue.     

Platelet-derived growth factor and regulation of Schwann cell proliferation in vivo.

To examine the role of platelet-derived growth factor (PDGF) in the in vivo regulation of Schwann cell proliferation, steady-state levels of mRNAs encoding PDGF A and B chains, and PDGF alpha and beta receptors were measured in immature and adult rat sciatic nerves and in cultured rat Schwann cells. PDGF B chain and PDGF beta receptor mRNAs are present in immature rat sciatic nerves and to a lesser extent in adult rat nerves. Short-term cultures of neonatal rat Schwann cells express PDGF beta receptor mRNA, but not PDGF B chain mRNA, and are stimulated to synthesize DNA by addition of PDGF BB to the medium. These data indicate that PDGF BB is a developmentally regulated paracrine growth factor for rat Schwann cells. Very long-term cultures of rat Schwann cells, which have lost normal dependence on exogenous growth factors, express PDGF B chain mRNA as well as mRNAs encoding the PDGF alpha and beta receptors, suggesting that, under these circumstances, PDGF BB also act as an autocrine growth factor. PDGF A chain mRNA is present in both immature and adult rat sciatic nerves and is expressed by primary and secondary cultures of rat Schwann cells as well. However, because the abundance of PDGF alpha receptor mRNA is very low in rat Schwann cells, PDGF AA is not likely to be a significant autocrine growth factor for rat Schwann cells.     

Rapamycin promotes Schwann cell migration and nerve growth factor secretion

Rapamycin, similar to FK506, can promote neural regeneration in vitro. We assumed that the mechanisms of action of rapamycin and FK506 in promoting peripheral nerve regeneration were similar. This study compared the effects of different concentrations of rapamycin and FK506 on Sc hwann cells and investigated effects and mechanisms of rapamycin on improving peripheral nerve regeneration. Results demonstrated that the lowest rapamycin concentration(1.53 nmol/L) more significantly promoted Schwann cell migration than the highest FK506 concentration(100 μmol/L). Rapamycin promoted the secretion of nerve growth factors and upregulated growth-associated protein 43 expression in Schwann cells, but did not significantly affect Schwann cell proliferation. Therefore, rapamycin has potential application in peripheral nerve regeneration therapy.     

Vascularized nerve grafts: an experimental study

Objective: The aim of this study is to define an experimental model in order to promote the functional recovery of the nerves using grafts with vascular support (Vascular Nerve Grafts – VNG). The aim of this study is to define, on an experimental model in normal recipient bed, whether the functional recovery with VNG is superior to that obtained non-vascularized graft (NNG).

Methods: Twenty male rabbits, which underwent dissection of sciatic nerve, were later treated by reinnervation through an autograft. In 10 animals the reconstruction of sciatic nerve was realized with VNG; in 10 control animals the reconstruction of sciatic nerve was realized with NNG.

Results: The VNG group showed a better axonal organization and a significantly higher number of regenerated axons in the early phases (after 30 days) than the NNG group, whereas the difference in the axonal number at day 90 was less significant; besides, the axon diameter and the myelin thickness were not significantly improved by VNG group.

Discussion: Our data suggests that the use of VNG leads to a faster regeneration process and a better functional recovery, although the final results are comparable to those of the NNG. VNG improve the quality of the axonal regeneration (axonal diameter and Schwann cells), although the increase in the axonal number is not significant and does not improve the long-term functional outcome.     

神经生长因子促再生坐骨神经血管生成的作用

BACKGROUND： It remains to be determined whether nerve growth factor （NGF） can promote angiogenesis in regenerating peripheral nerves during repairing peripheral nerve injury.
OBJECTIVE： To evaluate the effects of NGF on angiogenesis, and to analyze the influencing mechanisms of NGF, according to the expression patterns of CD34, von Willebrand factor （vWF）, vascular endothelial cell growth factor （VEGF）, and the NGF receptor TrkA in proliferating vascular endothelial cells from a rat model of sciatic nerve injury.
DESIGN, TIME AND SETTING： Randomized, controlled study performed at the Research Institute of Field Surgery, Daping Hospital affiliated to the Third Military Medical University of Chinese PLA, between October 2003 and July 2005.
MATERIALS： Forty-five healthy, adult, Wistar rats underwent sciatic nerve injury. The rats were randomly divided into four groups： NGF ＋ chitosan （n = 15）, NGF ＋ chitosan ＋ anti-VEGF （n = 10）, chitosan （n = 10）, and physiological saline （n = 10）. METHODS： A 1 -cm defected sciatic nerve was bridged with a silica gel conduit. NGF ＋ chitosan group： 100 μ L chitosan and 5 μ L NGF （20 mg/L） were injected into the silica gel conduit; NGF ＋ chitosan ＋ anti-VEGF group： an additional 5μ L anti-VEGF monoclonal antibody （1 g/L） was injected into the silica gel conduit; chitosan group： 100μL chitosan and 5 μL physiological saline were injected into the silica gel conduit; physiological saline group： only 5μL physiological saline was injected into the silica gel conduit.
MAIN OUTCOME MEASURES： CD34 and vWf were used to label blood capillaries and large-diameter blood vessels in the regenerating peripheral nerves, respectively. At day 14 following surgery, immunohistochemistry was used to detect and semi-quantitatively analyze expressions of CD34, vWf, VEGF, and TrkA in proliferating vascular endothelial cells in the regenerating sciatic nerve. A confocal laser microscope was used to determine co-expression. RESULTS： Expressions of TrkA, CD34, vWf, and VEGF in the NGF ＋ chitosan group were significantly greater than the physiological saline and chitosan groups （P 〈 0.05-0.01）. Expressions of CD34 and VEGF in the NGF ＋ chitosan ＋ anti-VEGF group were completely inhibited, while expressions of vWf and TrkA gradually decreased, compared with the NGF ＋ chitosan group （P 〈 0.01）. Confocal microscopy revealed strong co-expression of VEGF and CD34 in the regenerating sciatic nerve, and CD34 expression positively correlated with VEGF expression. In addition, VEGF expression was greater than CD34 expression, and coexpression of VEGF and vWf was also strong.
CONCLUSION： VEGF was expressed in blood capillaries and large-diameter blood vessels, while exogenous NGF promoted VEGF expression in regenerating sciatic nerves, thereby increasing angiogenesis.     

维拉帕米与神经生长因子促进大鼠坐骨神经再生的协同作用

背景：实验证明周围神经损伤时,轴突的变性与神经元凋亡都与Ca2+的超载有着极其密切的关系。 目的：利用大鼠坐骨神经损伤模型观察L型钙离子通道阻滞剂维拉帕米联合神经生长因子促进周围神经再生的协同作用。 设计、时间及地点：随机对照动物实验,于2007-04/2008-11在辽宁医学院手外科实验室完成。 材料：同系健康雄性SD大鼠32只,体质量220~260 g;维拉帕米为辽宁卫星制药厂产品,国药准字H21022847;神经生长因子为sigma公司产品。 方法：同系SD大鼠32只随机分为4组,每组8只,分别在右侧梨状肌下缘5 mm切断坐骨神经后立即原位缝合造成坐骨神经损伤模型。①维拉帕米+神经生长因子组：腹腔注射维拉帕米4 mg/(kg•d),术侧腓肠肌肉注射神经生长因子0.6 μg/d。②维拉帕米组：腹腔注射维拉帕米4 mg/(kg•d),术侧腓肠肌注射等量生理盐水。③神经生长因子组：术侧腓肠肌注神经生长因子0.6 μg/d,并腹腔注射等量生理盐水。④空白对照组：分别腹腔,肌注等量生理盐水。以左侧坐骨神经为正常对照。 主要观察指标：术后12周对各组再生神经进行大体观察,神经电生理测定,组织学观察及有髓神经纤维计数。 结果：术后12周,维拉帕米+神经生长因子组足部溃疡的出现与愈合以及展抓反射出现的时间均早于其他各组。神经传导速度恢复率和有髓神经纤维计数恢复率分析表明：维拉帕米+神经生长因子组>维拉帕米组>神经生长因子组>空白对照组。光镜和电镜下可见：维拉帕米+神经生长因子组再生的神经纤维最多,轴突较为粗大。有髓神经纤维多,髓鞘完整,优于其他3组。神经纤维直径恢复率分析表明：维拉帕米+神经生长因子组>神经生长因子组>维拉帕米组>空白对照组。 结论：维拉帕米与神经生长因子对促进周围神经形态结构和功能的恢复均具有明显的协同作用。     

神经生长因子治疗周围神经损伤的疗效观察

目的 观察神经生长因子治疗周围神经损伤的临床疗效.方法 纳入60例周围神经损伤患者,采用随机数字表法分为2组.试验组30例采用鼠NGF肌内注射治疗,对照组30例采用维生素B12治疗,治疗4周后观察疗效.观察指标包括疼痛(VAS)、麻木等临床症状和体征,同时观察单神经的神经电生理情况.结果 疼痛改善:试验组总有效率93.33％,对照组为53.33％;麻木改善:试验组总有效率86.67％,对照组为66.67％;2组比较差异均有统计学意义(P＜0.05).试验组恢复神经的感觉及运动电位的潜伏期时间均明显短于对照组,差异有统计学意义(P＜0.05);而波幅则均显著高于对照组,差异有显著性意义(P＜0.05).结论 神经生长因子能有效改善患者的疼痛、麻木症状,而且能对神经纤维的修复、电生理功能有促进作用.     

Schwann cells upregulate vascular endothelial growth factor secondary to chronic nerve compression injury

To better understand the pathogenesis of chronic nerve compression injuries, we investigated the possibility that Schwann cell production of vascular endothelial growth factor (VEGF) is responsible for the increased vascularity and Schwann cell proliferation associated with chronic nerve injury. In situ hybridization was used to evaluate VEGF mRNA production with immunohistochemistry to further localize the production of VEGF and its receptor proteins in an animal model of chronic nerve compression injury. VEGF mRNA and protein expression increased within Schwann cells as early as 2 weeks after compression and peaked by 1 month with a subsequent marked increase in the number of blood vessels. Thus, chronic nerve compression injury induces Schwann cells to increase VEGF production, which may be responsible for changes in neural vasculature secondary to chronic nerve compression injury. With a better understanding of these nerve injuries, more effective treatments may be developed to help patients with these impairments.     

神经再生素和神经生长液联合应用对成年兔视神经挫伤后修复的影响

目的研究中药神经再生素（NRF）和神经生长液对成年兔视神经挫伤后修复的影响。方法16只成年兔随机分成实验组和对照组．每组8只。建立兔右眼视神经挫伤模型后．分别将载有0．06mL NRF（浓度为2g／L，实验组）或等量磷酸盐缓冲液（PBS）（对照组）的组织工程化神经移植于视神经损伤处；并向右眼玻璃体腔内注入0．02mL NRF（浓度为2g／L，实验组）或等量PBS（对照组）。实验组兔术后每日喂服神经生长液（5mL／kg），共6周。伤后1d、2周、8周进行闪光视觉诱发电位（FVEP）检查。挫伤后8周时作光镜和电镜检查观察视网膜神经节细胞（RGC）、视网膜神经纤维层和视神经的改变，同时用计算机图像处理系统作视神经纤维计数。结果术后8周时实验组致伤眼与未致伤眼FVEP幅值比为0．774±0．184，对照组为0．409±0．119，差异有显著性（P〈0．01）。术后8周时的光镜和电镜检查示：实验组RGC、视神经纤维的退变较对照组轻。两组视神经纤维计数分别为（15045±716．2）根／mm^2（实验组）和（7898±608．8）根／mm^2（对照组），差异有显著性（P〈0．01）。结论NRF和神经生长液联合应用能够增加RGC的存活，促进轴突的再生，因而对视神经挫伤后的修复、视功能的恢复具有一定的促进作用。     

纤维蛋白凝胶携载血管内皮生长因子对大鼠损伤坐骨神经运动功能的影响

背景：坐骨神经损伤后的修复方法多样,但由于坐骨神经解剖和功能上的特殊性,神经功能的恢复仍不理想。 目的：观察局部应用纤维蛋白凝胶携载血管内皮生长因子,对损伤坐骨神经组织神经功能恢复的疗效。 方法：将Wistar大鼠左侧坐骨神经切断,神经两断端原位缝合,制作大鼠坐骨神经损伤动物模型,然后随机分为2组,实验组于坐骨神经切断处外膜内、外注射纤维蛋白凝胶/血管内皮生长因子复合体;对照组于同处注射血管内皮生长因子165质粒。于用药后4,8,12周行大体观察、神经功能指数检测、电生理检测(测运动神经传导速度)。 结果与结论：两组动物伤口均为一期愈合。实验组用药后1周有6只出现足底溃疡伴肌萎缩;对照组有5只出现足底溃疡。实验组4周时,纤维蛋白凝胶基本被吸收;8周时完全吸收;12周时,神经外形基本正常。对照组4周时,神经轻度充血、水肿;8周时,神经无水肿,与周围组织见少量粘连;12周时,神经周围见瘢痕形成。实验组4,8周的神经功能指数、运动神经传导速度较对照组降低(P < 0.05),12周无显著性差异(P > 0.05)。提示纤维蛋白凝胶可以作为血管内皮生长因子的载体,纤维蛋白凝胶携载血管内皮生长因子给药可以促进损伤神经结构和功能的恢复。 关键词：坐骨神经;损伤;纤维蛋白凝胶;血管内皮生长因子;载体 doi:10.3969/j.issn.1673-8225.2010.29.015     

Incorporation of [P]phosphate into nucleotides of the dorsal root ganglia of regenerating rat sciatic nerve

[³²P]Phosphate incorporation into nucleotides of the dorsal root ganglia (DRG) was studied after a crush lesion of the rat sciatic nerve. DRG were labelled during a 2-h, in vitro incubation in a balanced salt solution containing [³²P]orthophosphate, 1,2,4 and 8 days after the crush lesion. Nucleotides were analyzed by HPLC on an ion-exchange column. An increased incorporation of ³²P was found among in DRG of the injured nerve for all the studied time periods. This increase was unevenly distributed among the nucleotides. UTP, CTP and ADP showed the largest and most persistent increases in labelling. The specific activity of 4 analyzed nucleotides (ATP, ADP, UTP and CDP) remained constant in DRG from crushed nerves. Thus, the observed increase in ³²P-labelling could not solely be due to an increased uptake of label but must also reflect an enhanced metabolism of nucleotides in regenerating DRG. The finding that alterations of nucleotide metabolism could be observed within one day after the crush lesion suggests that this response can be used as a valuable tool for studies of the initial events of regeneration.     

Cultured rat Schwann cells express low affinity receptors for nerve growth factor

Schwann cell cultures prepared from postnatal Sprague-Dawley rat sciatic nerves were used to demonstrate the presence of specific receptors for the beta-subunit of nerve growth factor (NGF) on rat Schwann cells. Indirect immunofluorescence microscopy with a monoclonal antineuronal NGF receptor (NGFR) antibody indicated that NGFR antigen was expressed on the surface of Schwann cells but not of endoneurial fibroblasts. Studies with 125I-NGF confirmed this distribution of NGFR in the cultures and showed that the Schwann cell NGFR had a single NGF binding affinity (Kd of 1.8 x 10(-9) M). 125I-NGF binding by the cultured Schwann cells increased with time in vitro, reaching a plateau level on the 4th day, but decreased with increasing age, reaching 40% of the neonatal value in Schwann cells isolated from 12-day-old rats. Treatment of the cultures with NGF did not alter Schwann cell phenotype, survival or proliferation.     

血管性认知功能障碍及痴呆患者血浆内皮素-1和血管内皮生长因子含量变化及意义

目的探讨血浆内皮素-1（ET-1）和血管内皮生长因子（VEGF）在血管性认知功能障碍（VCI）及痴呆（VaD）发病过程中的作用。方法脑梗死143例,随访3个月,依据蒙特利尔认知评估量表（MoCA）和临床痴呆评定量表（CDR）评分将其分为无认知功能障碍（N-VCI）组、血管性认知障碍无痴呆（VCIND）组、血管性痴呆（VaD）组,用放射免疫法测定血浆ET-1水平,酶联免疫分析法测定血浆VEGF的水平,并对血浆ET-1和VEGF进行相关性分析。结果 （1）VaD组患者血浆ET-1含量明显高于VCIND组及N-VCI组,VCIND组患者血浆ET-1水平明显高于N-VCI组,差异均具统计学意义（P〈0.01）;VaD组患者血浆VEGF含量明显低于VCIND组及N-VCI组,VCIND组亦明显低于N-VCI组,差异均具统计学意义（P〈0.01）。（2）血浆ET-1水平与VEGF存在明显负相关（r=-0.808,P〈0.01）。（3）VaD组患者血浆ET-1与MoCA值成负相关（r=-0.719,P〈0.01）,VaD患者血浆VEGF与MoCA评分成正相关（r=0.670,P=0.01）;而N-VCI、VCIND组患者血浆ET-1、VEGF与MoCA值无相关性（P〉0.05）。结论高ET-1和低VEGF参与了VCI及VaD的发生发展过程,血浆ET-1与VaD病情成正相关,血浆VEGF与VaD病情成负相关,这些指标的监测可作为判断VaD病情轻重的重要依据。     

Enhancement of sciatic nerve regeneration after vascular endothelial growth factor (VEGF) gene therapy

F. R. Pereira Lopes, B. C. G. Lisboa, F. Frattini, F. M. Almeida, M. A. Tomaz, P. K. Matsumoto, F. Langone, S. Lora, P. A. Melo, R. Borojevic, S. W. Han and A. M. B. Martinez (2011) Neuropathology and Applied Neurobiology 37, 600–612 Enhancement of sciatic nerve regeneration after vascular endothelial growth factor (VEGF) gene therapy Aims: Recent studies have emphasized the beneficial effects of the vascular endothelial growth factor (VEGF) on neurone survival and Schwann cell proliferation. VEGF is a potent angiogenic factor, and angiogenesis has long been recognized as an important and necessary step during tissue repair. Here, we investigated the effects of VEGF on sciatic nerve regeneration. Methods: Using light and electron microscopy, we evaluated sciatic nerve regeneration after transection and VEGF gene therapy. We examined the survival of the neurones in the dorsal root ganglia and in lumbar 4 segment of spinal cord. We also evaluated the functional recovery using the sciatic functional index and gastrocnemius muscle weight. In addition, we evaluated the VEGF expression by immunohistochemistry. Results: Fluorescein isothiocyanate‐dextran (FITC‐dextran) fluorescence of nerves and muscles revealed intense staining in the VEGF‐treated group. Quantitative analysis showed that the numbers of myelinated fibres and blood vessels were significantly higher in VEGF‐treated animals. VEGF also increased the survival of neurone cell bodies in dorsal root ganglia and in spinal cord. The sciatic functional index and gastrocnemius muscle weight reached significantly higher values in VEGF‐treated animals. Conclusion: We demonstrate a positive relationship between increased vascularization and enhanced nerve regeneration, indicating that VEGF administration can support and enhance the growth of regenerating nerve fibres, probably through a combination of angiogenic, neurotrophic and neuroprotective effects.