移植壳聚糖导管修复大鼠坐骨神经缺损

目的:研究移植结合了碱性成纤维细胞生长因子(bFGF)的壳聚糖导管促进周围神经损伤再生的情况。方法:成年Wistar大鼠造成10mm坐骨神经缺损后,以壳聚糖导管(移植组,10只)作桥梁桥接神经两断端,以假手术组和单纯损伤组(造成10mm坐骨神经缺损后,不加以任何干预措施)各10只分别为阳性和阴性对照,术后通过肉眼观察和神经微丝(NF)、乙酰胆碱酯酶(AChE)免疫组织化学染色方法对损伤神经局部及远端靶肌肉运动终板的再生情况进行观察。结果:移植组大鼠术后3个月,新生的神经纤维已越过缺损部位并到达损伤远端。免疫组织化学染色显示:术后3个月,移植组大鼠坐骨神经缺损处再生组织内可观察到均匀、密集分布的NF免疫阳性纤维,且在腓肠肌终板区内可见AChE免疫阳性终末,至5个月时阳性染色明显增强。在术后3个月时可见新生的运动终板,但轮廓不规则、边界不清晰;而在5个月时,新生的运动终板的形态与密度均接近假手术组水平。结论:结合了bFGF的壳聚糖导管对缺损的坐骨神经修复具有良好的桥梁作用和促进神经生长及终板再生的作用。     

Effects of Nogo-A and its receptor on the repair of sciatic nerve injury in rats

Regeneration of injured peripheral nerves is an extremely complex process. Nogo-A (neurite outgrowth inhibitor-A) inhibits axonal regeneration by interacting with Nogo receptor in the myelin sheath of the central nervous system (CNS). The aim of this study was to investigate the effects of Nogo-A and its receptor on the repair of sciatic nerve injury in rats. Sprague-Dawley rats (n=96) were randomly divided into 4 groups: control group (control), sciatic nerve transection group (model), immediate repair group (immediate repair), and delayed repair group (delayed repair). The rats were euthanized 1 week and 6 weeks after operation. The injured end tissues of the spinal cord and sciatic nerve were obtained. The protein expressions of Nogo-A and Nogo-66 receptor (NgR) were detected by immunohistochemistry. The protein expressions of Nogo-A, NgR, and Ras homolog family member A (RhoA) were detected by western blot. At 1 week after operation, the pathological changes in the immediate repaired group were less, and the protein expressions of Nogo-A, NgR, and RhoA in the spinal cord and sciatic nerve tissues were decreased (P<0.05) compared with the model group. After 6 weeks, the pathological changes in the immediate repair group and the delayed repair group were alleviated and the protein expressions decreased (P<0.05). The situation of the immediate repair group was better than that of the delayed repair group. Our data suggest that the expression of Nogo-A and its receptor increased after sciatic nerve injury, indicating that Nogo-A and its receptor play an inhibitory role in the repair process of sciatic nerve injury in rats.     

Interleukin-1 beta promotes sensory nerve regeneration after sciatic nerve injury

Nerve injury brings about axonal disconnection, and thus axonal extension is one of the important steps for nerve regeneration. Expression of the pro-inflammatory cytokine interleukin-1 beta (IL-1beta) is increased at the early stage of nervous system injury, and previously IL-1beta has been reported to promote neurite outgrowth by inhibiting RhoA activity in vitro. However, the effect of IL-1beta on axonal extension in vivo has not been obvious. Now we examine whether IL-1beta takes advantages on sciatic nerve regeneration. Sciatic nerves of rats are transected and sutured, and IL-1beta or PBS is locally administered for 2 weeks. Although IL-1beta does not influence on motor functional recovery, it promotes sensory functional recovery, estimated by toe pinch test, and increases the number and the area of neurofilament-positive axons at 12 weeks compared with PBS. Moreover IL-1beta, which promotes Schwann cell proliferation and thus may inhibit myelination, does not impair remyelination, estimated by myelin basic protein. These findings suggest that IL-1beta may contribute to sensory nerve regeneration following sciatic nerve injury by promoting axonal extension.     

Dexamethasone and vitamin B12 synergistically promote peripheral nerve regeneration in rats by upregulating the expression of brain-derived neurotrophic factor

Introduction

Dexamethasone and vitamin B₁₂ are currently used in the clinic to treat peripheral nerve damage but their mechanisms of action remain incompletely understood. In this study we hypothesized that dexamethasone and vitamin B₁₂ promote the production of endogenous neurotrophic factors, thereby enhancing peripheral nerve repair.

Material and methods

Ninety-six adult male Wistar rats were employed to establish a sciatic nerve injury model. They were then randomly divided into 4 groups to be subjected to different treatment: saline (group A), dexamethasone (group B), vitamin B₁₂ (group C), and dexamethasone combined with vitamin B₁₂ (group D). The walking behavior of rats was evaluated by footprint analysis, and the nerve regeneration was assessed by electrophysiological analysis and ultrastructural examination. The expression of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor, NT-3 and IL-6 in the injured sciatic nerves was detected by immunohistochemical and RT-PCR analysis.

Results

Dexamethasone and vitamin B₁₂ promoted the regeneration of myelinated nerve fibers and the proliferation of Schwann cells. Furthermore, dexamethasone and vitamin B₁₂ promoted the recovery of sciatic functional index and sensory nerve conduction velocity, and upregulated BDNF expression in the injured sciatic nerves.

Conclusions

Dexamethasone and vitamin B₁₂ promote peripheral nerve repair in a rat model of sciatic nerve injury through the upregulation of BDNF expression. These findings provide new insight into the neurotrophic effects of dexamethasone and vitamin B₁₂ and support the application of these agents in clinical treatment of peripheral nerve injury.     

β-1,4-半乳糖苷键在周围神经损伤后的表达变化

为了探讨正常和损伤的周围神经中β-1,4-半乳糖苷键的表达定位和表达变化 ,本研究用特异识别β-1,4-半乳糖苷键的蓖麻凝集素 -I免疫组织化学方法结合 S-10 0和 neurofilam ent免疫双标记 ,研究了大鼠坐骨神经损伤对 β-1,4-半乳糖苷键的合成影响。结果表明 ,β-1,4-半乳糖苷键主要分布在正常和损伤坐骨神经的 Schwann细胞中 ,图像分析表明β-1,4-半乳糖苷键的表达在周围神经损伤后 1～ 2 d内有所增高 ,以后随时间延长表达量逐步下降。本研究结果提示 ,周围神经损伤对 β-1,4-半乳糖苷键的表达有影响 ,Schwann细胞表达的β-1,4-半乳糖苷键可能参与周围神经损伤修复相关因子的修饰调控     

Influences of mechanical properties and permeability on chitosan nano/microfiber mesh tubes as a scaffold for nerve regeneration

We have developed chitosan nonwoven micro/nanofiber mesh tubes and examined the effects of their mechanical strength and permeability on nerve regeneration. Chitosan nano/microfibrous tubes with a deacetylation rate (DAc) of 78% or 93% were prepared by electrospinning. A chitosan film tube with a DAc of 93% was also fabricated and combined with the nano/microfibrous tubes to form bilayered tubes with a nano/microfiber mesh inner structure and a film outer layer. Nano/microfiber mesh tubes with a DAc of 78% or 93%, bilayered tubes with a nano/microfiber mesh inner structure with a DAc of 78% or 93% and a film outer layer with a DAc of 93%, and film tubes with a DAc of 93% were each tested as bridge grafts into injured rat sciatic nerve. Isografting was performed as a control. Although the functional recovery of motor activity was delayed in each group, sensory function reemerged first in the isograft group followed by the group receiving nano/microfiber mesh tubes with a DAc of 93%. Histological analysis was consistent with these results. The chitosan nano/microfiber mesh tubes with a DAc of 93% have sufficient mechanical properties to preserve tube space, provide a better scaffold for cell migration and attachment, and facilitate humoral permeation to enhance nerve regeneration.     

Erythropoietin promotes peripheral nerve regeneration in rats by upregulating expression of insulin-like growth factor-1

Introduction

Erythropoietin (EPO) has been shown to have beneficial effects on peripheral nerve damage, but its mechanism of action remains incompletely understood. In this study we hypothesized that EPO promotes peripheral nerve repair via neurotrophic factor upregulation.

Material and methods

Thirty adult male Wistar rats were employed to establish a sciatic nerve injury model. They were then randomly divided into two groups to be subjected to different treatment: 0.9% saline (group A) and 5000 U/kg EPO (group B). The walking behavior of rats was evaluated by footprint analysis, and the nerve regeneration was assessed by electron microscopy. The expression of insulin-like growth factor-1 (IGF-1) in the injured sciatic nerves was detected by immunohistochemical analysis.

Results

Compared to saline treatment, EPO treatment led to the growth of myelin sheath, the recovery of normal morphology of axons and Schwann cells, and higher density of myelinated nerve fibers. Erythropoietin treatment promoted the recovery of SFI in the injured sciatic nerves. In addition, EPO treatment led to increased IGF-1 expression in the injured sciatic nerves.

Conclusions

Erythropoietin may promote peripheral nerve repair in a rat model of sciatic nerve injury through the upregulation of IGF-1 expression. These findings reveal a novel mechanism underlying the neurotrophic effects of EPO.     

Macrophage and lymphocyte invasion of dorsal root ganglia after peripheral nerve lesions in the rat

The distribution of major histocompatibility complex class II (MHC II)-positive non-neuronal cells and T-lymphocytes was examined immunohistochemically in dorsal root ganglia (DRGs) up to 12 weeks following transection of one sciatic or lumbar spinal nerve in adult rats. Unlike within the brain, MHC II immunopositive (+) and T-cells are normally present within DRGs. After nerve transection, MHC II+ cell density increased (by about four times after each lesion) in DRGs projecting into lesioned nerves. Subsequently the number declined after sciatic but not spinal nerve transection. MHC II+ cells did not contain glial markers, even when these were up-regulated after the lesions. Initially, MHC II+ cells lay outside the satellite glia but, by 11 weeks, they had moved through them to lie against the somata. T-cells invaded the lesioned DRGs earlier than the MHC II+ cells. They achieved greater numbers after spinal (30 x control) than after sciatic (12 x control) nerve transection. They also increased in undamaged ganglia adjacent to the spinal nerve injury. T-cell density progressively declined after spinal but not sciatic nerve transection. Both cell types appeared to invade the DRGs initially through blood vessels and the meninges, particularly near the subarachnoid angle. At later stages, occasional neurones had dense aggregations of T-cell receptor+ and MHC II+ cells associated with them.We conclude that the magnitude and time course of changes in MHC II expression and T-cell numbers in lesioned DRGs differ from the responses within motor nuclei after axotomy. The influx of inflammatory cells may contribute to neurone survival in the short term. Their long-term presence has implications for patients. These cells have the potential to release excitatory cytokines that may generate ectopic impulse activity in sensory neurones after nerve injury and so may play a role in the generation of chronic neuropathic pain.     

Differential effects of endogenous brain-derived neurotrophic factor on the survival of axotomized sensory neurons in dorsal root ganglia: a possible role for the p75 neurotrophin receptor

After peripheral nerve injury, axotomized sensory neurons in dorsal root ganglia (DRG) undergo apoptosis and up-regulate brain-derived neurotrophic factor (BDNF). We tested whether endogenous BDNF plays any role in the survival of axotomized sensory neurons using in vitro and in vivo models. In the in vitro model, treatment with BDNF antibody significantly reduced apoptosis of sensory neurons in DRG explants from both adult and neonate rats and adult mice cultured for 48 h. Consistently, exogenous BDNF increased the percentage of apoptotic neurons in the DRGs from mice. The effects of the BDNF antibody and BDNF were not seen in DRGs from p75NTR(-/-) mice. In the in vivo model, sciatic nerve transection in neonatal rats decreased the total number of neurons in the injured DRG and treatment with antiserum to BDNF significantly exaggerated the loss of DRG neurons. Numbers of sensory neurons expressing BDNF and p75NTR in cultured DRGs increased but that expressing TrkB decreased. In contrast, sciatic nerve transection in vivo reduced the numbers of neurons expressing both p75NTR and TrkB but increased the numbers of cells expressing BDNF, 1 and 7 days after the surgery. These results suggest that BDNF may have differential effects on the survival of sensory neurons depending on the expression of p75NTR. While endogenous BDNF induced apoptosis of axotomized sensory neurons through p75NTR in vitro where more neurons expressed p75NTR, it prevented apoptosis in vivo where fewer neurons expressed p75NTR after sciatic nerve transection.     

N-糖链合成相关β-1,4-半乳糖基转移酶在大鼠坐骨神经损伤后的表达变化

为了分析与 N-糖链合成相关β-1,4-半乳糖基转移酶 - 、 、 (β-1,4-galactosyltransferase , , ,β-1,4-Gal T- , , ) m RNA在正常和损伤坐骨神经组织的表达变化。本研究采用 RT-PCR方法 ,分析 β-1,4-Gal T- 、 、 在小鼠坐骨神经中的表达存在。以扩增的 c DNA片断标记探针 ,Northern blot分析β-1,4-Gal T- 、 、 m RNA在正常和损伤大鼠坐骨神经的表达变化。结果表明 :通过 RT-PCR方法 ,检测到 β-1,4-Gal T- 、 、 在小鼠坐骨神经中的表达存在 ;采用 Northern blot方法 ,发现β-1,4-Gal T- 、 、 在正常大鼠坐骨神经中有表达 ,并在坐骨神经损伤后发生表达变化 ,但三种同功酶的表达变化各不相同。结论 :本实验发现 β-1,4-Gal T- 、 、 在坐骨神经有表达 ,并在坐骨神经损伤后发生表达变化。提示与 N-糖链合成相关的蛋白修饰调节在周围神经损伤后再生和退变过程中可能发挥一定的作用     

化学去细胞异体神经联合骨髓间充质干细胞修复损伤坐骨神经的生物力学评价

文题释义： 生物力学：是应用力学原理和方法对生物体中的力学问题定量研究的生物物理学分支,其研究范围从生物整体到系统、器官(包括血液、体液、脏器、骨骼等),从鸟飞、鱼游、鞭毛和纤毛运动到植物体液的输运等。生物力学的基础是能量守恒、动量定律、质量守恒定律并加上描写物性的本构方程。生物力学研究的重点是与生理学、医学有关的力学问题。依研究对象的不同可分为生物流体力学、生物固体力学和运动生物力学等。 周围神经研究热点和发展趋势：周围神经损伤的治疗已经取得了突破性的进展,但由于周围神经走行长、结构复杂、功能多样,损伤后其自身和靶器官会发生改变,而且是动态的、有时间效应的改变,因此以整体统一的理念研究周围神经损伤是今后研究重点。如何将基础研究与临床相结合,最终实现成果转化服务于患者,是研究者们的努力方向。国内外学者对自体神经损伤移植替代材料的研究从未间断过。随着组织工程和生物力学的发展,同种异体神经和人工神经已逐渐应用于临床,去细胞神经移植物也已取得了很好的临床效果。背景：以拉伸力学指标评估化学去细胞异体神经联合骨髓间充质干细胞治疗坐骨神经损伤的效果,目前鲜有报道。 目的：评估化学去细胞异体神经联合骨髓间充质干细胞移植治疗坐骨神经损伤的效果。 方法：将45只SD大鼠随机分为自体神经移植组、化学去细胞异体神经移植组、化学去细胞异体神经联合骨髓间充质干细胞移植组,每组15只,制备10 mm坐骨神经损伤模型,分别以自体神经、化学去细胞异体神经、化学去细胞异体神经联合骨髓间充质干细胞修复坐骨神经损伤,术后20周,进行坐骨神经电生理检测和坐骨神经单向拉伸实验。 结果与结论：①化学去细胞异体神经联合骨髓间充质干细胞移植组与自体神经移植组波幅值、运动传导速度值大于化学去细胞异体神经移植组(P < 0.05);②化学去细胞异体神经联合骨髓间充质干细胞移植组与自体神经移植组拉伸弹性限度应变、弹性限度应力、最大应变、最大应力大于化学去细胞异体神经移植组(P < 0.05);③结果表明,化学去细胞异体神经联合骨髓间充质干细胞移植对坐骨神经损伤具有明显的修复效果。ORCID: 0000-0002-1029-8117(吴志峰) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Extracellular matrix of human amnion manufactured into tubes as conduits for peripheral nerve regeneration

The human amnion consists of the epithelial cell layer and underlying connective tissue. After removing the epithelial cells, the resulting acellular connective tissue matrix was manufactured into thin dry sheets called amnion matrix sheets. The sheets were further processed into tubes, amnion matrix tubes (AMTs), of varying diameters, with the walls of varying numbers of amnion matrix sheets with or without a gelatin coating. The AMTs were implanted into rat sciatic nerves. Regenerating nerves extended in bundles through tubes of 1-2 mm in diameter and further elongated into host distal nerves 1-3 weeks after implantation. Morphometrical analysis of the regenerated nerve cable at the middle of each amnion matrix tube 3 weeks after implantation was performed. The average numbers of myelinated axons were almost the same (ca. 80-112/10(4) microm(2)) in AMTs of 1-2 mm in diameter, as in the normal sciatic nerve (ca. 95/10(4) microm(2)). No myelinated fibers were found in AMTs composed of multiple thin tubes of 0.2 mm in diameter. The myelinated axons were thinner in implanted tubes than those in the normal sciatic nerve. The rate of occurrences of myelinated axons less than 4 microm in diameter was significantly higher in the AMTs, whereas axons in the normal sciatic nerve were diverse in distribution, with the highest population at 8-12 microm in diameter. Reinnervation to the gastrocnemius muscle was demonstrated electrophysiologically 9 months after implantation. It was concluded that the extracellular matrix sheet from the human amnion is an effective conduit material for peripheral nerve regeneration.     

种植施万细胞的脱细胞同种异体神经移植物对大鼠坐骨神经缺损的修复作用

目的观察种植施万细胞的脱细胞同种异体神经移植物,桥接大鼠坐骨神经缺损后的神经再生。方法应用酶反复消化法与差速贴壁法体外分离培养乳鼠施万细胞;显微注射法将施万细胞种植到脱细胞同种异体神经移植物内;再应用种植施万细胞的脱细胞同种异体神经移植物桥接大鼠坐骨神经10 mm缺损。光镜、透射电镜和扫描电镜观察再生神经的形态结构、有髓神经纤维数量、平均髓鞘厚度并进行统计学分析。结果光、电镜观察到实验组(SCs+ARSN)的施万细胞在再生神经纤维中互相连结纵行排列成类似Büngner带样细胞链,对照组(ARSN)未见到施万细胞的链状排列。实验组再生有髓神经纤维的髓鞘厚度较对照组均匀且较厚,有髓神经纤维数量和平均髓鞘厚度明显多于对照组(P<0.05)。结论种植施万细胞的脱细胞同种异体神经移植物对缺损的坐骨神经再生有更加有效的促进作用。     

毛囊干细胞对坐骨神经损伤修复的影响

背景：毛囊干细胞具有多分化潜能,可分化成神经细胞,极有希望成为治疗周围神经损伤的种子细胞。 目的：观察毛囊干细胞对坐骨神经损伤修复的影响。 方法：体外分离培养SD大鼠乳鼠胡须处的毛囊干细胞,经鉴定备用。36只SD大鼠随机分为实验组和对照组,建立坐骨神经损伤模型后,实验组于坐骨神经损伤处的上方注入浓度约10⁶ L^-1的毛囊干细胞50 μL,对照组注射等量的磷酸盐缓冲液。 结果与结论：各组坐骨神经功能指数均随观察时间进行性增加,其中实验组大鼠神经功能恢复早于对照组;免疫组织化学检测移植后的毛囊干细胞大量存活并分化成神经细胞。结果提示毛囊干细胞能够有效的促进损伤的坐骨神经修复。     

骨髓神经组织定向干细胞性组织工程化神经移植修复坐骨神经损伤

目的:为临床周围神经损伤的组织工程化神经替代治疗提供可靠的实验依据。方法:采用体外成功构建的骨髓神经组织定向干细胞(NTCSCs)组织工程化神经,桥接缺损10mm的大鼠坐骨神经。通过术后行为学、神经功能指数分析(SFI)、神经电生理功能检查和HRP逆行追踪,以及对移植至支架的标记细胞在体内的存活、增殖及分化的形态学观察,综合评价损伤神经的功能恢复情况。结果:(1)SFI及神经电生理功能检查显示,NTCSCs组织工程化神经移植能明显促进神经传导功能及运动功能的恢复。(2)HRP逆行追踪结果显示NTCSCs组织工程化神经移植能明显促进神经纤维再生。(3)免疫荧光双标结果显示移植到体内的NTCSCs,从4周到12周,其细胞数显著增加,体内的NTCSCs细胞能分化成少量NSE阳性细胞,但大部分分化成S-100阳性细胞。结论:该骨髓神经组织定向干细胞性组织工程化神经能够有效的促进损伤坐骨神经的功能恢复。     

微囊化兔坐骨神经组织移植对大鼠脊髓损伤神经元的影响

目的：观察大鼠脊髓半横断损伤后植入微囊化兔坐骨神经组织对一氧化氮合酶(NOS)表达的影响。方法：尼氏染色和NADPH-d组织化学染色。利用图像分析系统检测染色标记细胞数和阳性细胞平均面积、平均光密度。结果：脊髓损伤后神经元数量减少,尼氏体脱失、溶解。术后3d,微囊组NOS阳性细胞数、阳性细胞平均面积及平均光密度均明显高于单损组;术后7d微囊组NOS阳性细胞数和阳性细胞平均面积较细胞组高;术后14d,细胞组NOS阳性细胞数急剧增高超过微囊组,但微囊组仍平稳上升。结论：微囊化兔坐骨神经组织移植能诱导早期NOS表达增加及抑制后期NO过量产生,减轻脊髓继发性损伤,有利于损伤脊髓的修复和再生。     

Highly permeable polylactide-caprolactone nerve guides enhance peripheral nerve regeneration through long gaps.

We compared regeneration and functional reinnervation after sciatic nerve resection and tubulization repair with bioresorbable guides of poly(L-lactide-co-epsilon-caprolactone) (PLC) and permanent guides of polysulfone (POS) with different degrees of permeability, leaving a 6 mm gap in different groups of mice. Functional reinnervation was assessed to determine recovery of motor, sensory and sweating functions in the hindpaw during four months postoperation. Highly permeable PLC guides allowed for faster and higher levels of reinnervation for the four functions tested than impermeable or low-permeable PLC guides, while semipermeable 30 and 100 kDa POS tubes yielded very low levels of reinnervation. The regeneration success rate was higher with PLC than with POS tubes. Morphometrical analysis of cross-sectional nerves under light microscopy showed the highest number of regenerated myelinated fibers at mid tube and distal nerve in high-permeable PLC guides. Impermeable PLC guides allowed slightly worse levels of regeneration, while low-permeable PLC guides promoted neuroma and limited distal regeneration. The lowest number of regenerated fibers were found in POS tubes. In summary, highly permeable bioresorbable PLC guides offer a suitable alternative for repairing long gaps in injured nerves, approaching the success of autologous nerve grafts.     

Effects of percutaneous electrical stimulation on peripheral nerve regeneration using silicone rubber chambers

The purpose of this study was to determine whether 0.8-1 mA, 2 Hz of percutaneous electrical stimulation could affect the regeneration of a 10-mm gap of rat sciatic nerve created between the proximal and distal nerve stumps, which were sutured into silicone rubber tubes. Six weeks after implantation, though the group receiving the electrical stimulation had a lower success percentage of regeneration (57%) compared with the controls receiving no stimulation (70%), quantitative histology of the successfully regenerated nerves revealed that the mean values of the axon density, blood vessel number, blood vessel area, and percentage of blood vessel area in total nerve area in the group with the electrical stimulation were all significantly larger than those in the controls (p < 0.05). These results showed that the electrical stimulation could elicit rehabilitating effects on the regenerated nerves.     

Transplantation of embryonic stem cells improves nerve repair and functional recovery after severe sciatic nerve axotomy in rats

Extensive research has focused on transplantation of pluripotent stem cells for the treatment of central nervous system disorders, the therapeutic potential of stem cell therapy for injured peripheral nerves is largely unknown. We used a rat sciatic nerve transection model to test the ability of implanted embryonic stem (ES) cell-derived neural progenitor cells (ES-NPCs) in promoting repair of a severely injured peripheral nerve. Mouse ES cells were neurally induced in vitro; enhanced expression and/or secretion of growth factors were detected in differentiating ES cells. One hour after removal of a 1-cm segment of the left sciatic nerve, ES-NPCs were implanted into the gap between the nerve stumps with the surrounding epineurium as a natural conduit. The transplantation resulted in substantial axonal regrowth and nerve repair, which were not seen in culture medium controls. One to 3 months after axotomy, co-immunostaining with the mouse neural cell membrane specific antibody M2/M6 and the Schwann cell marker S100 suggested that transplanted ES-NPCs had survived and differentiated into myelinating cells. Regenerated axons were myelinated and showed a uniform connection between proximal and distal stumps. Nerve stumps had near normal diameter with longitudinally oriented, densely packed Schwann cell-like phenotype. Fluoro-Gold retrogradely labeled neurons were found in the spinal cord (T12-13) and DRG (L4-L6), suggesting reconnection of axons across the transection. Electrophysiological recordings showed functional activity recovered across the injury gap. These data suggest that transplanted neurally induced ES cells differentiate into myelin-forming cells and provide a potential therapy for severely injured peripheral nerves.     

Muscle-specific protein MDP77 specifically promotes motor nerve regeneration in rats

This study has examined the effects of recombinant human MDP77 (rhMDP77) on sciatic motor nerve regeneration in vivo. We carried out bridge grafting (14 mm) into the sciatic nerve of Sprague–Dawley rats using silicone tubes containing a mixture of type-I collagen and 0, 5, 10, or 20 μg/ml of rhMDP77, or containing phosphate-buffered solution (N=6 in each group). Electrophysiological and histological evaluations carried out 12 weeks after implantation suggest that rhMDP77 has a positive effect on terminal and collateral sprouting of regenerating nerves and thereby promotes motor nerve regeneration in a dose-dependent manner.