Olfactory ensheathing cells can reduce the tissue loss but not the cavity formation in contused spinal cord of rats

In recent years, olfactory ensheathing cells (OECs) have been used as a therapeutic strategy to repair the anatomical structure and promote the function recovery of injured spinal cord in both animal and human. In this study, OECs were transplanted into contused spinal cords of adult rats. After dorsal laminectomy at T10 vertebra, spinal cord was injured by a force of 10 g with NYU II impactor from 25 mm above the exposed cord. The contused spinal cord received injections of OECs in DMEM or DMEM alone at one week after injury. The migration and distribution of OECs in the contused spinal cord were observed by the light microscope. The intact tissue area, injured tissue area, cavity size, number of myelinated nerve fibers and neurons labeled by CB-HRP in T8 segment were measured and counted by the semi-quantitative techniques at 6 weeks after transplantation. Locomotor ability and conductive function of the spinal cord were evaluated by the BBB score and cortical somatosensory evoked potentials (CSEP) recording. OECs were found in both lesion site and tissue near the lesion. The intact tissue area was significantly larger in the OECs-transplanted rats than that in the DMEM-injected animals, whereas the injured tissue area was significantly smaller in the OECs-rats than that in the DMEM-rats. The number of myelinated nerve fibers in the lesion site and preserved neurons in T8 was significantly greater in the OECs-group than in the DMEM-group, but the cavity size detected was not significantly different between the two groups. The BBB score and CSEP recording showed a better performance of locomotor ability and conductive function in the OECs-transplanted rats than in the DMEM-injected animals. These results indicate that OECs can counteract secondary tissue degeneration after spinal cord injury. Although they cannot reduce the cavity formation, they can promote morphological preservation and functional improvement of the contused spinal cord.     

Kappa opioid receptor antagonist and N-methyl-D- aspartate receptor antagonist affect dynorphin- induced spinal cord electrophysiologic impairment

The latencies of motor-and somatosensory-evoked potentials were prolonged to different degrees, and wave amplitude was obviously decreased, after injection of dynorphin into the rat subarachnoid cavity. The wave amplitude and latencies of motor-and somatosensory-evoked potentials were significantly recovered at 7 and 14 days after combined injection of dynorphin and either the kappa opioid receptor antagonist nor-binaltorphimine or the N-methyl-D-aspartate receptor antagonist MK-801. The wave amplitude and latency were similar in rats after combined injection of dynorphin and nor-binaltorphimine or MK-801. These results suggest that intrathecal injection of dynorphin causes damage to spinal cord function. Prevention of N-methyl-D-aspartate receptor or kappa receptor activation lessened the injury to spinal cord function induced by dynorphin.     

低能激光照射嗅鞘细胞促进脊髓损伤大鼠神经功能的修复

BACKGROUND： Previous studies have demonstrated that low-power laser （LPL） irradiation can promote the regeneration of peripheral nerves and central nerves, as well as influence cellular proliferation. Therefore, it is thought to be a potential treatment for spinal cord injury. OBJECTIVE： Utilizing histological observations and behavioral evaluations, the aim of this study was to investigate the influence of transplanted olfactory ensheathing cells （OECs）, irradiated by LPL, on functional repair of rats following transversal spinal cord injury. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the animal experimental center in the First Affiliated Hospital of Xinjiang Medical University between January 2007 and February 2008. MATERIALS： A total of 52 Sprague Dawley rats were included in this experiment. Twelve rats were used to harvest OECs, some of which were irradiated by LPL on days 3, 5, and 7 in culture. The remaining 40 rats were used to establish T12 complete spinal cord transection injury. DMEM/F12 medium was purchased from Sigma, USA, Fluorogold was provided by Chemicon, USA, and the LY/JG650-D500-16 low-power laser was produced by Xi＇an Lingyue Electromechanical Science And Technology Co., Ltd., China. METHODS： The successful rat models were randomly divided into three groups： OEC transplantation, LPL-irradiated OEC transplantation, and control. These animals were microinjected with OEC suspension, LPL-irradiated OEC suspension, and DMEM/F12 medium （10μL） respectively 4 weeks after spinal cord was completely transected at the T12 level. MAIN OUTCOME MEASURES： Spinal cord injury was observed using hematoxylin-eosin staining Expression of nerve growth factor receptor p75 and glial fibrillary acidic protein were determined using immunohistochemical staining. Regeneration of spinal nerve fibers in rats was assayed by Fluorogold retrograde labeling method. Basso, Beattie and Bresnahan （BBB） scores were used to evaluate motor functions of rat lower limbs. RESULTS： Structural disturbances were observed following spinal cord injury in each group, and a large amount of scar tissue covered the broken ends, accompanied by porosis and inflammatory cell infiltration. Following OEC transplantation, the distal end connected to the proximal end. nerve growth factor receptor p75 and glial fibrillary acidic protein immunohistochemistry revealed positive OECs in the cephalad and caudal area of rats that received LPL-irradiated OEC transplantation. In the OECs group, only glial fibrillary acidic protein staining was observed. No staining was found in the control group. Neural fibers labeled with Fluorogold extended across the lesion area and into the cephalad and caudal area in the OECs and LPL-irradiated OECs groups, but were not present in the control group. BBB scores revealed statistically significant differences among the three groups （P 〈 0.05）： OECs irradiated by LPL group 〉 OECs group 〉 control group. CONCLUSION： Transplantation of OECs and LPL-irradiated OECs promoted functional repair in the injured spinal cord of rats, although LPL-irradiated OECs resulted in greater beneficial effects.     

嗅鞘细胞移植损伤脊髓组织的超微结构变化

背景：脊髓损伤后神经功能难以自行恢复,嗅鞘细胞具有外周性和中枢性两种胶质细胞的成鞘功能,是修复受损神经最有前途的种子细胞。嗅鞘细胞移植到受损脊髓后的组织学和超微结构的变化可能帮助解释嗅鞘细胞发挥修复作用的机制。 目的: 验证嗅球源性嗅鞘细胞移植对脊髓损伤功能恢复的促进作用,并观察移植的嗅鞘细胞对神经元和轴突组织和超微结构的影响。 方法：将已制备脊髓模型的Wistar大鼠随机分为3组,对照组不做任何注射操作,DMEM/F12组注射DMEM/F12培养基,嗅鞘细胞组注射嗅鞘细胞悬液。每周进行肢体活动BBB评分,8周后取脊髓标本进行组织学和免疫组织化学观察,评价脊髓损伤的修复情况,并观察嗅鞘细胞移植对脊髓组织和超微结构的影响。 结果与结论：3组动物均出现后肢运动功能的恢复,嗅鞘细胞组优于对照组和DMEM/F12组,在4周后更为明显。组织学观察可见,在嗅鞘细胞组可见有神经纤维通过损伤处。损伤处附近,嗅鞘细胞组脊髓腹侧的神经纤维和神经元形态较好,损伤较轻。而对照组和DMEM/F12组神经纤维和神经元损害严重。嗅鞘细胞组的caspsase-3阳性细胞数少于对照组和DMEM/F12组。超微结构观察可见,嗅鞘细胞组的神经纤维和细胞形态均优于对照组和DMEM/F12组。结果表明嗅鞘细胞移植对大鼠脊髓损伤修复有明显的促进作用,并可恢复损伤神经的部分功能,对受损神经纤维和神经元有保护作用。     

不同来源嗅鞘细胞修复脊髓损伤的效果比较

背景：研究表明嗅鞘细胞所分泌的细胞黏附分子和神经营养因子具有保护脊髓神经元和促进脊髓轴突再生的效应。 目的：比较嗅球及嗅黏膜固有层来源的嗅鞘细胞异体移植修复脊髓损伤的能力。 设计、时间及地点：随机对照动物实验,于2007-06/2008-06在西电集团医院中心实验室完成。 材料：随机选取雄性3月龄及23月龄SD大鼠各6只,分为实验组(23月龄)和对照组(3月龄),用于嗅鞘细胞的体外培养和纯化;SD大鼠30只随机分为乳鼠嗅球嗅鞘细胞移植组、正常嗅黏膜嗅鞘细胞移植组、对照组,每组10只。 方法：30只SD大鼠制造脊髓损伤模型,分别将体外培养的乳鼠和SD大鼠嗅鞘细胞进行脊髓损伤模型的异体移植,对照组不做移植。 主要观察指标：术后4,8周,进行BBB神经功能评分,诱发电位,组织病理学观察。 结果：实验过程中大鼠死亡7只,各组死亡率大致相同。移植后第4,8周时,乳鼠嗅鞘细胞移植组、正常嗅黏膜嗅鞘细胞组评分差异无显著性意义(P > 0.05),均显著高于空白对照组(P < 0.001);嗅鞘细胞移植2组评分8周高于4周(P < 0.01)。术后4周,各组动物均未引出运动诱发电位,移植后8周时,2组嗅鞘细胞移植组动物均可引出运动诱发电位,2组差异无显著性意义(P > 0.05),空白对照组动物仍未引出运动诱发电位(P < 0.001)。移植后8周,2组嗅鞘细胞移植组脊髓损伤区有较多细胞浸润,对照组细胞数目较少。 结论：来源于嗅球与嗅黏膜的嗅鞘细胞对脊髓损伤修复均有促进作用,且两者作用无明显差异。     

甲基强的松龙联合嗅鞘细胞移植对急性脊髓损伤大鼠运动功能和诱发电位的影响

背景：嗅鞘细胞移植和甲基强的松龙是两种非常有前途的治疗脊髓损伤方法,关于二者联合治疗脊髓损伤的报道较少,结果也不尽相同。 目的：通过对大鼠行为学评分和诱发电位学检测了解嗅球嗅鞘细胞移植和甲基强的松龙对大鼠急性脊髓损伤的修复作用以及二者之间有无协同作用。 方法：以NYU脊髓打击法建立大鼠急性T10脊髓损伤模型,术后分别注射嗅鞘细胞、甲基强的松龙、嗅鞘细胞+甲基强的松龙、无血清的DF12培养液、生理盐水。于术后8周进行后肢体感诱发电位、运动诱发电位检测,并通过BBB评分了解各组大鼠手术前、后运动功能的变化。 结果与结论：术后8周,嗅鞘细胞组、甲基强的松龙组、嗅鞘细胞+甲基强的松龙组与损伤组、DF12组比较,大鼠后肢BBB评分明显升高,体感诱发电位、运动诱发电位 N1波潜伏期缩短,波幅升高,差异有显著性意义(P < 0.05)。嗅鞘细胞+甲基强的松龙组与嗅鞘细胞组、甲基强的松龙组比较,大鼠后肢BBB评分明显升高,体感诱发电位、运动诱发电位N1波潜伏期缩短,波幅升高,差异有显著性意义(P < 0.05)。说明嗅鞘细胞移植和甲基强的松龙单独应用均可以显著促进急性脊髓损伤大鼠运动功能恢复。二者联合促进急性脊髓损伤大鼠运动功能恢复的效果更加显著。     

A re-assessment of the consequences of delayed transplantation of olfactory lamina propria following complete spinal cord transection in rats

This study is part of the NIH "Facilities of Research-Spinal Cord Injury" contract to support independent replication of published studies. We repeated a study reporting that delayed transplantation of olfactory lamina propria (OLP) into the site of a complete spinal cord transection led to significant improvement in hindlimb motor function and induced axon regeneration. Adult female rats received complete spinal cord transections at T10. Thirty days post-injury, pieces of OLP, which contains olfactory ensheathing cells (OECs), or respiratory lamina propria (RLP), which should not contain OECs, were placed into the transection site. Hindlimb motor function was tested using the BBB scale from day 1 post-injury through 10 weeks following transplantation. To assess axonal regeneration across the transection site, Fluorogold was injected into the distal segment, and the distribution of 5HT-containing axons was assessed using immunostaining. BBB analyses revealed no significant recovery after OLP transplantation and no significant differences between OLP vs. RLP transplant groups. Fluorogold injections into caudal segments did not lead to retrograde labeling in any animals. Immunostaining for 5HT revealed that a few 5HT-labeled axons extended into both RLP and OLP transplants and a few 5HT-labeled axons were present in sections caudal to the injury in 2 animals that received OLP transplants and 1 animal that received RLP transplants. Our results indicate that, although OLP transplants may stimulate regeneration under some circumstances, the effect is not so robust as to reliably overcome the hostile setting created by a complete transection paradigm.     

Acute transplantation of olfactory ensheathing cells or Schwann cells promotes recovery after spinal cord injury in the rat

We compared the neurological and electrophysiological outcome, glial reactivity, and spared spinal cord connectivity promoted by acute transplantation of olfactory ensheathing cells (group OEC) or Schwann cells (group SC) after a mild injury to the rat spinal cord. Animals were subjected to a photochemical injury of 2.5 min irradiation at the T8 spinal cord segment. After lesion, a suspension containing 180,000 OECs or SCs was injected. A control group (group DM) received the vehicle alone. During 3 months postsurgery, behavioral skills were assessed with open field-BBB scale, inclined plane, and thermal algesimetry tests. Motor (MEPs) and somatosensory evoked potentials (SSEPs) were performed to evaluate the integrity of spinal cord pathways, whereas lumbar spinal reflexes were evaluated by the H reflex responses. Glial fibrillary acidic protein and proteoglycan expressions were quantified immunohistochemically at the injured spinal segments, and the preservation of corticospinal and raphespinal tracts caudal to the lesion was evaluated. Both OEC- and SC-transplanted groups showed significantly better results in all the behavioral tests than the DM group. Furthermore, the OEC group had higher MEP amplitudes and lower H responses than the other two groups. At the injury site, the area of spared parenchyma was greater in transplanted than in control injured rats. OEC-transplanted animals had reduced astrocytic reactivity and proteoglycan expression in comparison with SC-transplanted and DM rats. Taken together, these results indicate that transplantation of both OEC and SC has potential for restoration of injured spinal cords. OEC grafts showed superior ability to reduce glial reactivity and to improve functional recovery.     

Local transcutaneous cooling of the spinal cord in the rat: effects on long-term outcomes after compression spinal cord injury

This study tested efficiency of a novel thermoelectric cooler for local transcutaneous spinal cord cooling. Spinal cord compression was made by epidural balloon inflation at T8-T9 level of the spinal cord. Experimental animals (n=20) were divided into two groups. In the hypothermic group, local cooling started 25 min after spinal cord injury and lasted for 1 h with paravertebral temperature maintained at 28.5 degrees C (+/-0.3). Normothermic group underwent identical procedures, but their temperature was maintained normothermic. The assessment of neurologic recovery was performed once a week during a 4 weeks survival period. After 4 weeks animals were sacrificed and the extent of the spinal cord lesion morphometrically evaluated. There were no statistically significant intergroup differences in BBB scores and preserved volumes of the spinal cord tissue. In consecutive cross-sectional areas, hypothermic animals had significantly more preserved white matter at the cranial periphery of the lesion. It was concluded that mild posttraumatic hypothermia (31.8 degrees C) had some protective effect on tissue loss after spinal cord injury but this effect was not associated with functional improvement.     

嗅鞘细胞移植修复大鼠脊髓损伤的组织病理学变化☆

背景：对于脊髓损伤,目前临床尚无有效的治疗对策,近年来嗅鞘细胞移植对脊髓损伤修复取得了一定的进展。 目的：观察嗅鞘细胞移植在缓解损伤脊髓的病理反应和超微结构变化,及其在发生发展中的作用。 方法：60只大鼠随机分为空白组,模型组,嗅鞘胞移植组和DF12组,每组15只。空白组：仅切开T10全椎板及T9,T11部分椎板,对脊髓未作其他处理,明胶海绵轻柔压迫止血;模型组：仅切断脊髓,未作特殊处理;嗅鞘细胞移植组和DF12组：切断脊髓后用微量注射器分别注射嗅鞘细胞和DF12培养液,随后缝合切口。脊髓损伤后1,3,7,14,28,42,56 d每组麻醉2只受检大鼠,取材做光镜观察和电镜观察。 结果与结论：单纯脊髓横切损伤后,发生了出血、水肿、变性、坏死以及囊腔形成,胶质细胞增生和神经纤维再生。嗅鞘细胞移植后,明显减轻了神经元和神经纤维的坏死变性程度,减轻病理反应,并能对损伤神经元实施保护;防止了胶质细胞过度增生形成瘢痕屏障,明显增加了再生神经纤维的数量。提示嗅鞘细胞移植对损伤脊髓具有减轻病理反应和促进修复的作用。     

Neuroprotective effects of electroacupuncture on early- and late-stage spinal cord injury

Previous studies have shown that the neurite growth inhibitor Nogo-A can cause secondary neural damage by activating Rho A. In the present study, we hypothesized that electroacupuncture promotes neurological functional recovery after spinal cord injury by inhibiting Rho A expression. We established a rat model of acute spinal cord injury using a modification of Allen's method. The rats were given electroacupuncture treatment at Dazhui(Du14), Mingmen(Du4), Sanyinjiao(SP6), Huantiao(GB30), Zusanli(ST36) and Kunlun(BL60) acupoints with a sparsedense wave at a frequency of 4 Hz for 30 minutes, once a day, for a total of 7 days. Seven days after injury, the Basso, Beattie and Bresnahan(BBB) locomotor scale and inclined plane test scores were significantly increased, the number of apoptotic cells in the spinal cord tissue was significantly reduced, and Rho A and Nogo-A m RNA and protein expression levels were decreased in rats given electroacupuncture compared with rats not given electroacupuncture. Four weeks after injury, pathological tissue damage in the spinal cord at the site of injury was alleviated, the numbers of glial fibrillary acidic protein- and neurofilament 200-positive fibers were increased, the latencies of somatosensory-evoked and motor-evoked potentials were shortened, and their amplitudes were increased in rats given electroacupuncture. These findings suggest that electroacupuncture treatment reduces neuronal apoptosis and decreases Rho A and Nogo-A m RNA and protein expression at the site of spinal cord injury, thereby promoting tissue repair and neurological functional recovery.     

嗅鞘细胞移植脊髓损伤大鼠Sema3A及其受体NP-1基因的表达

背景：嗅鞘细胞移植促进脊髓损伤修复机制中对神经生长抑制导向因子的研究较少。 目的：观察嗅鞘细胞移植对脊髓半横断损伤后神经生长抑制导向因子Sema3A及其受体NP-1在RNA水平表达的变化。 方法：17只SD大鼠随机分为嗅鞘细胞移植组、DMEM/F12 培养液移植组和正常对照组。制作T11~T12水平大鼠脊髓左侧半横断损伤模型,立刻分别注射嗅鞘细胞悬液或等量的DMEM/F12 培养液。 结果与结论：6周后取横断水平前后两个脊髓节段,用RT-PCR的方法对Sema3A、NP-1的mRNA进行半定量分析。①嗅鞘细胞在大鼠脊髓内仍有大量存活。②Sema3A及NP-1 mRNA的量,DMEM/F12 培养液移植组明显多于正常对照组(P < 0.05),嗅鞘细胞移植组与培养液移植组比较明显下调,且与正常对照组比较差异无显著性意义(P > 0.05)。③提示嗅鞘细胞移植有效减少了神经生长抑制导向因子Sema3A及其受体NP-1 mRNA的表达。     

Neurophysiological recording in rat spinal cord trauma

A model for studying spinal cord trauma is described using the rat. The neurophysiological parameters that can be monitored in this model include blood pressure, spinal cord blood flow, somatosensory-evoked potentials, electroencephalogram, blood gases, and vital signs. In addition, histological preparations for histochemical fluorescence and neuronal tissue stains can be made from cryostat sections of the cord tissue. Biochemical determinations of the cord tissue are discussed. The rat model is useful because this species is inexpensive and well suited to study the pathophysiology of spinal cord injury. It is a valuable teaching tool in learning basic anesthesiology, physiology, and surgery. The model may also be used to test potentially useful treatments following experimental injury before a larger animal model series is attempted.     

Utility of somatosensory and motor-evoked potentials in reflecting gross and fine motor functions after unilateral cervical spinal cord contusion injury

Fine motor skills are thought to rely on the integrity of ascending sensory pathways in the spinal dorsal column as well as descending motor pathways that have a neocortical origin.However, the neurophysiological processes underlying communication between the somatosensory and motor pathways that regulate fine motor skills during spontaneous recovery after spinal cord contusion injury remain unclear.Here, we established a rat model of cervical hemicontusive injury using C5 laminectomy followed by contusional displacement of 1.2 mm(mild injury) or 2.0 mm(severe injury) to the C5 spinal cord.Electrophysiological recordings were performed on the brachial muscles up to 12 weeks after injury to investigate the mechanisms by which spinal cord pathways participate in motor function.After spinal cord contusion injury, the amplitudes of somatosensory and motor-evoked potentials were reduced, and the latencies were increased.The forelimb open field locomotion test, grooming test, rearing test and Montoya staircase test revealed improvement in functions.With increasing time after injury, the amplitudes of somatosensory and motor-evoked potentials in rats with mild spinal cord injury increased gradually, and the latencies gradually shortened.In comparison, the recovery times of somatosensory and motor-evoked potential amplitudes and latencies were longer, and the recovery of motor function was delayed in rats with severe spinal cord injury.Correlation analysis revealed that somatosensoryevoked potential and motor-evoked potential parameters were correlated with gross and fine motor function in rats with mild spinal cord contusion injury.In contrast, only somatosensory-evoked potential amplitude was correlated with fine motor skills in rats with severe spinal cord injury.Our results show that changes in both somatosensory and motor-evoked potentials can reflect the changes in gross and fine motor functions after mild spinal cord contusion injury, and that the change in somatosensory-evoked potential amplitude can also reflect the change in fine motor function after severe spinal cord contusion injury.This study was approved by the Animal Ethics Committee of Nanfang Hospital, Southern Medical University, China(approval No.NFYY-2017-67) on June 11, 2017.     

Establishment and evaluation of a rat model of complete transected spinal cord injury*☆

BACKGROUND： The establishment of a rat model of complete transected spinal cord injury lacks technological specifications. The current models lack concordance and reliability, and the death rate of the experimental animals is high. Therefore, there is a great need for a reliable model to apply clinical applications of therapy. OBJECTIVE： To construct a rat model of complete transected spinal cord injury characterized by stability, reproducibility, and a high animal survival rate. DESIGN： Completely randomized controlled study. SETTING： Department of Neurosurgery, Xiangya Hospital of Central South University. MATERIALS： Fifty-five healthy specific pathogen free grade adult female Sprague Dawley rats were provided by the Experimental Animal Department, Xiangya Medical College, Central South University. Olympus BX51 imaging collecting analytic system was provided by Olympus Company, Japan; and SEN-7203 Nihon-Kohden electrical stimulator by Nihon Kohden, Japan. METHODS： This study was performed at the Laboratory of Neurosurgery, Xiangya Hospital of Central South University from April to June 2006. Experimental grouping： 55 rats were randomly divided into model group （n = 40） and sham surgery group （n = 15）. In the model group, a self-made sliver hook was passed through the ventral side to support the spinal cord at the T12 segment and to shear it off. A complete transected spinal cord, 2 mm in length, was resected. In the sham surgery group, the spinal cord was identically exposed. The dura mater of the spinal cord was cut open, but the spinal cord was not damaged. MAIN OUTCOME MEASURES： Histopathological changes after spinal cord injury at L2 segment were observed subsequent to hematoxylin and eosin staining under optical microscopy. Olympus BX51 imaging collecting analytic system was used to count spinal cord ventral horn neurons. Motor function of rat hindlimb was evaluated with the Basso, Beattie and Bresnahan （BBB） scale. Paraplegia was evaluated as 0 point, and complete normality as     

Chronic transplantation of olfactory ensheathing cells promotes partial recovery after complete spinal cord transection in the rat

The goal of this study was to ascertain whether olfactory ensheathing cells (OECs) were able to promote axonal regeneration and functional recovery when transplanted 45 days after complete transection of the thoracic spinal cord in adult rats. OECs promoted partial restitution of supraspinal pathways evaluated by motor evoked potentials and modest recovery of hindlimb movements. In addition, OEC grafts reduced lumbar reflex hyperexcitability from the first month after transplantation. Histological results revealed that OECs facilitated corticospinal and raphespinal axons regrowth through the injury site and into the caudal spinal cord segments. Interestingly, raphespinal but not corticospinal fibers regenerated long distances through the gray matter and reached the lower lumbar segments (L5) of the spinal cord. However, delayed OEC grafts failed to reduce posttraumatic astrogliosis. In conclusion, the beneficial effects found in the present study further support the use of OECs for treating chronic spinal cord injuries.     

The effect of direct current field polarity on recovery after acute experimental spinal cord injury

Recent evidence indicates that direct current (DC) fields promote recovery of acutely injured central and peripheral nervous system axons. The polarity of the applied DC field may play an important role in modulating these effects. In the present study, the effect of DC field polarity on recovery of injured spinal cord axons was examined anatomically, electrophysiologically and behaviourly in a rat model. After a 53 g clip compression injury of the cord at T1, 30 adult rats were randomly and blindly allocated to one of three groups (n = 10 each): one group received implantation of a DC stimulator (14 microA) with the cathode caudal to the injury site; the second group received implantation of a similar stimulator with the cathode rostral to the injury site; and the third group received a sham (O microA) stimulator. Clinical neurological function was assessed by the inclined plane technique and axonal function was assessed by motor- and somatosensory-evoked potentials (MEP and SSEP). A quantitative assessment of axonal integrity was performed by counting neurons in the brain retrogradely labelled by the axonal tracer horseradish peroxidase (HRP) and by counting axons at the injury site. The inclined plane scores (P less than 0.0001), MEP amplitude (P less than 0.02), counts of neurons retrogradely labelled by HRP (P less than 0.0001), and axon counts at the injury site (P less than 0.01) were significantly greater in the group treated with a DC field with the cathode caudal to the lesion than in the other two groups. Conversely, the cathode rostral DC field caused a decrease in the number of neurons retrogradely labelled by HRP (P less than 0.05) compared to the sham and cathode caudal groups. These data confirm our previous finding that DC fields promote recovery of acutely injured spinal cord axons. Furthermore, the polarity of the applied field is of critical importance to this effect.     

Survival and migration of human and rat olfactory ensheathing cells in intact and injured spinal cord

Increasing evidence indicates the potential of olfactory ensheathing cells (OECs) for treating spinal cord injuries. The present study compared proliferation and migration of adult rat and human OECs transplanted into the spinal cord of athymic (immunodeficient) rats. OECs were purified from the nasal lamina propria and prelabeled with a cytoplasmic dye. After OEC injection into the thoracic spinal cord, animals were perfused 4 hr, 24 hr, and 7 days later. Both rat and human OECs showed similar migration. Cells were seen leaving the injection site after 4 hr, and by 7 days both rat and human OECs had migrated approximately 1 mm rostrally and caudally within the cord (rat: 1,400 +/- 241 microm rostral, 1,134 +/- 262 microm caudal, n = 5; human: 1,337 +/- 192 microm rostral, 1,205 +/- 148 microm caudal, n = 6). Proliferation of transplanted OECs was evident at 4 hr, but most had ceased dividing by 24 hr. In 10 animals, the spinal cord was injured by a contralateral hemisection made 5 mm rostral to the transplantation site at the time of OEC transplantation. After 7 days, macrophages were numerous both around the injury and at the transplantation site. In the injured cord, rat and human OECs migrated for shorter distances, in both rostral and caudal directions (rat: 762 +/- 118 microm rostral, 554 +/- 142 microm caudal, n = 4; human: 430 +/- 55 microm rostral, 399 +/- 161 microm caudal, n = 3). The results show that rat and human OECs rapidly stop dividing after transplantation and have a similar ability to survive and migrate within the spinal cord of immunocompromised hosts. OECs migrated less in animals with a concomitant contralateral hemisection.     

Olfactory ensheathing cell transplantation and inhibition of NogoA, NgR and RhoA expression in the damaged zone to ameliorate spinal cord injury

BACKGROUND:Olfactory ensheathing cell(OEC)transplantation promotes repair of spinal cord injury. Neural regeneration inhibits binding of the myelin protein Nogo to its receptor(NgR),activates downstream inhibitory signal RhoA, and leads to axonal degeneration.OBJECTIVE: To determine the relationship between OECs transplantation for spinal cord injury and NogoA, NgR, and RhoA protein expression in the damaged zone.DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed from September 2006 to May 2007 at the Key Laboratory of Environment and Genes in Xi'an Jiaotong University School of Medicine, China.MATERIALS: OECs were harvested from healthy, adult, male, Sprague Dawley rats aged 6 months. Mouse anti-rat NogoA, NgR, and RhoA monoclonal antibodies were utilized for detection.METHODS: A total of 40 adult Sprague Dawley rats were randomly assigned to four groups: normal, model, OECs, and DF12, with 10 animals in each group. Transverse section spinal cord injury was established in the OECs and DF12 groups, followed by injection of 1 μL OECs suspension(1×108/mL)or equivalent DF12 medium at 1 mm above and below the injury site.MAIN OUTCOME MEASURES: Immunohistochemistry and Western blot were utilized to detect NogoA, NgR, and RhoA expression in the spinal cord injury lesions. Morphological changes were observed by argyrophilia staining, and lower extremity function of the animals was assessed using Basso, Beattie, and Bresnahan scores.RESULTS: Eight weeks following OECs transplantation, a significant increase in new axons was observed in the OECs group, and nerve fibers crossed the injury site to repair spinal cord injury.Qualitative and quantitative results from the OECs group were superior to the model and DF12 groups. At 8 weeks after transplantation, Basso, Beattie, and Bresnahan scores were significantly greater in the OECs group compared with the model and DF12 groups(P< 0.01), but expression of NogoA, NgR, and RhoA protein was significantly decreased compared with the model and DF12 groups(P< 0.05).CONCLUSION: OEC transplantation could inhibit NogoA, NgR, and RhoA expression in spinal cord injury lesions, thereby promoting repair of spinal cord injury.     

嗅鞘细胞静脉移植治疗脊髓损伤

背景：嗅鞘细胞移植治疗脊髓损伤在众多疗法中效果较佳,成为最有前景的治疗方法之一。目前移植方法为局部移植,存在操作复杂、创伤大、重复移植治疗困难等缺点。寻找一种简单易行且疗效好的移植方法成为各国学者研究的热点。 目的：分析嗅鞘细胞静脉移植治疗脊髓损伤的可行性和疗效。 方法：制备Wistar大鼠脊髓半切模型,随机分4组：嗅鞘细胞髓内局部移植组、嗅鞘细胞静脉移植组、D/F12静脉移植组和空白对照组。定期行CBS功能评分及组织学检查,评价脊髓修复情况。 结果与结论：嗅鞘细胞髓内局部移植组、嗅鞘细胞静脉移植组的功能恢复和组织学改变优于D/F12静脉移植组和空白对照组,嗅鞘细胞髓内局部移植组、嗅鞘细胞静脉移植组间无显著差别。说明嗅鞘细胞静脉移植可向脊髓损伤部位迁移并修复脊髓损伤,其疗效与嗅鞘细胞髓内局部移植相当。