Olig2-expressing Mesenchymal Stem Cells Enhance Functional Recovery after Contusive Spinal Cord Injury

BACKGROUND AND OBJECTIVES: Glial scarring and inflammation after spinal cord injury (SCI) interfere with neural regeneration and functional recovery due to the inhibitory microenvironment of the injured spinal cord. Stem cell transplantation can improve functional recovery in experimental models of SCI, but many obstacles to clinical application remain due to concerns regarding the effectiveness and safety of stem cell transplantation for SCI patients. In this study, we investigated the effects of transplantation of human mesenchymal stem cells (hMSCs) that were genetically modified to express Olig2 in a rat model of SCI. METHODS: Bone marrow-derived hMSCs were genetically modified to express Olig2 and transplanted one week after the induction of contusive SCI in a rat model. Spinal cords were harvested 7 weeks after transplantation. RESULTS: Transplantation of Olig2-expressing hMSCs significantly improved functional recovery in a rat model of contusive SCI model compared to the control hMSC-transplanted group. Transplantation of Olig2-expressing hMSCs also attenuated glial scar formation in spinal cord lesions. Immunohistochemical analysis showed that transplanted Olig2-expressing hMSCs were partially differentiated into Olig1-positive oligodendrocyte-like cells in spinal cords. Furthermore, NF-M-positive axons were more abundant in the Olig2-expressing hMSC-transplanted group than in the control hMSC-transplanted group. CONCLUSIONS: We suggest that Olig2-expressing hMSCs are a safe and optimal cell source for treating SCI.

Effects of Acupuncture Stimulation at Different Acupoints on Formalin-Induced Pain in Rats

Acupuncture is the process of stimulating skin regions called meridians or acupoints and has been used to treat pain-related symptoms. However, the pain-relieving effects of acupuncture may be different depending on acupoints. In the present study, the effects of acupuncture on behavioral responses and c-Fos expression were evaluated using a formalin test in male Sprague-Dawley rats in order to clarify the analgesic effects of three different acupoints. Each rat received manual acupuncture at the ST36 (Zusanli), SP9 (Yinlingquan) or BL60 (Kunlun) acupoint before formalin injection. Flinching and licking behaviors were counted by two blinded investigators. Fos-like immunoreactivity was examined by immunohistochemistry in the rat spinal cord. Manual acupuncture treatment at BL60 acupoint showed significant inhibition in flinching behavior but not in licking. Manual acupuncture at ST36 or SP9 tended to inhibit flinching and licking behaviors but the effects were not statistically significant. The acupuncture at ST36, SP9, or BL60 reduced c-Fos expression as compared with the control group. These results suggest that acupuncture especially at the BL60 acupoint is more effective in relieving inflammatory pain than other acupoints.

Effects of Human Mesenchymal Stem Cell Transplantation Combined with Polymer on Functional Recovery Following Spinal Cord Hemisection in Rats

The spontaneous axon regeneration of damaged neurons is limited after spinal cord injury (SCI). Recently, mesenchymal stem cell (MSC) transplantation was proposed as a potential approach for enhancing nerve regeneration that avoids the ethical issues associated with embryonic stem cell transplantation. As SCI is a complex pathological entity, the treatment of SCI requires a multipronged approach. The purpose of the present study was to investigate the functional recovery and therapeutic potential of human MSCs (hMSCs) and polymer in a spinal cord hemisection injury model. Rats were subjected to hemisection injuries and then divided into three groups. Two groups of rats underwent partial thoracic hemisection injury followed by implantation of either polymer only or polymer with hMSCs. Another hemisection-only group was used as a control. Behavioral, electrophysiological and immunohistochemical studies were performed on all rats. The functional recovery was significantly improved in the polymer with hMSC-transplanted group as compared with control at five weeks after transplantation. The results of electrophysiologic study demonstrated that the latency of somatosensory-evoked potentials (SSEPs) in the polymer with hMSC-transplanted group was significantly shorter than in the hemisection-only control group. In the results of immunohistochemical study, beta-gal-positive cells were observed in the injured and adjacent sites after hMSC transplantation. Surviving hMSCs differentiated into various cell types such as neurons, astrocytes and oligodendrocytes. These data suggest that hMSC transplantation with polymer may play an important role in functional recovery and axonal regeneration after SCI, and may be a potential therapeutic strategy for SCI.

c-Fos Expression in the Nucleus of the Solitary Tract in Response to Salt Stimulation in Rats

Salt signals in tongue are relayed to the nucleus of the solitary tract (NST). This signaling is very important to determine whether to swallow salt-related nutrition or not and suggests some implications in discrimination of salt concentration. Salt concentration-dependent electrical responses in the chorda tympani and the NST were well reported. But salt concentration-dependency and spatial distribution of c-Fos in the NST were not well established. In the present study, NaCl signaling in the NST was studied in urethane-anesthetized rats. The c-Fos immunoreactivity in the six different NST areas along the rostral-caudal axis and six subregions in each of bilateral NST were compared between applications of distilled water and different concentrations of NaCl to the tongue of experimental animals. From this study, salt stimulation with high concentration (1.0 M NaCl) induced significantly higher c-Fos expression in intermediate NST and dorsal-medial and dorsal-middle subregions of the NST compared to distilled water stimulation. The result represents the specific spatial distribution of salt taste perception in the NST.

Functional Mapping of Nervous System Using Optical Imaging Techniques

Functional mapping techniques including functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and magnetoencephalography (MEG) can be used to study the function of the nervous system. Optical imaging is an emerging technique for functional imaging of the nervous tissue. Functional optical imaging can be classified into two major streams; intrinsic signal optical imaging (ISO) and voltage-sensitive dye optical imaging (VDO). ISO is related to hemodynamic changes such as hemoglobin concentration and oxygenation changes, cytochrome oxidation change, and light scattering. On the contrary, VOD measures changes in membrane potentials of neural cells. Therefore, ISO reflects metabolic activity of neurons, while VOD directly reflects neural activity. Recent advances in optical imaging opened the possibility of its application to clinical situations as well as basic researches. Further, development of optical imaging may greatly contribute to the understanding of the function of the nervous system.

Manganese-Enhanced Magnetic Resonance Imaging of the Spinal Cord in Rats

Manganese-enhanced magnetic resonance imaging (MEMRI) offers a novel neuroimaging method in visualizing the activity patterns of neural circuits. MEMRI is using the divalent manganese ion, which has been used as a cellular contrast agent. The present study was conducted to determine the contrast-enhancing effects of manganese ion administered into the spinal cord of rats. Manganese ion was administered into the spinal cord by lumbar puncture. Ex vivo magnetic resonance images were obtained at 6, 12, 24, and 48 hours after manganese ion injection. Although the highly contrasted images were not observed 6 or 12 hr after manganese injection, the distinctive manganese-enhanced images began to appear at 24 hours after manganese ion injection. These results suggest that the gray matter is the foci of intense paramagnetic signals and MEMRI may provide an effective technique to visualize the activity-dependent patterns in the spinal cord.

New Trend of Pain Study by Brain Imaging Devices

The study of pain has recently received much attention, especially in understanding its neurophysiology by using new brain imaging techniques, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), both of which allow us to visualize brain function in vivo. Also the new brain imaging devices allow us to evaluate the patients pain status and plan to treat patients objectively. Functional activation of brain regions are thought to be reflected by increases in the regional cerebral blood flow in the brain imaging studies. Regional cerebral blood flow increases to noxious stimuli are observed in second somatic (SII) and insular regions and in the anterior cingulate cortex and with slightly less consistency in the first somatic area (S1), motor area, supplementary motor area, prefrontal area, amygdala and contralateral thalamus. These data suggest that pain has multidimensions such as sensory-discrimitive, motivational-affective and cognitive-evaluative.

New Trend of Pain Study by Brain Imaging Devices

The study of pain has recently received much attention, especially in understanding its neurophysiology by using new brain imaging techniques, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), both of which allow us to visualize brain function in vivo. Also the new brain imaging devices allow us to evaluate the patients pain status and plan to treat patients objectively. Functional activation of brain regions are thought to be reflected by increases in the regional cerebral blood flow in the brain imaging studies. Regional cerebral blood flow increases to noxious stimuli are observed in second somatic (SII) and insular regions and in the anterior cingulate cortex and with slightly less consistency in the first somatic area (S1), motor area, supplementary motor area, prefrontal area, amygdala and contralateral thalamus. These data suggest that pain has multidimensions such as sensory-discrimitive, motivational-affective and cognitive-evaluative.

Effects of Ascorbic and Dehydroascorbic Acids on Apoptotic Cell Death in Hippocampal Slice Culture

Ascorbic acid (AA) and dehydroascorbic acid (DHA) are known to have protective effects in experimental central nerve system disorder models such as stroke, ischemia, and epileptic seizures. The present study was conducted to examine the protective effect of AA and DHA on kainic acid (KA) neurotoxicity using organotypic hippocampal slice cultures (OHSC). Protective effects of AA and DHA on KA-induced cell death were evaluated by analyzing caspase-3. In addition, to determine if the prooxidant effect of AA is related to iron, the effect of AA on cell death was examined using desferrioxamine (DFO), an iron chelator. After 12h-KA treatment, significant delayed neuronal death was detected in CA3 region, but not in CA1. The AA (500 micrometer) and DHA (100 and 500 micrometer) pretreatments significantly prevented cell death by inhibiting caspase-3 activation in CA3 region. In the concentration of 1,000 micrometer, however, AA pretreatment might have prooxidant effect, but AA-induced oxidative reaction is mainly not related to transition metal ions. These data showed that the pretreatments of intermediate-dose AA and DHA protected KA-induced neuronal damage in OHSCs and co-pretreatment of AA and DFO did not affect cell death except for a few cases. These data suggest that both AA and DHA pretreatment have antioxidant or prooxidant effect depending on doses treated on KA-induced neuronal injury and the possible prooxidant effect of AA may not depend on the Fenton reaction.

Lesion of Subthalamic Nucleus in Parkinsonian Rats: Effects of Dopamine D1 and D2 Receptor Agonists on the Neuronal Activities of the Substantia Nigra Pars Reticulata

OBJECTIVE: It was hypothesized that dopamine agonist administration and subthalamic nucleus (STN) lesion in the rat might have a synergistic effect on the neuronal activities of substantia nigra pars reticulata (SNpr) as observed in patients with Parkinson's disease. The effects of SKF38393 (a D1 receptor agonist) and Quinpirole (a D2 receptor agonist) were compared in parkinsonian rat models with 6- hydroxydopamine (6-OHDA) after STN lesion. METHODS: SKF38393 and Quinpirole were consecutively injected intrastriatally. SNpr was microrecorded to ascertain the activity of the basal ganglia output structure. The effect of SKF38393 or Quinpirole injection on the firing rate and firing patterns of SNpr was investigated in medial forebrain bundle (MFB) lesioned rats and in MFB+STN lesioned rats. RESULTS: The administration of SKF38393 decreased SNpr neuronal firing rates and the percentage of burst neurons in the MFB lesioned rats, but did not alter them in MFB+STN lesioned rats. The administration of Quinpirole significantly decreased the spontaneous firing rate in the MFB lesioned rats. However, after an additional STN lesion, it increased the percentage of burst neurons. CONCLUSION: This study demonstrated that dopamine agonists and STN lesion decreased the hyperactive firing rate and the percentage of burst neurons of SNpr neurons in 6-OHDA lesioned rats, respectively. Quinpirole with STN lesion increased a percentage of burst neurons. To clear the exact interactive mechanism of D1 and D2 agonist and the corresponding location, it should be followed a study using a nonselective dopamine agonist and D1, D2 selective antagonist.

Antiallodynic Effects of Acupuncture in Neuropathic Rats

Peripheral nerve injury often results in abnormal neuropathic pain such as allodynia or hyperalgesia. Acupuncture, a traditional Oriental medicine, has been used to relieve pain and related symptoms. However, the efficiency of acupuncture in relieving neuropathic pain is not clear. The aim of this study was to investigate the anti-allodynic effects of acupuncture through behavioral and electrophysiological examinations. Male Sprague-Dawley rats were subjected to neuropathic surgery consisting of a tight ligation and transection of the left tibial and sural nerves, under pentobarbital anesthesia. The acupuncture experiment consisted of four different groups, one treated at each of three different acupoints (Zusanli (ST36), Yinlingquan (SP9), and a sham-acupoint) and a control group. Behavioral tests for mechanical allodynia and cold allodynia were performed for up to two weeks postoperatively. Extracellular electrophysiological recordings were made from the dorsal roots using platinum wire electrodes. Mechanical and cold allodynia were significantly reduced after acupuncture treatment at the Zusanli and Yinlingquan acupoints, respectively. Electrophysiological neural responses to von Frey and acetone tests were also reduced after acupuncture at the same two acupoints. These results suggest that acupuncture may be beneficial in relieving neuropathic pain.

Antiallodynic Effects of Acupuncture in Neuropathic Rats

Peripheral nerve injury often results in abnormal neuropathic pain such as allodynia or hyperalgesia. Acupuncture, a traditional Oriental medicine, has been used to relieve pain and related symptoms. However, the efficiency of acupuncture in relieving neuropathic pain is not clear. The aim of this study was to investigate the anti-allodynic effects of acupuncture through behavioral and electrophysiological examinations. Male Sprague-Dawley rats were subjected to neuropathic surgery consisting of a tight ligation and transection of the left tibial and sural nerves, under pentobarbital anesthesia. The acupuncture experiment consisted of four different groups, one treated at each of three different acupoints (Zusanli (ST36), Yinlingquan (SP9), and a sham-acupoint) and a control group. Behavioral tests for mechanical allodynia and cold allodynia were performed for up to two weeks postoperatively. Extracellular electrophysiological recordings were made from the dorsal roots using platinum wire electrodes. Mechanical and cold allodynia were significantly reduced after acupuncture treatment at the Zusanli and Yinlingquan acupoints, respectively. Electrophysiological neural responses to von Frey and acetone tests were also reduced after acupuncture at the same two acupoints. These results suggest that acupuncture may be beneficial in relieving neuropathic pain.

Behavioral Characteristics of a Mouse Model of Cancer Pain

Pain is a major symptom in cancer patients, and most cancer patients with advanced or terminal cancers suffer from chronic pain related to treatment failure and/or tumor progression. In the present study, we examined the development of cancer pain in mice. Murine hepatocarcinoma cells, HCa-1, were inoculated unilaterally into the thigh or the dorsum of the foot of male C3H/HeJ mice. Four weeks after inoculation, behavioral signs were observed for mechanical allodynia, cold allodynia, and hyperalgesia using a von Frey filament, acetone, and radiant heat, respectively. Bone invasion by the tumor commenced from 7 days after inoculation of tumor cells and was evident from 14 days after inoculation. Cold allodynia but neither mechanical allodynia nor hyperalgesia was observed in mice that received an inoculation into the thigh. On the contrary, mechanical allodynia and cold allodynia, but not hyperalgesia, were developed in mice with an inoculation into the foot. Sometimes, mirror-image pain was developed in these animals. These results suggest that carcinoma cells injected into the foot of mice may develop severe chronic pain related to cancer. This animal model of pain would be useful to elucidate the mechanisms of cancer pain in humans.

Effects of Methylprednisolone on the Neural Conduction of the Motor Evoked Potentials in Spinal Cord Injured Rats

Methylprednisolone (MP), a glucocorticoid steroid, has an anti-inflammatory action and seems to inhibit the formation of oxygen free radicals produced during lipid peroxidation in a spinal cord injury (SCI). However, the effects of MP on the functional recovery after a SCI is controversial. The present study was conducted to determine the effects of MP on the recovery of neural conduction following a SCI. A SCI was produced using the NYU spinal cord impactor. A behavioral test was conducted to measure neurological disorders, and motor evoked potentials (MEPs) were recorded. According to the behavioral test, using BBB locomotor scaling, MP-treated animals showed improved functional recoveries when compared to salinetreated animals. MEP latencies in the MP-treated group were shortened when compared to those in the control group. Peak amplitudes of MEPs were larger in the MP-treated group than those in the control group. The thresholds of MEPs tended to be lower in the MP-treated group than those in the control group. These results suggest that MP may improve functional recovery after a SCI.

Comparison of the Cerebral Protective Effects of Thiopental, Propofol and Dantrolene on Focal Cerebral Ischemia Induced by Temporary Middle Cerebral Artery Occlusion in the Rat Under the Monitoring of Compressed Spectral Array

OBJECTIVE: We evaluate the cerebral protective effect of thiopental, propofol and dantrolene in middle cerebral artery occlusion(MCAO) model of rats, which ventilated spontaneously and showed definitely decreased EEG activities which is compatible with cerebral focal ischemia. METHODS: Sprague-Dawley rats were anesthetized with halothane. In control group, halothane(1-1.3 vol%) was inhaled by mask. In thiopental and propofol group, halothane was switched to each drug about 20 minutes before MCAO. In dantrolene group, dantrolene was administered 20 minutes before MCAO with halothane inhalation. Middle cerebral artery was occluded for 120 minutes. The focal ischemic proess was confirmed by ipsilateral suppression of EEG, expressed by compressed spectral array. The volume percentage of infarcted brain was measured. RESULTS: The percentage of infarct volume in thiopental group(13.7+/-4.6%) was significantly smaller than other groups(control group : 28.4+/-4.2%, propofol group:32.3+/-6.7%, dantrolene group : 31.9+/-5.4%). But, there was no statistically meaningful difference between control group, propofol group, and dantrolene group. CONCLUSION: The results of this study indicate that only thiopental has brain protective effect against focal cerebral ischemia.

The Clinical Experiement to Develop the Brain Protection Protocol in Cerebral Ischemia Using Compressed Spectral Array

OBJECTIVE: The clinical experiment to establish the cerebral protection protocol for hemodynamically vulnerable patients from ischemic insult during surgery is presented. METHODS: The experiment divided in two parts, one is to analyze the effect of intravenous anesthetics and inhalation anesthetics on EEG activity in neurologically intact 81 patients. The others is to develop the stepwise cerebral protection protocol during aneurysm surgery which required temporary clipping, carotid endarterectomy and extracranial intracranial arterial bypass surgery in 61 patients. The cerebral protection protocol included the use of intraoperative compressed spectral array(CSA) monitoring, induced hypertension, thiopental induced burst suppression and moderate hypothermia. RESULTS: With the efforts of brain protection protocol, 59 of the 61 patients recovered without any newly developed neurological deficit from the surgery. One patient had carotid stenosis with multiple untreated aneurysms, and therefore, induced hypertension was not applied. This patient developed significant postoperative neurological deficits correlated well with the CSA changes. In one patient who has cerebral aneurysm, thiopental bolus injection was used. This patient has reduction of EEG activity during temporary clipping and developed the relatively well correlated neurologic deficit postoperatively. Among 28 carotid endarterectomy cases, three patients has definite reduction of EEG activities within 7 to 15 seconds of interval carotid artery(ICA) test clamping before endarterectomy. But, these patients recovered from surgery without any neurological deficit inspite of 28 to 35 minutes ICA clamping with the effort of thiopental induced burst suppression, induced hypertension and moderate hypothermia. CONCLUSION: Cerebral protection protocol under CSA monitoring could prevent ischemic insults from circulatory disruption on vulnerable ischemic hemisphere.

Characteristics and Pathways of the Somatosensory Evoked Field Potentials in the Rat

OBJECTIVE: Somatosensory evoked potentials(SSEPs) have been used widely both experimentally and clinically to monitor the function of central nervous system and peripheral nervous system. Studies of SSEPs have reported the various recording techniques and patterns of SSEP. The previous SSEP studies used scalp recording electrodes, showed mean vector potentials which included relatively constant brainstem potentials(far-field potentials) and unstable thalamocortical pathway potentials(near-field potentials). Even in invasive SSEP recording methods, thalamocortical potentials were variable according to the kinds, depths, and distance of two electrodes. So they were regarded improper method for monitoring of upper level of brainstem. The present study was conducted to investigate the characteristics of somatosensory evoked field potentials(SSEFPs) of the cerebral cortex that evoked by hindlimb stimulation using ball electrode and the pathways of SSEFP by recording the potentials simultaneously in the cortex, VPL nucleus of thalamus, and nucleus gracilis. METHODS: In the first experiment, a specially designed recording electrode was inserted into the cerebral cortex perpendicular to the cortical surface in order to recording the constant cortical field potentials and SSEFPs mapped from different areas of somatosensory cortex were analyzed. In the second experiment, SSEPs were recorded in the ipsilateral nucleus gracilis, the contralateral ventroposterolateral thalamic nucleus(VPL), and the cerebral cortex along the conduction pathway of somatosensory information. RESULTS: In the first experiment, we could constantly obtain the SSEFPs in cerebral cortex following the transcutaneous electrical stimulation of the hind limb, and it revealed that the first large positive and following negative waves were largest at the 2mm posterior and 2mm lateral to the bregma in the contralateral somatosensory cortex. The second experiment showed that the SSEPs were conducted by way of posterior column somatosensory pathway and thalamocortical pathway and that specific patterns of the SSEPs were recorded from the nucleus gracilis, VPL, and cerebral cortex. CONCLUSION: The specially designed recording electrode was found to be very useful in recording the localized SSEFPs and the transcutaneous electrical stimulation using ball electrode was effective in evoking SSEPs. The characteristic shapes, latencies, and conduction velocities of each potentials are expected to be used the fundamental data for the future study of brain functions, including the hydrocephalus model, middle cerebral artery ischemia model, and so forth.

Characteristics of Trigeminal Evoked Potential and It's Pathway in the Rat

No abstract available.

Role of different peripheral components in the expression of neuropathic pain syndrome

Peripheral nerve injury frequently leads to neuropathic pain like hyperalgesia, spontaneous pain, mechanical allodynia, thermal allodynia. It is uncertain where the neuropathic pain originates and how it is transmitted to the central nervous system. This study was performed in order to determine which peripheral component may lead to the symptoms of neuropathic pain. Under halothane anesthesia, male Sprague-Dawley rats were subjected to neuropathic surgery by tightly ligating and cutting the tibial and sural nerves and leaving the common peroneal nerve intact. Behavioral tests for mechanical allodynia, thermal allodynia, and spontaneous pain were performed for 2 weeks postoperatively. Subsequently, second operation was performed as follows: in experiment 1, the neuroma was removed; in experiment 2, the dorsal roots of the L4-L6 spinal segments were cut; in experiment 3, the dorsal roots of the L2-L6 spinal segments were cut. Behavioral tests were performed for 4 weeks after the second operation. Following the removal of the neuroma, neuropathic pain remained in experiment 1. After the cutting of the L4-L6 or L2-L6 dorsal roots, neuropathic pain was reduced in experiments 2 and 3. The most remarkable relief was seen after the cutting of the L2-L6 dorsal roots in experiment 3. According to the fact that the sciatic nerve is composed of the L4-L6 spinal nerves and the femoral nerve is composed of the L2-L4 spinal nerves, neuropathic pain is transmitted to the central nervous system via not only the injured nerves but also adjacent intact nerves. These results also suggest that the dorsal root ganglion is very important in the development of neuropathic pain syndrome.

Change of Somatosensory Evoked Field Potential according to the Severity of Hydrocephalus in Kaolin-induced Hydrocephalus of Rats

No abstract available.