Traumatic injury or inflammatory irritation of the peripheral nervous system often leads to persistent pathophysiological pain states. It has been well-documented that, after peripheral nerve injury or inflammation, functional and anatomical alterations sweep over the entire peripheral nervous system including the peripheral nerve endings, the injured or inflamed afferent fibers, the dorsal root ganglion (DRG), and the central afferent terminals in the spinal cord. Among all the changes, ectopic discharge or spontaneous activity of primary sensory neurons is of great clinical interest, as such discharges doubtless contribute to the development of pathological pain states such as neuropathic pain. Two key sources of abnormal spontaneous activity have been identified following peripheral nerve injury: the injured afferent fibers (neuroma) leading to the DRG, and the DRG somata. The purpose of this review is to provide a global account of the abnormal spontaneous activity in various animal models of pain. Particular attention is focused on the consequence of peripheral nerve injury and localized inflammation. Further, mechanisms involved in the generation of spontaneous activity are also reviewed; evidence of spontaneous activity in contributing to abnormal sympathetic sprouting in the axotomized DRG and to the initiation of neuropathic pain based on new findings from our research group are discussed. An improved understanding of the causes of spontaneous activity and the origins of neuropathic pain should facilitate the development of novel strategies for effective treatment of pathological pain.
Animals ; Axotomy ; Ganglia, Spinal ; cytology ; Humans ; Neuralgia ; physiopathology ; Neurons, Afferent ; cytology ; Peripheral Nerve Injuries ; physiopathology ; Spinal Cord ; cytology

OBJECTIVETo review the recent studies about human umbilical cord mesenchymal stem cells (hUCMSCs) and advances in the treatment of spinal cord injury. Data sources Published articles (1983 - 2007) about hUCMSCs and spinal cord injury were selected using Medline. Study selection Articles selected were relevant to development of mesenchymal stem cells (MSCs) for transplantation in spinal cord injury therapy. Of 258 originally identified articles 51 were selected that specifically addressed the stated purpose.

RESULTSRecent work has revealed that hUCMSCs share most of the characteristics with MSCs derived from bone marrow and are more appropriate to transplantation for cell based therapies.

CONCLUSIONSHuman umbilical cord could be regarded as a source of MSCs for experimental and clinical needs. In addition, as a peculiar source of stem cells, hUCMSCs may play an important role in the treatment of spinal cord injury.

Humans ; Mesenchymal Stromal Cells ; cytology ; physiology ; Models, Biological ; Spinal Cord Injuries ; pathology ; therapy ; Stem Cell Transplantation ; Umbilical Cord ; cytology

BACKGROUNDTreatments to regenerate different tissue involving the transplantation of bone marrow derived mesenchymal precursor cells are anticipated. Using an alternative methods, in vitro organotypic slice culture method, would be useful to transplant cells and assessing the effects. This study was to determine the possibility of differentiating human bone marrow precursor cells into cells of the neuronal lineage by transplanting into canine spinal cord organotypic slice cultures.

METHODSBone marrow aspirates were obtained from posterior superior iliac spine (PSIS) of patients that had undergone spinal fusion due to a degenerative spinal disorder. For cell imaging, mesenchymal precursor cells (MPCs) were pre-stained with PKH-26 just before transplantation to canine spinal cord slices. Canine spinal cord tissues were obtained from three adult beagle dogs. Spinal cords were cut into transverse slices of 1 mm using tissue chopper. Two slices were transferred into 6-well plate containing 3 ml DMEM with antibiotics. Prepared MPCs (1×10(4)) were transplanted into spinal cord slices. On days 0, 3, 7, 14, MPCs were observed for morphological changes and expression of neuronal markers through immunofluorescence and reverse transcription-polymerase chain reaction (RT-PCR).

RESULTSThe morphological study showed: spherical cells in the control and experiment groups on day 0; and on day 3, cells in the control group had one or two thick, short processes and ones in the experiment group had three or four thin, long processes. On day 7, these variously-sized processes contacted each other in the experiment group, but showed typical spindle-shaped cells in the control group. Immunofluorescence showed that PKH-26(+) MPCs stained positive for NeuN(+) and GFAP(+) in experimental group only. Also RT-PCR showed weak expression of β-tubulin III and GFAP.

CONCLUSIONSHuman bone marrow mesenchymal precursor cells (hMPCs) have the potential to differentiate into the neuronal like cells in this canine spinal cord organotypic slice culture model. Furthermore, these findings suggested the possibility that these cells can be utilized to treat patients with spinal cord injuries.

Animals ; Bone Marrow Cells ; cytology ; Cell Differentiation ; physiology ; Cells, Cultured ; Dogs ; Humans ; Mesenchymal Stromal Cells ; cytology ; Spinal Cord ; cytology

The cell body or soma in the dosal root ganglion (DRG) is normally excitable and this excitability can increase and persist after an injury of peripheral sensory neurons. In a rat model of radicular pain, an intraforaminal implantation of a rod that chronically compressed the lumbar DRG ("CCD" model) resulted in neuronal somal hyperexcitability and spontaneous activity that was accompanied by hyperalgesia in the ipsilateral hind paw. By the 5th day after onset of CCD, there was a novel upregulation in neuronal expression of the chemokine, monocyte chemoattractant protein-1 (MCP-1 or CCL2) and also its receptor, CCR2. The neurons developed, in response to topically applied MCP-1, an excitatory response that they normally do not have. CCD also activated non-neuronal cells including, for example, the endothelial cells as evidenced by angiogenesis in the form of an increased number of capillaries in the DRG after 7 days. A working hypothesis is that the CCD induced changes in neurons and non-neuronal cells that may act together to promote the survival of the injured tissue. The release of ligands such as CCL2, in addition to possibly activating nociceptive neurons (maintaining the pain), may also act to preserve injured cells in the face of ischemia and hypoxia, for example, by promoting angiogenesis. Thus, somal hyperexcitability, as often said of inflammation, may represent a double edged sword.
Animals ; Chemokine CCL2 ; metabolism ; Ganglia, Spinal ; cytology ; pathology ; Hyperalgesia ; pathology ; Neuroglia ; cytology ; Nociceptors ; cytology ; Pain ; pathology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Compression ; physiopathology ; Up-Regulation

The aim of the paper is to study the effect of spontaneous firing of injured dorsal root ganglion (DRG) neuron in chronic compression of DRG (CCD) model on excitability of wide dynamic range (WDR) neuron in rat spinal dorsal horn. In vivo intracellular recording was done in DRG neurons and in vivo extracellular recording was done in spinal WDR neurons. After CCD, incidence of spontaneous discharge and firing frequency enhanced to 59.46% and (4.30 ± 0.69) Hz respectively from 22.81% and (0.60 ± 0.08) Hz in normal control group (P < 0.05). Local administration of 50 nmol/L tetrodotoxin (TTX) on DRG neuron in CCD rats decreased the spontaneous activities of WDR neurons from (191.97 ± 45.20)/min to (92.50 ± 30.32)/min (P < 0.05). On the other side, local administration of 100 mmol/L KCl on DRG neuron evoked spontaneous firing in a reversible way (n = 5) in silent WDR neurons of normal rats. There was 36.36% (12/33) WDR neuron showing after-discharge in response to innocuous mechanical stimuli on cutaneous receptive field in CCD rats, while after-discharge was not seen in control rats. Local administration of TTX on DRG with a concentration of 50 nmol/L attenuated innocuous electric stimuli-evoked after-discharge of WDR neurons in CCD rats in a reversible manner, and the frequency was decreased from (263 ± 56.5) Hz to (117 ± 30) Hz (P < 0.05). The study suggests that the excitability of WDR neurons is influenced by spontaneous firings of DRG neurons after CCD.
Action Potentials ; Animals ; Ganglia, Spinal ; physiology ; Neurons ; physiology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Dorsal Horn ; cytology

The treatment of spinal cord injury is always a stubborn problem for neurosurgeons because nerve cell cannot regenerate and the glia scar can prevent the axonal regeneration. Olfactory ensheathing cells (OECs) is a kind of especial glia cell, which possesses the character of horizontal cell of central nervous system and schwann cell. Many foundational and clinical studies showed that the olfactory ensheathing cellscan promote axonal regeneration and prove axonal growth, some progress is made and this is bringing hope for treatment of spine injury.
Animals ; Cell Transplantation ; Cells, Cultured ; Humans ; Nerve Regeneration ; Neuroglia ; cytology ; transplantation ; Olfactory Mucosa ; cytology ; transplantation ; Spinal Cord Injuries ; therapy

Bone marrow mesenchymal cells (BMSCs) are regarded as donor cells in cell transplantation therapies for spinal cord injury (SCI) for they have the ability of favourable proliferation and multi-directional differentiation, and are easily isolated and culturd and have less immunological reaction. It has been confirmed that subarachnoid space injection is the most ideal delivery technique of BMSCs. Bone marrow mesenchymal stem cells transplantation is safe and its reconditioning role is certain for SCI in early clinical application. The mechanism of BMSCs promoting functional recovery after SCI is probably concerned with vicarious function, nerve trophism, immunosuppression and promoting axonal regeneration by BMSCs.
Animals ; Bone Marrow Cells ; cytology ; Humans ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stromal Cells ; cytology ; Spinal Cord Injuries ; surgery

OBJECTIVETo observe whether olfactory ensheathing cells could be used to promote axonal regeneration in a spontaneously nonregenerating system.

METHODSAfter laminectomy at the lower thoracic level, the spinal cords of adult rats were exposed and completely transected at T10. A suspension of ensheathing cells was injected into the lesion site in 12 adult rats, and control D/F-12 (1:1 mixture of DMEM and Ham's F-12) was injected in 12 adult rats. Six weeks and ten weeks after cell transplantation, the rats were evaluated by climbing test and motor evoked potentials (MEPs) monitoring. The samples were procured and studied with histologicl and immunohistochemical methods.

RESULTSAt the 6th week after cell transplantation, all the rats in both the transplanted and control groups were paraplegic and the MEPs could not be recorded. At the 10th week after cell transplantation, of 7 rats in the control group, 2 rats had muscles' contraction of the lower extremities, 2 rats had hips and/or knees' active movement; and 5 rats' MEPs could be recorded in the hind limbs in the transplanted group (n=7). None of the rats in the control group had functional improvement and no MEPs recorded (n=7). Numerous regenerating axons were observed through the transplantation and continued to regenerate into the denervated host tract. Cell labelling using anti-Myelin Basic Protein (MBP) and anti-Nerve Growth Factor Receptor (anti-NGFR) indicated that the regenerated axons were derived from the appropriate neuronal source and that donor cells migrated into the denervated host tract. But axonal degeneration existed and regenerating axons were not observed within the spinal cords of the adult rats with only D/F-12 injection.

CONCLUSIONSThe axonal regeneration in the transected adult rat spinal cord is possible after ensheathing cells transplantation.

Animals ; Axons ; physiology ; Brain Tissue Transplantation ; Cell Transplantation ; Male ; Nerve Regeneration ; Olfactory Bulb ; cytology ; transplantation ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; physiology ; Spinal Cord Injuries ; physiopathology ; surgery

OBJECTIVETo investigate the effects of mechanical vibration on the morphology of the acellular scaffold for the spinal cord and establish a procedure to construct an acellular rat spinal cord allograft retaining intact matrix fibers for repairing spinal cord injuries.

METHODSFifteen segments of rat spinal cord were divided randomly into 3 groups and subjected to mechanical vibration at the frequency 80 r/min (group A, n=5), 120 r/min (group B, n=5), and 160 r/min (group C, n=5) respectively. The spinal cord was treated with Triton X-100 and sodium deoxycholate at room temperature and washed with distilled water. The specimens were observed microscopically with HE staining, and the ultrastructure was observed using scanning electron microscope.

RESULTSIn group A, the spinal cord specimens contained numerous cells and neural sheaths. Vibration at 120 and 160 r/min (in groups B and C) resulted in depletion of all the cells, axons and neural sheaths from the spinal cord after treatment with Triton X-100 and sodium deoxycholate. The acellular spinal cord consisted of a meshwork of the matrix fibers in longitudinal arrangement. In group C, however, obvious disruption of both the spinal dura mater and the matrix fiber occurred in the acellular spinal cord.

CONCLUSIONAll the cells, axons and neural sheaths in the spinal cord can be removed by chemical extraction with Triton X-100 and sodium deoxycholate. Mechanical vibration at suitable frequency may cell preserve the 3-dimensional structure of the matrix fibers. The acellular spinal cord scaffold may serve as an ideal material for constructing tissue-engineered spinal cord.

Animals ; Cell Separation ; methods ; Female ; Male ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; anatomy & histology ; cytology ; Spinal Cord Injuries ; therapy ; Tissue Engineering ; methods ; Vibration

OBJECTIVETo observe the survival and the number of olfactory ensheathing cells (OECs) transplanted in the contused spinal cord, so as to provide a basis for further studying the biological action of OECs.

METHODSThe rat spinal cords were contused with NYU-impactor II at T10 level by dropping a 10 g rod from a height of 25 mm. At the 1st week after injury, OECs isolated freshly from green fluorecense protein (GFP) of the rats were transplanted into the spinal cord at injured site and other two sites 1 mm apart from the caudal and rostral ends with the OECs number of 30000/μl x 3 = 90000. The survival and the number of OECs were qualitatively and semi-quantitatively observed under the fluorescense microscope from 1 week to 13 weeks after transplantation. The motor function of the cord was evaluated with BBB score.

RESULTSGFP-OECs could survive at least for 13 weeks within the contused spinal cord. Their arrangement was from tight to loose and their number was decreased from 1 week to 13 weeks after injury. The average number of GFP-OECs was 536 at the 1st week, which was less than 1% of the number as compared with original transplantation. After then, the number of GFP-OECs was continually decreased, but the most obvious decrease was found during 1 week to 2 weeks. The extent of decrease at other time points was relatively mild. In contrast to the cell number, motor function of the cord was gradually recovered after transplantation.

CONCLUSIONSThe survival and the number of GFP-OECs are different between the animals and are affected by the pathological reaction of the host cord. Also it is related to the motor function recovery of the contused cord.

Animals ; Cell Count ; Cell Survival ; Cell Transplantation ; Motor Activity ; Nerve Degeneration ; Olfactory Bulb ; cytology ; transplantation ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; physiopathology ; Spinal Cord Injuries ; physiopathology ; surgery