Spinal Cord Injured Rats Research Articles

Stem Cell Factor Prevents Neuronal Cell Apoptosis After Acute Spinal Cord Injury

A rat spinal cord injury (SCI) model and immunohistochemistry were used to examine the levels of expression of stem cell factor and c-kit. In addition, we examined whether intraperitoneal administration of stem cell factor could prevent neural cells apoptosis after acute SCI. To evaluate the antiapoptotic effect of stem cell factor after SCI. It is well known that the mode of delayed neuronal and glial cell death after SCI is apoptosis. Inhibition of apoptosis might thus promote neurologic improvement after SCI. Stem cell factor and its receptor c-kit exhibit pleiotropic effects in early hematopoiesis, and are also known to prevent hematopoietic progenitor cell apoptosis. Stem cell factor has recently been reported to be a survival factor for neural stem cells in vitro. We examined the levels of expression of stem cell factor and c-kit in normal and injured rat spinal cord. In addition, we examined whether stem cell factor prevents neural cell apoptosis after acute SCI. We examined the expression of stem cell factor and c-kit in spinal cord after injury by quantitative RT-PCR and immunohistochemistry. Antiapoptotic effects of stem cell factor were examined using rats with SCI that received stem cell factor intraperitoneally, and were examined immunohistochemically with anticleaved PARP antibody and antiactive caspase-3 antibody between 1 and 3 days after injury. Upregulation of stem cell factor and c-kit expression occured after SCI. We also found that neurons express stem cell factor, and neurons and oligodendrocytes express c-kit after SCI. In addition, intraperitoneal administration of stem cell factor prevented spinal neural cells apoptosis after injury. These findings suggest the possibility that stem cell factor, a hematopoietic cytokine, could be useful as an agent for treatment of SCI.

Human embryonic stem cell-derived neural precursor transplants in collagen scaffolds promote recovery in injured rat spinal cord

Several studies have reported functional improvement after transplantation of in vivo-derived neural progenitor cells (NPC) into injured spinal cord. However, the potential of human embryonic stem cell-derived NPC (hESC-NPC) as a tool for cell replacement of spinal cord injury (SCI) should be considered. We report on the generation of NPC as neural-like tubes in adherent and feeder-free hESC using a defined media supplemented with growth factors, and their transplantation in collagen scaffolds in adult rats subjected to midline lateral hemisection SCI. hESC-NPC were highly expressed molecular features of NPC such as Nestin, Sox1 and Pax6. Furthermore, these cells exhibited the multipotential characteristic of differentiating into neurons and glials in vitro. Implantation of xenografted hESC-NPC into the spinal cord with collagen scaffold improved the recovery of hindlimb locomotor function and sensory responses in an adult rat model of SCI. Analysis of transplanted cells showed migration toward the spinal cord and both neural and glial differentiation in vivo. These findings show that transplantation of hESC-NPC in collagen scaffolds into an injured spinal cord may provide a new approach to SCI.

Multipotent mesenchymal stromal cells attenuate chronic inflammation and injury-induced sensitivity to mechanical stimuli in experimental spinal cord injury

Previous reports established that after a contusion injury to the rat spinal cord, locomotor function was enhanced by the transplantation of cells from bone marrow referred to as either mesenchymal stem cells or multipotent mesenchymal stromal cells (MSCs). It has also been established that neural stem cells (NSCs) enhance locomotor function after transplantation into the injured rat spinal cord. However, the beneficial effects of NSCs are limited by graft-induced allodynia-like responses. Little is known about the effects of MSCs on sensory function in spinal cord injury. Therefore, the objective of this research was to determine whether transplantation of MSCs into the injured rat spinal cord induces allodynia-like responses. Contusion injuries of two different severities were induced in rats to examine the effects of transplantation with MSCs on sensorimotor deficits. The effects of MSCs on chronic inflammation were investigated, since inflammation is reported to have a role in the sensorimotor deficits associated with spinal cord injury. In addition, observations in other models suggest that MSCs possess immunosuppressive effects. We found that in contrast to previous observations with the transplantation of neural stem cells, transplantation of MSCs did not induce allodynia. MSCs attenuated injury-induced sensitivity to mechanical stimuli but had no effect on injury-induced sensitivity to cold stimuli. MSCs also significantly attenuated the chronic inflammatory response as assayed by GFAP immunoreactivity for reactive astrocytes and ED1 immunoreactivity for activated macrophages/microglia. In addition, transplantation of MSCs increased white matter volumes and decreased cyst size in sections of the cord containing the lesion. The results suggest that the sensorimotor enhancements produced by MSCs can at least in part be explained by anti-inflammatory/immunosuppressive effects of the cells, similar to such effects of these cells observed in other experimental models.

Alterations in the expression of the apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/ref-1) and DNA damage in the caudal region of acute and chronic spinal cord injured rats treated by embryonic neural stem cells

The oxidative mechanisms of injury-induced damage of neurons within the spinal cord are not very well understood. We used a model of T8-T9 spinal cord injury (SCI) in the rat to induce neuronal degeneration. In this spinal cord injury model, unilateral avulsion of the spinal cord causes oxidative stress of neurons. We tested the hypothesis that apurinic/apyrimidinic endonuclease (or redox effector factor-1, APE/Ref-1) regulates this neuronal oxidation mechanism in the spinal cord region caudal to the lesion, and that DNA damage is an early upstream signal. The embryonic neural stem cell therapy significantly decreased DNA-damage levels in both study groups - acutely (followed up to 7 days after SCI), and chronically (followed up to 28 days after SCI) injured animals. Meanwhile, mRNA levels of APE/Ref-1 significantly increased after embryonic neural stem cell therapy in acutely and chronically injured animals when compared to acute and chronic sham groups. Our data has demonstrated that an increase of APE/Ref-1 mRNA levels in the caudal region of spinal cord strongly correlated with DNA damage after traumatic spinal cord injury. We suggest that DNA damage can be observed both in lesional and caudal regions of the acutely and chronically injured groups, but DNA damage is reduced with embryonic neural stem cell therapy.

Intraspinal cord graft of autologous activated Schwann cells efficiently promotes axonal regeneration and functional recovery after rat's spinal cord injury

Basic research in spinal cord injury (SCI) has made great strides in recent years, and some new insights and strategies have been applied in promoting effective axonal regrowth and sprouting. However, a relatively safe and efficient transplantation technique remains undetermined. This study, therefore, was aimed to address a question of how to graft Schwann cells to achieve the best possible therapeutic effects. To clarify the issue, the rats were subjected to spinal cord injury at T10. Autologous activated Schwann cells (AASCs) were obtained by prior ligation of saphenous nerve and subsequently isolated and purified in vitro and then grafted into spinal cord-injured rats via three different routes (group I: intravenous, group II: intrathecal and group III: intraspinal cord). Neurologic function was serially evaluated by Basso, Beattie, Bresnahan locomotor rating scale and footprint analysis. We also evaluated the migration of the transplanted cells at 2 weeks after transplantation. Using biotinylated dextran amine (BDA) anterograde tracing, we demonstrated that more regenerative axons of corticospinal tract (CST) surrounding the injured cavity in group III than those in the other two groups, and we also confirmed it further by quantitative analysis. The microenvironment surrounding the injured spinal cord has been improved to the greatest extent in group III, as determined by immunohistological staining. Relatively complete myelin sheaths and more neurofilaments in axons were found in groups II and III than those in group I under electron microscopy. The results showed that intraspinal cord injection of AASCs promoted recovery of hindlimb locomotor function of injured rats more efficiently than the other grafting routes. In addition, intact myelin sheaths and sufficient neurofilaments in axons were not adequate for full functional recovery after SCI, suggesting that reestablishment of normal synaptic connection is indispensable. The findings in this study strongly suggest that transplantation of AASCs directly into the spinal cord may be one of the promising candidates for potential scaffold for injured spinal cord, and such strategy of transplantation of AASCs could be hopeful to treat patients with SCI.

Regularized positive-definite fourth order tensor field estimation from DW-MRI

In Diffusion Weighted Magnetic Resonance Image (DW-MRI) processing, a 2nd order tensor has been commonly used to approximate the diffusivity function at each lattice point of the DW-MRI data. From this tensor approximation, one can compute useful scalar quantities (e.g. anisotropy, mean diffusivity) which have been clinically used for monitoring encephalopathy, sclerosis, ischemia and other brain disorders. It is now well known that this 2nd-order tensor approximation fails to capture complex local tissue structures, e.g. crossing fibers, and as a result, the scalar quantities derived from these tensors are grossly inaccurate at such locations. In this paper we employ a 4th order symmetric positive-definite (SPD) tensor approximation to represent the diffusivity function and present a novel technique to estimate these tensors from the DW-MRI data guaranteeing the SPD property. Several articles have been reported in literature on higher order tensor approximations of the diffusivity function but none of them guarantee the positivity of the estimates, which is a fundamental constraint since negative values of the diffusivity are not meaningful. In this paper we represent the 4th-order tensors as ternary quartics and then apply Hilbert's theorem on ternary quartics along with the Iwasawa parametrization to guarantee an SPD 4th-order tensor approximation from the DW-MRI data. The performance of this model is depicted on synthetic data as well as real DW-MRIs from a set of excised control and injured rat spinal cords, showing accurate estimation of scalar quantities such as generalized anisotropy and trace as well as fiber orientations.

Reflections

CNS white matter from higher vertebrates and cultured differentiated oligodendrocytes are nonpermissive substrates for neurite growth and fibroblast spreading. Membrane proteins of 35 kd and 250 kd with highly nonpermissive substrate properties could be extracted from CNS myelin fractions. Monoclonal antibodies were raised against these proteins: IN-1 and IN-2 bound both to the 35 kd and 250 kd inhibitors and to the surface to differentiated cultured oligodendrocytes. Adsorption of nonpermissive CNS myelin or nonpermissive oligodendrocytes with either antibody markedly improved their substrate properties. Optic nerve explants injected with IN-1 or IN-2 allowed axon ingrowth of cocultured sensory and sympathetic neurons. We conclude that the nonpermissive substrate properties of CNS white matter are due to these membrane proteins on the surface of differentiated oligodendrocytes and to their in vivo product, myelin.

Functional reorganization in rat somatosensory cortex assessed by fMRI: Elastic image registration based on structural landmarks in fMRI images and application to spinal cord injured rats

The accuracy at which changes in cortical functional topology can be assessed by functional MRI (fMRI) depends on the quality of the reference coordinate system used for comparison of data sets obtained in different imaging sessions. Current procedures comprise an overlay of activation clusters on registered high-resolution anatomical images. Yet, fMRI images are frequently distorted due to susceptibility artifacts, which are prominent in rodent studies due to the small dimensions involved and high magnetic field strengths used. Therefore, a procedure for co-registration of activation maps has been developed based on anatomical landmarks defined on fMR echo planar images (EPI) themselves. Validation studies in control rats revealed that the centers of activated areas in somatosensory cortex S1, evoked through sensory forepaw stimulation fell within an area of 1 × 1 mm 2 in agreement with known electrophysiological coordinates. The technique was applied to detect changes in activation patterns in rats following smaller unilateral spinal cord injuries (SCI) in their cervical segments (C3/C4) 12 weeks after lesion. Despite of an almost complete behavioral recovery, fMRI responses remained altered in SCI animals with both significantly reduced fMRI signal amplitude and reduced latency to reach the peak response. Moreover, in SCI animals the activated S1 area corresponding to the contralesional forepaw was significantly enlarged and the center-of-mass for the ipsilesional paw was shifted rostrally. The mapping technique described combined with the temporal analysis of the BOLD response enabled a noninvasive quantitative characterization of cortical functional reorganization following SCI in rats.

Survival, migration and differentiation of allogenic BMSCs in injured spinal cord in rats

Objective To observe survival, migration and differentiation of marrow derived mes-enehymal stem cells (BMSCs) after transplantation into the injured spinal cord in rats. Methods Allo-genie BMSCs stained with Hoechst were transplanted into the spinal cord that had been semi-transected in rats. Two months later, the animals were killed to observe the survival, migration and differentiation of the BMSCs.Results Two months after transplantation, a dense mass of the transplanted Hoechst stained BMSCs was observed surrounding the injection spot and transferred into the center of injury site. lees than 10% of the transplanted BMSCs expressed the mark proteins of neurons and astroeytes. Conclusion Allogenic BMSCs can well survive, proliferate and transfer in the injured spinal cord in rats and a few of them can differentiate into neural-like cells. Key words: Bone marrow cells; Spinal cord injury; Transplantaion; Survival; Differenti-ation

Neuroprotective Effects of Caspase-3 Inhibition on Functional Recovery and Tissue Sparing After Acute Spinal Cord Injury

We used gene microarrays and found that caspase-related death genes were upregulated. We tested caspase inhibition and evaluated its effect on the spinal cord after traumatic injury. The logical extension of previous studies was to determine whether downstream CASP genes might also be involved and whether inhibition might prevent injury-induced cell death. Apoptotic cell death occurs in all endogenous cellular compartments of the spinal cord, peaking at 3 days after injury in neurons, astrocytes, and microglia. The downstream effector caspase-3 cleaves several important cellular sites after being activated by upstream initiator caspases. Along with others, we have previously identified caspase signature cleavage of PARP, alpha-fodrin, and DFF45/ICAD in the injured rat spinal cord. We also showed rapid upregulation of caspase-3 gene expression along with localization of active caspase-3 in neurons and activated microglia after SCI. Others have reported that a more general active-site mimetic peptide ketone, benzylocarbonyl-Val-Ala-Asp-fluromethylketone (zVAD-fmk) was neuroprotective after rat spinal cord injury (SCI). In this study, we administered the caspase-3 subfamily tetrapeptide cell permeable inhibitor Z-Asp(O-Me)-Glu(O-Me)-Val-Asp(O-Me) fluoromethyl ketone (DEVD-fmk) intraperitoneally 1 hour after laminectomy and moderate (25 g cm force) SCI in rats. RESULTS.: We used the open field locomotor rating (LRS) over a 14-day course and found statistically significant improvement in DEVD-fmk-treated rats, LRS, 9.8 +/- 0.93 SEM, compared with vehicle, 6.6 +/- 0.4 (P < 0.05). Histologic analysis of percent spinal cord tissue volume spared was 50% greater for DEVD-fmk versus control (P < 0.5). These results indicate neuroprotection at both the cellular level and with substantial functional recovery, suggesting caspase-3 inhibition may be a viable therapy in the early hours after experimental SCI.

The recovery of 5-HT transporter and 5-HT immunoreactivity in injured rat spinal cord

Experimental spinal cord injury. To determine the role of serotonin (5-HT) and 5-HT transporter in recovery from spinal cord injury. We examined 5-HT and 5-HT transporter of spinal cord immunohistologically and assessed locomotor recovery after extradural compression at the thoracic (T8) spinal cord in 21 rats. Eighteen rats had laminectomy and spinal cord injury, while the remaining three rats received laminectomy only. All rats were evaluated every other day for 4 weeks, using a 0-14 point scale open field test. Extradural compression markedly reduced mean hindlimbs scores from 14 to 1.5 +/- 2.0 (mean +/- standard error of mean). The rats recovered apparently normal walking by 4 weeks. The animals were perfused with fixative 1-3 days, 1, 2 and 4 weeks (three rats in each) after a spinal cord injury. The 5-HT transporter immunohistological study revealed a marked reduction of 5-HT transporter-containing terminals by 1 day after injury. By 4 weeks after injury, 5-HT transporter immunoreactive terminals returned to the control level. The 5-HT immunohistological study revealed a reduction of 5-HT-containing terminals by 1 week after injury. By 4 weeks after injury, 5-HT immunoreactive fibers and terminals returned to the control level. We estimated the recovery of 5-HT transporter and 5-HT neural elements in lumbosacral ventral horn by ranking 5-HT transporter and 5-HT staining intensity and counting 5-HT and 5-HT transporter terminals. The return of 5-HT transporter and 5-HT immunoreactivity of the lumbosacral ventral horn correlated with locomotor recovery, while 5-HT transporter showed closer relationship with locomotor recovery than 5-HT. The presence of 5-HT transporter indicates that the 5-HT fibers certainly function. This study shows that return of the function of 5-HT fibers predict the time course and extent of locomotory recovery after thoracic spinal cord injury.

Transplantation of olfactory mucosa following spinal cord injury promotes recovery in rats

Several recent studies have demonstrated the potential therapeutic role of olfactory ensheathing cells in spinal cord injury. The aim of this study was to elucidate whether grafts of nasal olfactory mucosa containing olfactory ensheathing cells can repair the injured rat spinal cord as compared with the nasal respiratory mucosa containing no olfactory ensheathing cells. These grafts were then transplanted into the partially removed rat spinal cord. Compared with the respiratory mucosa-transplanted rats, the olfactory mucosa-transplanted rats partially recovered the movement of their hindlimbs and joints. Corticospinal tracing indicated that olfactory mucosa transplantation restored the severed tract. Therefore, olfactory mucosa has potential value in the repair of spinal cord injury.

Quantitative Assessment of Injury in Rat Spinal Cords In Vivo by MRI of Water Diffusion Tensor

Magnetic resonance diffusion tensor imaging (DTI) of control and injured spinal cord of rats in vivo during first 6 h after the trauma was reported. DTI and histopathological results were compared. The aim of this work was to correlate the presence of damage of rat spinal cord with statistically significant changes in the apparent diffusion tensor components, in order to find the parameters that are useful in the visualization of the injury. Apparent diffusion tensor weighted data were measured in vivo 1 h after traumatic injury induced by a controlled weight drop on healthy and injured rat spinal cords for defined dozen regions of interest. Significant alternations in the injured regions of gray matter and white matter were detected. The differences in gray matter can be explained on the basis of cytotoxic edema due to ischemia and they are confirmed by the histological observations of neurons. The white matter changes in diffusional attributes are associated with the destruction of the nerve microstructure by the mechanical implant.

Suppression of detrusor-sphincter dysynergia by GABA-receptor activation in the lumbosacral spinal cord in spinal cord-injured rats

We investigated the effects of intrathecal application of GABAA- or GABAB-receptor agonists on detrusor-sphincter dyssynergia (DSD) in spinal cord transection (SCT) rats. Adult female Sprague-Dawley rats were used. At 4 wk after Th9-10 SCT, simultaneous recordings of intravesical pressure and urethral pressure were performed under an awake condition to examine the effect of intrathecal application of GABAA and GABAB agonists (muscimol and baclofen, respectively) or GABAA and GABAB antagonists (bicuculline and saclofen, respectively) at the level of L6-S1 spinal cord. In spinal-intact rats, the effects of bicuculline and saclofen on bladder and urethral activity were also examined. During urethral pressure measurements, DSD characterized by urethral pressure increases during isovolumetric bladder contractions were observed in 95% of SCT rats. However, after intrathecal application of muscimol or baclofen, urethral pressure showed urethral relaxation during isovolumetric bladder contractions. The effective dose to induce inhibition of urethral activity was lower compared with the dose that inhibited bladder contractions. The effect of muscimol and baclofen was antagonized by intrathecal bicuculline and saclofen, respectively. In spinal-intact rats, intrathecal application of bicuculline induced DSD-like changes. These results indicate that GABAA- and GABAB-receptor activation in the spinal cord exerts the inhibitory effects on DSD after SCT. Decreased activation of GABAA receptors due to hypofunction of GABAergic mechanisms in the spinal cord might be responsible, at least in part, for the development of DSD after SCT.

Brain fiber tract plasticity in experimental spinal cord injury: Diffusion tensor imaging

Diffusion tensor imaging (DTI) and immunohistochemistry were performed in spinal cord injured rats to understand the basis for activation of multiple regions in the brain observed in functional magnetic resonance imaging (fMRI) studies. The measured fractional anisotropy (FA), a scalar measure of diffusion anisotropy, along the region encompassing corticospinal tracts (CST) indicates significant differences between control and injured groups in the 3 to 4 mm area posterior to bregma that correspond to internal capsule and cerebral peduncle. Additionally, DTI-based tractography in injured animals showed increased number of fibers that extend towards the cortex terminating in the regions that were activated in fMRI. Both the internal capsule and cerebral peduncle demonstrated an increase in GFAP-immunoreactivity compared to control animals. GAP-43 expression also indicates plasticity in the internal capsule. These studies suggest that the previously observed multiple regions of activation in spinal cord injury are, at least in part, due to the formation of new fibers.

High‐resolution myelin water measurements in rat spinal cord

Multiecho imaging data were acquired at 7T from control and injured (dorsal column transection) rat spinal cords ex vivo with in-plane resolution of 61, 78, and 100 microm, and from a control rat spinal cord in vivo with in-plane resolution of 117 microm. The myelin water maps were calculated using nonnegative least-squares (NNLS) analysis of the decay curves. For the control cords, myelin water maps showed details of the cord morphology, and the average myelin water fraction (MWF) values in white matter and gray matter corresponded well with previously published results and the expected amounts of myelin within the cord, and correlated very well with Luxol Fast Blue stain (R(2)=0.95). Myelin water maps from an injured cord showed excellent qualitative correlation with histology. This pilot study demonstrates that high-resolution myelin water mapping in rat spinal cord is feasible, and this technique has potential to be a valuable tool in studying white matter damage in rat models of spinal cord injury.

Analysis of laminar activity in normal and injured rat spinal cord by manganese enhanced MRI

The present study provides an account of a sensitive and rapid experimental approach for MRI visualization and analysis of spinal cord (SC) laminar activity in normal and injured animals. This approach is based upon neuronal activity-dependant manganese (Mn) uptake after focal SC injection of MnCl2, and subsequent ex-vivo magnetic resonance imaging (MRI) of activated SC pathways. The method was designed as an alternative to time-intensive histochemical and behavioral approaches typically used for analysis of spinal cord injury (SCI) and our results provide both anatomical and functional insights. We show that ex vivo imaging can determine layer-specific activity over an extended region of the rat SC. In addition, we demonstrate that the Mn concentration profile along the SC axis accurately reflects the type of SC injury. The approach is flexible since MRI analysis can be done immediately after animal sacrifice, or alternatively several days later, without a loss of sensitivity. Moreover, the integrity and functional state of SC circuitry can be analyzed in less than 1 h whereas several days and weeks are necessary to perform classical histochemical and behavioral analysis. Thus our method can be used for precise assessment of the extent of dysfunction or change in SC disorders and may facilitate the screening of molecules with therapeutic potential after SC injury.

Salvianolic acid B promotes survival of transplanted mesenchymal stem cells in spinal cord-injured rats

Stem cells hold great promise for brain and spinal cord injuries (SCI), but cell survival following transplantation to adult central nervous system has been poor. Salvianolic acid B (Sal B) has been shown to improve functional recovery in brain-injured rats. The present study was designed to determine whether Sal B could improve transplanted mesenchymal stem cell (MSC) survival in SCI rats. SCI rats were treated with Sal B. The Basso-Beatie-Bresnahan (BBB) scale was used to test the functional recovery. Sal B was used to protect MSC from being damaged by TNF-alpha in vitro. Bromodeoxyuridine-labeled MSC were transplanted into SCI rats with Sal B intraperitoneal injection, simultaneously. MSC were examined, and the functional recovery of the SCI rats was tested. Sal B treatment significantly reduced the lesion area from 0.26+/-0.05 mm2 to 0.15+/-0.03 mm2 (P<0.01) and remarkably raised the BBB scores on d 28, post-injury, from 7.3+/-0.9 to 10.5+/-1.3 (P<0.05), compared with the phosphate-buffered saline (PBS) control group. MSC were protected from the damage of TNF-alpha by Sal B. The number of surviving MSC in the MSC plus Sal B groups were 1143.3+/-195.6 and 764.0+/-81.3 on d 7 and 28, post-transplantation, more than those in the MSC group, which was 569.3+/-72.3 and 237.0+/-61.3, respectively (P<0.05). Rats with MSC transplanted and Sal B injected obtained higher BBB scores than those with MSC transplanted alone (P<0.05) and PBS (P<0.01). Sal B provides neuroprotection to SCI and promotes the survival of MSC in vitro and after cell transplantation to the injured spinal cord in vivo.

Administration of phosphodiesterase inhibitors and an adenosine A1 receptor antagonist induces phrenic nerve recovery in high cervical spinal cord injured rats

High cervical spinal cord hemisection interrupts the descending respiratory drive from the medulla to the ipsilateral phrenic motoneurons, consequently leading to the paralysis of the ipsilateral hemidiaphragm. Previous studies have shown that chronic oral administration of theophylline, a phosphodiesterase inhibitor and an adenosine receptor antagonist, can restore function to the quiescent phrenic nerve and hemidiaphragm ipsilateral to hemisection. Both of these actions of theophylline result in an increase in 3′-5′-cyclic adenosine monophosphate (cAMP). Furthermore, the chronic theophylline-mediated respiratory recovery persists long after the animals have been weaned from the drug. To date, the precise cellular mechanisms underlying the recovery induced by theophylline are still not known. Since theophylline has two modes of action, in the present study we tested whether chronic administration of pentoxifylline, a non-selective phosphodiesterase inhibitor, rolipram, a phosphodiesterase-4 specific inhibitor, and 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A1 receptor antagonist, would induce recovery similar to that induced by theophylline in male Sprague–Dawley rats following a left C2 spinal cord lesion. Recovery of left phrenic nerve activity was assessed at 5 or 10 days after the last drug administrations to assess the persistent nature of the recovery. Pentoxifylline, rolipram and DPCPX, all capable of modulating 3′,5′-cyclic monophosphate (cAMP) levels, brought about long-term respiratory recovery in the phrenic nerve ipsilateral to the left C2 lesion at 5 and 10 days after the last drug administration. Therefore, these results suggest that compounds capable of regulating cAMP levels may be therapeutically useful in promoting functional recovery following spinal cord injury.

Electro-Acupuncture Improves Survival and Migration of Transplanted Neural Stem Cells in Injured Spinal Cord in Rats

This study investigated whether electro-acupuncture (EA) would improve the survival and migration of neural stem cells (NSCs) transplanted in injured spinal cord as well as the potential mechanisms. T10 spinal cord segments of 50 adult Sprague-Dawley (SD) rats were completely transected, and then NSCs were immediately transplanted into the transected site of the experimental animals, while control animals were sham operated without transplantation. Five days post-operation, electro-acupuncture treatment on GV9 (Zhiyang), GV6 (Jizhong), GV2 (Yaoshu) and GV1 (Changqiang) acupoints was applied for 14 days (EA+NSCs 14d) and 30 days (EA+NSCs 30d). ELISA and immunohistochemical staining were used to assess the content of neurotrophine-3 (NT-3) and the characteristics of transplanted NSCs. We found that the number of transplanted NSCs the survived in EA+NSCs14d group was significantly increased as compared to that of the NSCs30d group (5825.20 +/- 819.01 vs 4781.40 +/- 500.49, P<0.05). Immunostaining indicated that some transplanted NSCs developed into microtubule association protein 2 (MAP2) positive cells and many of them developed into glial fibrillary acidic protein (GFAP) positive cells in the NSCs30d group. Further, the migration length of transplanted NSCs toward caudal tissue in the injured site was longer in the EA+NSCs30d group than that in NSCs30d group (5.98 +/- 0.79 mm vs 3.96 +/- 1.72 mm; P<0.05). Also NT-3 in injured spinal cord tissue was 23% increased in the EA+NSCs14d group. These results suggest that the combination of EA and NSCs improves the survival and migration of NSCs in injured spinal cord in rats.