Protease-activated receptor-2 regulates glial scar formation via JNK signaling.

The study aimed to determine the effects of protease-activated receptor-2 (PAR-2) on glial scar formation after spinal cord injury (SCI) in Sprague-Dawley (SD) rats and the underlying mechanisms. Rivlin and Tator's acute extradural clip compression injury (CCI) model of severe SCI was established in this study. Animals were divided into four groups: 1) sham group (laminectomy only); 2) model group, treated with normal saline; 3) PAR-2 inhibitor group; 4) PAR-2 activator group. Enhanced GFAP and vimentin expression were the markers of glial scar formation. To determine whether JNK was involved in the effects of PAR-2 on GFAP and vimentin expression, we administered anisomycin (a JNK activator) in the presence of PAR-2 inhibitor and SP600125 (a JNK inhibitor) in the presence of PAR-2 activator. At 1, 7, 14 and 28 day after SCI, Basso, Beattie, and Bresnahan (BBB) locomotor score test was used to assess the locomotor functional recovery; immunofluorescence and western blot analysis were used to assess the expression level of GFAP, vimentin and p-JNK. Double immunofluorescence staining with GFAP and tubulin beta was used to assess the glial scar formation and the remaining neurons. Results suggested that PAR-2 is involved in glial scar formation and reduces neurons residues which can cause a further worsening in the functional outcomes after SCI via JNK signaling. Therefore, it may be effective to target PAR-2 in the treatment of SCI.

[Effect of suppressing apoptosis signal regulating kinase 1 on GFAP and vimentin expression and hindlimb mobility in rats after spinal cord injury].

OBJECTIVE: To investigate the effect of suppressing apoptosis signal regulating kinase 1 (ASK1) on glial fibrillary acidic protein (GFAP) and vimentin expressions at the injury site and on hindlimb mobility in rats after spinal cord injury (SCI). METHODS: The rat models of SCI were established by extradural compression of the spinal cord using an aneurysm clip. The injured rats were treated with normal saline (model group), ASK1 specific inhibitor thioredoxin (Trx group), or ASK1 monoclonal antibody (Anti-ASK1 group), and the rats receiving a sham operation underwent laminectomy without SCI. The expression of GFAP and vimentin were detected by Western blotting and immunofluorescence assay at 1, 7, 14 and 28 days after SCI. The motion function of the hindlimbs of the injured rats was assessed with Basso Beattie Bresnahan (BBB) scores, and somatosensory-evoked potentials (SEP) and motor-evoked potentials (MEP) were determined to examine the electrophysiological changes. RESULTS: At 1 day after SCI, the expressions of GFAP and vimentin showed no significant differences among the groups; at 7, 14 and 28 days after SCI, GFAP and vimentin expressions significantly increased in Trx and Anti-ASK1 groups compared with those in the model group (P<0.01). The BBB scores showed no significant differences among the groups at 1, 7 and 14 days after SCI, while at 28 days, the BBB scores in Trx and Anti-ASK1 groups were significantly higher than those in the model group (P<0.01). At 28 days after SCI, the latent period of SEP and MEP decreased and the amplitude increased significantly in Trx and Anti-ASK1 groups compared with that in the model group (P<0.01). CONCLUSION: Blocking ASK1 can inhibit the expression of GFAP and vimentin in glial scars and improve the outcomes of hindlimb mobility in rats after SCI.

Functional recovery in acute traumatic spinal cord injury after transplantation of human umbilical cord mesenchymal stem cells.

OBJECTIVE: Spinal cord injury results in loss of neurons, degeneration of axons, formation of glial scar, and severe functional impairment. Human umbilical cord mesenchymal stem cells can be induced to form neural cells in vitro. Thus, these cells have a potential therapeutic role for treating spinal cord injury. DESIGN AND SETTING: Rats were randomly divided into three groups: sham operation group, control group, and human umbilical cord mesenchymal stem cell group. All groups were subjected to spinal cord injury by weight drop device except for sham group. SUBJECTS: Thirty-six female Sprague-Dawley rats. INTERVENTIONS: The control group received Dulbecco's modified essential media/nutrient mixture F-12 injections, whereas the human umbilical cord mesenchymal stem cell group undertook cells transplantation at the dorsal spinal cord 2 mm rostrally and 2 mm caudally to the injury site at 24 hrs after spinal cord injury. MEASUREMENTS: Rats from each group were examined for neurologic function and contents of brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, and neurotrophin-3. Survival, migration, and differentiation of human umbilical cord mesenchymal stem cells, regeneration of axons, and formation of glial scar were also explored by using immunohistochemistry and immunofluorescence. MAIN RESULTS: Recovery of hindlimb locomotor function was significantly enhanced in the human umbilical cord mesenchymal stem cells grafted animals at 5 wks after transplantation. This recovery was accompanied by increased length of neurofilament-positive fibers and increased numbers of growth cone-like structures around the lesion site. Transplanted human umbilical cord-mesenchymal stem cells survived, migrated over short distances, and produced large amounts of glial cell line-derived neurotrophic factor and neurotrophin-3 in the host spinal cord. There were fewer reactive astrocytes in both the rostral and caudal stumps of the spinal cord in the human umbilical cord-mesenchymal stem cell group than in the control group. CONCLUSIONS: Treatment with human umbilical cord mesenchymal stem cells can facilitate functional recovery after traumatic spinal cord injury and may prove to be a useful therapeutic strategy to repair the injured spinal cord.

Bovine serum albumin promotes IL-1beta and TNF-alpha secretion by N9 microglial cells.

Bovine serum albumin (BSA) is generally used in biomedical experiments. In the solution of some reagents, BSA is necessary to maintain the stability and concentration of the effective component. Therefore, the potential impact of BSA on experimental results should not be neglected when BSA is used. In this study, we observed that BSA induced significant upregulation of mRNA expression and release of pro-inflammatory cytokines, IL-1beta, and TNF-alpha, by N9 microglial cells. Our results suggest that the effects of BSA should be taken into account in experiments on microglia or the central nervous system when BSA is used. In light of the high similarity and homology among mammalian albumins, our findings also indicate that serum albumin may be a potent trigger of cytokine release by microglia.

In vitro labeling of human umbilical cord mesenchymal stem cells with superparamagnetic iron oxide nanoparticles.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) transplantation has been shown to promote regeneration and neuroprotection in central nervous system (CNS) injuries and neurodegenerative diseases. To develop this approach into a clinical setting it is important to be able to follow the fates of transplanted cells by noninvasive imaging. Neural precursor cells and hematopoietic stem cells can be efficiently labeled by superparamagnetic iron oxide (SPIO) nanoparticle. The purpose of our study was to prospectively evaluate the influence of SPIO on hUC-MSCs and the feasibility of tracking for hUC-MSCs by noninvasive imaging. In vitro studies demonstrated that magnetic resonance imaging (MRI) can efficiently detect low numbers of SPIO-labeled hUC-MSCs and that the intensity of the signal was proportional to the number of labeled cells. After transplantation into focal areas in adult rat spinal cord transplanted SPIO-labeled hUC-MSCs produced a hypointense signal using T2-weighted MRI in rats that persisted for up to 2 weeks. This study demonstrated the feasibility of noninvasive imaging of transplanted hUC-MSCs.