Nerve regeneration in adult mammalian spinal cord is poor because of the lack of intrinsic regeneration of neurons and extrinsic factors - the glial scar is triggered by injury and inhibits or promotes regeneration. Recent technological advances in spatial transcriptomics (ST) provide a unique opportunity to decipher most genes systematically throughout scar formation, which remains poorly understood. Here, we first constructed the tissue-wide gene expression patterns of mouse spinal cords over the course of scar formation using ST after spinal cord injury from 32 samples. Locally, we profiled gene expression gradients from the leading edge to the core of the scar areas to further understand the scar microenvironment, such as neurotransmitter disorders, activation of the pro-inflammatory response, neurotoxic saturated lipids, angiogenesis, obstructed axon extension, and extracellular structure re-organization. In addition, we described 21 cell transcriptional states during scar formation and delineated the origins, functional diversity, and possible trajectories of subpopulations of fibroblasts, glia, and immune cells. Specifically, we found some regulators in special cell types, such as Thbs1 and Col1a2 in macrophages, CD36 and Postn in fibroblasts, Plxnb2 and Nxpe3 in microglia, Clu in astrocytes, and CD74 in oligodendrocytes. Furthermore, salvianolic acid B, a blood-brain barrier permeation and CD36 inhibitor, was administered after surgery and found to remedy fibrosis. Subsequently, we described the extent of the scar boundary and profiled the bidirectional ligand-receptor interactions at the neighboring cluster boundary, contributing to maintain scar architecture during gliosis and fibrosis, and found that GPR37L1_PSAP, and GPR37_PSAP were the most significant gene-pairs among microglia, fibroblasts, and astrocytes. Last, we quantified the fraction of scar-resident cells and proposed four possible phases of scar formation: macrophage infiltration, proliferation and differentiation of scar-resident cells, scar emergence, and scar stationary. Together, these profiles delineated the spatial heterogeneity of the scar, confirmed the previous concepts about scar architecture, provided some new clues for scar formation, and served as a valuable resource for the treatment of central nervous system injury.
Mice ; Animals ; Gliosis/pathology* ; Cicatrix/pathology* ; Spinal Cord Injuries ; Astrocytes/metabolism* ; Spinal Cord/pathology* ; Fibrosis ; Mammals ; Receptors, G-Protein-Coupled

OBJECTIVE AND METHODSTo evaluate synaptic changes using synaptophysin immunohistochemstry in rat and mouse, which spinal cords were subjected to graded compression trauma at the level of Th8-9.

RESULTSNormal animals showed numerous fine dots of synaptophysin immunoreactivity in the gray matter. An increase in synaptophysin immunoreactivity was observed in the neuropil and synapses at the surface of motor neurons of the anterior horns in the Th8-9 segments lost immunoreactivity at 4-hour point after trauma. The immunoreactive synapses reappeared around motor neurons at 9-day point. Unexpected accumulation of synaptophysin immunoreactivity occurred in injured axons of the white matter of the compressed spinal cord.

CONCLUSIONSynaptic changes were important components of secondary injuries in spinal cord trauma. Loss of synapses on motor neurons may be one of the factors causing motor dysfunction of hind limbs and formation of new synapses may play an important role in recovery of motor function. Synaptophysin immunohistochemistry is also a good tool for studies of axonal swellings in spinal cord injuries.

Animals ; Axons ; metabolism ; pathology ; Female ; Immunohistochemistry ; Male ; Mice ; Mice, Inbred Strains ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Compression ; Spinal Cord Injuries ; metabolism ; pathology ; Synapses ; metabolism ; pathology ; Synaptophysin ; metabolism

Glial scar formed by central nervous system (CNS) injury is the main inhibitory barrier of nerve regeneration. How to promote axonal regeneration after injury,how to accelerate neural network reconstruction and how to improve brain function recovery have become a hot problem to be solved in the field of neuroscience. This article focuses on the recent advances of therapeutic strategies for axonal regeneration.
Animals ; Astrocytes ; pathology ; Brain Injuries ; pathology ; physiopathology ; Cicatrix ; prevention & control ; Humans ; Nerve Regeneration ; Neuroglia ; pathology ; Neuronal Plasticity ; physiology ; Neurons ; physiology ; Proteoglycans ; metabolism ; Spinal Cord Injuries ; pathology ; physiopathology

OBJECTIVETo observe the pathological changes in rabbits with spinal cord injury induced by decompression sickness (DCS), and to investigate the role of tumor necrosis factor-alpha (TNF-α) in spinal cord injury induced by DCS.

METHODSRabbits were randomly divided into normal control group, DCS group, and safe decompression group. The rabbit model of DCS was established. Light microscopy, real-time PCR, and immunohistochemical method were used to observe the pathomorphological changes in the thoracolumbar spinal cord and the mRNA and protein expression of TNF-α, respectively. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to observe the apoptosis in the spinal cord.

RESULTSIn the DCS group, cavities formed in the white matter of spinal cord and gliosis occurred around necrotic areas. Moreover, the mRNA and protein expression of TNF-α was significantly higher in the DCS group than in the normal control group and the safe decompression group (P<0.01). The results of TUNEL showed that the number of positive apoptotic cells was significantly larger in the DCS group than in the normal control group and the safe decompression group (P<0.05).

CONCLUSIONApoptosis plays an important role in spinal cord injury induced by DCS. In the early stage of DCS, the massive release of TNF-α initiates apoptosis and contributes to the pathological changes in spinal cord injury induced by DCS.

Animals ; Apoptosis ; Decompression Sickness ; metabolism ; pathology ; Disease Models, Animal ; In Situ Nick-End Labeling ; RNA, Messenger ; Rabbits ; Spinal Cord ; pathology ; Spinal Cord Injuries ; metabolism ; pathology ; Tumor Necrosis Factor-alpha ; metabolism

The aim of the study was to investigate the effect of chondroitinase ABC (ChABC) on ephrin A4 (EphA4) expression after spinal cord impairment (SCI) in rats. Adult female SD rats were randomly divided into three groups: ChABC group, normal saline (NS) group and sham group. In the ChABC and NS group, the SCI model was produced by the spinal cord hemisection. The rats in sham group received sham operation without the spinal hemisection. ChABC and NS groups were intrathecally injected with ChABC and normal saline, respectively. At different time points after SCI, injured region of spinal cord was taken out as sample. The levels of EphA4 expression were measured by immunofluorescence technique and Western blot. And the expressions of growth associated protein 43 (GAP-43) and glial fibrillary acidic protein (GFAP) were detected using double immunofluorescent staining. Immunofluorescent results showed that, compared with that in sham group, the EphA4 expression was significantly down-regulated on 1, 3 and 7 d after SCI, then up-regulated on 14 and 21 d after SCI in NS group. In ChABC group, the level of EphA4 expression was significantly less than that in the NS group during the whole time after SCI. Western blot showed an identical result to that of immunofluorescent staining. The double labeling results showed that on 3 d after SCI, the number of GFAP, glial cells marker, positive cells in NS group was lower than that in sham group, but higher than that in ChABC group. Moreover, GAP-43 was not detected in all three groups. These results suggest that ChABC can decrease the expression level of EphA4 and reduce the number of astrocytes after SCI, thus improving microenvironment of the injured region and promoting axonal growth and extension.
Animals ; Astrocytes ; pathology ; Chondroitin ABC Lyase ; pharmacology ; Ephrin-A4 ; metabolism ; Female ; Neurons ; metabolism ; Neuroprotective Agents ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; metabolism ; pathology ; Spinal Cord Injuries ; metabolism

OBJECTIVETo detect the expression of telomerase in glial scar and its correlation with glial scar.

METHODSThere were 120 Sprague Dawley rats were randomly divided into non-interference group of telomerase, interference group of telomerase and control group. Non-interference group and interference group were for spinal cord injury, which adopted Allen's Weight Dropping to make molding; control group was for sham operation to open the vertebral plate and expose spinal marrow, in which spinal cord injury would not be caused. The expression of telomerase and glial fibrillary acidic profein (GFAP) was detected by PCR-ELISA and Western blot, and the formation of glial scar was observed by immunofluorescence on the 1st, 3rd, 5th, 7th, 14th, 28th, 42 th and 56th day after the spinal injury, and analyzed its relativity.

RESULTSThe expression of telomerase in non-interference group was (0.180 ± 0.004 - 1.217 ± 0.072), which was significantly higher than those in interference group (0.028 ± 0.007 - 0.092 ± 0.004, χ(2) = 28.753 - 37.518, P < 0.05) and control group (0.072 ± 0.007 - 0.075 ± 0.004, χ(2) = 18.618 - 41.093, P < 0.05) at all the time, with statistical significance. The expression of GFAP in non-interference group was (1.98 ± 0.15 - 19.40 ± 0.55) which was significantly higher than those in interference group (1.10 ± 0.13 - 16.64 ± 1.02, χ(2) = 14.538 - 37.366, P < 0.05) and control group (0.44 ± 0.05 - 0.48 ± 0.04, χ(2) = 16.733 - 34.041, P < 0.05) at all the time, with statistical significance. The expression of GFAP showed a linear correlation with that of telomerase in non-interference group, and with statistical differences (r = 0.755, P < 0.01). The expression of telomerase in interference group and control group were always negative. Glial scar observed by immunofluorescence in non-interference group was heavier than that in interference group, and control group showed no formation of glial scar.

CONCLUSIONSTelomerase shows a dynamic expression in glial scar and has positive correlational linear relationship with GFAP which shows the formation of glial scar. And the telomerase may be an important factor in promoting the formation of glial scar.

Animals ; Cicatrix ; enzymology ; Glial Fibrillary Acidic Protein ; metabolism ; Neuroglia ; enzymology ; pathology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; enzymology ; pathology ; Telomerase ; metabolism

OBJECTIVETo determine whether spinal cord decompression plays a role in neural cell apoptosis after spinal cord injury.

STUDY DESIGNWe used an animal model of compressive spinal cord injury with incomplete paraparesis to evaluate neural cell apoptosis after decompression. Apoptosis and cellular damage were assessed by staining with terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) and immunostaining for caspase-3, Bcl-2 and Bax.

METHODSExperiments were conducted in male Sprague-Dawley rats (n=78) weighing 300-400 g. The spinal cord was compressed posteriorly at T10 level using a custom-made screw for 6 h, 24 h or continuously, followed by decompression by removal of the screw. The rats were sacrificed on Day 1 or 3 or in Week 1 or 4 post-decompression. The spinal cord was removed en bloc and examined at lesion site, rostral site and caudal site (7.5 mm away from the lesion).

RESULTSThe numbers of TUNEL-positive cells were significantly lower at the site of decompression on Day 1, and also at the rostral and caudal sites between Day 3 and Week 4 post-decompression, compared with the persistently compressed group. The numbers of cells between Day 1 and Week 4 were immunoreactive to caspase-3 and B-cell lymphoma-2 (Bcl-2)-associated X-protein (Bax), but not to Bcl-2, correlated with those of TUNEL-positive cells.

CONCLUSIONOur results suggest that decompression reduces neural cell apoptosis following spinal cord injury.

Animals ; Apoptosis ; Caspase 3 ; metabolism ; Decompression, Surgical ; Immunohistochemistry ; Male ; Neurons ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; pathology ; surgery

OBJECTIVETo determine cell proliferation and nestin expression in the ependyma of adult rat spinal cord after injury.

METHODSRat spinal cord injury models were established by aneurysm clip compression, and nestin expression and proliferation of ependymal cells at different times were shown with pathological and immuno-histochemical staining.

RESULTSEpendymal cells adjacent to the injured site demonstrated a dramatic increase in nestin expression 24 hours after compression. Proliferating cell nuclear antigen was positive, and significant proliferation was observed after 7 days. Nestin expression was down regulated as time went by.

CONCLUSIONNormally quiescent mature ependymal cells appear to revert to an embryonic state in response to spinal cord injury.

Animals ; Cell Division ; Ependyma ; cytology ; metabolism ; Immunohistochemistry ; Intermediate Filament Proteins ; biosynthesis ; Male ; Nerve Tissue Proteins ; Nestin ; Rats ; Rats, Wistar ; Spinal Cord Injuries ; metabolism ; pathology

OBJECTIVETo study the effect of adenovirus-mediated basic fibroblast growth factor(FGF-2) gene transfer in vivo on oligodendrocyte cell numbers throughout ventrolateral white matter following spinal cord injury in rats.

METHODSThirty-two adult female Sprague Dawley rats were injured with the Infinite Horizon Impactor, and then were randomly assigned to four groups: FGF-2-Adts high-titer group (1.27x10(7) pfu/rat), FGF-2-Adts intermediate-titre group (6.37x10(6) pfu/rat), FGF-2-Adts low-titer group (3.18 x 10(6) pfu/rat), and green fluorescent protein (GFP)-Adts group (5.9x10(7) pfu/rat). The transgenic expression in vivo was detected with fluorescence microscopy. The locomotor function of the hindlimbs of rats was evaluated using Rivlin plate. Slides mounted with tissue sections were processed for immunohistochemical detection and quantification of oligodendrocytes (CC1(+)) in the ventral lateral funiculi (VLF) of injured spinal cords.

RESULTSOne week after spinal cord injury, GFP showed that many cells had expressed objective gene in vivo and the angles of the occlusal plane of rats in FGF-2 groups were significantly higher than in GFP-Adts group. Also, there was a significant difference among the FGF-2-Adts treatment groups for the volume of gray matter sparing. However, there were no significant differences for total white matter sparing. Stereological quantification of total CC1(+) cell numbers in the spared VLF showed a significant reduction in numbers with GFP controls compared to all other groups 4 weeks after injury. In contrast, the FGF-2 Adts intermediate-titer group had significantly more CC1(+) cells when compared to both the FGF-2-Adts high- and low-titer groups.

CONCLUSIONAdenovirus-mediated FGF-2 gene transfer can promote the functional recovery of the injured spinal cord by enhancing the proliferation and/or differentiation of oligodendrocytes.

Adenoviridae ; genetics ; Animals ; Disease Models, Animal ; Female ; Fibroblast Growth Factor 2 ; genetics ; metabolism ; Genetic Therapy ; Oligodendroglia ; pathology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; metabolism ; physiopathology ; therapy ; Transfection

OBJECTIVETo investigate the effects of complement inhibiting component of Ephedra sinica on immunological inflammation following acute spinal cord injury (SCI) in rats.

METHODSThe complement inhibiting component of Ephedra sinica was isolated by multiple precipitation steps and thin layer chromatography, and then the activity was analyzed. Fifty healthy SD rats were selected and randomly divided into the control group and the experimental group, 25 in each group. Induction of SCI was performed following a modified Allen's weight-drop method. The complement inhibiting component from Ephedra sinica (15 mg/kg) dissolving in 5 mL normal saline was immediately administered by gastrogavage after SCI, once daily. Equal volume of normal saline was administered to rats in the control group by gastrogavage. Hematoxylin and eosin (H&E) staining and C3 immunohistochemical staining were performed in SCI tissue at 12 h, day 1, 3, 7, and 14 after SCI. C3 positive expressions and myeloperoxidase (MPO) activity were assessed. Intercellular adhesion molecule-1 (ICAM-1) mRNA expression level was evaluated by Real-time PCR technique.

RESULTSC3 positive expression, MPO activity, and ICAM-1 mRNA level were significantly weaker in the Ephedra sinica group than in the control group at all time points (12 h, day 1, day 3, day 7, and day 14 after SCI) (P < 0.01, P < 0.05).

CONCLUSIONSThere existed complement system activation following acute SCI. The complement inhibiting component of Ephedra sinica significantly reduced immunological inflammation after SCI, and played an important role in secondary SCI.

Animals ; Complement Activation ; drug effects ; immunology ; Complement Inactivating Agents ; pharmacology ; Ephedra sinica ; chemistry ; Inflammation ; immunology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; immunology ; metabolism ; pathology