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

When ischemia or hemorrhagic stroke occurs, astrocytes are activated by a variety of endogenous regulatory factors to become reactive astrocytes. Subsequently, reactive astrocytes proliferate, differentiate, and migrate around the lesion to form glial scar with the participation of microglia, neuron-glial antigen 2(NG2) glial cells, and extracellular matrix. The role of glial scars at different stages of stroke injury is different. At the middle and late stages of the injury, the secreted chondroitin sulfate proteoglycan and chondroitin sulfate are the main blockers of axon regeneration and nerve function recovery. Targeted regulation of glial scars is an important pathway for neurological rehabilitation after stroke. Chinese medicine has been verified to be effective in stroke rehabilitation in clinical practice, possibly because it has the functions of promoting blood resupply, anti-inflammation, anti-oxidative stress, inhibiting cell proliferation and differentiation, and benign intervention in glial scars. This study reviewed the pathological process and signaling mechanisms of glial scarring after stroke, as well as the intervention of traditional Chinese medicine upon glial scar, aiming to provide theoretical reference and research evidence for developing Chinese medicine against stroke in view of targeting glial scarring.
Astrocytes ; Axons/pathology* ; Cicatrix/pathology* ; Gliosis/pathology* ; Humans ; Medicine, Chinese Traditional ; Nerve Regeneration ; Stroke/drug therapy*

BACKGROUND: Stroke involving the cerebral white matter (WM) has increased in prevalence, but most experimental studies have focused on ischemic injury of the gray matter. This study was performed to investigate the WM in a unique rat model of photothrombotic infarct targeting the posterior limb of internal capsule (PLIC), focusing on the identification of the most vulnerable structure in WM by ischemic injury, subsequent glial reaction to the injury, and the fundamental histopathologic feature causing different neurologic outcomes. METHODS: Light microscopy with immunohistochemical stains and electron microscopic examinations of the lesion were performed between 3 hours and 21 days post-ischemic injury. RESULTS: Initial pathological change develops in myelinated axon, concomitantly with reactive change of astrocytes. The first pathology to present is nodular loosening to separate the myelin sheath with axonal wrinkling. Subsequent pathologies include rupture of the myelin sheath with extrusion of axonal organelles, progressive necrosis, oligodendrocyte degeneration and death, and reactive gliosis. Increase of glial fibrillary acidic protein (GFAP) immunoreactivity is an early event in the ischemic lesion. WM pathologies result in motor dysfunction. Motor function recovery after the infarct was correlated to the extent of PLIC injury proper rather than the infarct volume. CONCLUSIONS: Pathologic changes indicate that the cerebral WM, independent of cortical neurons, is highly vulnerable to the effects of focal ischemia, among which myelin sheath is first damaged. Early increase of GFAP immunoreactivity indicates that astrocyte response initially begins with myelinated axonal injury, and supports the biologic role related to WM injury or plasticity. The reaction of astrocytes in the experimental model might be important for the study of pathogenesis and treatment of the WM stroke.
Astrocytes ; Axons ; Coloring Agents ; Extremities ; Glial Fibrillary Acidic Protein ; Gliosis ; Gray Matter ; Internal Capsule* ; Ischemia ; Microscopy ; Models, Animal ; Models, Theoretical ; Myelin Sheath ; Necrosis ; Neurons ; Oligodendroglia ; Organelles ; Pathology ; Plastics ; Prevalence ; Recovery of Function ; Rupture ; Stroke ; White Matter

Two major vascular pathologies underlie brain damage in patients with disease of small size penetrating brain arteries and arterioles; 1) thickening of the arterial media and 2) obstruction of the origins of penetrating arteries by parent artery intimal plaques. The media of these small vessels may be thickened by fibrinoid deposition and hypertrophy of smooth muscle and other connective tissue elements that accompanies degenerative changes in patients with hypertension and or diabetes or can contain foreign deposits as in amyloid angiopathy and genetically mediated conditions such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. These pathological changes lead to 2 different pathophysiologies: 1) brain ischemia in regions supplied by the affected arteries. The resultant lesions are deep small infarcts, most often involving the basal ganglia, pons, thalami and cerebral white matter. And 2) leakage of fluid causing edema and later gliosis in white matter tracts. The changes in the media and adventitia effect metalloproteinases and other substances within the matrix of the vessels and lead to abnormal blood/brain barriers in these small vessels. and chronic gliosis and atrophy of cerebral white matter.
Adventitia ; Amyloid ; Arteries ; Arterioles ; Atrophy ; Basal Ganglia ; Brain ; Brain Ischemia ; CADASIL ; Cerebral Amyloid Angiopathy ; Cerebral Small Vessel Diseases ; Connective Tissue ; Edema ; Gliosis ; Humans ; Hypertension ; Hypertrophy ; Metalloproteases ; Muscle, Smooth ; Parents ; Pathology* ; Pons ; Stroke, Lacunar* ; Tunica Media

BACKGROUNDIn response to the injury of the central nervous system (CNS), the astrocytes upregulate the expression of glial fibrillary acidic protein (GFAP), which largely contributes to the reactive gliosis after brain injury. The regulatory mechanism of this process is still not clear. In this study, we aimed to compare the ephrin-B2 deficient mice with the wild type ones with regard to gliosis after traumatic brain injury.

METHODSWe generated ephrin-B2 knockout mice specifically in CNS astrocytes. Twelve mice from this gene-knockout strain were randomly selected along with twelve mice from the wild type littermates. In both groups, a modified controlled cortical impact injury model was applied to create a closed traumatic brain injury. Twenty-eight days after the injury, Nissl staining and GFAP immunofluorescence staining were used to compare the brain atrophy and GFAP immunoreactivity between the two groups. All the data were analyzed by t-test for between-group comparison.

RESULTSWe successfully set up the conditional ephrin-B2 knockout mice strain, which was confirmed by genotyping and ephrin-B2/GFAP double staining. These mice developed normally without apparent abnormality in general appearance. Twenty-eight days following brain injury, histopathology revealed by immunohistochemistry showed different degrees of cerebral injuries in both groups. Compared with wild-type group, the ephrin-B2 knockout group exhibited less brain atrophy ratio for the injured hemispheres (P = 0.005) and hippocampus (P = 0.027). Also the wild-type group demonstrated greater GFAP immunoreactivity increment within hippocampal regions (P = 0.008).

CONCLUSIONSThe establishment of conditional ephrin-B2 knockout mice provides us with a new way to explore the role of ephrin-B2 in astrocytes. Our findings revealed less atrophy and GFAP immunoreactivity in the knockout mice strain after traumatic brain injury, which implied ephrin-B2 could be one of the promoters to upregulate gliosis following brain injury.

Animals ; Atrophy ; Brain ; pathology ; Brain Injuries ; complications ; pathology ; Ephrin-B2 ; deficiency ; physiology ; Glial Fibrillary Acidic Protein ; Gliosis ; etiology ; Immunohistochemistry ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Nerve Tissue Proteins ; analysis

OBJECTIVETo investigate the immunohistochemical expression of isocitrate dehydrogenase 1 gene (IDH1) R132H in glioma and its diagnostic utility.

METHODSImmunohistochemical study of IDH1R132H expression was performed on formalin-fixed paraffin-embedded tissue samples of 75 gliomas, including 33 cases of grade II, 20 cases of grade III and 22 cases of grade IV tumors. Six cases of pilocytic astrocytoma and 12 cases of gliosis were used as controls.

RESULTSNineteen in 33 cases of grade II (57.6%), 8 in 20 cases of grade III (40.0%), 6 in 22 cases of grade IV (27.3%) showed positive cytoplasmic staining of IDH1R132H. Scattered invasive glioma cells at the tumor periphery also expressed IDH1R132H. Gliomas involving the frontal lobe showed more strong IDH1R132H staining. In contrast, none of the pilocytic astrocytomas and gliosis showed IDH1R132H staining. Moreover, the rate of p53 immunopositivities were 42.4% (14/33) in grade II, 65.0% (13/20) in grade III and 77.3% (17/22) in grade IV gliomas. There were no statistic correlations between expression of IDH1R132H and p53.

CONCLUSIONIDH1R132H tends to express preferentially in low-grade gliomas, and it thus may serve as a valuable marker in distinguishing low grade gliomas from gliosis.

Adolescent ; Adult ; Aged ; Astrocytoma ; metabolism ; pathology ; Brain Neoplasms ; metabolism ; pathology ; Child ; Diagnosis, Differential ; Female ; Glioma ; metabolism ; pathology ; Gliosis ; metabolism ; pathology ; Humans ; Isocitrate Dehydrogenase ; genetics ; metabolism ; Male ; Middle Aged ; Mutation ; Tumor Suppressor Protein p53 ; metabolism ; Young Adult

Even though there is no direct evidence to prove the cellular and molecular changes induced by radiofrequency (RF) radiation itself, we cannot completely exclude the possibility of any biological effect of mobile phone frequency radiation. We established a carousel-type exposure chamber for 849 MHz or 1763 MHz of mobile phone RF radiation to expose RF to the heads of C57BL mice. In this chamber, animals were irradiated intermittently at 7.8 W/kg for a maximum of 12 months. During this period, the body weights of 3 groups-sham, 849 MHz RF, and 1763 MHz RF-did not show any differences between groups. The brain tissues were obtained from 3 groups at 6 months and 12 months to examine the differences in histology and cell proliferation between control and RF exposure groups, but we could not find any change upon RF radiation. Likewise, we could not find changes in the expression and distribution of NeuN and GFAP in hippocampus and cerebellum, or in cell death by TUNEL assay in RF exposure groups. From these data, we conclude that the chronic exposure to 849 MHz and 1763 MHz RF radiation at a 7.8 W/kg specific absorption rate (SAR) could not induce cellular alterations such as proliferation, death, and reactive gliosis.
Animals ; Apoptosis/*radiation effects ; Body Weight/radiation effects ; Brain/pathology/*radiation effects ; Cell Proliferation/*radiation effects ; *Cellular Phone ; Dose-Response Relationship, Radiation ; Gliosis/etiology/pathology ; In Situ Nick-End Labeling ; Mice ; Mice, Inbred C57BL ; Nerve Tissue Proteins/biosynthesis/genetics ; Proliferating Cell Nuclear Antigen/biosynthesis/genetics ; Radio Waves/*adverse effects

OBJECTIVENeuroinflammation with microglial activation has been implicated to have a strong association with the progressive dopaminergic neuronal loss in Parkinson's disease (PD). The present study was undertaken to evaluate the activation profile of microglia in 1-methyl-4-phenyl pyridinium (MPP+)-induced hemiparkinsonian rats. Triptolide, a potent immunosuppressant and microglia inhibitor, was then examined for its efficacy in protecting dopaminergic neurons from injury and ameliorating behavioral disabilities induced by MPP+.

METHODSThe rat model of PD was established by intranigral microinjection of MPP+. At baseline and on day 1, 3, 7, 14, 21 following MPP+ injection, the degree of microglial activation was examined by detecting the immunodensity of OX-42 (microglia marker) in the substantia nigra (SN). The number of viable dopaminergic neurons was determined by measuring tyrosine hydroxylase (TH) positive neurons in the SN. Behavioral performances were evaluated by counting the number of rotations induced by apomorphine, calculating scores of forelimb akinesia and vibrissae-elicited forelimb placing asymmetry.

RESULTSIntranigral injection of MPP+ resulted in robust activation of microglia, progressive depletion of dopaminergic neurons, and ongoing aggravation of behavioral disabilities in rats. Triptolide significantly inhibited microglial activation, partially prevented dopaminergic cells from death and improved behavioral performances.

CONCLUSIONThese data demonstrated for the first time a neuroprotective effect of triptolide on dopaminergic neurons in MPP+-induced hemiparkinsonian rats. The protective effect of triptolide may, at least partially, be related to the inhibition of MPP+-induced microglial activation. Our results lend strong support to the use of immunosuppressive agents in the management of PD.

1-Methyl-4-phenylpyridinium ; antagonists & inhibitors ; toxicity ; Animals ; Biomarkers ; metabolism ; CD11b Antigen ; analysis ; metabolism ; Cell Count ; Cell Survival ; drug effects ; physiology ; Disability Evaluation ; Diterpenes ; pharmacology ; therapeutic use ; Dopamine ; metabolism ; Encephalitis ; drug therapy ; immunology ; prevention & control ; Epoxy Compounds ; pharmacology ; therapeutic use ; Gliosis ; drug therapy ; immunology ; prevention & control ; Herbicides ; antagonists & inhibitors ; toxicity ; Immunosuppression ; methods ; Immunosuppressive Agents ; pharmacology ; therapeutic use ; Male ; Microglia ; drug effects ; immunology ; Neurons ; drug effects ; immunology ; pathology ; Parkinsonian Disorders ; drug therapy ; immunology ; physiopathology ; Phenanthrenes ; pharmacology ; therapeutic use ; Rats ; Rats, Sprague-Dawley ; Substantia Nigra ; drug effects ; immunology ; physiopathology ; Treatment Outcome ; Tyrosine 3-Monooxygenase ; analysis ; metabolism

OBJECTIVETo evaluate the role of thrombin-activated microglia in the neurodegeneration of nigral dopaminergic neurons in the rat substantia nigra (SN) in vivo.

METHODSAfter stereotaxic thrombin injection into unilateral SN of rats, immunostaining, reverse transcription polymerase chain reaction (RT-PCR) and biochemical methods were used to observe tyrosine hydroxylase (TH) immunoreactive positive cells, microglia activation, nitric oxide (NO) amount and inducible nitric-oxide synthase (iNOS) expression.

RESULTS(1) Selective damage to dopaminergic neurons was produced after thrombin injection, which was evidenced by loss of TH immunostaining in time-dependent manner; (2) Strong microglial activation was observed in the SN; (3) RT-PCR demonstrated the early and transient expression of neurotoxic factors iNOS mRNA in the SN. Immunofluorescence results found that thrombin induced expression of iNOS in microglia. The NO production in the thrombin-injected rats was significantly higher than that of controls (P < 0.05).

CONCLUSIONThrombin intranigral injection can injure the dopaminergic neurons in the SN. Thrombin-induced microglia activation precedes dopaminergic neuron degeneration, which suggest that activation of microglia and release of NO may play important roles in dopaminergic neuronal death in the SN.

Animals ; Disease Progression ; Dopamine ; biosynthesis ; Encephalitis ; chemically induced ; metabolism ; physiopathology ; Female ; Gliosis ; chemically induced ; metabolism ; physiopathology ; Immunohistochemistry ; Inflammation Mediators ; toxicity ; Injections ; Microglia ; drug effects ; metabolism ; Nerve Degeneration ; chemically induced ; metabolism ; physiopathology ; Neurons ; drug effects ; metabolism ; pathology ; Nitric Oxide ; biosynthesis ; Nitric Oxide Synthase Type II ; drug effects ; metabolism ; Oxidative Stress ; drug effects ; physiology ; Parkinsonian Disorders ; chemically induced ; metabolism ; physiopathology ; RNA, Messenger ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Substantia Nigra ; drug effects ; metabolism ; physiopathology ; Thrombin ; toxicity ; Time Factors ; Tyrosine 3-Monooxygenase ; drug effects ; genetics ; metabolism ; Up-Regulation ; drug effects ; physiology

PURPOSE: Infantile spam is a kind of epileptic syndrome causing delayed psychomotor development in children and one of the most common type of epileptic encephalopathy. Some cases of infantile spasm are known to be caused by focal abnormalities of cerebral cortex thus curable by operating them. Here we analyzed the results of surgical treatments on intractable epilepsy with infantile spasm. METHODS: We performed retrospective study on 22 patients with infantile spasm who received epileptic surgery since 1999. Surgical outcome, pathologic findings, localization of lesions, and types of surgery were reviewed. RESULTS: Sex ratio of our 22 cases was 1:1.4(M:F) and the age at surgery was quite variable. The mean duration from diagnosing epilepsy till operation was 6-10 years in 8(36%) cases, 1-2 years in 7(32%). In preoperative EEG, abnormalities implying possible focal lesion were seen in all 22 patients. 7(32%) out of 22 cases showed focal lesions in MRI while 12(92%) out of 13 cases in ictal SPECT, 8(62%) out of 13 cases in interictal SPECT, and 11(61%) out of 18 cases of PET examination showed abnormal findings. Concerning the types of surgery, single lobectomy was most commonly performed, in 13 (59%) cases in which 11 among them received frontal lobectomy. Also, multilobar resection was performed in 6(27%) cases and hemispherotomy in 2(9%) as well. 19(86%) patients were classified as Engel class I after operations. In pathological examination, cortical dysplasia was most commonly observed, in 11(50%) cases, microdysgenesis in 3(14%), gliosis in 2(9%), and tuberous sclerosis in 2(9%). CONCLUSION: In cases of children with infantile spam not controlled by medical treatment, epileptic surgery should be strongly considered when cortical pathology can be identified from various studies.
Cerebral Cortex ; Child ; Electroencephalography ; Epilepsy* ; Gliosis ; Humans ; Infant ; Infant, Newborn ; Magnetic Resonance Imaging ; Malformations of Cortical Development ; Pathology ; Retrospective Studies ; Sex Ratio ; Spasms, Infantile* ; Tomography, Emission-Computed, Single-Photon ; Tuberous Sclerosis