Growth-associated protein 43 and neural cell adhesion molecule expression following bone marrow-derived mesenchymal stem cell transplantation in a rat model of ischemic brain injury

BACKGROUND： Transplantation of bone marrow-derived mesenchymal stem cells （BMSCs） improves motor functional recovery, but the mechanisms remain unclear. OBJECTIVE： To investigate expression of growth-associated protein 43 （GAP-43） and neural cell adhesion molecule following BMSC transplantation to the lateral ventricle in rats with acute focal cerebral ischemic brain damage. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment using immunohistochemistry was performed at the laboratories of Department of Neurology, Renmin Hospital of Wuhan University and Doctoral Scientific Research Work Station of C-BONS PHARMA, Hubei Province, China, from January 2007 to December 2008. MATERIALS： Monoclonal mouse anti-rat 5-bromo-2-deoxyuridine and neural cell adhesion molecule antibodies were purchased from Sigma, USA; monoclonal mouse anti-rat GAP-43 antibody was purchased from Wuhan Boster, China. METHODS： Rat models of right middle cerebral artery occlusion were established using the thread method. At 1 day after middle cerebral artery occlusion, 20μL culture solution, containing 5×10^5 BMSCs, was transplanted to the left lateral ventricle using micro-injection. MAIN OUTCOME MEASURES： Scores of neurological impairment were measured to assess neural function. Expression of GAP-43 and neural cell adhesion molecule at the lesion areas was examined by immunohistochemistry. RESULTS： GAP-43 and neural cell adhesion molecule expression was low in brain tissues of the sham-operated group, but expression increased at the ischemic boundary （P 〈 0.05）. Transplantation of BMSCs further enhanced expression of GAP-43 and neural cell adhesion molecule （P 〈 0.05） and remarkably improved neurological impairment of ischemic rats （P 〈 0.05）. CONCLUSION： BMSC transplantation promoted neurological recovery in rats by upregulating expression of GAP-43 and neural cell adhesion molecule.

Nerve bundle formation during the promotion of peripheral nerve regeneration:collagenⅥ-neural cell adhesion molecule 1 interaction

The formation of nerve bundles,which is partially regulated by neural cell adhesion molecule 1(NCAM1),is important for neural network organization during peripheral nerve regeneration.However,little is known about how the extracellular matrix(ECM)microenvironment affects this process.Here,we seeded dorsal root ganglion tissue blocks on different ECM substrates of peripheral nerve ECM-derived matrixgel,Matrigel,laminin 521,collagen I,and collagen IV,and observed well-aligned axon bundles growing in the peripheral nerve ECM-derived environment.We confirmed that NCAM1 is necessary but not sufficient to trigger this phenomenon.A protein interaction assay identified collagen VI as an extracellular partner of NCAM1 in the regulation of axonal fasciculation.Collagen VI interacted with NCAM1 by directly binding to the FNIII domain,thereby increasing the stability of NCAM1 at the axolemma.Our in vivo experiments on a rat sciatic nerve defect model also demonstrated orderly nerve bundle regeneration with improved projection accuracy and functional recovery after treatment with 10 mg/m L Matrigel and 20μg/m L collagen VI.These findings suggest that the collagen VI-NCAM1 pathway plays a regulatory role in nerve bundle formation.This study was approved by the Animal Ethics Committee of Guangzhou Medical University(approval No.GY2019048)on April 30,2019.

Alterations in the polysialylated neural cell adhesion molecule and retinal ganglion cell density in mice with diabetic retinopathy

AIM：To investigate the impact of polysialylated neural cell adhesion molecule（PSA-NCAM）on the survival of retinal ganglion cells（RGCs）in the experimentally induced diabetes in mice.METHODS：Diabetes was induced in 2.5 months old Swiss Webster mice by intraperitoneal injection of streptozotocin（STZ,90 mg/kg）once daily for two consecutive days.Examination of the proteins of interest in the retinas from diabetic mice at 2mo after diabetes induction was performed using immunohistochemistry and Western blot analysis.RGCs were counted in the wholemounted retinas,and Brn3a marker was used.RESULTS：Examination of retinas from diabetic mice at 2mo after diabetes induction revealed a considerable reduction in RGC density.Our experiments also demonstrated a redistribution of PSA-NCAM in the retina of diabetic animals.PSA-NCAM immunoreactivity was diminished in the inner part of the retina where RGCs were located.In contrast,an enhanced PSA-NCAM immunoreactivity was detected in the outer layers of the retina.PSA-NCAM signal was co-localized with glial fibrillary acidic protein immunoreactivity in the Müller cell branches.Previous studies have shown that matrix metalloproteinase-9（MMP-9）is responsible for the reduction in PSA-NCAM levels in neuronal cells.The reduced levels of PSA-NCAM in inner layers（nerve fiber layer,ganglion cell layer）were accompanied by the increased expression of MMP-9.In contrast,in the outer retinal layers,the expression of MMP-9 was much less pronounced.CONCLUSION：MMP-9 induces PSA-NCAM shedding in the inner part of the retina and the decreased level of PSA-NCAM in the inner part of the retina might be,at least in part,responsible for the loss of RGCs in diabetic mice.

Expression changes of nerve cell adhesion molecules L1 and semaphorin 3A after peripheral nerve injury

The expression of nerve cell adhesion molecule L1 in the neuronal growth cone of the central nervous system is strongly associated with the direction of growth of the axon, but its role in the regeneration of the peripheral nerve is still unknown. This study explored the problem in a femoral nerve section model in rats. L1 and semaphorin 3A m RNA and protein expressions were measured over the 4-week recovery period. Quantitative polymerase chain reaction showed that nerve cell adhesion molecule L1 expression was higher in the sensory nerves than in motor nerves at 2 weeks after injury, but vice versa for the expression of semaphorin 3A. Western blot assay results demonstrated that nerve cell adhesion molecule L1 expression was higher in motor nerves than in the sensory nerves at the proximal end after injury, but its expression was greater in the sensory nerves at 2 weeks. Semaphorin 3A expression was higher in the motor nerves than in the sensory nerves at 3 days and 1 week after injury. Nerve cell adhesion molecule L1 and semaphorin 3A expressions at the distal end were higher in the motor nerves than in the sensory nerves at 3 days, 1 and 2 weeks. Immunohistochemical staining results showed that nerve cell adhesion molecule L1 expression at the proximal end was greater in the sensory nerves than in the motor nerves; semaphorin 3A expression was higher in the motor nerves than in the sensory nerves at 2 weeks after injury. Taken together, these results indicated that nerve cell adhesion molecules L1 and semaphorin 3A exhibited different expression patterns at the proximal and distal ends of sensory and motor nerves, and play a coordinating role in neural chemotaxis regeneration.

Cognitive disorder and changes in cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor following brain injury

BACKGROUND： Learning and memory damage is one of the most permanent and the severest symptoms of traumatic brain injury; it can seriously influence the normal life and work of patients. Some research has demonstrated that cognitive disorder is closely related to nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor. OBJECTIVE： To summarize the cognitive disorder and changes in nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor following brain injury. RETRIEVAL STRATEGY： A computer-based online search was conducted in PUBMED for English language publications containing the key words ＂brain injured, cognitive handicap, acetylcholine, N-methyl-D aspartate receptors, neural cell adhesion molecule, brain-derived neurotrophic factor＂ from January 2000 to December 2007. There were 44 papers in total. Inclusion criteria： ① articles about changes in nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor following brain injury; ② articles in the same researching circle published in authoritative journals or recently published. Exclusion criteria： duplicated articles. LITERATURE EVALUATION： References were mainly derived from research on changes in these four factors following brain injury. The 20 included papers were clinical or basic experimental studies. DATA SYNTHESIS： After craniocerebral injury, changes in these four factors in brain were similar to those during recovery from cognitive disorder, to a certain degree. Some data have indicated that activation of nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor could greatly improve cognitive disorder following brain injury. However, there are still a lot of questions remaining; for example, how do these factors change at different time points after brain injury, and what is the relationship between associated factors and cognitive disorder. CONCLUSION： It is necessary to comprehensively study some associated factors, to analyze their changes and their relationship with cognitive disorder following brain injury, and to investigate their effects at different time points after brain injury.

Molecular and cellular changes in the post-traumatic spinal cord remodeling after autoinfusion of a genetically-enriched leucoconcentrate in a mini-pig model

Post-traumatic spinal cord remodeling includes both degenerating and regenerating processes,which affect the potency of the functional recovery after spinal cord injury(SCI).Gene therapy for spinal cord injury is proposed as a promising therapeutic strategy to induce positive changes in remodeling of the affected neural tissue.In our previous studies for delivering the therapeutic genes at the site of spinal cord injury,we developed a new approach using an autologous leucoconcentrate transduced ex vivo with chimeric adenoviruses(Ad5/35)carrying recombinant cDNA.In the present study,the efficacy of the intravenous infusion of an autologous genetically-enriched leucoconcentrate simultaneously producing recombinant vascular endothelial growth factor(VEGF),glial cell line-derived neurotrophic factor(GDNF),and neural cell adhesion molecule(NCAM)was evaluated with regard to the molecular and cellular changes in remodeling of the spinal cord tissue at the site of damage in a model of mini-pigs with moderate spinal cord injury.Experimental animals were randomly divided into two groups of 4 pigs each:the therapeutic(infused with the leucoconcentrate simultaneously transduced with a combination of the three chimeric adenoviral vectors Ad5/35‐VEGF165,Ad5/35‐GDNF,and Ad5/35‐NCAM1)and control groups(infused with intact leucoconcentrate).The morphometric and immunofluorescence analysis of the spinal cord regeneration in the rostral and caudal segments according to the epicenter of the injury in the treated animals compared to the control mini-pigs showed:(1)higher sparing of the grey matter and increased survivability of the spinal cord cells(lower number of Caspase-3-positive cells and decreased expression of Hsp27);(2)recovery of synaptophysin expression;(3)prevention of astrogliosis(lower area of glial fibrillary acidic protein-positive astrocytes and ionized calcium binding adaptor molecule 1-positive microglial cells);(4)higher growth rates of regeneratingβIII-tubulin-positive axons accompanied by a higher number of oligodendrocyte transcription factor 2-positive oligodendroglial cells in the lateral corticospinal tract region.These results revealed the efficacy of intravenous infusion of the autologous genetically-enriched leucoconcentrate producing recombinant VEGF,GDNF,and NCAM in the acute phase of spinal cord injury on the positive changes in the post-traumatic remodeling nervous tissue at the site of direct injury.Our data provide a solid platform for a new ex vivo gene therapy for spinal cord injury and will facilitate further translation of regenerative therapies in clinical neurology.

Pre-degenerated peripheral nerves co-cultured with bone marrow-derived cells: a new technique for harvesting high-purity Schwann cells

Schwann cells play an important role in the peripheral nervous system, especially in nerve repair following injury, so artificial nerve regen- eration requires an effective technique for obtaining purified Schwann cells. In vivo and in vitro pre-degeneration of peripheral nerves have been shown to obtain high-purity Schwann cells. We believed that in vitro pre-degeneration was simple and controllable, and available for the clinic. Thus, we co-cultured the crushed sciatic nerves with bone marrow-derived cells in vitro. Results demonstrated that, 3 hours after injury, a large number of mononuclear cells moved to the crushed nerves and a large number of bone marrow-derived cells infiltrated the nerve segments. These changes promoted the degradation of the nerve segments, and the dedifferentiation and proliferation of Schwann cells. Neural cell adhesion molecule and glial fibrillary acidic protein expression were detected in the crushed nerves. Schwann cell yield was 9.08 ± 2.01 ×104/mg. The purity of primary cultured Schwann cells was 88.4 ± 5.79%. These indicate a successful new method for ob- taining Schwann cells of high purity and yield from adult crushed sciatic nerve using bone marrow-derived cells.

Combination of epidural electrical stimulation with ex vivo triple gene therapy for spinal cord injury:a proof of principle study

Despite emerging contemporary biotechnological methods such as gene-and stem cell-based therapy,there are no clinically established therapeutic strategies for neural regeneration after spinal cord injury.Our previous studies have demonstrated that transplantation of genetically engineered human umbilical cord blood mononuclear cells producing three recombinant therapeutic molecules,including vascular endothelial growth factor(VEGF),glial cell-line derived neurotrophic factor(GDNF),and neural cell adhesion molecule(NCAM)can improve morpho-functional recovery of injured spinal cord in rats and mini-pigs.To investigate the efficacy of human umbilical cord blood mononuclear cells-mediated triple-gene therapy combined with epidural electrical stimulation in the treatment of spinal cord injury,in this study,rats with moderate spinal cord contusion injury were intrathecally infused with human umbilical cord blood mononuclear cells expressing recombinant genes VEGF165,GDNF,NCAM1 at 4 hours after spinal cord injury.Three days after injury,epidural stimulations were given simultaneously above the lesion site at C5(to stimulate the cervical network related to forelimb functions)and below the lesion site at L2(to activate the central pattern generators)every other day for 4 weeks.Rats subjected to the combined treatment showed a limited functional improvement of the knee joint,high preservation of muscle fiber area in tibialis anterior muscle and increased H/M ratio in gastrocnemius muscle 30 days after spinal cord injury.However,beneficial cellular outcomes such as reduced apoptosis and increased sparing of the gray and white matters,and enhanced expression of heat shock and synaptic proteins were found in rats with spinal cord injury subjected to the combined epidural electrical stimulation with gene therapy.This study presents the first proof of principle study of combination of the multisite epidural electrical stimulation with ex vivo triple gene therapy(VEGF,GDNF and NCAM)for treatment of spinal cord injury in rat models.The animal protocols were approved by the Kazan State Medical University Animal Care and Use Committee(approval No.2.20.02.18)on February 20,2018.

New antigens involved in membranous nephropathy beyond phospholipase A2 receptor

When the physiopathology of membranous nephropathy was first described,almost 30%of cases were recognized to be secondary to well-known diseases such as autoimmune diseases,tumors or infections.The remaining 70%cases were called primary membranous nephropathy as the exact mechanism or pathogenic factor involved was unknown.The discovery of the M type phospholipase A2 receptor and thrombospondin type 1 domain containing 7A as causative antigens in these“so called”primary membranous nephropathies provided new insights into the effective causes of a large proportion of these cases.Novel techniques such as laser microdissection and tandem mass spectrometry as well as immunochemistry with antibodies directed against novel proteins allowed the confirmation of new involved antigens.Finally,using confocal microscopy to localize these new antigens and immunoglobulin G and Western blot analysis of serum samples,these new antigens were detected on the glomerular membrane,and the related antibodies were detected in serum samples.The same antigens have been recognized in some cases of secondary membranous disease due to autoimmune diseases,tumors and infections.This has allowed examination of the relationship between antigens in primary membranous nephropathy and their presence in some secondary nephropathies.The aim of this study is to describe the characteristics of the new antigens discovered and their association with other diseases.

EndoN treatment allows neuroblasts to leave the rostral migratory stream and migrate towards a lesion within the prefrontal cortex of rats

The binding properties of neural cell adhesion molecule are modulated by a polysialic acid moiety. This plays an important role in the migration of adult born neuroblasts from their area of origin, the subventricular zone, towards the olfactory bulb. Polysialisation increases the migration speed of the cells and helps to prevent the neuroblasts from leaving their migration route, the rostral migratory stream. Here, we evaluated the potential of intraventricular application of endoneuraminidase-N, an enzyme that specifically cleaves polysialic acid from neural cell adhesion molecule, in a rat model for structural prefrontal cortex damage. As expected, endoneuraminidase-N caused the rostral migratory stream to become wider, with a less uniform cellular orientation. Furthermore, endoneuraminidase-N treatment caused the neuroblasts to leave the rostral migratory stream and migrate towards the lesioned tissue. Despite the neuroblasts not being differentiated into neurons after a survival time of three weeks, this technique provides a solid animal model for future work on the migration and differentiation of relocated neuroblasts and might provide a basis for a future endogenous stem cell-based therapy for structural brain damage. The experiments were approved by the local animal care committee(522-27-11/02-00, 115;Senatorin für Wissenschaft, Gesundheit und Verbraucherschutz, Bremen, Germany) on February 10, 2016.

Structure,function,and pathology of Neurexin-3

Neurexin-3 is primarily localized in the presynaptic membrane and forms complexes with various ligands located in the postsynaptic membrane.Neurexin-3 has important roles in synapse development and synapse functions.Neurexin-3 mediates excitatory presynaptic differentiation by interacting with leucine-rich-repeat transmembrane neuronal proteins.Meanwhile,neurexin-3 modulates the expression of presynapticα-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors andγ-aminobutyric acid A receptors by interacting with neuroligins at excitatory and inhibitory synapses.Numerous studies have documented the potential contribution of neurexin-3 to neurodegenerative and neuropsychiatric disorders,such as Alzheimer's disease,addiction behaviors,and other diseases,which raises hopes that understanding the mechanisms of neurexin-3 may hold the key to developing new strategies for related illnesses.This review comprehensively covers the literature to provide current knowledge of the structure,function,and clinical role of neurexin-3.

Modulation of Neuroimmune Responses on Glia in the Central Nervous System： Implication in Therapeutic Intervention against Neuroinflammation

It has long been known that the brain is an immunologically privileged site in normal conditions. Although the cascade of immune responses can occur as long as there is a neuronal injury or a potent immune stimulation, how the brain keeps glial cells in a quiescent state is still unclear. Increasing efforts have been made by several laboratories to elucidate how repression oi~ immune responses is achieved in the neuronal environment. The suppression factors include neurotransmitters, neurohormones, neurotrophic factors, anti-inflammatory factors, and cell-cell contact via adhesion molecules or CD200 receptor. This review discusses how these factors affect the cascade of cerebral immune responses because no single factor listed above can fully account for the immune suppression. While several factors contribute to the suppression of immune responses, activation of glial cells and their production of pro-inflammatory factors do occur as long as there is a neuronal injury, suggesting that some neuronal components facilitate immune responses. This review also discusses which signals initiate or augment cerebral immune responses so that stimulatory signals override the suppressive signals. Increasing lines of evidence have demonstrated that immune responses in the brain are not always detrimental to neurons. Attempt to simply clear off inflammatory factors in the CNS may not be appropriate for neurons in neurological disorders. Appropriate control of immune cells in the CNS may be beneficial to neurons or even neuroregeneration. Therefore, understanding the mechanisms underlying immune suppression may help us to reshape pharmacological interventions against inflammation in many neurological disorders.