Bone marrow mesenchymal stem cells can differentiate into neurons and astrocytes after trans- plantation in the spinal cord of rats with ischemia/reperfusion injury. Although bone marrow mesenchymal stem cells are kno...Bone marrow mesenchymal stem cells can differentiate into neurons and astrocytes after trans- plantation in the spinal cord of rats with ischemia/reperfusion injury. Although bone marrow mesenchymal stem cells are known to protect against spinal cord ischemia/reperfusion injury through anti-apoptotic effects, the precise mechanisms remain unclear. In the present study, bone marrow mesenchymal stem cells were cultured and proliferated, then transplanted into rats with ischemia/reperfusion injury via retro-orbital injection. Immunohistochemistry and immunofluorescence with subsequent quantification revealed that the expression of the axonal regeneration marker, growth associated protein-43, and the neuronal marker, microtubule-as- sociated protein 2, significantly increased in rats with bone marrow mesenchymal stem cell transplantation compared with those in rats with spinal cord ischemia/reperfusion injury. Fur- thermore, the expression of the autophagy marker, microtubule-associated protein light chain 3B, and Beclin 1, was significantly reduced in rats with the bone marrow mesenchymal stem cell transplantation compared with those in rats with spinal cord ischemia/reperfusion injury. Western blot analysis showed that the expression of growth associated protein-43 and neuro- filament-H increased but light chain 3B and Beclin 1 decreased in rats with the bone marrow mesenchymal stem cell transplantation. Our results therefore suggest that bone marrow mes- enchymal stem cell transplantation promotes neurite growth and regeneration and prevents autophagy. These responses may likely be mechanisms underlying the protective effect of bone marrow mesenchymal stem cells against spinal cord ischemia/reperfusion injury.展开更多
Neuronal injuries such as stroke,traumatic brain injury,and spinal cord injury are leading causes of major disability and death.Chronic therapy for these neuronal injuries requires the promotion of axonal regeneration...Neuronal injuries such as stroke,traumatic brain injury,and spinal cord injury are leading causes of major disability and death.Chronic therapy for these neuronal injuries requires the promotion of axonal regeneration from the remaining neurons（Schwab and Strittmatter,2014）.展开更多
Glia-derived axonal growth inhibitory proteins limit functional repair following damage to the adult cen- tral nervous system （CNS）. Nogo proteins, myelin-as- sociated glycoprotein （MAG）, oligodendrocyte myelin gl...Glia-derived axonal growth inhibitory proteins limit functional repair following damage to the adult cen- tral nervous system （CNS）. Nogo proteins, myelin-as- sociated glycoprotein （MAG）, oligodendrocyte myelin glycoprotein （OMgp） and B lymphocyte stimulator （BLyS）, are 4 inhibitors that commonly interact with the neuronal receptor, Nogo receptor-1 （NgR1）, lead- ing to inhibition of axonal growth. Here, we demon- strate that lateral olfactory tract usher substance （LOTUS） binds to NgR1 and blocks the binding of all four ligands to NgR1, resulting in the suppression of axonal growth inhibition induced by these NgR1 li- gands. LOTUS allows neurons to overcome NgRl-me- diated axonal growth inhibition, raising the possibility that LOTUS may be useful in future therapeutic ap- proaches as an endogenous potent inhibitor of NgR1 for promoting neuronal regeneration.展开更多
Damage to the adult mammalian central nervous system （CNS） often results in persistent neurological deficits with limited recovery of functions. The past decade has seen in- creasing research efforts in neural regen...Damage to the adult mammalian central nervous system （CNS） often results in persistent neurological deficits with limited recovery of functions. The past decade has seen in- creasing research efforts in neural regeneration research with the ultimate goal of achieving functional recovery. Many studies have focused on prevention of further neural damage and restoration of functional connections that are com- promised after iniurY or pathological damage.展开更多
It is well established that guidance of axons during neuronal development is regulated by a variety of extracellular signals,governing cytoskeletal dynamics in growth cones.The actin and microtubule（MT）cytoskeleton ...It is well established that guidance of axons during neuronal development is regulated by a variety of extracellular signals,governing cytoskeletal dynamics in growth cones.The actin and microtubule（MT）cytoskeleton have both been shown to play important roles.However,a growing body of work suggests that a critical issue is the proper coordination of changes within these two major cytoskeletal systems（reviewed in Cammara-ta et al., 2016）.展开更多
Neuronal growth, extension, branching, and formation of neural networks are markedly influenced by the extracellular matrix—a complex network composed of proteins and carbohydrates secreted by cells. In addition to p...Neuronal growth, extension, branching, and formation of neural networks are markedly influenced by the extracellular matrix—a complex network composed of proteins and carbohydrates secreted by cells. In addition to providing physical support for cells, the extracellular matrix also conveys critical mechanical stiffness cues. During the development of the nervous system, extracellular matrix stiffness plays a central role in guiding neuronal growth, particularly in the context of axonal extension, which is crucial for the formation of neural networks. In neural tissue engineering, manipulation of biomaterial stiffness is a promising strategy to provide a permissive environment for the repair and regeneration of injured nervous tissue. Recent research has fine-tuned synthetic biomaterials to fabricate scaffolds that closely replicate the stiffness profiles observed in the nervous system. In this review, we highlight the molecular mechanisms by which extracellular matrix stiffness regulates axonal growth and regeneration. We highlight the progress made in the development of stiffness-tunable biomaterials to emulate in vivo extracellular matrix environments, with an emphasis on their application in neural repair and regeneration, along with a discussion of the current limitations and future prospects. The exploration and optimization of the stiffness-tunable biomaterials has the potential to markedly advance the development of neural tissue engineering.展开更多
The canonical Wnt/β-catenin pathway is a highly conserved signaling cascade that plays critical roles during embryogenesis. Wnt ligands regulate axonal extension, growth cone guidance and synaptogenesis throughout th...The canonical Wnt/β-catenin pathway is a highly conserved signaling cascade that plays critical roles during embryogenesis. Wnt ligands regulate axonal extension, growth cone guidance and synaptogenesis throughout the developing central nervous system （CNS）. Recently, studies in mammalian and fish model systems have demonstrated that Wnt/β-catenin signaling also promotes axonal regeneration in the adult optic nerve and spinal cord after injury, raising the possibility that Wnt could be developed as a therapeutic strategy. In this review, we summarize experimental evidence that reveals novel roles for Wnt signaling in the injured CNS, and discuss possible mechanisms by which Wnt ligands could overcome molecular barriers inhibiting axonal growth to promote regeneration. A central challenge in the neuroscience field is developing therapeutic strategies that induce robust axonal regeneration. Although adult axons have the capacity to respond to axonal guidance molecules after injury, there are several major obstacles for axonal growth, including extensive neuronal death, glial scars at the injury site, and lack of axonal guidance signals. Research in rodents demonstrated that activation of Wnt/β-catenin signaling in retinal neurons and radial glia induced neuronal survival and axonal growth, but that activation within reactive glia at the injury site promoted proliferation and glial scar formation. Studies in zebrafish spinal cord injury models confirm an axonal regenerative role for Wnt/β-catenin signaling and identified the cell types responsible. Additionally, in vitro and in vivo studies demonstrated that Wnt induces axonal and neurite growth through transcription-dependent effects of its central mediator β-catenin, potentially by inducing regeneration-promoting genes. Canonical Wnt signaling may also function through transcription-independent interactions of β-catenin with cytoskeletal elements, which could stabilize growing axons and control growth cone movement. Therefore, these studies suggest that Wnt-induced pathways responsible for regulating axonal growth during embryogenesis could be repurposed to promote axonal growth after injury.展开更多
A mathematical model has been formulated in accordance with cell chemotaxis and relevant experimental data. A three-dimensional lattice Boltzmann method was used for numerical simulation. The present study observed th...A mathematical model has been formulated in accordance with cell chemotaxis and relevant experimental data. A three-dimensional lattice Boltzmann method was used for numerical simulation. The present study observed the effects of glial scar size and inhibitor concentration on regenerative axonal growth following spinal cord transection. The simulation test comprised two parts： （1） when release rates of growth inhibitor and promoter were constant, the effects of glial scar size on axonal growth rate were analyzed, and concentrations of inhibitor and promoters located at the moving growth cones were recorded. （2） When the glial scar size was constant, the effects of inhibitor and promoter release rates on axonal growth rate were analyzed, and inhibitor and promoter concentrations at the moving growth cones were recorded. Results demonstrated that （1） a larger glial scar and a higher release rate of inhibitor resulted in a reduced axonal growth rate. （2） The axonal growth rate depended on the ratio of inhibitor to promoter concentrations at the growth cones. When the average ratio was 〈 1.5, regenerating axons were able to grow and successfully contact target cells.展开更多
Non-nerve cell-derived extracellular matrix(ECM)wa s coated on the aligned porous polypyrrole-poly(Llactide)(PPy-PLLA)fiber-films with the conductivity of^12 mS/m via L929 cells culture and lysing,resulting in^10%incr...Non-nerve cell-derived extracellular matrix(ECM)wa s coated on the aligned porous polypyrrole-poly(Llactide)(PPy-PLLA)fiber-films with the conductivity of^12 mS/m via L929 cells culture and lysing,resulting in^10%increase of PC12 cells attachment and^26μm increase of neurites length.The neurite length of^149μm in EGF/NGF group(optimal concentration radio of 12.5/50(ng/mL))on aligned and ECM-conjugated fiber-films was significantly larger than^94μm in only NGF group(50 ng/mL),confirming the synergy of EGF,NGF and aligned ECM-conjuaged PPy-PLLA fibers.When differentiated PC12 cells were exerted electrical stimulation(ES)of 100 mV/cm for 4 h/day in 2 day through ECM-PPyPLLA fiber-films,their neurite length reached to^251μm,significantly larger than^149μm of group without ES,due to the higer expression of related neural proteins in ES group.A simple mechanism was proposed to analyze synergistical effect of ECM,EGF,NGF on axons adhesion and elongation along the aligned ECM-coated fibers under ES condition.展开更多
A typical neuron is comprised of an information input compartment, or the dendrites, and an output compartment, known as the axon. These two compartments are the structural basis for functional neural circuits, Howeve...A typical neuron is comprised of an information input compartment, or the dendrites, and an output compartment, known as the axon. These two compartments are the structural basis for functional neural circuits, However, little is known about how dendritic and axonal growth are differentially regulated. Recent studies have uncovered two distinct types of regulatory mechanisms that differentiate dendritic and axonal growth： dedicated mechanisms and bimodal mechanisms. Dedicated mechanisms regulate either dendrite- specific or axon-specific growth; in contrast, bimodal mechanisms direct dendritic and axonal development in opposite manners. Here, we review the dedicated and bimodal regulators identified by recent Drosophila and mammalian studies. The knowledge of these underlying molecular mechanisms not only expands our understanding about how neural circuits are wired, but also provides insights that will aid in the rational design of therapies for neurological diseases.展开更多
Spinal cord injury results in permanent loss of neurological functions due to severance of neural networks.Transplantation of neural stem cells holds promise to repair disrupted connections.Yet,ensuring the survival a...Spinal cord injury results in permanent loss of neurological functions due to severance of neural networks.Transplantation of neural stem cells holds promise to repair disrupted connections.Yet,ensuring the survival and integration of neural stem cells into the host neural circuit remains a formidable challenge.Here,we investigated whether modifying the intrinsic properties of neural stem cells could enhance their integration post-transplantation.We focused on phosphatase and tensin homolog(PTEN),a well-characterized tumor suppressor known to critically regulate neuronal survival and axonal regeneration.By deleting Pten in mouse neural stem cells,we observed increased neurite outgrowth and enhanced resistance to neurotoxic environments in culture.Upon transplantation into injured spinal cords,Pten-deficient neural stem cells exhibited higher survival and more extensive rostrocaudal distribution.To examine the potential influence of partial PTEN suppression,rat neural stem cells were treated with short hairpin RNA targeting PTEN,and the PTEN knockdown resulted in significant improvements in neurite growth,survival,and neurosphere motility in vitro.Transplantation of sh PTEN-treated neural stem cells into the injured spinal cord also led to an increase in graft survival and migration to an extent similar to that of complete deletion.Moreover,PTEN suppression facilitated neurite elongation from NSC-derived neurons migrating from the lesion epicenter.These findings suggest that modifying intrinsic signaling pathways,such as PTEN,within neural stem cells could bolster their therapeutic efficacy,offering potential avenues for future regenerative strategies for spinal cord injury.展开更多
The regenerative capacity of peripheral nerves is limited after nerve injury.A number of growth factors modulate many cellular behaviors,such as proliferation and migration,and may contribute to nerve repair and regen...The regenerative capacity of peripheral nerves is limited after nerve injury.A number of growth factors modulate many cellular behaviors,such as proliferation and migration,and may contribute to nerve repair and regeneration.Our previous study observed the dynamic changes of genes in L4–6 dorsal root ganglion after rat sciatic nerve crush using transcriptome sequencing.Our current study focused on upstream growth factors and found that a total of 19 upstream growth factors were dysregulated in dorsal root ganglions at 3,9 hours,1,4,or 7 days after nerve crush,compared with the 0 hour control.Thirty-six rat models of sciatic nerve crush injury were prepared as described previously.Then,they were divided into six groups to measure the expression changes of representative genes at 0,3,9 hours,1,4 or 7 days post crush.Our current study measured the expression levels of representative upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin genes,and explored critical signaling pathways and biological process through bioinformatic analysis.Our data revealed that many of these dysregulated upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin,participated in tissue remodeling and axon growth-related biological processes Therefore,the experiment described the expression pattern of upstream growth factors in the dorsal root ganglia after peripheral nerve injury.Bioinformatic analysis revealed growth factors that may promote repair and regeneration of damaged peripheral nerves.All animal surgery procedures were performed in accordance with Institutional Animal Care Guidelines of Nantong University and ethically approved by the Administration Committee of Experimental Animals,China(approval No.20170302-017)on March 2,2017.展开更多
The gold standard for treating peripheral nerve injuries that have large nerve gaps where the nerves cannot be directly sutured back together because it creates tension on the nerve,is to incorporate an autologous ner...The gold standard for treating peripheral nerve injuries that have large nerve gaps where the nerves cannot be directly sutured back together because it creates tension on the nerve,is to incorporate an autologous nerve graft.However,even with the incorporation of a nerve graft,generally patients only regain a small portion of function in limbs affected by the injury.Although,there has been some promising results using growth factors to induce more axon growth through the nerve graft,many of these previous therapies are limited in their ability to release growth factors in a sustained manner and tailor them to a desired time frame.The ideal drug delivery platform would deliver growth factors at therapeutic levels for enough time to grow axons the entire length of the nerve graft.We hypothesized that mineral coated microparticles(MCMs)would bind,stabilize and release biologically active glial cell-derived neurotrophic factor(GDNF)and nerve growth factor(NGF)in a sustained manner.Therefore,the objective of this study was to test the ability of MCMs releasing growth factors at the distal end of a 10 mm sciatic nerve graft,to induce axon growth through the nerve graft and restore hind limb function.After sciatic nerve grafting in Lewis rats,the hind limb function was tested weekly by measuring the angle of the ankle at toe lift-off while walking down a track.Twelve weeks after grafting,the grafts were harvested and myelinated axons were analyzed proximal to the graft,in the center of the graft,and distal to the graft.Under physiological conditions in vitro,the MCMs delivered a burst release of NGF and GDNF for 3 days followed by a sustained release for at least 22 days.In vivo,MCMs releasing NGF and GDNF at the distal end of sciatic nerve grafts resulted in significantly more myelinated axons extending distal to the graft when compared to rats that received nerve grafts without growth factor treatment.The rats with nerve grafts incorporated with MCMs releasing NGF and GDNF also showed significant improvement in hind limb function starting at 7 weeks postoperatively and continuing through 12 weeks postoperatively when compared to rats that received nerve grafts without growth factor treatment.In conclusion,MCMs released biologically active NGF and GDNF in a sustained manner,which significantly enhanced axon growth resulting in a significant improvement of hind limb function in rats.The animal experiments were approved by University of Wisconsin-Madison Animal Care and Use Committee(ACUC,protocol#M5958)on January 3,2018.展开更多
After injury of the central and peripheral nervous systems,functional recovery is impaired by axon regeneration failure.Various approaches for promoting axon growth have been attempted but their low efficacy has preve...After injury of the central and peripheral nervous systems,functional recovery is impaired by axon regeneration failure.Various approaches for promoting axon growth have been attempted but their low efficacy has prevented them from being clinically applicable.展开更多
Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challengin...Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challenging issues in spinal cord injury. As spinal cord injury progresses to the chronic phase, lost motor and sensory functions are not recovered. Several reasons may be attributed to the failure of recovery from chronic spinal cord injury. These include factors that inhibit axonal growth such as activated astrocytes, chondroitin sulfate proteoglycan, myelin-associated proteins, inflammatory microglia, and fibroblasts that accumulate at lesion sites. Skeletal muscle atrophy due to denervation is another chronic and detrimental spinal cord injury–specific condition. Although several intervention strategies based on multiple outlooks have been attempted for treating spinal cord injury, few approaches have been successful. To treat chronic spinal cord injury, neural cells or tissue substitutes may need to be supplied in the cavity area to enable possible axonal growth. Additionally, stimulating axonal growth activity by extrinsic factors is extremely important and essential for maintaining the remaining host neurons and transplanted neurons. This review focuses on pharmacotherapeutic approaches using small compounds and proteins to enable axonal growth in chronic spinal cord injury. This review presents some of these candidates that have shown promising outcomes in basic research(in vivo animal studies) and clinical trials: AA-NgR(310)ecto-Fc(AXER-204), fasudil, phosphatase and tensin homolog protein antagonist peptide 4, chondroitinase ABC, intracellular sigma peptide,(-)-epigallocatechin gallate, matrine, acteoside, pyrvate kinase M2, diosgenin, granulocyte-colony stimulating factor, and fampridine-sustained release. Although the current situation suggests that drug-based therapies to recover function in chronic spinal cord injury are limited, potential candidates have been identified through basic research, and these candidates may be subjects of clinical studies in the future. Moreover, cocktail therapy comprising drugs with varied underlying mechanisms may be effective in treating the refractory status of chronic spinal cord injury.展开更多
The greatest challenge to successful treatment of spinal cord injury is the limited regenerative capacity of the central nervous system and its inability to replace lost neurons and severed axons following injury. Neu...The greatest challenge to successful treatment of spinal cord injury is the limited regenerative capacity of the central nervous system and its inability to replace lost neurons and severed axons following injury. Neural stem cell grafts derived from fetal central nervous system tissue or embryonic stem cells have shown therapeutic promise by differentiation into neurons and glia that have the potential to form functional neuronal relays across injured spinal cord segments. However, implementation of fetal-derived or embryonic stem cell-derived neural stem cell ther- apies for patients with spinal cord injury raises ethical concerns. Induced pluripotent stem cells can be generated from adult somatic cells and differentiated into neural stem cells suitable for therapeutic use, thereby providing an ethical source of implantable cells that can be made in an autologous fashion to avoid problems of immune rejection. This review discusses the therapeutic potential of human induced pluripotent stem cell-derived neural stem cell transplantation for treatment of spinal cord injury, as well as addressing potential mechanisms, future perspectives and challenges.展开更多
Neurons in the mammalian central nervous system （CNS） cannot regenerate axons after injury. In contrast, neurons in the mammalian peripheral nervous system and in some non-mammalian models, such as C. elegans and Dr...Neurons in the mammalian central nervous system （CNS） cannot regenerate axons after injury. In contrast, neurons in the mammalian peripheral nervous system and in some non-mammalian models, such as C. elegans and Drosophila, are able to regrow axons. Understanding the molecular mechanisms by which these neurons support axon regeneration will help us find ways to enhance mammalian CNS axon regeneration. Here, recent studies in which signaling pathways regulating naturally-occurring axon regeneration that have been identified are reviewed, focusing on how these pathways control gene expression and growth-cone function during axon regeneration.展开更多
A combined approach in spinal cord injury （SCI） therapy is the modulation of the cellular and molecular processes involved in glial scarring. Aldaynoglial cells are neural cell precursors with a high capacity to dif...A combined approach in spinal cord injury （SCI） therapy is the modulation of the cellular and molecular processes involved in glial scarring. Aldaynoglial cells are neural cell precursors with a high capacity to differentiate into neurons, promote axonal growth, wrapping and myelination of resident neurons. These important characteristics of aldaynoglia can be combined with specific inhibition of the RhoGTPase activity in astroglia and microglia that cause reduction of glial proliferation, retraction of glial cell processes and myelin production by oligodendrocytes. Previously we used experimental central nervous system （CNS） injury models, like spinal cord contusion and striatal lacunar infarction and observed that administration of RhoGTPase glycolipid inhibitor or aldaynoglial cells, respectively, produced a significant gain of functional recovery in treated animals. The combined therapy with neuro-regenerative properties strategy is highly desirable to treat SCI for functional potentiation of neurons and oligodendrocytes, resulting in better locomotor recovery. Here we suggest that treatment of spinal lesions with aldaynoglia from new rospheres plus local administration of a RhoGTPase inhibitor could have an additive effect and promote recovery from SCI.展开更多
Overexpression of neurotrophic factors in nigral dopamine neurons is a promising approach to reverse neurodegeneration of the nigrostriatal dopamine system,a hallmark in Parkinson's disease.The human cerebral dopa...Overexpression of neurotrophic factors in nigral dopamine neurons is a promising approach to reverse neurodegeneration of the nigrostriatal dopamine system,a hallmark in Parkinson's disease.The human cerebral dopamine neurotrophic factor(h CDNF)has recently emerged as a strong candidate for Parkinson's disease therapy.This study shows that h CDNF expression in dopamine neurons using the neurotensinpolyplex nanoparticle system reverses 6-hydroxydopamine-induced morphological,biochemical,and behavioral alterations.Three independent electron microscopy techniques showed that the neurotensin-polyplex nanoparticles containing the h CDNF gene,ranging in size from 20 to 150 nm,enabled the expression of a secretable h CDNF in vitro.Their injection in the substantia nigra compacta on day 21 after the 6-hydroxydopamine lesion resulted in detectable h CDNF in dopamine neurons,whose levels remained constant throughout the study in the substantia nigra compacta and striatum.Compared with the lesioned group,tyrosine hydroxylase-positive(TH^(+))nigral cell population and TH+fiber density rose in the substantia nigra compacta and striatum after h CDNF transfection.An increase inβIII-tubulin and growth-associated protein 43 phospho-S41(GAP43 p)followed TH^(+)cell recovery,as well as dopamine and its catabolite levels.Partial reversal(80%)of drugactivated circling behavior and full recovery of spontaneous motor and non-motor behavior were achieved.Brain-derived neurotrophic factor recovery in dopamine neurons that also occurred suggests its participation in the neurotrophic effects.These findings support the potential of nanoparticle-mediated h CDNF gene delivery to develop a disease-modifying treatment against Parkinson's disease.The Institutional Animal Care and Use Committee of Centro de Investigación y de Estudios Avanzados approved our experimental procedures for animal use(authorization No.162-15)on June 9,2019.展开更多
The mechanism involved in neural regeneration after spinal cord injury is unclear. The my-elin-derived protein Nogo-A, which is speciifc to the central nervous system, has been identiifed to negatively affect the cyto...The mechanism involved in neural regeneration after spinal cord injury is unclear. The my-elin-derived protein Nogo-A, which is speciifc to the central nervous system, has been identiifed to negatively affect the cytoskeleton and growth program of axotomized neurons. Studies have shown that Nogo-A exerts immediate and chronic inhibitory effects on neurite outgrowth.In vivo, inhibitors of Nogo-A have been shown to lead to a marked enhancement of regenerative axon extension. We established a spinal cord injury model in rats using a free-falling weight drop device to subsequently investigate Nogo-A expression. Nogo-A mRNA and protein expression and immunoreactivity were detected in spinal cord tissue using real-time quantitative PCR, immu-nohistochemistry and western blot analysis. At 24 hours after spinal cord injury, Nogo-A protein and mRNA expression was low in the injured group compared with control and sham-operated groups. The levels then continued to drop further and were at their lowest at 3 days, rapidly rose to a peak after 7 days, and then gradually declined again after 14 days. These changes were observed at both the mRNA and protein level. The transient decrease observed early after injury followed by high levels for a few days indicates Nogo-A expression is time dependent. This may contribute to the lack of regeneration in the central nervous system after spinal cord injury. The dynamic varia-tion of Nogo-A should be taken into account in the treatment of spinal cord injury.展开更多
基金supported by the National Natural Science Foundation of China,No.30972153the Science and Technology Development Program of Jilin Provincial Science and Technology Department in China,No.200905183the Scientific Research Foundation of Jilin Department of Health of China,No.2008Z041
文摘Bone marrow mesenchymal stem cells can differentiate into neurons and astrocytes after trans- plantation in the spinal cord of rats with ischemia/reperfusion injury. Although bone marrow mesenchymal stem cells are known to protect against spinal cord ischemia/reperfusion injury through anti-apoptotic effects, the precise mechanisms remain unclear. In the present study, bone marrow mesenchymal stem cells were cultured and proliferated, then transplanted into rats with ischemia/reperfusion injury via retro-orbital injection. Immunohistochemistry and immunofluorescence with subsequent quantification revealed that the expression of the axonal regeneration marker, growth associated protein-43, and the neuronal marker, microtubule-as- sociated protein 2, significantly increased in rats with bone marrow mesenchymal stem cell transplantation compared with those in rats with spinal cord ischemia/reperfusion injury. Fur- thermore, the expression of the autophagy marker, microtubule-associated protein light chain 3B, and Beclin 1, was significantly reduced in rats with the bone marrow mesenchymal stem cell transplantation compared with those in rats with spinal cord ischemia/reperfusion injury. Western blot analysis showed that the expression of growth associated protein-43 and neuro- filament-H increased but light chain 3B and Beclin 1 decreased in rats with the bone marrow mesenchymal stem cell transplantation. Our results therefore suggest that bone marrow mes- enchymal stem cell transplantation promotes neurite growth and regeneration and prevents autophagy. These responses may likely be mechanisms underlying the protective effect of bone marrow mesenchymal stem cells against spinal cord ischemia/reperfusion injury.
文摘Neuronal injuries such as stroke,traumatic brain injury,and spinal cord injury are leading causes of major disability and death.Chronic therapy for these neuronal injuries requires the promotion of axonal regeneration from the remaining neurons（Schwab and Strittmatter,2014）.
基金supported by a grant-in-aid from the Ministry of Education,Culture,Sports,Science and Technology of Japangrants for Research and Development project of Yokohama City University
文摘Glia-derived axonal growth inhibitory proteins limit functional repair following damage to the adult cen- tral nervous system （CNS）. Nogo proteins, myelin-as- sociated glycoprotein （MAG）, oligodendrocyte myelin glycoprotein （OMgp） and B lymphocyte stimulator （BLyS）, are 4 inhibitors that commonly interact with the neuronal receptor, Nogo receptor-1 （NgR1）, lead- ing to inhibition of axonal growth. Here, we demon- strate that lateral olfactory tract usher substance （LOTUS） binds to NgR1 and blocks the binding of all four ligands to NgR1, resulting in the suppression of axonal growth inhibition induced by these NgR1 li- gands. LOTUS allows neurons to overcome NgRl-me- diated axonal growth inhibition, raising the possibility that LOTUS may be useful in future therapeutic ap- proaches as an endogenous potent inhibitor of NgR1 for promoting neuronal regeneration.
基金supported by grants from NIH National Institute of Mental Health MH085267National Institute of Neurological Disorders and Stroke NS060017
文摘Damage to the adult mammalian central nervous system （CNS） often results in persistent neurological deficits with limited recovery of functions. The past decade has seen in- creasing research efforts in neural regeneration research with the ultimate goal of achieving functional recovery. Many studies have focused on prevention of further neural damage and restoration of functional connections that are com- promised after iniurY or pathological damage.
基金supported by the Hungarian Science Foundation(OTKA)(K109330 to JM)the Hungarian Brain Research Program(KTIA_NAP_13-2-2014-0007 to JM)+1 种基金the National Research,Development and Innovation Office(GINOP-2.3.2-15-2016-00001 and GINOP-2.3.2-15-2016-00032 to JM)by an MTA Postdoctoral Fellowship(to IF)
文摘It is well established that guidance of axons during neuronal development is regulated by a variety of extracellular signals,governing cytoskeletal dynamics in growth cones.The actin and microtubule（MT）cytoskeleton have both been shown to play important roles.However,a growing body of work suggests that a critical issue is the proper coordination of changes within these two major cytoskeletal systems（reviewed in Cammara-ta et al., 2016）.
基金supported by the Natio`nal Natural Science Foundation of China,No. 81801241a grant from Sichuan Science and Technology Program,No. 2023NSFSC1578Scientific Research Projects of Southwest Medical University,No. 2022ZD002 (all to JX)。
文摘Neuronal growth, extension, branching, and formation of neural networks are markedly influenced by the extracellular matrix—a complex network composed of proteins and carbohydrates secreted by cells. In addition to providing physical support for cells, the extracellular matrix also conveys critical mechanical stiffness cues. During the development of the nervous system, extracellular matrix stiffness plays a central role in guiding neuronal growth, particularly in the context of axonal extension, which is crucial for the formation of neural networks. In neural tissue engineering, manipulation of biomaterial stiffness is a promising strategy to provide a permissive environment for the repair and regeneration of injured nervous tissue. Recent research has fine-tuned synthetic biomaterials to fabricate scaffolds that closely replicate the stiffness profiles observed in the nervous system. In this review, we highlight the molecular mechanisms by which extracellular matrix stiffness regulates axonal growth and regeneration. We highlight the progress made in the development of stiffness-tunable biomaterials to emulate in vivo extracellular matrix environments, with an emphasis on their application in neural repair and regeneration, along with a discussion of the current limitations and future prospects. The exploration and optimization of the stiffness-tunable biomaterials has the potential to markedly advance the development of neural tissue engineering.
基金provided by the NEI grant R01EY026546AU is a recipient of a Research to Prevent Blindness Medical Student Eye Research Fellowship+2 种基金Financial support from Fight for Sight(summer student fellowship to AU)is gratefully acknowledgedInstitutional support is from an NIH Center Core Grant P30EY014801a Research to Prevent Blindness Unrestricted Grant
文摘The canonical Wnt/β-catenin pathway is a highly conserved signaling cascade that plays critical roles during embryogenesis. Wnt ligands regulate axonal extension, growth cone guidance and synaptogenesis throughout the developing central nervous system （CNS）. Recently, studies in mammalian and fish model systems have demonstrated that Wnt/β-catenin signaling also promotes axonal regeneration in the adult optic nerve and spinal cord after injury, raising the possibility that Wnt could be developed as a therapeutic strategy. In this review, we summarize experimental evidence that reveals novel roles for Wnt signaling in the injured CNS, and discuss possible mechanisms by which Wnt ligands could overcome molecular barriers inhibiting axonal growth to promote regeneration. A central challenge in the neuroscience field is developing therapeutic strategies that induce robust axonal regeneration. Although adult axons have the capacity to respond to axonal guidance molecules after injury, there are several major obstacles for axonal growth, including extensive neuronal death, glial scars at the injury site, and lack of axonal guidance signals. Research in rodents demonstrated that activation of Wnt/β-catenin signaling in retinal neurons and radial glia induced neuronal survival and axonal growth, but that activation within reactive glia at the injury site promoted proliferation and glial scar formation. Studies in zebrafish spinal cord injury models confirm an axonal regenerative role for Wnt/β-catenin signaling and identified the cell types responsible. Additionally, in vitro and in vivo studies demonstrated that Wnt induces axonal and neurite growth through transcription-dependent effects of its central mediator β-catenin, potentially by inducing regeneration-promoting genes. Canonical Wnt signaling may also function through transcription-independent interactions of β-catenin with cytoskeletal elements, which could stabilize growing axons and control growth cone movement. Therefore, these studies suggest that Wnt-induced pathways responsible for regulating axonal growth during embryogenesis could be repurposed to promote axonal growth after injury.
基金supported by the National Natural Science Foundation of China,No. 10572085Shanghai Leading Academic Discipline Projects,No. S30106
文摘A mathematical model has been formulated in accordance with cell chemotaxis and relevant experimental data. A three-dimensional lattice Boltzmann method was used for numerical simulation. The present study observed the effects of glial scar size and inhibitor concentration on regenerative axonal growth following spinal cord transection. The simulation test comprised two parts： （1） when release rates of growth inhibitor and promoter were constant, the effects of glial scar size on axonal growth rate were analyzed, and concentrations of inhibitor and promoters located at the moving growth cones were recorded. （2） When the glial scar size was constant, the effects of inhibitor and promoter release rates on axonal growth rate were analyzed, and inhibitor and promoter concentrations at the moving growth cones were recorded. Results demonstrated that （1） a larger glial scar and a higher release rate of inhibitor resulted in a reduced axonal growth rate. （2） The axonal growth rate depended on the ratio of inhibitor to promoter concentrations at the growth cones. When the average ratio was 〈 1.5, regenerating axons were able to grow and successfully contact target cells.
基金supported by the National Natural Science Foundation of China(No.51273122)Sichuan Science and Technology Project(No.2018JY0535)。
文摘Non-nerve cell-derived extracellular matrix(ECM)wa s coated on the aligned porous polypyrrole-poly(Llactide)(PPy-PLLA)fiber-films with the conductivity of^12 mS/m via L929 cells culture and lysing,resulting in^10%increase of PC12 cells attachment and^26μm increase of neurites length.The neurite length of^149μm in EGF/NGF group(optimal concentration radio of 12.5/50(ng/mL))on aligned and ECM-conjugated fiber-films was significantly larger than^94μm in only NGF group(50 ng/mL),confirming the synergy of EGF,NGF and aligned ECM-conjuaged PPy-PLLA fibers.When differentiated PC12 cells were exerted electrical stimulation(ES)of 100 mV/cm for 4 h/day in 2 day through ECM-PPyPLLA fiber-films,their neurite length reached to^251μm,significantly larger than^149μm of group without ES,due to the higer expression of related neural proteins in ES group.A simple mechanism was proposed to analyze synergistical effect of ECM,EGF,NGF on axons adhesion and elongation along the aligned ECM-coated fibers under ES condition.
基金supported by grants from the NIH (R01MH091186 and R21AA021204) and the Pew Charitable Trusts
文摘A typical neuron is comprised of an information input compartment, or the dendrites, and an output compartment, known as the axon. These two compartments are the structural basis for functional neural circuits, However, little is known about how dendritic and axonal growth are differentially regulated. Recent studies have uncovered two distinct types of regulatory mechanisms that differentiate dendritic and axonal growth： dedicated mechanisms and bimodal mechanisms. Dedicated mechanisms regulate either dendrite- specific or axon-specific growth; in contrast, bimodal mechanisms direct dendritic and axonal development in opposite manners. Here, we review the dedicated and bimodal regulators identified by recent Drosophila and mammalian studies. The knowledge of these underlying molecular mechanisms not only expands our understanding about how neural circuits are wired, but also provides insights that will aid in the rational design of therapies for neurological diseases.
基金supported by the National Research Foundation of Korea,Nos.2021R1A2C2006110,2021M3E5D9021364,2019R1A5A2026045(to BGK)the Korea Initiative for Fostering University of Research and Innovation(KIURI)Program of the NRF funded by the MSIT(to HK),No.NRF2021M3H1A104892211(to HSK)。
文摘Spinal cord injury results in permanent loss of neurological functions due to severance of neural networks.Transplantation of neural stem cells holds promise to repair disrupted connections.Yet,ensuring the survival and integration of neural stem cells into the host neural circuit remains a formidable challenge.Here,we investigated whether modifying the intrinsic properties of neural stem cells could enhance their integration post-transplantation.We focused on phosphatase and tensin homolog(PTEN),a well-characterized tumor suppressor known to critically regulate neuronal survival and axonal regeneration.By deleting Pten in mouse neural stem cells,we observed increased neurite outgrowth and enhanced resistance to neurotoxic environments in culture.Upon transplantation into injured spinal cords,Pten-deficient neural stem cells exhibited higher survival and more extensive rostrocaudal distribution.To examine the potential influence of partial PTEN suppression,rat neural stem cells were treated with short hairpin RNA targeting PTEN,and the PTEN knockdown resulted in significant improvements in neurite growth,survival,and neurosphere motility in vitro.Transplantation of sh PTEN-treated neural stem cells into the injured spinal cord also led to an increase in graft survival and migration to an extent similar to that of complete deletion.Moreover,PTEN suppression facilitated neurite elongation from NSC-derived neurons migrating from the lesion epicenter.These findings suggest that modifying intrinsic signaling pathways,such as PTEN,within neural stem cells could bolster their therapeutic efficacy,offering potential avenues for future regenerative strategies for spinal cord injury.
基金supported by the Natural Science Foundation of Jiangsu Higher Education Institutions of China(Major Program),No.16KJA310005(to SYL)the Natural Science Foundation of Nantong City of China,No.JC2018058(to TMQ)the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘The regenerative capacity of peripheral nerves is limited after nerve injury.A number of growth factors modulate many cellular behaviors,such as proliferation and migration,and may contribute to nerve repair and regeneration.Our previous study observed the dynamic changes of genes in L4–6 dorsal root ganglion after rat sciatic nerve crush using transcriptome sequencing.Our current study focused on upstream growth factors and found that a total of 19 upstream growth factors were dysregulated in dorsal root ganglions at 3,9 hours,1,4,or 7 days after nerve crush,compared with the 0 hour control.Thirty-six rat models of sciatic nerve crush injury were prepared as described previously.Then,they were divided into six groups to measure the expression changes of representative genes at 0,3,9 hours,1,4 or 7 days post crush.Our current study measured the expression levels of representative upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin genes,and explored critical signaling pathways and biological process through bioinformatic analysis.Our data revealed that many of these dysregulated upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin,participated in tissue remodeling and axon growth-related biological processes Therefore,the experiment described the expression pattern of upstream growth factors in the dorsal root ganglia after peripheral nerve injury.Bioinformatic analysis revealed growth factors that may promote repair and regeneration of damaged peripheral nerves.All animal surgery procedures were performed in accordance with Institutional Animal Care Guidelines of Nantong University and ethically approved by the Administration Committee of Experimental Animals,China(approval No.20170302-017)on March 2,2017.
文摘The gold standard for treating peripheral nerve injuries that have large nerve gaps where the nerves cannot be directly sutured back together because it creates tension on the nerve,is to incorporate an autologous nerve graft.However,even with the incorporation of a nerve graft,generally patients only regain a small portion of function in limbs affected by the injury.Although,there has been some promising results using growth factors to induce more axon growth through the nerve graft,many of these previous therapies are limited in their ability to release growth factors in a sustained manner and tailor them to a desired time frame.The ideal drug delivery platform would deliver growth factors at therapeutic levels for enough time to grow axons the entire length of the nerve graft.We hypothesized that mineral coated microparticles(MCMs)would bind,stabilize and release biologically active glial cell-derived neurotrophic factor(GDNF)and nerve growth factor(NGF)in a sustained manner.Therefore,the objective of this study was to test the ability of MCMs releasing growth factors at the distal end of a 10 mm sciatic nerve graft,to induce axon growth through the nerve graft and restore hind limb function.After sciatic nerve grafting in Lewis rats,the hind limb function was tested weekly by measuring the angle of the ankle at toe lift-off while walking down a track.Twelve weeks after grafting,the grafts were harvested and myelinated axons were analyzed proximal to the graft,in the center of the graft,and distal to the graft.Under physiological conditions in vitro,the MCMs delivered a burst release of NGF and GDNF for 3 days followed by a sustained release for at least 22 days.In vivo,MCMs releasing NGF and GDNF at the distal end of sciatic nerve grafts resulted in significantly more myelinated axons extending distal to the graft when compared to rats that received nerve grafts without growth factor treatment.The rats with nerve grafts incorporated with MCMs releasing NGF and GDNF also showed significant improvement in hind limb function starting at 7 weeks postoperatively and continuing through 12 weeks postoperatively when compared to rats that received nerve grafts without growth factor treatment.In conclusion,MCMs released biologically active NGF and GDNF in a sustained manner,which significantly enhanced axon growth resulting in a significant improvement of hind limb function in rats.The animal experiments were approved by University of Wisconsin-Madison Animal Care and Use Committee(ACUC,protocol#M5958)on January 3,2018.
文摘After injury of the central and peripheral nervous systems,functional recovery is impaired by axon regeneration failure.Various approaches for promoting axon growth have been attempted but their low efficacy has prevented them from being clinically applicable.
文摘Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challenging issues in spinal cord injury. As spinal cord injury progresses to the chronic phase, lost motor and sensory functions are not recovered. Several reasons may be attributed to the failure of recovery from chronic spinal cord injury. These include factors that inhibit axonal growth such as activated astrocytes, chondroitin sulfate proteoglycan, myelin-associated proteins, inflammatory microglia, and fibroblasts that accumulate at lesion sites. Skeletal muscle atrophy due to denervation is another chronic and detrimental spinal cord injury–specific condition. Although several intervention strategies based on multiple outlooks have been attempted for treating spinal cord injury, few approaches have been successful. To treat chronic spinal cord injury, neural cells or tissue substitutes may need to be supplied in the cavity area to enable possible axonal growth. Additionally, stimulating axonal growth activity by extrinsic factors is extremely important and essential for maintaining the remaining host neurons and transplanted neurons. This review focuses on pharmacotherapeutic approaches using small compounds and proteins to enable axonal growth in chronic spinal cord injury. This review presents some of these candidates that have shown promising outcomes in basic research(in vivo animal studies) and clinical trials: AA-NgR(310)ecto-Fc(AXER-204), fasudil, phosphatase and tensin homolog protein antagonist peptide 4, chondroitinase ABC, intracellular sigma peptide,(-)-epigallocatechin gallate, matrine, acteoside, pyrvate kinase M2, diosgenin, granulocyte-colony stimulating factor, and fampridine-sustained release. Although the current situation suggests that drug-based therapies to recover function in chronic spinal cord injury are limited, potential candidates have been identified through basic research, and these candidates may be subjects of clinical studies in the future. Moreover, cocktail therapy comprising drugs with varied underlying mechanisms may be effective in treating the refractory status of chronic spinal cord injury.
基金supported by grants from the Veterans Administration and the California Institute for Regenerative Medicine
文摘The greatest challenge to successful treatment of spinal cord injury is the limited regenerative capacity of the central nervous system and its inability to replace lost neurons and severed axons following injury. Neural stem cell grafts derived from fetal central nervous system tissue or embryonic stem cells have shown therapeutic promise by differentiation into neurons and glia that have the potential to form functional neuronal relays across injured spinal cord segments. However, implementation of fetal-derived or embryonic stem cell-derived neural stem cell ther- apies for patients with spinal cord injury raises ethical concerns. Induced pluripotent stem cells can be generated from adult somatic cells and differentiated into neural stem cells suitable for therapeutic use, thereby providing an ethical source of implantable cells that can be made in an autologous fashion to avoid problems of immune rejection. This review discusses the therapeutic potential of human induced pluripotent stem cell-derived neural stem cell transplantation for treatment of spinal cord injury, as well as addressing potential mechanisms, future perspectives and challenges.
基金supported by grants from the NiH (R01NS064288)The Craig H. Neilsen Foundation
文摘Neurons in the mammalian central nervous system （CNS） cannot regenerate axons after injury. In contrast, neurons in the mammalian peripheral nervous system and in some non-mammalian models, such as C. elegans and Drosophila, are able to regrow axons. Understanding the molecular mechanisms by which these neurons support axon regeneration will help us find ways to enhance mammalian CNS axon regeneration. Here, recent studies in which signaling pathways regulating naturally-occurring axon regeneration that have been identified are reviewed, focusing on how these pathways control gene expression and growth-cone function during axon regeneration.
文摘A combined approach in spinal cord injury （SCI） therapy is the modulation of the cellular and molecular processes involved in glial scarring. Aldaynoglial cells are neural cell precursors with a high capacity to differentiate into neurons, promote axonal growth, wrapping and myelination of resident neurons. These important characteristics of aldaynoglia can be combined with specific inhibition of the RhoGTPase activity in astroglia and microglia that cause reduction of glial proliferation, retraction of glial cell processes and myelin production by oligodendrocytes. Previously we used experimental central nervous system （CNS） injury models, like spinal cord contusion and striatal lacunar infarction and observed that administration of RhoGTPase glycolipid inhibitor or aldaynoglial cells, respectively, produced a significant gain of functional recovery in treated animals. The combined therapy with neuro-regenerative properties strategy is highly desirable to treat SCI for functional potentiation of neurons and oligodendrocytes, resulting in better locomotor recovery. Here we suggest that treatment of spinal lesions with aldaynoglia from new rospheres plus local administration of a RhoGTPase inhibitor could have an additive effect and promote recovery from SCI.
基金supported by the Consejo Nacional de Ciencia Tecnología(Conacyt)de México(Grant#254686,to DMF)。
文摘Overexpression of neurotrophic factors in nigral dopamine neurons is a promising approach to reverse neurodegeneration of the nigrostriatal dopamine system,a hallmark in Parkinson's disease.The human cerebral dopamine neurotrophic factor(h CDNF)has recently emerged as a strong candidate for Parkinson's disease therapy.This study shows that h CDNF expression in dopamine neurons using the neurotensinpolyplex nanoparticle system reverses 6-hydroxydopamine-induced morphological,biochemical,and behavioral alterations.Three independent electron microscopy techniques showed that the neurotensin-polyplex nanoparticles containing the h CDNF gene,ranging in size from 20 to 150 nm,enabled the expression of a secretable h CDNF in vitro.Their injection in the substantia nigra compacta on day 21 after the 6-hydroxydopamine lesion resulted in detectable h CDNF in dopamine neurons,whose levels remained constant throughout the study in the substantia nigra compacta and striatum.Compared with the lesioned group,tyrosine hydroxylase-positive(TH^(+))nigral cell population and TH+fiber density rose in the substantia nigra compacta and striatum after h CDNF transfection.An increase inβIII-tubulin and growth-associated protein 43 phospho-S41(GAP43 p)followed TH^(+)cell recovery,as well as dopamine and its catabolite levels.Partial reversal(80%)of drugactivated circling behavior and full recovery of spontaneous motor and non-motor behavior were achieved.Brain-derived neurotrophic factor recovery in dopamine neurons that also occurred suggests its participation in the neurotrophic effects.These findings support the potential of nanoparticle-mediated h CDNF gene delivery to develop a disease-modifying treatment against Parkinson's disease.The Institutional Animal Care and Use Committee of Centro de Investigación y de Estudios Avanzados approved our experimental procedures for animal use(authorization No.162-15)on June 9,2019.
基金financially supported by a grant from the Natural Science Foundation of Jiangsu Province,No.BK2011180Ordinary University Graduate Student Scientific Research Innovation Projects of Jiangsu Province,No.CXZZ13-0614,CXZZ12-0609
文摘The mechanism involved in neural regeneration after spinal cord injury is unclear. The my-elin-derived protein Nogo-A, which is speciifc to the central nervous system, has been identiifed to negatively affect the cytoskeleton and growth program of axotomized neurons. Studies have shown that Nogo-A exerts immediate and chronic inhibitory effects on neurite outgrowth.In vivo, inhibitors of Nogo-A have been shown to lead to a marked enhancement of regenerative axon extension. We established a spinal cord injury model in rats using a free-falling weight drop device to subsequently investigate Nogo-A expression. Nogo-A mRNA and protein expression and immunoreactivity were detected in spinal cord tissue using real-time quantitative PCR, immu-nohistochemistry and western blot analysis. At 24 hours after spinal cord injury, Nogo-A protein and mRNA expression was low in the injured group compared with control and sham-operated groups. The levels then continued to drop further and were at their lowest at 3 days, rapidly rose to a peak after 7 days, and then gradually declined again after 14 days. These changes were observed at both the mRNA and protein level. The transient decrease observed early after injury followed by high levels for a few days indicates Nogo-A expression is time dependent. This may contribute to the lack of regeneration in the central nervous system after spinal cord injury. The dynamic varia-tion of Nogo-A should be taken into account in the treatment of spinal cord injury.
