Runx2 regulates peripheral nerve regeneration to promote Schwann cell migration and re-myelination

Runx2 is a major regulator of osteoblast differentiation and function;however,the role of Runx2 in peripheral nerve repair is unclea r.Here,we analyzed Runx2expression following injury and found that it was specifically up-regulated in Schwann cells.Furthermore,using Schwann cell-specific Runx2 knocko ut mice,we studied peripheral nerve development and regeneration and found that multiple steps in the regeneration process following sciatic nerve injury were Runx2-dependent.Changes observed in Runx2 knoc kout mice include increased prolife ration of Schwann cells,impaired Schwann cell migration and axonal regrowth,reduced re-myelination of axo ns,and a block in macrophage clearance in the late stage of regeneration.Taken together,our findings indicate that Runx2 is a key regulator of Schwann cell plasticity,and therefore peripheral nerve repair.Thus,our study shows that Runx2 plays a major role in Schwann cell migration,re-myelination,and peripheral nerve functional recovery following injury.

RNA sequencing of exosomes secreted by fibroblast and Schwann cells elucidates mechanisms underlying peripheral nerve regeneration

Exosomes exhibit complex biological functions and mediate a variety of biological processes,such as promoting axonal regeneration and functional recove ry after injury.Long non-coding RNAs(IncRNAs)have been reported to play a crucial role in axonal regeneration.Howeve r,the role of the IncRNA-microRNAmessenger RNA(mRNA)-competitive endogenous RNA(ceRNA)network in exosome-mediated axonal regeneration remains unclear.In this study,we performed RNA transcriptome sequencing analysis to assess mRNA expression patterns in exosomes produced by cultured fibroblasts(FC-EXOs)and Schwann cells(SCEXOs).Diffe rential gene expression analysis,Gene Ontology analysis,Kyoto Encyclopedia of Genes and Genomes analysis,and protein-protein intera ction network analysis were used to explo re the functions and related pathways of RNAs isolated from FC-EXOs and SC-EXOs.We found that the ribosome-related central gene Rps5 was enriched in FC-EXOs and SC-EXOs,which suggests that it may promote axonal regeneration.In addition,using the miRWalk and Starbase prediction databases,we constructed a regulatory network of ceRNAs targeting Rps5,including 27 microRNAs and five IncRNAs.The ceRNA regulatory network,which included Ftx and Miat,revealed that exsosome-derived Rps5 inhibits scar formation and promotes axonal regeneration and functional recovery after nerve injury.Our findings suggest that exosomes derived from fibro blast and Schwann cells could be used to treat injuries of peripheral nervous system.

Chemokine platelet factor 4 accelerates peripheral nerve regeneration by regulating Schwann cell activation and axon elongation

Schwann cells in peripheral nerves react to traumatic nerve injury by attempting to grow and regenerate.Howeve r,it is unclear what factors play a role in this process.In this study,we searched a GEO database and found that expression of platelet factor 4 was markedly up-regulated after sciatic nerve injury.Platelet factor is an important molecule in cell apoptosis,diffe rentiation,survival,and proliferation.Further,polymerase chain reaction and immunohistochemical staining confirmed the change in platelet factor 4 in the sciatic nerve at different time points after injury.Enzyme-linked immunosorbent assay confirmed that platelet factor 4 was secreted by Schwann cells.We also found that silencing platelet factor 4 decreased the proliferation and migration of primary cultured Schwann cells,while exogenously applied platelet factor 4 stimulated Schwann cell prolife ration and migration and neuronal axon growth.Furthermore,knocking out platelet factor 4 inhibited the prolife ration of Schwann cells in injured rat sciatic nerve.These findings suggest that Schwann cell-secreted platelet factor 4 may facilitate peripheral nerve repair and regeneration by regulating Schwann cell activation and axon growth.Thus,platelet factor 4 may be a potential therapeutic target for traumatic peripheral nerve injury.

Treating amyotrophic lateral sclerosis with allogeneic Schwann cell-derived exosomal vesicles: a case report

Schwann cells are essential for the maintenance and function of motor neurons,axonal networks,and the neuromuscular junction.In amyotrophic lateral sclerosis,where motor neuron function is progressively lost,Schwann cell function may also be impaired.Recently,important signaling and potential trophic activities of Schwann cell-derived exosomal vesicles have been reported.This case report describes the treatment of a patient with advanced amyotrophic lateral sclerosis using serial intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles,marking,to our knowledge,the first instance of such treatment.An 81-year-old male patient presented with a 1.5-year history of rapidly progressive amyotrophic lateral sclerosis.After initial diagnosis,the patient underwent a combination of generic riluzole,sodium phenylbutyrate for the treatment of amyotrophic lateral sclerosis,and taurursodiol.The patient volunteered to participate in an FDA-approved single-patient expanded access treatment and received weekly intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles to potentially restore impaired Schwann cell and motor neuron function.We confirmed that cultured Schwann cells obtained from the amyotrophic lateral sclerosis patient via sural nerve biopsy appeared impaired(senescent)and that exposure of the patient’s Schwann cells to allogeneic Schwann cell-derived exosomal vesicles,cultured expanded from a cadaver donor improved their growth capacity in vitro.After a period of observation lasting 10 weeks,during which amyotrophic lateral sclerosis Functional Rating Scale-Revised and pulmonary function were regularly monitored,the patient received weekly consecutive infusions of 1.54×1012(×2),and then consecutive infusions of 7.5×1012(×6)allogeneic Schwann cell-derived exosomal vesicles diluted in 40 mL of Dulbecco’s phosphate-buffered saline.None of the infusions were associated with adverse events such as infusion reactions(allergic or otherwise)or changes in vital signs.Clinical lab serum neurofilament and cytokine levels measured prior to each infusion varied somewhat without a clear trend.A more sensitive in-house assay suggested possible inflammasome activation during the disease course.A trend for clinical stabilization was observed during the infusion period.Our study provides a novel approach to address impaired Schwann cells and possibly motor neuron function in patients with amyotrophic lateral sclerosis using allogeneic Schwann cell-derived exosomal vesicles.Initial findings suggest that this approach is safe.

Chondroitinase ABC combined with Schwann cell transplantation enhances restoration of neural connection and functional recovery following acute and chronic spinal cord injury

Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous Schwann cells to treat patients with spinal cord injury.A major challenge for Schwann cell transplantation is that grafted Schwann cells are confined within the lesion cavity,and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar,thus limiting axonal reentry into the host spinal cord.Here we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with injection of lentivirus-mediated transfection of chondroitinase ABC gene at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted Schwann cells in adult rats following a mid-thoracic contusive spinal cord injury.We report that when the glial scar was degraded by chondroitinase ABC at the rostral and caudal lesion borders,Schwann cells migrated for considerable distances in both rostral and caudal directions.Such Schwann cell migration led to enhanced axonal regrowth,including the serotonergic and dopaminergic axons originating from supraspinal regions,and promoted recovery of locomotor and urinary bladder functions.Importantly,the Schwann cell survival and axonal regrowth persisted up to 6 months after the injury,even when treatment was delayed for 3 months to mimic chronic spinal cord injury.These findings collectively show promising evidence for a combinatorial strategy with chondroitinase ABC and Schwann cells in promoting remodeling and recovery of function following spinal cord injury.

Gp78 regulates PMP22 and causes ER stress and autophagy in EV71-VP1-overexpressing mouse Schwann cells

Background:During Enterovirus type 71(EV71)infection,the structural viral protein 1(VP1)activates endoplasmic reticulum(ER)stress associated with peripheral myelin protein 22(PMP22)accumulation and induces autophagy.However,the specific mechanism behind this process remains elusive.Methods:In this research,we used the VP1-overexpressing mouse Schwann cells(SCs)models co-transfected with a PMP22 silencing or Autocrine motility factor receptor(AMFR/gp78)overexpressing vector to explore the regulation of gp78 on PMP22 and its relationship with autophagy and apoptosis.Results:The activity of gp78 could be influenced by EV71-VP1,leading to a decrease in the ubiquitination and degradation of PMP22,resulting in PMP22 accumulation in ER.In VP1-overexpressing mouse SCs,all three ER stress sensors,including pancreatic endoplasmic reticulum kinase(PERK),activating transcription factor 6(ATF6)and inositol-requiring enzyme 1(IRE1)and the related downstream signals(C/EBP-homologous protein(CHOP)and Caspase 12)were activated,as well as the ER-resident chaperone Glucose-regulated protein 78(GRP78).In addition,VP1 upregulated the autophagy marker Microtubule-associated protein 1 light chain 3 beta(LC3B),while PMP22 silencing or gp78 overexpression reversed the phenomenon.Meanwhile,PMP22 silencing or gp78 overexpression increased proliferation of EV71-VP1-transfected mouse SCs.Conclusion:Gp78 could regulate PMP22 accumulation through ubiquitination degradation and cause ER stress and autophagy in EV71-VP1-overexpressing mouse SCs.Therefore,the gp78/PMP22/ER stress axis might emerge as a promising therapeutic target for myelin and neuronal damage induced by EV71 infection.

The circ_0002538/miR-138-5p/plasmolipin axis regulates Schwann cell migration and myelination in diabetic peripheral neuropathy

Circular RNAs(circRNAs)play a vital role in diabetic peripheral neuropathy.However,their expression and function in Schwann cells in individuals with diabetic peripheral neuropathy remain poorly understood.Here,we performed protein profiling and circRNA sequencing of sural nerves in patients with diabetic peripheral neuropathy and controls.Protein profiling revealed 265 differentially expressed proteins in the diabetic peripheral neuropathy group.Gene Ontology indicated that differentially expressed proteins were mainly enriched in myelination and mitochondrial oxidative phosphorylation.A real-time polymerase chain reaction assay performed to validate the circRNA sequencing results yielded 11 differentially expressed circRNAs.circ_0002538 was markedly downregulated in patients with diabetic peripheral neuropathy.Further in vitro experiments showed that overexpression of circ_0002538 promoted the migration of Schwann cells by upregulating plasmolipin(PLLP)expression.Moreover,overexpression of circ_0002538 in the sciatic nerve in a streptozotocin-induced mouse model of diabetic peripheral neuropathy alleviated demyelination and improved sciatic nerve function.The results of a mechanistic experiment showed that circ_0002538 promotes PLLP expression by sponging miR-138-5p,while a lack of circ_0002538 led to a PLLP deficiency that further suppressed Schwann cell migration.These findings suggest that the circ_0002538/miR-138-5p/PLLP axis can promote the migration of Schwann cells in diabetic peripheral neuropathy patients,improving myelin sheath structure and nerve function.Thus,this axis is a potential target for therapeutic treatment of diabetic peripheral neuropathy.

Long noncoding RNA Pvt1 promotes the proliferation and migration of Schwann cells by sponging microRNA-214 and targeting c-Jun following peripheral nerve injury

Research has shown that long-chain noncoding RNAs(lncRNAs) are involved in the regulation of a variety of biological processes, including peripheral nerve regeneration, in part by acting as competing endogenous RNAs. c-Jun plays a key role in the repair of peripheral nerve injury. However, the precise underlying mechanism of c-Jun remains unclear. In this study, we performed microarray and bioinformatics analysis of mouse crush-injured sciatic nerves and found that the lncRNA Pvt1 was overexpressed in Schwann cells after peripheral nerve injury. Mechanistic studies revealed that Pvt1 increased c-Jun expression through sponging miRNA-214. We overexpressed Pvt1 in Schwann cells cultured in vitro and found that the proliferation and migration of Schwann cells were enhanced, and overexpression of miRNA-214 counteracted the effects of Pvt1 overexpression on Schwann cell proliferation and migration. We conducted in vivo analyses and injected Schwann cells overexpressing Pvt1 into injured sciatic nerves of mice. Schwann cells overexpressing Pvt1 enhanced the regeneration of injured sciatic nerves following peripheral nerve injury and the locomotor function of mice was improved. Our findings reveal the role of lncRNAs in the repair of peripheral nerve injury and highlight lncRNA Pvt1 as a novel potential treatment target for peripheral nerve injury.

Artificial nerve graft constructed by coculture of activated Schwann cells and human hair keratin for repair of peripheral nerve defects

Studies have shown that human hair keratin(HHK) has no antigenicity and excellent mechanical properties. Schwann cells, as unique glial cells in the peripheral nervous system, can be induced by interleukin-1β to secrete nerve growth factor, which promotes neural regeneration. Therefore, HHK with Schwann cells may be a more effective approach to repair nerve defects than HHK without Schwann cells. In this study, we established an artificial nerve graft by loading an HHK skeleton with activated Schwann cells. We found that the longitudinal HHK microfilament structure provided adhesion medium, space and direction for Schwann cells, and promoted Schwann cell growth and nerve fiber regeneration. In addition, interleukin-1β not only activates Schwann cells, but also strengthens their activity and increases the expression of nerve growth factors. Activated Schwann cells activate macrophages, and activated macrophages secrete interleukin-1β, which maintains the activity of Schwann cells. Thus, a beneficial cycle forms and promotes nerve repair. Furthermore, our studies have found that the newly constructed artificial nerve graft promotes the improvements in nerve conduction function and motor function in rats with sciatic nerve injury, and increases the expression of nerve injury repair factors fibroblast growth factor 2 and human transforming growth factor B receptor 2. These findings suggest that this artificial nerve graft effectively repairs peripheral nerve injury.

Schwann cell extracellular vesicles:judging a book by its cover

Schwann cells(SCs)are essential in the development of the peripheral nervous system(PNS),in PNS inj ury,and the aging PNS.SCs comprise greater than 90%of the nucleated cells in peripheral nerves(Campana,2007).Myelinating SCs insulate large-diameter axons,forming a 1:1relationship and promoting saltatory conduction of axonal action potentials.Non-myelinating SCs ensheathe clusters of smaller diameter axons in Remak bundles.Both types of SCs provide essential metabolic and trophic support to axons,which is essential for maintaining axon integrity in healthy peripheral nerves.

Glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor regulate the interaction between astrocytes and Schwann cells at the trigeminal root entry zone

The trigeminal root entry zone is the zone at which the myelination switches from peripheral Schwann cells to central oligodendrocytes.Its special anatomical and physiological structure renders it susceptible to nerve injury.The etiology of most primary trigeminal neuralgia is closely related to microvascular compression of the trigeminal root entry zone.This study aimed to develop an efficient in vitro model mimicking the glial environment of trigeminal root entry zone as a tool to investigate the effects of glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor on the structural and functional integrity of trigeminal root entry zone and modulation of cellular interactions.Primary astrocytes and Schwann cells isolated from trigeminal root entry zone of postnatal rats were inoculated into a two-well silicon culture insert to mimic the trigeminal root entry zone microenvironment and treated with glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor.In monoculture,glial cell line-derived neurotrophic factor promoted the migration of Schwann cells,but it did not have effects on the migration of astrocytes.In the co-culture system,glial cell line-derived neurotrophic factor promoted the bidirectional migration of astrocytes and Schwann cells.Brain-derived neurotrophic factor markedly promoted the activation and migration of astrocytes.However,in the co-culture system,brain-derived neurotrophic factor inhibited the migration of astrocytes and Schwann cells to a certain degree.These findings suggest that glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor are involved in the regulation of the astrocyte-Schwann cell interaction in the co-culture system derived from the trigeminal root entry zone.This system can be used as a cell model to study the mechanism of glial dysregulation associated with trigeminal nerve injury and possible therapeutic interventions.

Sequential expression of miR-221-3p and miR-338-3p in Schwann cells as a therapeutic strategy to promote nerve regeneration and functional recovery

The functional properties of endogenous Schwann cells(SCs)during nerve repair are dynamic.Optimizing the functional properties of SCs at different stages of nerve repair may have therapeutic benefit in improving the repair of damaged nerves.Previous studies showed that miR-221-3p promotes the proliferation and migration of SCs,and miR-338-3p promotes the myelination of SCs.In this study,we established rat models of sciatic nerve injury by bridging the transected sciatic nerve with a silicone tube.We injected a miR-221 lentiviral vector system together with a doxycycline-inducible Tet-On miR-338 lentiviral vector system into the cavity of nerve conduits of nerve stumps to sequentially regulate the biological function of endogenous SCs at different stages of nerve regeneration.We found that the biological function of SCs was sequentially regulated,the diameter and density of myelinated axons were increased,the expression levels of NF200 and myelin basic protein were increased,and the function of injured peripheral nerve was improved using this system.miRNA Target Prediction Database prediction,Nanopore whole transcriptome sequencing,quantitative PCR,and dual luciferase reporter gene assay results predicted and verified Cdkn1b and Nrp1 as target genes of miR-221-3p and miR-338-3p,respectively,and their regulatory effects on SCs were confirmed in vitro.In conclusion,here we established a new method to enhance nerve regeneration through sequential regulation of biological functions of endogenous SCs,which establishes a new concept and model for the treatment of peripheral nerve injury.The findings from this study will provide direct guiding significance for clinical treatment of sciatic nerve injury.

良性腺性Schwann瘤

目的 :报道罕见的Schwann瘤 1例及复习该瘤的病理特征。方法 :应用组织化学和免疫组织化学染色检测肿瘤组织中梭形细胞成分和腺性结构。结果 :肿瘤由典型Schwann瘤和腺性成分组成。腺性结构表达Leu 7、GFAP、MBP、CEA、AE1 AE3、34 βE12。 结论

补阳还五汤提取液对Schwann细胞氧化损伤的保护作用

本实验建立了Schwann细胞的体外氧化损伤模型,从对Schwann细胞的抗氧化损伤作用探讨补阳还五汤的疗效机制。用原代培养的Schwann细胞建立氧化损伤模型,将培养细胞分为氧化损伤组,补阳还五汤处理组及正常组:(1)应用MTT方法检测细胞的活性;(2)应用生化技术检测细胞内超氧化物歧化酶(SOD)的含量;(3)采用荧光探针Fluo-3-AM标记细胞,用激光共聚焦显微镜观察H_2O_2对Schwann细胞内游离钙([Ca2+])抗氧化损伤的影响。结果显示:与对照组相比,H2O2处理组细胞活性降低(P<0.01),SOD含量明显减少(P<0.01),而补阳还五汤预处理后细胞内[Ca2+]i升高明显被减弱(P<0.01),细胞存活率明显升高(P<0.01)。以上结果表明补阳还五汤能通过抗过氧化损伤保护Schwann细胞。

筋脉通含药血清对高糖培养的Schwann细胞诱导型一氧化氮合酶和NADPH氧化酶p22-phox亚基表达的影响

目的:探讨筋脉通含药血清对高糖培养的Schwann细胞诱导型一氧化氮合酶(inducible nitric oxide synthase,i NOS)蛋白表达及烟酰胺腺嘌呤二核苷酸磷酸(nicotinamide adenine dinucleotidephosphate,NADPH)氧化酶p22-phox亚基mRNA表达的影响。方法:雄性Wistar大鼠随机分为3组,分别灌胃筋脉通、维生素C或蒸馏水制备含药血清和对照血清。取新出生大鼠的双侧坐骨神经用于制备Schwann细胞。将体外培养的Schwann细胞分为高糖组、筋脉通组(加入筋脉通含药血清)、维生素C组(加入维生素C含药血清)及正常对照组。培养48h后,采用免疫荧光法检测Schwann细胞内i NOS蛋白的表达,实时荧光定量聚合酶链式反应法检测NADPH氧化酶p22-phox亚基mRNA的表达。结果:高糖培养的Schwann细胞内i NOS蛋白表达及NADPH氧化酶p22-phox亚基mRNA表达均较正常对照组明显升高(P<0.01);与高糖组比较,筋脉通组i NOS蛋白表达及NADPH氧化酶p22-phox亚基mRNA表达明显降低(P<0.01),且明显优于维生素C组(P<0.01)。结论:筋脉通含药血清可以下调高糖培养的Schwann细胞i NOS蛋白及NADPH氧化酶p22-phox亚基mRNA的表达。

电刺激对背根节神经元/Schwann细胞联合培养体系髓鞘蛋白P0表达的影响

目的:建立体外背根节神经元与Schwann细胞联合培养模型,观察短时低频电刺激对Schwann细胞髓鞘蛋白表达的影响。方法:培养和纯化背根节神经元与Schwann细胞,制成背根节神经元/Schwann细胞联合培养体系。于L-ascorbic acid诱导的同时,施予低频电刺激(20Hz,100μs,3V),持续作用1h,分别于L-ascorbicacid诱导后第0,2,4,8和10d取各组培养基上清以ELISA测定其中脑衍生物神经生长因子(BDNF)的水平。另外,于诱导后第7d和14d检测培养体系中髓鞘蛋白P0的表达。结果:电刺激组各时间点BDNF的浓度较对照组显著升高(P<0.01)。经电刺激作用后,联合培养体系中P0表达上调(P<0.05)。然而,电刺激结束后在培养液中加入TrkB-Fc,P0的表达水平则显著降低(P<0.05)。结论:在神经元存在的条件下,短时低频电刺激可促进离体Schwann细胞合成P0,初步认为该作用通过刺激神经元分泌BDNF增多所致。

Schwann细胞表达β1,4半乳糖基转移酶-Ⅰ对神经元轴突生长的影响

为了探讨周围神经Schwann细胞中不同β1,4半乳糖基转移酶-1(β-1,4-GalT-I)表达水平对神经元轴突生长的影响,本实验首先构建了正、反义β-1,4-GalT-I表达质粒,然后将构建的不同浓度的正、反义表达质粒超表达于分离、纯化的大鼠Schwann细胞,最后将转染的Schwann细胞与分离的大鼠背根神经节共培养;根据共培养神经元轴突延伸的数目和面积,分析Schwann细胞中不同β-1,4-GalT-I表达水平对神经元轴突生长的影响。结果发现:转染正义β-1,4-GalT-I的Schwann细胞能促进共培养神经节神经元轴突的长出和延伸。在一定的转染浓度内,这种促神经生长作用随转染浓度增大而增强,而转染反义β-1,4-GalT-I却有相反的作用。提示周围神经Schwann细胞中表达β-1,4-GalT-I可能在维持正常神经的功能和促进损伤神经的修复发挥重要作用。

Schwann细胞在壳聚糖纤维上的立体培养

目的 :探讨壳聚糖纤维与体外培养Schwann细胞的相容性和亲和力。方法 :新生SD鼠的臂丛和坐骨神经组织块种植于壳聚糖纤维支架上培养Schwann细胞。结果 :壳聚糖纤维支架上的Schwann细胞为橄榄形或椭圆形 ,细胞在纤维上分裂、迁移 ,形成链状结构 ,细胞突起的末端呈扁平状膨大 ,伸出爪形伪足贴附于纤维。结论 :壳聚糖纤维不仅与Schwann细胞的相容性良好 。

冷酶消化法在分离和培养新生大鼠Schwann细胞的应用

Schwann细胞(SCs)是公认的周围神经组织工程的种子细胞,在周围神经损伤后的再生中扮演着重要的角色。为了快速分离和培养大量的SCs,本研究采用冷酶消化法对Wister乳鼠坐骨神经的细胞进行分离和培养,结果得到的细胞数量超过106,经S-100蛋白免疫组化染色鉴定,SCs的纯度超多了90%。从培养细胞的形态和生长曲线可见,冷酶消化法是一种简单快捷地分离SCs的方法,使用该法得到的SCs具有良好的生物学特性,并在细胞的分离时间、数量、纯度以及生物活性等方面,均达到了实用要求。

体外培养Schwann细胞缺氧模型的建立

目的:建立体外培养Schwann细胞的缺氧模型。方法:取体外培养Schwann细胞,置于通入体积分数为5%CO2和95%N2的有机玻璃盒中继续缺氧培养10、15和20min,用H-E染色观察细胞形态,MTT比色试验检测细胞的活力。结果:缺氧10min组细胞形态及活力与正常组无明显差异;而缺氧15min组的细胞突起回缩,活力为缺氧前的66·3%;缺氧20min组的细胞多数死亡,活力仅为缺氧前的20·6%。结论:本方法可以成功建立有效、简便、易行的Schwann细胞缺氧模型。