Role of CD36 in central nervous system diseases

CD36 is a highly glycosylated integral membrane protein that belongs to the scavenger receptor class B family and regulates the pathological progress of metabolic diseases.CD36 was recently found to be widely expressed in various cell types in the nervous system,including endothelial cells,pericytes,astrocytes,and microglia.CD36 mediates a number of regulatory processes,such as endothelial dysfunction,oxidative stress,mitochondrial dysfunction,and inflammatory responses,which are involved in many central nervous system diseases,such as stroke,Alzheimer’s disease,Parkinson’s disease,and spinal cord injury.CD36 antagonists can suppress CD36 expression or prevent CD36 binding to its ligand,thereby achieving inhibition of CD36-mediated pathways or functions.Here,we reviewed the mechanisms of action of CD36 antagonists,such as Salvianolic acid B,tanshinone IIA,curcumin,sulfosuccinimidyl oleate,antioxidants,and small-molecule compounds.Moreover,we predicted the structures of binding sites between CD36 and antagonists.These sites can provide targets for more efficient and safer CD36 antagonists for the treatment of central nervous system diseases.

miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

Our previous study found that rat bone marrow–derived neural crest cells(acting as Schwann cell progenitors)have the potential to promote long-distance nerve repair.Cell-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular communication.Nevertheless,the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain unclear.To investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves,we collected conditioned culture medium from hypoxia-pretreated neural crest cells,and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose deprivation.The mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest cells.We performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest cells.Subsequently,to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons,we used a microfluidic axonal dissociation model of sensory neurons in vitro,and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons,which was greatly dependent on loaded miR-21-5p.Finally,we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb,as well as muscle tissue morphology of the hind limbs,were obviously restored.These findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in miRNA-21-5p.miRNA-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell secretome.This helps to explain the mechanism of action of the secretome and extracellular vesicles of neural crest cells in repairing damaged peripheral nerves,and also promotes the application of miR-21-5p in tissue engineering regeneration medicine.

Combined Antitumor Effect of Ursolic Acid And 5-Fluorouracil on Human Esophageal Carcinoma Cell Eca-109 In Vitro

Objective： To study the combined antitumor effect and possible mechanisms of ursolic acid with 5-fluorouracil （5-FU） on human esophageal carcinoma cell Eca-109 in vitro. Methods： Eca-109 cells were treated with ursolic acid （10-50 μmol/L） and/or 5-fluorouracil （48.0-768.8 μmol/L） for 48 h in vitro. And then cell proliferation was determined by MTT assay. Cell cycle and apoptosis rate were analyzed by flow cytometry （FCM）. The morphological changes of apoptosis were observed by fluorescent microscopy. At last the expression of P27kipl, bcl-2 and bax were detected by western blot. Results： Results： In comparison with single agent treatment, the combination of ursolic acid and 5-fluorouracil produced greater efficacy in growth inhibition, cell cycle arrest at G0/G1 phase, and apoptosis induction （P〈0.05）. Western blot analysis showed that the combination use of ursolic acid and 5-fluorouracil suppressed the expression of bcl-2 and increased the expressions of bax and P27kip1. Conclusion： Ursolic acid combined with 5-fluorouracil showed adjuvant antiproliferative effects on human esophageal carcinoma cell Eca-109 in vitro, which mainly due to the induction of cell cycle arrest as well as apoptosis.

Developmental Temporal Patterns and Molecular Network Features in the Transcriptome of Rat Spinal Cord

The molecular network features of spinal cord development that are integral to tissue engineering remain poorly understood in placental mammals,especially in terms of their relationships with vital biological processes such as regeneration.Here,using a large-scale temporal transcriptomic analysis of rat spinal cord from the embryonic stage to adulthood,we show that fluctuating RNA expression levels reflect highly active transcriptional regulation,which may initiate spinal cord patterning.We also demonstrate that microRNAs(miRNAs)and transcriptional factors exhibit a mosaic profile based on their expression patterns,while differential alternative splicing events reveal that alternative splicing may be a driving force for the development of the node of Ranvier.Our study also supports the existence of a negative correlation between innate immunity and intrinsic growth capacity.Epigenetic modifications appear to perform their respective regulatory functions at different stages of development,while guanine nucleotidebinding protein(G protein)-coupled receptors(including olfactory receptors(ORs))may perform pleiotropic roles in axonal growth.This study provides a valuable resource for investigating spinal cord development and complements the increasing number of single-cell datasets.These findings also provide a genetic basis for the development of novel tissue engineering strategies.

KIAA1199 induces advanced biological behavior and development of ovarian cancer through activation of the IL-6/STAT3 pathway

Recently,abnormal expression of KIAA1199 has been detected in Epithelial Ovarian Cancer(EOC).However,the underlined anti-ovarian cancer mechanism of KIAA1199 remains to be enlightened.In our study,we performed to elucidate the effects of KIAA1199 on the advanced biological behavior of EOC cells through activation of the IL-6/STAT3 pathway.Confirmed by immunohistochemistry,KIAA1199 was highly expressed in ovarian borderline and malignant epithelial tumors.A retrospective analysis found that EOC patients with low expression of KIAA1199 had a significantly higher 5-year survival rate than those with high expression.Mechanistically,IL-6 was used to stimulate EOC cells,and the expression of KIAA1199,STAT3 and p-STAT3 increased after IL-6 stimulation.These results could show that KIAA1199 is transcriptionally activated by IL6/STAT3 pathway,thereby accelerating the deterioration of EOC.KIAA1199 could also be used as a poor prognosis factor and potential target in treatment.

Peripheral nerve fibroblasts secrete neurotrophic factors to promote axon growth of motoneurons

Peripheral nerve fibroblasts play a critical role in nerve development and regeneration.Our previous study found that peripheral nerve fibroblasts have different sensory and motor phenotypes.Fibroblasts of different phenotypes can guide the migration of Schwann cells to the same sensory or motor phenotype.In this study,we analyzed the different effects of peripheral nerve-derived fibroblasts and cardiac fibroblasts on motoneurons.Compared with cardiac fibroblasts,peripheral nerve fibroblasts greatly promoted motoneuron neurite outgrowth.Transcriptome analysis results identified 491 genes that were differentially expressed in peripheral nerve fibroblasts and cardiac fibroblasts.Among these,130 were significantly upregulated in peripheral nerve fibroblasts compared with cardiac fibroblasts.These genes may be involved in axon guidance and neuron projection.Three days after sciatic nerve transection in rats,peripheral nerve fibroblasts accumulated in the proximal and distal nerve stumps,and most expressed brain-derived neurotrophic factor.In vitro,brain-derived neurotrophic factor secreted from peripheral nerve fibroblasts increased the expression ofβ-actin and F-actin through the extracellular regulated protein kinase and serine/threonine kinase pathways,and enhanced motoneuron neurite outgrowth.These findings suggest that peripheral nerve fibroblasts and cardiac fibroblasts exhibit different patterns of gene expression.Peripheral nerve fibroblasts can promote motoneuron neurite outgrowth.

Silencing the enhancer of zeste homologue 2,Ezh2,represses axon regeneration of dorsal root ganglion neurons

Recovery from injury to the peripheral nervous system is different from that of the central nervous system in that it can lead to gene reprogramming that can induce the expression of a series of regeneration-associated genes.This eventually leads to axonal regeneration of injured neurons.Although some regeneration-related genes have been identified,the regulatory network underlying axon regeneration remains largely unknown.To explore the regulator of axon regeneration,we performed RNA sequencing of lumbar L4 and L5 dorsal root ganglion(DRG)neurons at different time points(0,3,6,12 hours,1,3 and 7 days)after rat sciatic nerve crush.The isolation of neurons was carried out by laser capture microscopy combined with NeuN immunofluorescence staining.We found 1228 differentially expressed genes in the injured sciatic nerve tissue.The hub genes within these differentially expressed genes include Atf3,Jun,Myc,Ngf,Fgf2,Ezh2,Gfap and Il6.We verified that the expression of the enhancer of zeste homologue 2 gene(Ezh2)was up-regulated in DRG neurons after injury,and this up-regulation differed between large-and small-sized dorsal root ganglion neurons.To investigate whether the up-regulation of Ezh2 impacts axonal regeneration,we silenced Ezh2 with siRNA in cultured DRG neurons and found that the growth of the newborn axons was repressed.In our investigation into the regulatory network of Ezh2 by interpretive phenomenal analysis,we found some regulators of Ezh2(including Erk,Il6 and Hif1a)and targets(including Atf3,Cdkn1a and Smad1).Our findings suggest that Ezh2,as a nerve regeneration-related gene,participates in the repair of the injured DRG neurons,and knocking down the Ezh2 in vitro inhibits the axonal growth of DRG neurons.All the experimental procedures approved by the Administration Committee of Experimental Animals of Jiangsu Province of China(approval No.S20191201-201)on March 21,2019.

Proteolysis targeting chimera technology:a novel strategy for treating diseases of the central nervous system

Neurological diseases such as stroke,Alzheimer’s disease,Parkinson’s disease,and Huntington’s disease are among the intractable diseases for which appropriate drugs and treatments are lacking.Proteolysis targeting chimera(PROTAC)technology is a novel strategy to solve this problem.PROTAC technology uses the ubiquitin-protease system to eliminate mutated,denatured,and harmful proteins in cells.It can be reused,and utilizes the protein destruction mechanism of the cells,thus making up for the deficiencies of traditional protein degradation methods.It can effectively target and degrade proteins,including proteins that are difficult to identify and bind.Therefore,it has extremely important implications for drug development and the treatment of neurological diseases.At present,the targeted degradation of mutant BTK,mHTT,Tau,EGFR,and other proteins using PROTAC technology is gaining attention.It is expected that corresponding treatment of nervous system diseases can be achieved.This review first focuses on the recent developments in PROTAC technology in terms of protein degradation,drug production,and treatment of central nervous system diseases,and then discusses its limitations.This review will provide a brief overview of the recent application of PROTAC technology in the treatment of central nervous system diseases.

Using 3D bioprinting to produce mini-brain

Recent progresses in three-dimensional （3D） bioprinting technology accelerate the coming of the era of personalized medicine. With vari- ous printing approaches and materials developed, 3D bioprinting may have a broad range of medical applications, including the fabrication of delicate tissues/organs/or the clinical use in the future or for the es- tablishment of tissues in disease models. The principal advantages of 3D bioprinting are personalized design and precise fabrication, which are of critical importance for tissue engineering. To date, several types of biomimetic tissues, such as cartilage, skin, and vascular tissues have been fabricated by 3D bioprinting （Liaw and Guvendiren, 2017）.

Biodegradable materials for bone defect repair

Compared with non-degradable materials,biodegradable biomaterials play an increasingly important role in the repairing of severe bone defects,and have attracted extensive attention from researchers.In the treatment of bone defects,scaffolds made of biodegradable materials can provide a crawling bridge for new bone tissue in the gap and a platform for cells and growth factors to play a physiological role,which will eventually be degraded and absorbed in the body and be replaced by the new bone tissue.Traditional biodegradable materials include polymers,ceramics and metals,which have been used in bone defect repairing for many years.Although these materials have more or fewer shortcomings,they are still the cornerstone of our development of a new generation of degradable materials.With the rapid development of modern science and technology,in the 21 st century,more and more kinds of new biodegradable materials emerge in endlessly,such as new intelligent micro-nano materials and cell-based products.At the same time,there are many new fabrication technologies of improving biodegradable materials,such as modular fabrication,3 D and 4 D printing,interface reinforcement and nanotechnology.This review will introduce various kinds of biodegradable materials commonly used in bone defect repairing,especially the newly emerging materials and their fabrication technology in recent years,and look forward to the future research direction,hoping to provide researchers in the field with some inspiration and reference.

Spatiotemporal Dynamics of the Molecular Expression Pattern

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

Micro-nanofiber composite biomimetic conduits promote long-gap peripheral nerve regeneration in canine models

Peripheral nerve injuries may result in severe long-gap interruptions that are challenging to repair.Autografting is the gold standard surgical approach for repairing long-gap nerve injuries but can result in prominent donor-site complications.Instead,imitating the native neural microarchitecture using synthetic conduits is expected to offer an alternative strategy for improving nerve regeneration.Here,we designed nerve conduits composed of high-resolution anisotropic microfiber grid-cordes with randomly organized nanofiber sheaths to interrogate the positive effects of these biomimetic structures on peripheral nerve regeneration.Anisotropic microfiber-grids demonstrated the capacity to directionally guide Schwann cells and neurites.Nanofiber sheaths conveyed adequate elasticity and permeability,whilst exhibiting a barrier function against the infiltration of fibroblasts.We then used the composite nerve conduits bridge 30-mm long sciatic nerve defects in canine models.At 12 months post-implant,the morphometric and histological recovery,gait recovery,electrophysiological function,and degree of muscle atrophy were assessed.The newly regenerated nerve tissue that formed within the composite nerve conduits showed restored neurological functions that were superior compared to sheaths-only scaffolds and Neurolac nerve conduit controls.Our findings demonstrate the feasibility of using synthetic biophysical cues to effectively bridge long-gap peripheral nerve injuries and indicates the promising clinical application prospects of biomimetic composite nerve conduits.

Application of stem cells in peripheral nerve regeneration

Traumatic peripheral nerve injury is a worldwide clinical issue with high morbidity.The severity of peripheral nerve injury can be classified as neurapraxia,axonotmesis or neurotmesis,according to Seddon’s classification,or five different degrees according to Sunderland’s classification.Patients with neurotmesis suffer from a complete transection of peripheral nerve stumps and are often in need of surgical repair of nerve defects.The applications of autologous nerve grafts as the golden standard for peripheral nerve transplantation meet some difficulties,including donor nerve sacrifice and nerve mismatch.Attempts have been made to construct tissue-engineered nerve grafts as supplements or even substitutes for autologous nerve grafts to bridge peripheral nerve defects.The incorporation of stem cells as seed cells into the biomaterial-based scaffolds increases the effectiveness of tissue-engineered nerve grafts and largely boosts the regenerative process.Numerous stem cells,including embryonic stem cells,neural stem cells,bone marrow mesenchymal stem cells,adipose stem cells,skin-derived precursor stem cells and induced pluripotent stem cells,have been used in neural tissue engineering.In the current review,recent trials of stem cell-based tissue-engineered nerve grafts have been summarized;potential concerns and perspectives of stem cell therapeutics have also been contemplated.

Identification of three novel SRD5A2 mutations in Chinese patients with 5α-reductase 2 deficiency

In this study,we investigated the genetics,clinical features,and therapeutic approach of 14 patients with 5a-reductase deficiency in China.Genotyping analysis was performed by direct sequencing of PCR products of the steroid 5α-reductase type 2 gene(SRD5A2).The 5a-reductase activities of three novel mutations were investigated by mutagenesis and an in vitro transfection assay.Most patients presented with a microphallus,variable degrees of hypospadias,and cryptorchidism.Eight of 14 patients(57.1%)were initially reared as females and changed their social gender from female to male after puberty.Nine mutations were identified in the 14 patients.p.G203S,p.Q6X,and p.R227Q were the most prevalent mutations.Three mutations(p.K35N,p.H162P,and p.Y136X)have not been reported previously.The nonsense mutation p.Y136X abolished enzymatic activity,whereas p.K35N and p.H162P retained partial enzymatic activity.Topical administration of dihydrotestosterone during infancy or early childhood combined with hypospadia repair surgery had good therapeutic results.In conclusion,we expand the mutation profile of SRD5A2 in the Chinese population.A rational clinical approach to this disorder requires early and accurate diagnosis,especially genetic diagnosis.

Transcriptome Analysis of Schwann Cells at Various Stages of Myelination Implicates Chromatin Regulator Sin3A in Control of Myelination Identity

Enhancing remyelination after injury is of utmost importance for optimizing the recovery of nerve function.While the formation of myelin by Schwann cells(SCs)is critical for the function of the peripheral nervous system,the temporal dynamics and regulatory mechanisms that control the progress of the s lineage through myelination require further elucidation.Here,using in vitro co-culture models,gene expression profiling of laser capture-microdissected SCs at various stages of myelination,and multilevel bioinformatic analysis,we demonstrated that SCs exhibit three distinct transcriptional characteristics duringmyelination:the immature,promyelinating,and myelinating states.We showed that suppressor interacting 3a(Sin3A)and 16 other transcription factors and chromatin regulators play important roles in the progress of myelination.Sin3A knockdown in the sciatic nerve or specifically in SCs reduced or delayed the myelination of regenerating axons in a rat crushed sciatic nerve model,while overexpression of Sin3A greatly promoted the remyelination of axons.Further,in vitro experiments revealed that Sin3A silencing inhibited SC migration and differentiation at the promyelination stage and promoted SC proliferation at the immature stage.In addition,SC differentiation and maturation may be regulated by the Sin3A/histone deacetylase2(HDAC2)complex functionally cooperating with Sox10,as demonstrated by rescue assays.Together,these results complement the recent genome and proteome analyses of SCs during peripheral nerve myelin formation.The results also reveal a key role of Sin3A-dependent chromatin organization in promoting myelinogenic programs and SC differentiation to control peripheral myelination and repair.These findings may inform new treatments for enhancing remyelination and nerveregeneration.

Mesenchymal stem cells targeting the GVHD

Acute graft-versus-host disease(GVHD) occurs after allogeneic hematopoietic stem cell transplant and is a reaction of donor immune cells against host tissues.About 35%-50% of hematopoietic stem cell transplant(HSCT) recipients will develop acute GVHD.It is associated with considerable morbidity and mortality,particularly in patients who do not respond to primary therapy,which usually consists of glucocorticoids(steroids).Most of the available second-line and third-line treatments for steroid-refractory acute GVHD induce severe immunodeficiency,which is commonly accompanied by lethal infectious complications.Mesenchymal stem cells(MSCs) have been shown to mediate immunomodulatory effects.The recently elucidated immunosuppressive potential of mesenchymal stem cells has set the stage for their clinical testing as cellular immunosuppressants,MSCs have been used in patients with steroid-refractory acute GVHD,and encouraging responses have been obtained in many studies.The utility of MSCs for the treatment of GVHD is becoming clear.

Deciphering glial scar after spinal cord injury

Spinal cord injury(SCI)often leads to permanent disability,which is mainly caused by the loss of functional recovery.In this review,we aimed to investigate why the healing process is interrupted.One of the reasons for this interruption is the formation of a glial scar around the severely damaged tissue,which is usually covered by reactive glia,macrophages and fibroblasts.Aiming to clarify this issue,we summarize the latest research findings pertaining to scar formation,tissue repair,and the divergent roles of blood-derived monocytes/macrophages,ependymal cells,fibroblasts,microglia,oligodendrocyte progenitor cells(OPCs),neuron-glial antigen 2(NG2)and astrocytes during the process of scar formation,and further analyse the contribution of these cells to scar formation.In addition,we recapitulate the development of therapeutic treatments targeting glial scar components.Altogether,we aim to present a comprehensive decoding of the glial scar and explore potential therapeutic strategies for improving functional recovery after SCI.

Sympathetic Nerve Mediated Spinal Glia Activation Underlies Itch in a Cutaneous T-Cell Lymphoma Model

Dear Editor,Cancer-associated itch can be described as pruritus associated with malignancy.Although intractable itch associated with specific types of cancer afflicts patients badly,few effective treatments are available due to limited knowledge about the mechanisms of such itch.Globally,cancer-associated itch is an uncommon symptomin malignancy.