Nucleus Pulposus Cells from Calcified Discs Promote the Degradation of the Extracellular Matrix through Upregulation of the GATA3 Expression

Objective Disc calcification is strongly associated with disc degeneration;however,the underlying mechanisms driving its pathogenesis are poorly understood.This study aimed to provide a gene expression profile of nucleus pulposus cells(NPCs)from calcified discs,and clarify the potential mechanism in disc degeneration.Methods Primary NPCs were isolated from calcified and control discs(CAL-NPC and CON-NPC),respectively.The proliferation and extracellular matrix(ECM)metabolism capacities of the cells were evaluated using MTT and Western blotting,respectively.RNA sequencing was used to identify differentially expressed genes(DEGs)in the CAL-NPCs.The biological functions of the DEGs were analyzed using the Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)databases.The transcription factor database and Cytoscape software were used to construct the transcription factor-DEGs regulatory network.The role of the verified transcription factor in NPC proliferation and ECM metabolism was also investigated.Results The CAL-NPCs exhibited a lower proliferation rate and higher ECM degradation capacity than the CON-NPCs.In total,375 DEGs were identified in the CAL-NPCs.The GO and KEGG analyses showed that the DEGs were primarily involved in the regulation of ribonuclease activity and NF-kappa B and p53 signaling pathways.GATA-binding protein 3(GATA3)with the highest verified levels was selected for further studies.Overexpression of GATA3 in the CON-NPCs significantly inhibited their proliferation and promoted their ECM degradation function,while the knockdown of GATA3 in the CAL-NPCs resulted in the opposite phenotypes.Conclusion This study provided a comprehensive gene expression profile of the NPCs from the calcified discs and supported that GATA3 could be a potential target for reversing calcification-associated disc degeneration.

Differentiation of Mesenchymal Stem Cells into Nucleus Pulposus Cells In Vitro

To find a new source of seed cells for constructing tissue-engineered intervertebral disc, nucleus pulposus （NP） cells and mesenchymal stem cells （MSCs） were isolated from New Zealand white rabbits. The nucleus pulposus cells population was fluorescence-ladled and co-cultured with MSCs with or without direct contact. Morphological changes were observed every 12 h. Semi-quantitaive reverse transcriptase-polymerase chain reaction was performed to assess the expression levels of Sox-9, aggreacan and type Ⅱ collagen every 24 h after the co-culture. MSCs treated with direct contact rounded up and presented a ring-like appearance. The expression of marker genes was significantly increased when cells were co-cultured with direct contact for 24 h. No significant change was found after coculture without direct contact. Co-culture of NP cells and MSCs with direct contact is a reliable method for generating large amount of NP cells used for cell-based tissue engineering therapy.

Normal and Degenerated Rabbit Nucleus Pulposus Cells in in vitro Cultures: A Biological Comparison

This study examined the biological characteristics of normal and degenerated rabbit nucleus pulposus （NP） cells in vitro in order to provide seed cells for intervertebral disc （IVD） tissue engineering. A total of 8 adult New Zealand white rabbits underwent annulus puncture to establish models ofintervertebral disc degeneration （IDD）. Four weeks later, normal and degenerated NP cells were obtained. Cell morphology was observed by light and electron microscopy. Cell viability was measured by MTT assay. Cell cycle and expression of extracellular matrix （ECM）-related genes （aggrecan and type II col- lagen） were determined by using flow cytometry and RT-PCR respectively. The growth curve of normal NP cells showed that the cells at passage 4 tended to slowly grow on the fifth day of culture. The density of normal NP cells at passages 5 to 7 was significantly less than that of the first-passage cells 2 or 3 days after seeding （P〈0.05）. The degenerated NP cells at passage 3 showed slow growth at 4th day. After 5 passages, the degenerated NP cells assumed stagnant growth and the growth seemed to stop at passage 7. The MTT assay revealed that for both normal and degenerated NP cells, the absorbance （.4） value at passages 4-7 was obviously decreased as compared with that at passage 1 （P〈0.05）. Cell cycle analysis showed that the proportion of normal NP cells at G1 phase was 65.4%-3.5%, significantly lower than that of degenerated NP cells at the same cell cycle phase With the value being 77.6%-4.8%. The degen- erated NP cells were predominantly arrested at Gt phase and failed to enter S phase. The expression of type II collagen and aggrecan was significantly decreased with passaging. It was concluded that normal NP cells possessed good viability and proliferative capacity by the third passage, and they could secrete large amounts of ECM within this period. The normal NP cells may serve as seed cells for IVD tissue engineering.

How to enhance the ability of mesenchymal stem cells to alleviate intervertebral disc degeneration

Intervertebral disc(ID)degeneration(IDD)is one of the main causes of chronic low back pain,and degenerative lesions are usually caused by an imbalance between catabolic and anabolic processes in the ID.The environment in which the ID is located is harsh,with almost no vascular distribution within the disc,and the nutrient supply relies mainly on the diffusion of oxygen and nutrients from the blood vessels located under the endplate.The stability of its internal environment also plays an important role in preventing IDD.The main feature of disc degeneration is a decrease in the number of cells.Mesenchymal stem cells have been used in the treatment of disc lesions due to their ability to differentiate into nucleus pulposus cells in a nonspecific anti-inflammatory manner.The main purpose is to promote their regeneration.The current aim of stem cell therapy is to replace the aged and metamorphosed cells in the ID and to increase the content of the extracellular matrix.The treatment of disc degeneration with stem cells has achieved good efficacy,and the current challenge is how to improve this efficacy.Here,we reviewed current treatments for disc degeneration and summarize studies on stem cell vesicles,enhancement of therapeutic effects when stem cells are mixed with related substances,and improvements in the efficacy of stem cell therapy by adjuvants under adverse conditions.We reviewed the new approaches and ideas for stem cell treatment of disc degeneration in order to contribute to the development of new therapeutic approaches to meet current challenges.

An esterase-responsive ibuprofen nano-micelle pre-modified embryo derived nucleus pulposus progenitor cells promote the regeneration of intervertebral disc degeneration

Stem cell-based transplantation is a promising therapeutic approach for intervertebral disc degeneration(IDD).Current limitations of stem cells include with their insufficient cell source,poor proliferation capacity,low nucleus pulposus(NP)-specific differentiation potential,and inability to avoid pyroptosis caused by the acidic IDD microenvironment after transplantation.To address these challenges,embryo-derived long-term expandable nucleus pulposus progenitor cells(NPPCs)and esterase-responsive ibuprofen nano-micelles(PEG-PIB)were prepared for synergistic transplantation.In this study,we propose a biomaterial pre-modification cell strategy;the PEG-PIB were endocytosed to pre-modify the NPPCs with adaptability in harsh IDD microenvironment through inhibiting pyroptosis.The results indicated that the PEG-PIB pre-modified NPPCs exhibited inhibition of pyroptosis in vitro;their further synergistic transplantation yielded effective functional recovery,histological regeneration,and inhibition of pyroptosis during IDD regeneration.Herein,we offer a novel biomaterial pre-modification cell strategy for synergistic transplantation with promising therapeutic effects in IDD regeneration.

Barriers to mesenchymal stromal cells for low back pain

Intervertebral disc degeneration is the main cause of low back pain.In the past 20 years,the injection of mesenchymal stromal cells(MSCs)into the nucleus pulposus of the degenerative disc has become the main approach for the treatment of low back pain.Despite the progress made in this field,there are still many barriers to overcome.First,intervertebral disc is a highly complex loadbearing composite tissue composed of annulus fibrosus,nucleus pulposus and cartilaginous endplates.Any structural damage will change its overall biomechanical function,thereby causing progressive degeneration of the entire intervertebral disc.Therefore,MSC-based treatment strategies should not only target the degenerated nucleus pulposus but also include degenerated annulus fibrosus or cartilaginous endplates.Second,to date,there has been relatively little research on the basic biology of annulus fibrosus and cartilaginous endplates,although their pathological changes such as annular tears or fissures,Modic changes,or Schmorl's nodes are more commonly associated with low back pain.Given the high complexity of the structure and composition of the annulus fibrosus and cartilaginous endplates,it remains an open question whether any regeneration techniques are available to achieve their restorative regeneration.Finally,due to the harsh microenvironment of the degenerated intervertebral disc,the delivered MSCs die quickly.Taken together,current MSC-based regenerative medicine therapies to regenerate the entire disc complex by targeting the degenerated nucleus pulposus alone are unlikely to be successful.

Transplantation of gene-modified nucleus pulposus cells reverses rabbit intervertebral disc degeneration

Background Intervertebral disc degeneration is the main cause of low back pain. The purpose of this study was to explore potential methods for reversing the degeneration of lumbar intervertebral discs by transplantation of gene-modified nucleus pulposus cells into rabbit degenerative lumbar intervertebral discs after transfecting rabbit nucleus pulposus cells with adeno-associated virus 2 （AAV2）-mediated connective tissue growth factor （CTGF） and tissue inhibitor of metalloproteinases 1 （TIMP1） genes in vitro. Methods Computer tomography （CT）-guided percutaneous annulus fibrosus injury was performed to build degenerative lumbar intervertebral disc models in 60 New Zealand white rabbits, rAAV2-CTGF-IRES-TIMPI-transfected rabbit nucleus pulposus cells were transplanted into degenerative lumbar intervertebral discs （transplantation group）, phosphate-buffered saline （PBS） was injected into degenerative lumbar intervertebral discs （degeneration control group） and normal lumbar intervertebral discs served as a blank control group. After 6, 10 and 14 weeks, the disc height index （DHI） and signal intensity in intervertebral discs were observed by X-ray and magnetic resonance imaging （MRI） analysis The expression of CTGF and TIMP1 in nucleus pulposus tissue was determined by Western blotting analysis, the synthesis efficiency of proteoglycan was determined by a 35S-sulfate incorporation assay, and the mRNA expression of type II collagen and proteoglycan was detected by RT-PCR. Results MRI confirmed that degenerative intervertebral discs appeared two weeks after percutaneous puncture. Transgenic nucleus pulposus cell transplantation could retard the rapid deterioration of the DHI. MRI indicated that degenerative intervertebral discs were relieved in the transplantation group compared with the degeneration control group. The expression of collagen II mRNA and proteoglycan mRNA was significantly higher in the transplantation group and the blank control group compared with the degeneration control group （P 〈0.05）. Conclusions CT-guided percutaneous puncture can successfully build rabbit degenerative intervertebral disc models. Both CTGF and TIMPl-transfected cell transplantation helps to maintain disc height, and promotes the biosynthesis of tvDe II collaQen and proteoalvcan in intervertebral discs, reversinq the de（：ieneration of intervertebral discs.

Specific Inhibitory Protein Dkk-1 Blocking Wnt/β-catenin Signaling Pathway Improve Protectives Effect on the Extracellular Matrix

The present study examined the role of Wnt/β-catenin signaling pathway in the degeneration of nucleus pulposus cells and the protective effect of DKK1 on nucleus pulposus cells. The model of nucleus pulposus cell degeneration was induced by intra-disc injection of TNF-α, and the expression of β-catenin protein was detected by Western blotting. The cultured rabbit nucleus pulposus cells were divided into 4 groups. In group A, the cells were cultured with normal medium and served as control group. In group B, the cells were cultured with TNF-α and acted as degeneration group. In group C, the cells were cultured with TNF-α and transfected with Adv-eGFP and was used as fluorescence control group. In group D, the cells were cultured with TNF-α and transfected with Adv-hDKK1-eGFP, serving as intervention group. The expression of typeⅡcollagen, proteoglycan, β-catenin, and MMP-13 in each group was detected by immunocytochemistry and RT-PCR. The result showed that TNF-α increased the expression of β-catenin and MMP-13, and significantly inhibited the synthesis of type Ⅱ collagen and proteoglycan, which resulted in the degeneration of nucleus pulposus cells. This effect could be obviously reversed by DKK1. We are led to concluded that TNF-α could activate the Wnt/β-catenin signaling pathway, and increase the expression of MMP-13, thereby resulting in disc degeneration. Specifically blocking Wnt/β-catenin signaling pathway by DKK-1 could protect the normal metabolism of intervertebral disc tissue. The Wnt pathway plays an important role in the progression of the intervertebral disc degeneration.

Evaluation of CD24 as a marker to rapidly define the mesenchymal stem cell phenotype and its differentiation in human nucleus pulposus

Background Recent studies have indicated that human nucleus pulposus contain mesenchymal stem cells （NP-MSCs）. However, the immunophenotypic variation of NP-MSCs in vitro was unclear. The present study was conducted to address the immunophenotypic variation of mesenchymal stem cells in nucleus pulposus under continuous proliferation in vitro and show the difference between mesenchymal stem cells and nucleus pulposus cell. Methods Tissue samples were obtained from thoracolumbar burst fracture patients and degenerative disc disease patients who underwent discectomy and fusion procedures. Flow cytometric and laser scanning confocal microscope （LSCM） were used to detect the variation of mesenchymal stem cells in nucleus pulposus which were expressing CD105 and CD24 in condition with or without transforming growth factor [31 （TGF-131）. Results More than 90% of the analyzed primary cells of mesenchymal stem cells in nucleus pulposus fulfilled the general immunophenotyping criteria for MSCs, such as CD44, CD105 and CD29, but the marker of mature NP cells characterized as CD24 was negative. In continuous cultures, the proportion of mesenchymal stem cells which were expressing CD44, CD105 and CD29 in nucleus pulposus gradually decreased. The mesenchymal stem cells in nucleus pulposus cells were positive for CD105 and CD29, with slight positivity for CD44. The CD24 expression gradually increased in proliferation. Bi- parametric flow cytometry and laser scanning confocal microscopy confirmed the presence of cells which were expressing CD105 and CD24 independently, and only a small part of cells expressed both CD105 and CD24 simultaneously. TGF-{31 could stimulate mesenchymal stem cells in nucleus pulposus to express CD24. Conclusions Non-degenerative and degenerative NP contains mesechymal stem cells. The variation of CD24 can be used as a marker to identify the NP-MSCs differentiation into NP-like cells.

舒芬太尼对IL-1β诱导的椎间盘退变的作用研究

目的 探究舒芬太尼(sufentanil)对白细胞介素(IL)-1β诱导的椎间盘退变的作用.方法 无菌分离SD大鼠髓核细胞(NPC)进行传代培养,并分为对照组,IL-1β组,IL-1β+Sufentanil低、中、高浓度组(0.125、0.25、0.5μmol/L).CCK-8检测NPC增殖能力;流式细胞和Hoechast 33258染色检测NPC凋亡,Western印迹检测凋亡蛋白、基质金属蛋白酶1(MMP-1)、MMP-13、环氧合酶2(COX-2)、金属蛋白酶组织抑制因子1(TIMP-1)、肿瘤坏死因子(TNF-α)和IL-10的表达;ELISA检测炎性因子水平.结果 Sufentanil 0.5μmol/L浓度内对NPC无显著毒性,选择sufentanil 0.125,0.25,0.5μmol/L进行后续实验.与对照组比较,IL-1β诱导NPC的凋亡,MMP-1、COX-2和MMP-13的表达及炎性因子水平显著上调(P<0.05),TIMP-1的表达显著下调(P<0.05).与IL-1β组比较,sufentanil抑制NPC凋亡及凋亡蛋白的表达(P<0.05),下调MMP-1,COX-2和MMP-13的表达及TNF-α和IL-1β水平(P<0.05),上调TIMP-1的表达及IL-10水平(P<0.05).结论 Sufentanil能够抑制IL-1β诱导的NPC凋亡,细胞外基质(ECM)的降解和炎性反应.

AAV6 as an effective gene delivery vector for prolonged transgene expression in intervertebral disc cells in vivo

Intervertebral disc degeneration is the main contributor to low back pain,now the leading cause of disability worldwide.Gene transfer,either in a therapeutic attempt or in basic research to understand the mechanisms of disc degeneration,is a fascinating and promising tool to manipulate the complex physiology of the disc.Viral vectors based on the adeno-associated virus(AAV)have emerged as powerful transgene delivery vehicles yet a systematic investigation into their respective tropism,transduction efficiency,and relative toxicity have not yet been performed in the disc in vivo.Herein,we used in vivo bioluminescence imaging to systematically compare multiple AAV serotypes,injection volumes,titers,promoters,and luciferase reporters to determine which result in high transduction efficiency of murine nucleus pulposus(NP)cells in vivo.We find that AAV6 using a CAG promoter to drive transgene expression,delivered into the NP of murine caudal discs at a titer of 1011 GC/mL,provides excellent transduction efficiency/kinetics and low toxicity in vivo.We also show,for the first time,that the transduction of NP cells can be significantly boosted in vivo by the use of small cell permeabilization peptides.Finally,to our knowledge,we are the first to demonstrate the use of optical tissue clearing and three-dimensional lightsheet microscopy in the disc,which was used to visualize fine details of tissue and cell architecture in whole intact discs following AAV6 delivery.Taken together,these data will contribute to the success of using AAV-mediated gene delivery for basic and translational studies of the IVD.

SDF1/CXCR4轴通过PI3K/AKT通路对退变椎间盘血管长入发挥作用

[目的]观察SDF1/CXCR4对髓核细胞(NPCs)诱导血管内皮细胞(VECs)成血管能力的影响。[方法]通过病毒转染上调原代髓核细胞中基质细胞衍生因子1(SDF1)表达,并根据表达量分为D组和UP组,将不同分组的髓核细胞(或条件培养基)与血管内皮细胞进行共培养,分别进行细胞计数试剂盒8(CCK8)、细胞迁移实验、管腔形成实验,以观察髓核细胞对于血管内皮细胞成血管能力的影响。[结果]在mRNA和蛋白水平检验证实SDF1表达在UP组上调成功。NPCs和VECs共培养后,UP组VECs中pAKT水平较D组显著升高,PTEN水平较D组下降,差异均具有统计学意义。后续的共培养体系中,UP组的VECs在细胞活力、迁移能力、形成管腔样结构能力上较D组均显著增强,差异具有统计学意义。加入MK-2206后,UP+MK-2206组在细胞活力、迁移能力、管腔样结构形成能力上较UP组均显著下降,差异具有统计学意义。加入SF1670后,UP+SF1670组的细胞活力、迁移能力、管腔样结构形成能力均较UP组进一步增强,差异具有统计学意义。[结论]本实验通过体外培养证明退变髓核细胞可通过SDF1/CXCR4信号轴来诱导血管内皮细胞成血管活动,并且这一活动在内皮细胞内通过PI3K/AKT通路调控。

兔髓核间充质干细胞与髓核细胞非接触式共培养的生物学效应

[目的]通过非接触式共培养探索兔髓核间充质干细胞(NPMSCs)与兔髓核细胞(NPCs)的间接生物学效应.[方法]将第3代兔来源NPMSCs与NPCs进行非接触共培养,分设三组:NPCs/NPCs自身共培养对照组,NPMSCs/NPMSCs自身共培养对照组,NPMSCs/NPCs共培养组.分别在共培养3、5、7d后,比较两种细胞增殖情况,ELISA检测上清液中转化生长因子β1(TGF-β1)、胰岛素样生长因子(IGF)的含量;采用RT-PCR检测共培养7d后NPMSCs与NPCs的Col Ⅱc1、AGG基因表达变化;免疫荧光染色检测NPMSCs中Col Ⅱ的蛋白表达情况.[结果]在共培养第5d和第7d,共培养组NPCs的细胞数量均高于自身对照组(P<0.05),在第7d,共培养组NPMSCs的细胞数量均高于自身对照组;在共培养3、5、7d后,共培养组上清液TGF-β1、IGF的含量均高于自身对照组(P<0.05);在培养7d后,共培养组NPMSCs中Col Ⅱ免疫荧光强度高于自身对照组,NPCs与NPMSCs的Col Ⅱa1、AGG基因的表达较自身对照组显著升高(P<0.05).[结论]NPMSCs与NPCs非接触共培养可以促进细胞因子分泌、细胞增殖、基质合成与分泌.