RESUMO
Degenerative disc disease is the leading cause of lower back and leg pain, considerably impacting daily life and incurring substantial medical expenses for those affected. The development of annulus fibrosus tissue engineering offers hope for treating this condition. However, the current annulus fibrosus tissue engineering scaffolds fail to accurately mimic the natural biological environment of the annulus fibrosus, resulting in limited secretion of extracellular matrix produced by the seeded cells and poor biomechanical properties of the constructed biomimetic annulus fibrosus tissue. This inability to match the biomechanical performance of the natural annulus fibrosus hinders the successful treatment of annulus fibrosus defects. In this study, we fabricated decellularized annulus fibrosus matrix (DAFM)/chitosan hydrogel-1 (DAFM: Chitosan 6:2) and DAFM/chitosan hydrogel-2 (DAFM: Chitosan 4:4) by varying the ratio of DAFM to chitosan. Rat annulus fibrosus (AF)-derived stem cells were cultured on these hydrogel scaffolds, and the cell morphology, AF-related gene expression, and Interleukin-6 (IL-6) levels were investigated. Additionally, magnetic resonance imaging, Hematoxylin and eosin staining, and Safranine and Fast Green staining were performed to evaluate the repair effect of the DAFM/chitosan hydrogels in vivo. The gene expression results showed that the expression of Collagen type I (Col-I), Collagen type I (Col-II), and aggrecan by annulus fibrosus stem cells (AFSCs) cultured on the DAFM/chitosan-1 hydrogel was higher compared with the DAFM/chitosan-2 hydrogel. Conversely, the expression of metalloproteinase-9 (MMP-9) and IL-6 was lower on the DAFM/chitosan-1 hydrogel compared with the DAFM/chitosan-2 hydrogel. In vivo, both the DAFM/chitosan-1 and DAFM/chitosan-2 hydrogels could partially repair large defects of the annulus fibrosus in rat tail vertebrae. In conclusion, the DAFM/chitosan-1 hydrogel could be regarded as a candidate scaffold material for the repair of annulus fibrosus defects, offering the potential for improved treatment outcomes.
Assuntos
Anel Fibroso , Quitosana , Hidrogéis , Ratos Sprague-Dawley , Animais , Ratos , Alicerces Teciduais , Engenharia Tecidual/métodos , Degeneração do Disco Intervertebral/terapia , Masculino , Matriz Extracelular Descelularizada , Células CultivadasRESUMO
Intervertebral disc herniation is not a common injury in the adolescent population, but the correlation between trauma and herniation warrants concern. Previous research demonstrated the capacity for rapid internal pressurization to reduce the mechanical integrity of the intervertebral disc's annulus fibrosus, even in the absence of fracture. The purpose of this study was to modify previous internal pressurization procedures towards a more transferable injury model, then investigate the capacity for these procedures to damage the mechanical integrity of the annulus fibrosus. Porcine cervical motion segments with intact facet joints were confined between a vice and force plate under 300 N of static compression, then a single, manual, rapid internal pressurization was delivered. Posterolateral annulus samples were extracted and situated in a 180° peel test configuration, exposing the interlamellar matrix of samples to separations of 0.5 mm/s, until complete separation of the sample occurred. Multilayer tensile testing was performed on superficial and mid-span samples of annulus by applying uniaxial tension of 1 %/s to 50 % strain. Compared to unpressurized controls, rapid pressurization causing fracture resulted in reduced lamellar adhesion and increased toe-region stress and strain properties in the annulus. Morphological assessment reported similar fracture patterns between endplate fractures achieved in the present experiment and endplate fractures documented in human patients. Mechanical plus morphological results suggest that rapid internal pressurization resulting in endplate fracture may represent a potent mechanism for subsequent damage to the intervertebral disc.
Assuntos
Anel Fibroso , Pressão , Animais , Suínos , Fenômenos Biomecânicos , Fenômenos Mecânicos , Estresse Mecânico , Testes Mecânicos , Disco Intervertebral/lesões , Resistência à TraçãoRESUMO
BACKGROUND: Intervertebral disc (IVD) degeneration is a multifactorial pathological process resulting in the dysregulation of IVD cell activity. The catabolic shift observed in IVD cells during degeneration leads to increased inflammation, extracellular matrix (ECM) degradation, aberrant intracellular signaling and cell loss. Importantly, these pathological processes are known to be interconnected and to collectively contribute to the progression of the disease. MicroRNAs (miRNAs) are known as strong post-transcriptional regulators, targeting multiple genes simultaneously and regulating numerous intracellular pathways. Specifically, miR-155-5p has been of particular interest since it is known as a pro-inflammatory mediator and contributing factor to diseases like cancer and osteoarthritis. This study investigated the role of miR-155-5p in IVD degeneration with a specific focus on inflammation and mechanosensing. METHODS: Gain- and loss-of-function studies were performed through transfection of human Nucleus pulposus (NP) and Annulus fibrosus (AF) cells isolated from degenerated IVDs with miR-155-5p mimics, inhibitors or their corresponding non-targeting control. Transfected cells were then subjected to an inflammatory environment or mechanical loading. Conditioned media and cell lysates were collected for phosphorylation and cytokine secretion arrays as well as gene expression analysis. RESULTS: Increased expression of miR-155-5p in AF cells resulted in significant upregulation of interleukin (IL)-8 cytokine secretion during cyclic stretching and a similar trend in IL-6 secretion during inflammation. Furthermore, miR-155-5p mimics increased the expression of the brain-derived neurotrophic factor (BDNF) in AF cells undergoing cyclic stretching. In NP cells, miR-155-5p gain-of-function resulted in the activation of the mitogen-activated protein kinase (MAPK) signaling pathway through increased phosphorylation of p38 and p53. Lastly, miR-155-5p inhibition caused a significant increase in the anti-inflammatory cytokine IL-10 in AF cells and the tissue inhibitor of metalloproteinases (TIMP)-4 in NP cells respectively. CONCLUSION: Overall, these results show that miR-155-5p contributes to IVD degeneration by enhancing inflammation through pro-inflammatory cytokines and MAPK signaling, as well as by promoting the catabolic shift of AF cells during mechanical loading. The inhibition of miR-155-5p may constitute a potential therapeutic approach for IVD degeneration and low back pain.
Assuntos
Inflamação , Degeneração do Disco Intervertebral , MicroRNAs , MicroRNAs/genética , MicroRNAs/metabolismo , Degeneração do Disco Intervertebral/genética , Degeneração do Disco Intervertebral/metabolismo , Degeneração do Disco Intervertebral/patologia , Humanos , Inflamação/genética , Inflamação/patologia , Inflamação/metabolismo , Núcleo Pulposo/metabolismo , Núcleo Pulposo/patologia , Masculino , Suporte de Carga , Pessoa de Meia-Idade , Feminino , Anel Fibroso/metabolismo , Anel Fibroso/patologiaRESUMO
Intervertebral disc (IVD) herniation is a leading cause of disability and lower back pain, causing enormous socioeconomic burdens. The standard of care for disc herniation is nucleotomy, which alleviates pain but does not repair the annulus fibrosus (AF) defect nor recover the biomechanical function of the disc. Existing bioadhesives for AF repair are limited by insufficient adhesion and significant mechanical and geometrical mismatch with the AF tissue, resulting in the recurrence of protrusion or detachment of bioadhesives. Here, we report a composite hydrogel sealant constructed from a composite of a three-dimensional (3D)-printed thermoplastic polyurethane (TPU) mesh and tough hydrogel. We tailored the fiber angle and volume fraction of the TPU mesh design to match the angle-ply structure and mechanical properties of native AF. Also, we proposed and tested three types of geometrical design of the composite hydrogel sealant to match the defect shape and size. Our results show that the sealant could mimic native AF in terms of the elastic modulus, flexural modulus, and fracture toughness and form strong adhesion with the human AF tissue. The bovine IVD tests show the effectiveness of the composite hydrogel sealant for AF repair and biomechanics recovery and for preventing herniation with its heightened stiffness and superior adhesion. By harnessing the combined capabilities of 3D printing and bioadhesives, these composite hydrogel sealants demonstrate promising potential for diverse applications in tissue repair and regeneration.
Assuntos
Anel Fibroso , Hidrogéis , Animais , Anel Fibroso/efeitos dos fármacos , Hidrogéis/química , Hidrogéis/farmacologia , Bovinos , Humanos , Impressão Tridimensional , Poliuretanos/química , Poliuretanos/farmacologia , Adesivos Teciduais/farmacologia , Adesivos Teciduais/químicaRESUMO
This study sought to evaluate the effects of prolonged cyclic loading on the tissue-level mechanical properties of the spinal annulus fibrosus. Functional spinal units (FSUs) were obtained from porcine cervical spines at the C3-C4 and C5-C6 levels. Following a 15-min preload of 300 N of axial compression, the FSUs were split into three groups: the cyclic loading group cycled between 0.35 MPa and 0.95 MPa for 2 h (n = 8); the static loading group was compressed at 0.65 MPa for 2 h (n = 10); and a control group which only underwent the 300 N preload (n = 11). Following loading, samples of the annulus were excised to perform intralamellar tensile testing and interlamellar 180 deg peel tests. Variables analyzed from the intralamellar test were stress and strain at the end of the toe region, stress and strain at initial failure (yield point), Young's modulus, ultimate stress, and strain at ultimate stress. Variables evaluated from the interlamellar tests were lamellar adhesion strength, adhesion strength variability, and stiffness. The analysis showed no significant differences between conditions on any measured variable; however, there was a trend (p = 0.059) that cyclically loaded tissues had increased adhesion strength variability compared to the static and control conditions. The main finding of this study is that long-duration axial loading did not impact the intra- or interlamellar mechanical properties of the porcine annulus. A trend of increased adhesion strength variability in cyclically loaded samples could indicate a potential predisposition of the annulus to delamination.
Assuntos
Anel Fibroso , Estresse Mecânico , Suporte de Carga , Animais , Anel Fibroso/fisiologia , Suínos , Fenômenos Biomecânicos , Testes Mecânicos , Teste de Materiais , Resistência à Tração , Módulo de Elasticidade/fisiologiaRESUMO
BACKGROUND CONTEXT: Large annulus fibrosus (AF) defects often lead to a high rate of reherniation, particularly in the medial AF region, which has limited self-healing capabilities. The increasing prevalence of herniated discs underscores the need for effective repair strategies. PURPOSE: The objectives of this study were to design an AF repair technique to reduce solve the current problems of insufficient mechanical properties and poor sealing capacity. STUDY DESIGN: In vitro biomechanical experiments and finite element analysis. METHODS: The materials used in this study were patches and hydrogels with good biocompatibility and sufficient mechanical properties to withstand loading in the lumbar spine. Five repair techniques were assessed in this study: hydrogel filler (HF), AF patch medial barrier (MB), AF patch medial barrier and hydrogel filler (MB&HF), AF patch medial-lateral barrier (MLB), and AF patch medial-lateral barrier and hydrogel filler (MLB&HF). The repair techniques were subjected to in vitro testing (400 N axial compression and 0-500 N fatigue loading at 5Hz) and finite element analysis (400 N axial compression) to evaluate the effectiveness at repairing large AF defects. The evaluation included repair tightness, spinal stability, and fatigue resistance. RESULTS: From the in vitro testing, the failure load of the repair techniques was in the following order HF
Assuntos
Anel Fibroso , Hidrogéis , Deslocamento do Disco Intervertebral , Anel Fibroso/cirurgia , Deslocamento do Disco Intervertebral/cirurgia , Hidrogéis/administração & dosagem , Humanos , Análise de Elementos Finitos , Fenômenos Biomecânicos , Recidiva , Animais , Vértebras Lombares/cirurgiaRESUMO
BACKGROUND: The objective of this research was to identify differentially expressed genes (DEGs) related to ferroptosis in the annulus fibrosus (AF) during intervertebral disc degeneration (IDD). METHODS: We analyzed gene data from degenerated and normal AF obtained from the GSE70362 and GSE147383 datasets. An analysis to determine the functional significance of the DEGs was conducted, followed by the creation of a network illustrating the interactions between proteins. We further analyzed the immune infiltration of the DEGs and determined the hub DEGs using LASSO regression analysis. Finally, we identified the hub ferroptosis-related DEGs (FRDEGs) and verified their expression levels using Real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, Immunohistochemical Staining (IHC), and Immunofluorescence (IF). RESULTS: By analyzing the GSE70362 and GSE147383 datasets, we identified 118 DEGs. In degenerative AF groups, we observed a significant increase in immune infiltration of resting memory CD4+ T cells. LASSO regression analysis revealed 9 hub DEGs. The construction of a Receiver Operating Characteristic (ROC) curve yielded an Area Under the Curve (AUC) value of 0.762. Furthermore, we found that MGST1 is a hub gene related to ferroptosis. Our examination of immune infiltration indicated that MGST1 primarily influences macrophage M0 in different immune cell expression groups. Finally, our observations revealed a marked upregulation of MGST1 expression in the degenerated annulus fibrosus tissue. CONCLUSION: Our findings indicate an upsurge in MGST1 levels within degenerative AF, potentially playing a crucial role in the exacerbation of IDD. These findings provide a foundation for further exploration of the pathological mechanisms underlying IDD and offer potential drug targets for intervention.
Assuntos
Anel Fibroso , Biologia Computacional , Ferroptose , Glutationa Transferase , Degeneração do Disco Intervertebral , Humanos , Anel Fibroso/metabolismo , Anel Fibroso/patologia , Biologia Computacional/métodos , Bases de Dados Genéticas , Ferroptose/genética , Perfilação da Expressão Gênica/métodos , Redes Reguladoras de Genes , Disco Intervertebral/metabolismo , Disco Intervertebral/patologia , Degeneração do Disco Intervertebral/genética , Degeneração do Disco Intervertebral/metabolismo , Degeneração do Disco Intervertebral/patologia , Mapas de Interação de Proteínas/genética , Glutationa Transferase/genética , Glutationa Transferase/metabolismoRESUMO
This study addresses three primary objectives related to lumbar intervertebral disc (IVD) biomechanics under ramping quasi-static loading conditions. First, we explore the conditions justifying the simplification of axisymmetric elastic fiber families into single fiber bundles through discretized strain energy functions. Simulations reveal that a concentration factor exceeding 10 allows for a consistent deviation below 10% between simplified and non-simplified responses. Second, we investigate the impact of elastic fibers on the physiological stiffness in IVDs, revealing minimal influence on biological motions but significant effects on degeneration. Lastly, we examine the initiation and progression of annulus fibrosus (AF) damage. Our findings confirm the validity of simplifying elastic fiber families and underscore the necessity of considering elastic fiber damage in biomechanical studies of AF tissues. Elastic fibers contribute to increased biaxial stretch stiffness, and their damage significantly affects the loading capacity of the inner AF. Additionally, degeneration significantly alters the susceptibility to damage in the AF, with specific regions exhibiting higher vulnerability. Damage tends to extend circumferentially and radially, emphasizing the regional variations in collagen and elastic fiber properties. This study offers useful insights for refining biomechanical models, paving the way for a more comprehensive understanding of IVD responses and potential clinical implications.
Assuntos
Anel Fibroso , Fenômenos Biomecânicos , Fenômenos Mecânicos , Tecido Elástico , Degeneração do Disco Intervertebral/fisiopatologia , Degeneração do Disco Intervertebral/patologia , Estresse Mecânico , Humanos , Disco Intervertebral , Modelos Biológicos , Suporte de CargaRESUMO
Syndecan 4 (SDC4), a cell surface heparan sulfate proteoglycan, is known to regulate matrix catabolism by nucleus pulposus cells in an inflammatory milieu. However, the role of SDC4 in the aging spine has never been explored. Here we analyzed the spinal phenotype of Sdc4 global knockout (KO) mice as a function of age. Micro-computed tomography showed that Sdc4 deletion severely reduced vertebral trabecular and cortical bone mass, and biomechanical properties of vertebrae were significantly altered in Sdc4 KO mice. These changes in vertebral bone were likely due to elevated osteoclastic activity. The histological assessment showed subtle phenotypic changes in the intervertebral disc. Imaging-Fourier transform-infrared analyses showed a reduced relative ratio of mature collagen crosslinks in young adult nucleus pulposus (NP) and annulus fibrosus (AF) of KO compared to wildtype discs. Additionally, relative chondroitin sulfate levels increased in the NP compartment of the KO mice. Transcriptomic analysis of NP tissue using CompBio, an AI-based tool showed biological themes associated with prominent dysregulation of heparan sulfate GAG degradation, mitochondria metabolism, autophagy, endoplasmic reticulum (ER)-associated misfolded protein processes and ER to Golgi protein processing. Overall, this study highlights the important role of SDC4 in fine-tuning vertebral bone homeostasis and extracellular matrix homeostasis in the mouse intervertebral disc.
Assuntos
Envelhecimento , Doenças Ósseas Metabólicas , Homeostase , Camundongos Knockout , Sindecana-4 , Animais , Camundongos , Sindecana-4/metabolismo , Sindecana-4/genética , Envelhecimento/metabolismo , Envelhecimento/genética , Doenças Ósseas Metabólicas/genética , Doenças Ósseas Metabólicas/metabolismo , Doenças Ósseas Metabólicas/patologia , Microtomografia por Raio-X , Disco Intervertebral/metabolismo , Disco Intervertebral/patologia , Núcleo Pulposo/metabolismo , Núcleo Pulposo/patologia , Matriz Extracelular/metabolismo , Matriz Extracelular/genética , Coluna Vertebral/metabolismo , Coluna Vertebral/patologia , Coluna Vertebral/diagnóstico por imagem , Anel Fibroso/metabolismo , Anel Fibroso/patologia , Osteoclastos/metabolismoRESUMO
Low back pain stands as a significant factor in disability, largely resulting from intervertebral disc degeneration (IVDD). High glucose (HG) levels have been implicated in the pathogenesis of IVDD. However, the detailed mechanism of HG in IVDD is largely unknown. Our clinical results revealed that fibrosis markers such as CTGF, Col1a1, ATF4, and EIF2 are highly expressed in advanced-stage IVDD patients. Stimulation of human annulus fibrosus cells (HAFCs) with HG, but not mannitol, promotes fibrosis protein production. Ingenuity Pathway Analysis in the GSE database found that the mTOR, PKCδ, and NF-κB pathways were significantly changed during IVDD. The mTOR, PKCδ, and NF-κB inhibitors or siRNAs all abolished HG-induced fibrosis protein production. In addition, treatment of HAFCs with HG enhances the activation of mTOR, PKCδ, and NF-κB pathways. Thus, HG facilitates fibrosis in IVDD through mTOR, PKCδ, and NF-κB pathways. These results underscore the critical role of HG as a fibrotic factor in the progression of IVDD.
Assuntos
Anel Fibroso , Fibrose , Glucose , NF-kappa B , Proteína Quinase C-delta , Transdução de Sinais , Serina-Treonina Quinases TOR , Humanos , Serina-Treonina Quinases TOR/metabolismo , Proteína Quinase C-delta/metabolismo , Fibrose/metabolismo , NF-kappa B/metabolismo , Glucose/metabolismo , Anel Fibroso/metabolismo , Anel Fibroso/patologia , Degeneração do Disco Intervertebral/metabolismo , Degeneração do Disco Intervertebral/patologia , Masculino , Feminino , Pessoa de Meia-Idade , Células Cultivadas , AdultoRESUMO
PURPOSE: The aim of this study was to investigate the clinical efficacy of full endoscopic lumbar annulus fibrosus suture in the treatment of single-segment lumbar disc herniation (LDH). METHODS: The clinical data of patients with single-segment LDH who underwent full endoscopic lumbar discectomy from January 2017 to January 2019 in our hospital were retrospectively analysed. Patients with full endoscopic lumbar discectomy combined with annulus fibrosus suture were divided into group A, and those with simple full endoscopic lumbar discectomy were divided into group B. The general information, surgery-related data, visual analog scale (VAS), Oswestry disability index (ODI), modified MacNab score at the last follow-up, reoperation rate and recurrence were compared between the two groups. RESULTS: All patients were followed up for 12 to 24 months, and the surgical time was 133.6 ± 9.6 min in group A and 129.0 ± 11.7 min in group B. The difference was not statistically significant (p > 0.05). The blood loss of group A was higher than that of group B, and the difference was statistically significant when comparing the groups (p < 0.05). The postoperative symptoms of patients in both groups were significantly relieved, and the VAS score of low back pain and ODI index were significantly lower than the preoperative ones at all postoperative time points (1 month after surgery, 3 months after surgery, and at the last follow-up) (p < 0.05), but there was no significant difference between the groups (p > 0.05). The excellent rate of MacNab at the last follow-up in the two groups were 93.55% and 87.80%, respectively, with no statistically significant difference (p > 0.05). At the last follow-up, the recurrence rate of group A was significantly lower than that of group B, and the difference was statistically significant (p < 0.05), while the difference between the reoperation rate of the two groups was not statistically significant (p > 0.05). CONCLUSIONS: Full endoscopic lumbar discectomy combined with annulus fibrosus repair reduces the postoperative recurrence rate and achieves satisfactory clinical outcomes.
Assuntos
Anel Fibroso , Endoscopia , Deslocamento do Disco Intervertebral , Vértebras Lombares , Humanos , Masculino , Feminino , Vértebras Lombares/cirurgia , Deslocamento do Disco Intervertebral/cirurgia , Adulto , Pessoa de Meia-Idade , Estudos Retrospectivos , Endoscopia/métodos , Anel Fibroso/cirurgia , Resultado do Tratamento , Seguimentos , Técnicas de Sutura , Discotomia/métodosRESUMO
Intervertebral disc degeneration (IVDD) has been considered a major cause of low back pain. Therefore, further molecular subtypes of IVDD and identification of potential critical genes are urgently needed. First, consensus clustering was used to classify patients with IVDD into two subtypes and key module genes for subtyping were identified using weighted gene co-expression network analysis (WGCNA). Then, key module genes for the disease were identified by WGCNA. Subsequently, SVM and GLM were used to identify hub genes. Based on the above genes, a nomogram was constructed to predict the subtypes of IVDD. Finally, we find that ROM1 is lowered in IVDD and is linked to various cancer prognoses. The present work offers innovative diagnostic and therapeutic biomarkers for molecular subtypes of IVDD.
Assuntos
Anel Fibroso , Degeneração do Disco Intervertebral , Humanos , Anel Fibroso/metabolismo , Degeneração do Disco Intervertebral/genética , Degeneração do Disco Intervertebral/metabolismo , TranscriptomaRESUMO
PURPOSE: This study explores the potential of Omilancor in treating Intervertebral Disc Degeneration (IDD) through MAP2K6 targeting. METHODS: We analyzed mRNA microarray datasets to pinpoint MAP2K6 as a key regulator implicated in IDD progression. Follow-up studies demonstrated that cisplatin (DDP) could prompt cellular senescence in vitro by upregulating MAP2K6 expression. Through molecular docking and other analyses, we identified Omilancor as a compound capable of binding to MAP2K6. This interaction effectively impeded the cellular senescence induced by DDP. RESULTS: We further showed that administration of Omilancor could significantly alleviate the degeneration of IVDs in annulus fibrosus puncture-induced rat model. CONCLUSIONS: Omilancor shows promise as a treatment for IDD by targeting MAP2K6-mediated cellular senescence.
Assuntos
Anel Fibroso , Degeneração do Disco Intervertebral , Núcleo Pulposo , Ratos , Animais , Núcleo Pulposo/metabolismo , Simulação de Acoplamento Molecular , Degeneração do Disco Intervertebral/metabolismo , Senescência Celular/fisiologia , Anel Fibroso/metabolismoRESUMO
Elucidating how cell populations promote onset and progression of intervertebral disc degeneration (IDD) has the potential to enable more precise therapeutic targeting of cells and mechanisms. Single-cell RNA-sequencing (scRNA-seq) is performed on surgically separated annulus fibrosus (AF) (19,978; 26,983 cells) and nucleus pulposus (NP) (20,884; 24,489 cells) from healthy and diseased human intervertebral discs (IVD). In both tissue types, depletion of cell subsets involved in maintenance of healthy IVD is observed, specifically the immature cell subsets - fibroblast progenitors and stem cells - indicative of an impairment of normal tissue self-renewal. Tissue-specific changes are also identified. In NP, several fibrotic populations are increased in degenerated IVD, indicating tissue-remodeling. In degenerated AF, a novel disease-associated subset is identified, which expresses disease-promoting genes. It is associated with pathogenic biological processes and the main gene regulatory networks include thrombospondin signaling and FOXO1 transcription factor. In NP and AF cells thrombospondin protein promoted expression of genes associated with TGFß/fibrosis signaling, angiogenesis, and nervous system development. The data reveal new insights of both shared and tissue-specific changes in specific cell populations in AF and NP during IVD degeneration. These identified mechanisms and molecules are novel and more precise targets for IDD prevention and treatment.
Assuntos
Anel Fibroso , Degeneração do Disco Intervertebral , Núcleo Pulposo , Humanos , Degeneração do Disco Intervertebral/genética , Degeneração do Disco Intervertebral/metabolismo , Degeneração do Disco Intervertebral/patologia , Núcleo Pulposo/metabolismo , Núcleo Pulposo/patologia , Anel Fibroso/metabolismo , Anel Fibroso/patologia , Masculino , Pessoa de Meia-Idade , Feminino , Adulto , Disco Intervertebral/metabolismo , Disco Intervertebral/patologiaRESUMO
Chronic painful intervertebral disc (IVD) degeneration (i.e., discogenic pain) is a major source of global disability needing improved knowledge on multiple-tissue interactions and how they progress in order improve treatment strategies. This study used an in vivo rat annulus fibrosus (AF) injury-driven discogenic pain model to investigate the acute and chronic changes in IVD degeneration and spinal inflammation, as well as sensitization, inflammation, and remodeling in dorsal root ganglion (DRG) and spinal cord (SC) dorsal horn. AF injury induced moderate IVD degeneration with acute and broad spinal inflammation that progressed to DRG to SC changes within days and weeks, respectively. Specifically, AF injury elevated macrophages in the spine (CD68) and DRGs (Iba1) that peaked at 3 days post-injury, and increased microglia (Iba1) in SC that peaked at 2 weeks post-injury. AF injury also triggered glial responses with elevated GFAP in DRGs and SC at least 8 weeks post-injury. Spinal CD68 and SC neuropeptide Substance P both remained elevated at 8 weeks, suggesting that slow and incomplete IVD healing provides a chronic source of inflammation with continued SC sensitization. We conclude that AF injury-driven IVD degeneration induces acute spinal, DRG, and SC inflammatory crosstalk with sustained glial responses in both DRGs and SC, leading to chronic SC sensitization and neural plasticity. The known association of these markers with neuropathic pain suggests that therapeutic strategies for discogenic pain need to target both spinal and nervous systems, with early strategies managing acute inflammatory processes, and late strategies targeting chronic IVD inflammation, SC sensitization, and remodeling.
Assuntos
Anel Fibroso , Dor Crônica , Degeneração do Disco Intervertebral , Disco Intervertebral , Ratos , Animais , Disco Intervertebral/lesões , Doenças Neuroinflamatórias , Gânglios Espinais , Degeneração do Disco Intervertebral/complicações , Dor Crônica/complicações , Medula EspinalRESUMO
Avascular dense connective tissues (e.g., the annulus fibrosus (AF) rupture, the meniscus tear, and tendons and ligaments injury) repair remains a challenge due to the "biological barrier" that hinders traditional drug permeation and limits self-healing of the injured tissue. Here, accurate delivery of nitric oxide (NO) to penetrate the "AF biological barrier" is achieved thereby enabling programmable AF repair. NO-loaded BioMOFs are synthesized and mixed in a modified polyvinyl alcohol and PCL-composited electrospun fiber membrane with excellent reactive oxygen species-responsive capability (LN@PM). The results show that LN@PM could respond to the high oxidative stress environment at the injured tissue and realize continuous and substantial NO release. Based on low molecular weight and lipophilicity, NO could penetrate through the "biological barrier" for accurate AF drug delivery. Moreover, the dynamic characteristics of the LN@PM reaction can be matched with the pathological microenvironment to initiate programmable tissue repair including sequential remodeling microenvironment, reprogramming the immune environment, and finally promoting tissue regeneration. This tailored programmable treatment strategy that matches the pathological repair process significantly repairs AF, ultimately alleviating intervertebral disc degeneration. This study highlights a promising approach for avascular dense connective tissue treatment through intelligent NO release, effectively overcoming "AF biological barriers" and programmable treatment.
Assuntos
Óxido Nítrico , Óxido Nítrico/metabolismo , Animais , Anel Fibroso/efeitos dos fármacos , Sistemas de Liberação de Medicamentos/métodos , Tecido Conjuntivo , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Álcool de Polivinil/química , Degeneração do Disco Intervertebral/metabolismo , Masculino , Ratos , Camundongos , CoelhosRESUMO
Annulus fibrosus (AF) defect is an important cause of disc re-herniation after discectomy. The self-regeneration ability of the AF is limited, and AF repair is always hindered by the inflammatory microenvironment after injury. Hydrogels represent one of the most promising materials for AF tissue engineering strategies. However, currently available commercial hydrogels cannot withstand the harsh mechanical load within intervertebral disc. In the present study, an innovative triple cross-linked oxidized hyaluronic acid (OHA)-dopamine (DA)- polyacrylamide (PAM) composite hydrogel, modified with collagen mimetic peptide (CMP) and supplied with transforming growth factor beta 1 (TGF-ß1) (OHA-DA-PAM/CMP/TGF-ß1 hydrogel) was developed for AF regeneration. The hydrogel exhibited robust mechanical strength, strong bioadhesion, and significant self-healing capabilities. Modified with collagen mimetic peptide, the hydrogel exhibited extracellular-matrix-mimicking properties and sustained the AF cell phenotype. The sustained release of TGF-ß1 from the hydrogel was pivotal in recruiting AF cells and promoting extracellular matrix production. Furthermore, the composite hydrogel attenuated LPS-induced inflammatory response and promote ECM synthesis in AF cells via suppressing NFκB/NLRP3 pathway. In vivo, the composite hydrogel successfully sealed AF defects and alleviated intervertebral disk degeneration in a rat tail AF defect model. Histological evaluation showed that the hydrogel integrated well with host tissue and facilitated AF repair. The strategy of recruiting endogenous cells and providing an extracellular-matrix-mimicking and anti-inflammatory microenvironment using the mechanically tough composite OHA-DA-PAM/CMP/TGF-ß1 hydrogel may be applicable for AF defect repair in the clinic. STATEMENT OF SIGNIFICANCE: Annulus fibrosus (AF) repair is challenging due to its limited self-regenerative capacity and post-injury inflammation. In this study, a mechanically tough and highly bioadhesive triple cross-linked composite hydrogel, modified with collagen mimetic peptide (CMP) and supplemented with transforming growth factor beta 1 (TGF-ß1), was developed to facilitate AF regeneration. The sustained release of TGF-ß1 enhanced AF cell recruitment, while both TGF-ß1 and CMP could modulate the microenvironment to promote AF cell proliferation and ECM synthesis. In vivo, this composite hydrogel effectively promoted the AF repair and mitigated the intervertebral disc degeneration. This research indicates the clinical potential of the OHA-DA-PAM/CMP/TGF-ß1 composite hydrogel for repairing AF defects.
Assuntos
Anel Fibroso , Degeneração do Disco Intervertebral , Deslocamento do Disco Intervertebral , Disco Intervertebral , Ratos , Animais , Anel Fibroso/patologia , Fator de Crescimento Transformador beta1/farmacologia , Fator de Crescimento Transformador beta1/metabolismo , Hidrogéis/química , Adesivos/farmacologia , Preparações de Ação Retardada/farmacologia , Disco Intervertebral/metabolismo , Degeneração do Disco Intervertebral/tratamento farmacológico , Degeneração do Disco Intervertebral/metabolismo , Ácido Hialurônico/farmacologia , Ácido Hialurônico/metabolismo , Colágeno/metabolismoRESUMO
Intervertebral disc degeneration is closely related to abnormal phenotypic changes in disc cells. However, the mechanism by which disc cell phenotypes are maintained remains poorly understood. Here, Hedgehog-responsive cells were found to be specifically localized in the inner annulus fibrosus and cartilaginous endplate of postnatal discs, likely activated by Indian Hedgehog. Global inhibition of Hedgehog signaling using a pharmacological inhibitor or Agc1-CreERT2-mediated deletion of Smo in disc cells of juvenile mice led to spontaneous degenerative changes in annulus fibrosus and cartilaginous endplate accompanied by aberrant disc cell differentiation in adult mice. In contrast, Krt19-CreER-mediated deletion of Smo specifically in nucleus pulposus cells led to healthy discs and normal disc cell phenotypes. Similarly, age-related degeneration of nucleus pulposus was accelerated by genetic inactivation of Hedgehog signaling in all disc cells, but not in nucleus pulposus cells. Furthermore, inactivation of Gli2 in disc cells resulted in partial loss of the vertebral growth plate but otherwise healthy discs, whereas deletion of Gli3 in disc cells largely corrected disc defects caused by Smo ablation in mice. Taken together, our findings not only revealed for the first time a direct role of Hedgehog-Gli3 signaling in maintaining homeostasis and cell phenotypes of annuls fibrosus and cartilaginous endplate, but also identified disc-intrinsic Hedgehog signaling as a novel non-cell-autonomous mechanism to regulate nucleus pulposus cell phenotype and protect mice from age-dependent nucleus pulposus degeneration. Thus, targeting Hedgehog signaling may represent a potential therapeutic strategy for the prevention and treatment of intervertebral disc degeneration.
Assuntos
Anel Fibroso , Degeneração do Disco Intervertebral , Disco Intervertebral , Camundongos , Animais , Degeneração do Disco Intervertebral/genética , Proteínas Hedgehog/genética , FenótipoRESUMO
The suture technique for a ruptured annulus fibrosus (AF) under full-endoscopy remains challenging. Direct suturing of a ruptured annular tear after full decompression has been shown to decrease the recurrence rate of lumbar disc herniation during endoscopic surgery. Traditional suture operations under endoscopy involve only simple suturing of the ruptured AF. Due to the weak and poor quality of the AF tissue around the tear portal, using this area as needle insertion points during suturing may lead to insufficient tension and a low success rate of AF closure. Currently, there is no detailed technical illustration based on video for AF tear suturing under lumbar full-endoscopy. We innovatively propose a method of covering and suturing the AF tear by pulling up the posterior longitudinal ligament (PLL) under lumbar endoscopy and using three stitches (PLL-AF suture technique). The patient who received the novel suture technique achieved satisfactory results. Six months after the operation, lumbar MRI showed no evidence of recurrence in the outpatient clinic.