Intervertebral Disc Degeneration Research Articles

Intradiscal Steroid Injections for Degenerative Disc Disease With Modic Changes: A Retrospective Study of Therapeutic and Diagnostic Features

Intradiscal Steroid Injections for Degenerative Disc Disease With Modic Changes: A Retrospective Study of Therapeutic and Diagnostic Features

Targeted multifidus muscle activation reduces fibrosis of multifidus muscle following intervertebral disc injury.

Aerobic exercise produces beneficial outcomes in patients with low back pain and partially attenuates the fibrotic changes to the multifidus in a model of intervertebral disc (IVD) degeneration. More targeted exercise might be required to fully attenuate these fibrotic alterations. This study aimed to investigate whether activation of the multifidus induced by neurostimulation could reduce fibrosis of the multifidus in a model of IVD degeneration in sheep. IVD degeneration was induced in 18 merino sheep via a partial thickness unilateral annulus fibrosus lesion to the L1/2 and L3/4 IVDs. All sheep received an implantable neurostimulation device that provides stimulation of the L2 medial branch of the dorsal ramus. Three months after surgery, the animals were assigned to Injury or Activated groups. Activated animals received neurostimulation and the Injury group received no stimulation. Six months after surgery, the multifidus was harvested at L2 and L4. Van Gieson's, Sirius Red and immunofluorescence staining for Collagen-I and -III and quantitative PCR was used to examine fibrosis. Muscle harvested from a previous study without IVD injury was used as a control. Neurostimulation of the multifidus attenuated IVD degeneration dependent increases in the connective tissue, including Collagen-I but not Collagen-III, compared to the Injury group at L4. No measures of the multifidus muscle at L2, which received no stimulation, differed between the Injury and Activated groups. These data reveal that targeted activation of the multifidus muscle attenuates IVD degeneration dependent fibrotic alterations to the multifidus.

CARMA3 Drives NF-κB Activation and Promotes Intervertebral Disc Degeneration: Involvement of CARMA3-BCL10-MALT1 Signalosome.

Intervertebral disc degeneration (IDD) diseases are common and frequent diseases in orthopedics. The caspase recruitment domain (CARD) and membrane-associated guanylate kinase-like protein 3 (CARMA3) is crucial in the activation of the NF-κB pathway. However, the biological function of CARMA3 in IDD remains unknown. Here, CARMA3 expression was elevated in nucleus pulposus (NP) tissues of IDD rats and nutrient deprivation (ND)-induced NP cells. The main pathological manifestations observed in IDD rats were shrinkage of the NP, reduction of NP cells, fibrosis of NP tissues, and massive reduction of proteoglycans. These changes were accompanied by a decrease in the expression of collagen II and aggrecan, an increase in the expression of the extracellular matrix (ECM) catabolic proteases MMP-3, MMP-13, and metalloprotease with ADAMTS-5, and an increase in the activity of the pro-apoptotic protease caspase-3. The expression of p-IκBαSer32/36 and p-p65Ser536 was also upregulated. However, these effects were reversed with the knockdown of CARMA3. Mechanistically, CARMA3 bound to BCL10 and MALT1 to form a signalosome. Knockdown of CARMA3 reduced the CARMA3-BCL10-MALT1 signalosome-mediated NF-κB activation. CARMA3 activated the NF-κB signaling pathway in a manner that bound to BCL10 and MALT1 to form a signalosome, which affects NP cell damage and is involved in the development of IDD. This supports CARMA3-BCL10-MALT1-NF-κB as a promising targeting axis for the treatment of IDD.

Experimental validation and comprehensive analysis of m6A methylation regulators in intervertebral disc degeneration subpopulation classification

Intervertebral disc degeneration (IVDD) is one of the most prevalent causes of chronic low back pain. The role of m6A methylation modification in disc degeneration (IVDD) remains unclear. We investigated immune-related m6A methylation regulators as IVDD biomarkers through comprehensive analysis and experimental validation of m6A methylation regulators in disc degeneration. The training dataset was downloaded from the GEO database and analysed for differentially expressed m6A methylation regulators and immunological features, the differentially regulators were subsequently validated by a rat IVDD model and RT-qPCR. Further screening of key m6A methylation regulators based on machine learning and LASSO regression analysis. Thereafter, a predictive model based on key m6A methylation regulators was constructed for training sets, which was validated by validation set. IVDD patients were then clustered based on the expression of key m6A regulators, and the expression of key m6A regulators and immune infiltrates between clusters was investigated to determine immune markers in IVDD. Finally, we investigated the potential role of the immune marker in IVDD through enrichment analysis, protein-to-protein network analysis, and molecular prediction. By analysising of the training set, we revealed significant differences in gene expression of five methylation regulators including RBM15, YTHDC1, YTHDF3, HNRNPA2B1 and ALKBH5, while finding characteristic immune infiltration of differentially expressed genes, the result was validated by PCR. We then screen the differential m6A regulators in the training set and identified RBM15 and YTHDC1 as key m6A regulators. We then used RBM15 and YTHDC1 to construct a predictive model for IVDD and successfully validated it in the training set. Next, we clustered IVDD patients based on the expression of RBM15 and YTHDC1 and explored the immune infiltration characteristics between clusters as well as the expression of RBM15 and YTHDC1 in the clusters. YTHDC1 was finally identified as an immune biomarker for IVDD. We finally found that YTHDC1 may influence the immune microenvironment of IVDD through ABL1 and TXK. In summary, our results suggest that YTHDC1 is a potential biomarker for the development of IVDD and may provide new insights for the precise prevention and treatment of IVDD.

SP1/CTR1-mediated oxidative stress-induced cuproptosis in intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is an age-related disease and is responsible for low back pain. Oxidative stress-induced cell death plays a fundamental role in IDD pathogenesis. Cuproptosis is a recently discovered form of programmed cell death dependent on copper availability. Whether cuproptosis is involved in IDD progression remains unknown. Herein, we established in vitro and in vivo models to investigate cuproptosis in IDD and the mechanisms by which oxidative stress interacts with copper sensitivity in nucleus pulposus cells (NPCs). We found that ferredoxin-1 (FDX1) content increased in both rat and human degenerated discs. Sublethal oxidative stress on NPCs led to increased FDX1 expression, tricarboxylic acid (TCA) cycle-related proteins lipoylation and aggregation, and cell death in the presence of Cu2+ at physiological concentrations, while FDX1 knockdown inhibited cell death. Since copper homeostasis is involved in copper-induced cytotoxicity, we investigated the role of copper transport-related proteins, including importer (CTR1) and efflux pumps (ATPase transporter, ATP7A, and ATP7B). CTR1 and ATP7A content increased under oxidative stress, and blocking CTR1 reduced oxidative stress/copper-induced TCA-related protein aggregation and cell death. Moreover, oxidative stress promoted the expression of specific protein 1 (SP1) and SP1-mediated CTR1 transcription. SP1 inhibition decreased cell death rates, preserved disc hydration, and alleviated tissue degeneration. This suggests that oxidative stress upregulates FDX1 expression and copper flux through promoting SP1-mediated CTR1 transcription, leading to increased TCA cycle-related protein aggregation and cuproptosis. This study highlights the importance of cuproptosis in IDD progression and provides a promising therapeutic target for IDD treatment.

Injectable Hydrogel Based on Enzymatic Initiation of Keratin Methacrylate for Controlled Exosome Release in Intervertebral Disc Degeneration Therapy

AbstractThe treatment of intervertebral disc degeneration (IVDD) using bone marrow mesenchymal stem cell‐derived exosomes has shown success in alleviating inflammation and restoring the extracellular matrix (ECM), however, challenges persist due to the deficiency in mechanical support and controlled release. Herein, a carbon‐carbon double bond modified keratin (KeMA) is synthesized by 2‐isocyanatoethyl modification for exosomes wrapping. This injectable KeMA hydrogel, initiated by a biocompatible glucose/ glucose oxidase/ horse radish peroxidase enzymatic cascade reaction with acetylacetone and N‐vinylpyrrolidone, displayed rapid gelation, resembling nucleus pulposus (NP) elasticity, and excellent cytocompatibility. In vitro studies showcased that the exosomes‐loaded KeMA hydrogel (Exo@KeMA) enhanced exosome release kinetics, suppressed inflammation, fostered extracellular matrix (ECM) regeneration, and reinstated NP biomechanics. RNA‐seq analysis indicated Exo@KeMA's effects involved PI3K‐Akt signaling for matrix regeneration and NF‐κB signaling inhibition for anti‐inflammation. In vivo IVDD rat models demonstrated Exo@KeMA attenuated inflammation, maintained NP water content, preserved disc height, and promoted structural regeneration. This research introduces an injectable KeMA hydrogel as a promising therapy for IVDD, by facilitating biomechanics restoration, anti‐inflammatory response, and ECM regeneration.

Lipid Peroxidation, Reduced Glutathione, and Glutathione Peroxidase Levels in Intervertebral Discs of Patients with Lumbar Degenerative Disc Disease

Lipid Peroxidation, Reduced Glutathione, and Glutathione Peroxidase Levels in Intervertebral Discs of Patients with Lumbar Degenerative Disc Disease

The quality of life after Anterior Cervical Discectomy and Fusion

Cervical discopathy is commonly associated with pain in the cervical spine which may affect patients’ quality of life. If conservative treatment fails to relieve the pain for at least 6 months and/or if neurological deficit progresses, the surgical treatment is taken under consideration. The aim of this study was to evaluate health-related quality of life (HRQOL) and disability of patients after single- and multi-level anterior cervical discectomy and fusion (ACDF) with standalone polyetheretherketone (PEEK) cages. The study evaluated how ACDF influenced particular aspects of patients’ quality of life in the context of radiological outcome. The study included 30 consecutive patients with single- or multi-level cervical disc herniation. Patients underwent clinical and radiological evaluation before and one year after the ACDF procedure. For each patient, we assessed the severity of cervical pain with a numerical rating scale (NRS) and filled the neck disability index questionnaire (NDI). The health-related quality of life was assessed with the Polish version of 36-Item Short Form Survey (SF-36). A significant decrease in all NDI aspects indicates a significant improvement after surgery. The quality of life in all aspects assessed with SF-36 scale was also improved. A moderate decrease in cervical spine mobility coexisted with a good outcome of the neurosurgical procedure. In the opinion of patients, the most important aspect after the cervical spine surgery is the reduction of pain severity. ACDF surgery is an effective method to reduce the severity of pain in patients with degenerative disc disease. ACDF improves the quality of patient’s life. According to the study results the physical role improved most significantly; the least improvement was noted in role-emotional aspect. Up to 83% of patients achieved a reduction of the NDI index by 5 or more points after surgical treatment which proves the high effectiveness of the surgical treatment. No statistically significant difference was noted between patients with single and multi – level discopathy. Up to 97% of patients who underwent ACDF reported a significant decrease in pain severity measured with NRS.

[Retracted] MicroRNA‑25 protects nucleus pulposus cells against apoptosis via targeting SUMO2 in intervertebral disc degeneration.

Following the publication of this paper, the authors requested that the paper be retracted, specifically on account of deficiencies that were identified both in the documentation of patient records and in written consent pertaining to the data presented in Fig. 1. After having considered the authors' request, the Editor of Molecular Medicine Reports has agreed that this paper should be retracted from the Journal. All the authors are in agreement with the decision to retract this paper. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 24: 724, 2021; DOI: 10.3892/mmr.2021.12363].

Mast Cells and Their Related Gene HK-1 are Closely Associated with Discogenic Low Back Pain: A Bioinformatics and Clinical Sample Study.

Low back pain (LBP) is primarily caused by intervertebral disc degeneration (IVDD). Immune cells penetrating nucleus pulposus (NP) tissues may play an important role in generating IVDD and LBP. The clinical data from 100 cases of IVDD patients was initially analyzed retrospectively. Subsequently, peripheral blood and NP tissues from 41 IVDD patients were gathered for a validated investigation. Among them, ribosome-removed-RNA sequencing (RNA-seq) was performed on 10 cases of NP tissues of specific classifications (VAS 3 and Pfirrmann 3 were used as the controls, while patients with VAS 6 and Pfirrmann 5 were used as the experimental group). Differentially expressed genes (DEGs) were identified for the subsequent bioinformatics analysis. Further methods to confirm the underlying cause of discogenic LBP included mast cell immunohistochemistry (IHC), 12 cytokine detection, Western blot (WB), and real-time polymerase chain reaction (RT-PCR). Discogenic LBP and IVDD severity are strongly associated, and immunological cell infiltration has been demonstrated to be a significant factor in LBP by bioanalytical research. Tryptase-positive mast cells were found to be significantly more abundant in the VAS 6 NP tissues of IVDD patients than in the VAS 3 NP tissues. It was initially demonstrated that IVDD and LBP were significantly impacted by hemokinin-1 (HK-1), the mast cell-related gene. Furthermore, blood levels of interleukin 12 p70 (IL-12P70) are noticeably elevated and strongly correlated with HK-1, indicating that HK-1 may be involved in the regulation of mast cell activity and IL-12P70 production. The severity of LBP was observed to be positively correlated with the IVDD Pfirrmann grading. Further research indicates that patients with IVDD may experience persistent low back pain due to HK-1 activation of mast cells and the release of the cytokine IL12P70. This work will offer new insights into the diagnosis and treatment of discogenic LBP.

An injectable anti-vascularization functionalized hydrogel for degenerative nucleus pulposus repair

Neovascularization and inflammatory cell invasion within the nucleus pulposus (NP) constitute pivotal pathological changes during the acceleration stage of intervertebral disc degeneration (IDD). Mesenchymal stem cells (MSCs), renowned for their remarkable capacity in intervertebral disc (IVD) regeneration, also exhibit the capability to secrete pro-angiogenic factors, expediting IDD progression under hypoxic conditions. Consequently, we developed a hydrogel comprised of methacrylated hyaluronic acid (HAMA), rat tail collagen I (COL), and MSCs, incorporating the vascular endothelial growth factor receptor (VEGFR) inhibitor cabozantinib (Cabo@HAMA-COL/MSCs hydrogel). This innovative construct aimed to facilitate NP regeneration while mitigating vascularization and inflammation. Our findings revealed that the hydrogel aptly mimicked the mechanical characteristics of NP tissue, exhibiting injectability, low cytotoxicity, and the preservation of the cellular phenotype of NP cells. Co-culturing of MSCs and human umbilical vein endothelial cells (HUVECs) promoted migration, tube formation, and sprouting of HUVECs, which will be inhibited by cabozantinib. In vivo experiments demonstrated that Cabo@HAMA-COL/MSCs hydrogel maintained disc height, protected NP, and alleviated vascularization and inflammation in a puncture-induced rat caudal IDD model. Consequently, our results substantiate that Cabo@HAMA-COL/MSCs hydrogel can prevent IDD degeneration by ameliorating the vascularization-inflammation pathological microenvironment, offering a promising therapeutic strategy for IDD.

Role of Galectin-3 in intervertebral disc degeneration: an experimental study

BackgroundThis study investigated the role of Galectin-3 in the degeneration of intervertebral disc cartilage.MethodsThe patients who underwent lumbar spine surgery due to degenerative disc disease were recruited and divided into Modic I, Modic II, and Modic III; groups. HE staining was used to detect the pathological changes in endplates. The changes of Galectin-3, MMP3, Aggrecan, CCL3, and Col II were detected by immunohistochemistry, RT-PCR, and Western blot. MTT and flow cytometry were used to detect cartilage endplate cell proliferation, cell cycle, and apoptosis.ResultsWith the progression of degeneration (from Modic I to III), the chondrocytes and density of the cartilage endplate of the intervertebral disc decreased, and the collagen arrangement of the cartilage endplate of the intervertebral disc was broken and calcified. Meanwhile, the expressions of Aggrecan, Col II, Galectin-3, Aggrecan, and CCL3 gradually decreased. After treatment with Galectin-3 inhibitor GB1107, the proliferation of rat cartilage end plate cells was significantly reduced (P < 0.05). GB1107 (25 µmol/L) also significantly promoted the apoptosis of cartilage endplate cells (P < 0.05). Moreover, the percentage of cartilage endplate cells in the G1 phase was significantly higher, while that in the G2 and S phases was significantly lower (P < 0.05). Additionally, the mRNA and protein expression levels of MMP3, CCL3, and Aggrecan in rat cartilage end plate cells were lower than those in the control group.ConclusionsGalectin-3 decreases with the progression of the cartilage endplate degeneration of the intervertebral disc. Galectin-3 may affect intervertebral disc degeneration by regulating the degradation of the extracellular matrix.

Mo-fi-disc scoring system: Towards understanding the radiological tools to better delineate the disease process and enhancing our solutions for low back pain in artificial intelligence era

Background‘Mo-fi-disc’ is a new scoring system that quantifies degeneration of the lumbar spine and predicts the intensity of low back pain (LBP). However, its association with LBP-related disability is unknown. In the present study, we aimed to analyze whether ‘Mo-fi-disc’ scoring system could predict LBP-related disability and distinguish patients with LBP from asymptomatic subjects, while the spine medicine marching towards the era of artificial intelligence (AI). MethodsThis is a cross-sectional analysis of a prospectively collected database. We included age-, gender-, and BMI-matched 132 subjects (patients: 66, asymptomatic subjects: 66). Modic changes (Mo), fatty infiltration in the paraspinal muscles (fi), and intervertebral disc degeneration (disc) were evaluated using ‘Mo-fi-disc’ scoring system on lumbar spine magnetic resonance imaging. Pain and disability were evaluated with visual analogue scale (VAS) and Oswestry disability index (ODI), respectively. ResultsA Mo-fi-disc score of 5.5 was the most appropriate cut-off value. Mo-fi-disc scoring system had an OR of 1.79 in distinguishing patients with LBP from asymptomatic subjects. One point increment in VAS and ODI had ORs of 1.82 and 1.13 for predicting higher Mo-fi-disc scores. Conclusion‘Mo-fi-disc’ scoring system is a useful tool depicting intensity of LBP and LBP-related disability. The cut off value of Mo-fi-disc score is 5.5 to distinguish patients with LBP from asymptomatic subjects. This scoring system, with progressive improvement of its faults, could help clinicians to select appropriate patients for conservative and surgical management in the very near future, in AI-based spine medicine. IRB approval noATADEK 2019-12/4.

Potential Role of Odanacatib in the Treatment of Postmenopausal Intervertebral Disc Degeneration

Odanacatib (ODN), a cathepsin K (CatK) inhibitor, is widely used for the treatment of postmenopausal osteoporosis. However, whether ODN is efficient in delaying intervertebral disc degeneration (IVDD) remaining unknown. We aimed to explore the effect of ODN in the postmenopausal IVDD using an ovariectomized (OVX) mouse model. We collected the disc tissues from female spinal fracture patients and analyzed the CatK expression in different estrogen levels. Besides, we injected ranged concentration of OND subcutaneously in the OVX mice and tested the disc height index (DHI), aggrecan positive area, collagen I, collagen II, inflammatory factors, and apoptosis-related gene expression comparing to control. The intervertebral disc degraded and the CatK gene expression decreased in the disc lacking of estrogen. OVX method increased the collagen I, MMP-3, MMP-13, caspase-3, and caspase-8 expression, but reduced DHI, and the content of aggrecan and collagen II, indicating an IVDD tendency. However, the ODN treatment could suppress MMP-3, MMP-13, caspase-3, and caspase-8 and protect the stability of extracellular matrix (ECM). ODN is a potential drug to delay the IVDD by suppressing apoptosis and ECM degradation.

Association Between Vertebral Endplate Defects and Patient-reported Symptoms: An Immunohistochemical Study Investigating the COX-2/PGE-2/EP-4 Axis

Background ContextVertebral endplate defects are often implicated in degenerative disc disorders, yet their connection to patient-reported symptoms remains unclear. COX-2 and PGE-2 are known for their roles in inflammation and pain, with EP-4 receptor involvement in pain signaling. Examining their expression in vertebral endplate tissues may provide insights into pathomechanism of low back pain. PurposeTo investigate the association between endplate defects and patient-reported symptoms and to further clarify the role of the COX-2/PGE-2/EP-4 axis in the pathogenesis of chronic low back pain. Study Design/SettingRetrospective study Patient SampleA total of 71 patients who had undergone single-level L4/5 or L5/S1 modified laminectomy decompression preserving proximal upper laminae and transforaminal lumbar interbody fusion surgery were included in this study, including 18 patients diagnosed with lumbar disc herniation, 19 with lumbar disc herniation accompanied by degenerative lumbar spinal stenosis, and 34 with degenerative spondylolisthesis. Outcome MeasuresDemographic data, Pfirrmann grade, Modic changes, endplate defect score, visual analog scale (VAS) for back and leg pain, and Oswestry Disability Index (ODI) before surgery, 3-month and 6-month follow-up, and the percentage of immune-positive cells (COX-2, PGE-2, and EP-4) in endplate tissue sections. MethodsPatients were divided into Defect and Non-defect groups according to endplate morphology on lumbar MR. All intraoperative endplate specimens were immediately fixed in 10% formaldehyde, and then embedded in paraffin 3 days later for tissue sections. The outcome measures were compared between the Defect group and Non-defect group. Data were analyzed using independent t-tests and χ² tests. Pearson's rank correlation test was used to assess correlations between patient-reported symptoms and the percentage of immune-positive cells in the groups. Multivariable logistic regression models using the forward stepwise likelihood ratio method were used to identify the factors that were independently associated with endplate defects. ResultsThe age of Defect group was significantly higher than that of Non-defect group (52.5±7.7 vs. 57.2±9.1. P=0.024). There were no significant differences in gender, diagnosis, BMI, comorbidities, or surgical level between the two groups. Modic changes (Type Ⅱ/Type Ⅲ) were more common in patients of Defect group than Non-defect group (38.5% vs. 11.1%, P<0.001), and so was disc degeneration (Pfirrmann grade Ⅳ/Ⅴ) (69.2% vs. 33.3%, P<0.001). Defect group had significantly higher VAS-Back (6.5±2.0 vs. 4.9±1.6, P<0.001) and ODI scores (62.9±10.7 vs. 45.2±14.8, P<0.001) than Non-defect group, while there was no significant differences between the two groups during the 3 and 6-month follow-up after surgery. Histologically, Defect group was characterized by upregulation of COX-2, PGE-2, and EP-4 in endplate tissue sections. Both in Defect and Non-defect groups, VAS-Back showed moderate positive correlations with the expressions of COX-2 (r=0.643; r=0.558, p both<0.001), PGE-2 (r=0.611; r=0.640, p both<0.001), and EP-4 (r=0.643; r=0.563, p both<0.001). Multivariate regression analyses reveled that percentage of COX-2-positive cells was associated with endplate defects (OR=1.509, 95%CI [1.048∼2.171], P=0.027), as well as percentage of PGE-2-positive (OR=1.291, 95%CI [1.106∼1.508], P=0.001) and EP-4-positive cells (OR=1.284, 95%CI [1.048∼2.171], P=0.003). ConclusionsPatients with endplate defects had worse quality of life, more severe disc degeneration and Modic changes, and up-regulated COX-2/PGE-2/EP-4 axis expression in cartilage endplates in patients with defected endplates. Inflammatory factors may significantly contribute to the onset and progression of chronic low back pain in patients with endplate defects, consequently impacting patient-reported symptoms.

Activation of Nuclear Factor Erythroid 2-Related Factor 2 Antagonizes the Reactive Oxygen Species Modulator 1-Induced Oxidative Stress in Nucleus Pulposus Cells

This study investigates the role of Reactive Oxygen Species Modulator 1 (ROMO1) in oxidative stress within nucleus pulposus (NP) cells and its potential regulation by Nuclear factor erythroid 2-related factor 2 (Nrf2). Intervertebral disc samples from patients were collected, and ROMO1, Nrf2, collagen I/II levels were analyzed to establish their potential connection. Human NP cells were cultured and exposed to H2O2 to induce oxidative stress. To elucidate ROMO1’s impact on NP cell metabolism, NP cells were transfected with ROMO1. Concurrently, Nrf2 activators and inhibitors were used to modulate Nrf2 expression during culturing. Oxidative stress was assessed through CAT and SOD1 gene expression analysis and measurement of cellular reactive oxygen species (ROS) production. NP cell status was determined by evaluating cell viability and collagen I/II expression. Results indicated elevated ROMO1 expression in severe intervertebral disc degeneration (IDD) and after H2O2 treatment. ROMO1 overexpression increased ROS production, suppressed CAT, SOD, and collagen II expression, while elevating collagen I and negatively affecting cell viability. However, Nrf2 activation effectively suppressed ROMO1 expression and protected NP cells from oxidative stress induced by H2O2 or ROMO1. In conclusion, ROMO1 exacerbates oxidative stress and contributes to NP cell degeneration, a process mitigated by Nrf2 activation.

Viscoelastic hydrogels regulate adipose-derived mesenchymal stem cells for nucleus pulposus regeneration

Low back pain is a leading cause of disability worldwide, often attributed to intervertebral disc (IVD) degeneration with loss of the functional nucleus pulposus (NP). Regenerative strategies utilizing biomaterials and stem cells are promising for NP repair. Human NP tissue is highly viscoelastic, relaxing stress rapidly under deformation. However, the impact of tissue-specific viscoelasticity on the activities of adipose-derived stem cells (ASC) remains largely unexplored. Here, we investigated the role of matrix viscoelasticity in regulating ASC differentiation for IVD regeneration. Viscoelastic alginate hydrogels with stress relaxation time scales ranging from 100s to 1000s were developed and used to culture human ASCs for 21 days. Our results demonstrated that the fast-relaxing hydrogel significantly enhanced ASCs long-term cell survival and NP-like extracellular matrix secretion of aggrecan and type-II collagen. Moreover, gene expression analysis revealed a substantial upregulation of the mechanosensitive ion channel marker TRPV4 and NP-specific markers such as SOX9, HIF-1α, KRT18, CDH2 and CD24 in ASCs cultured within the fast-relaxing hydrogel, compared to slower-relaxing hydrogels. These findings highlight the critical role of matrix viscoelasticity in regulating ASC behavior and suggest that viscoelasticity is a key parameter for novel biomaterials design to improve the efficacy of stem cell therapy for IVD regeneration. Statement of significance•Systematically characterized the influence of tissue-mimetic viscoelasticity on ASC.•NP-mimetic hydrogels with tunable viscoelasticity and tissue-matched stiffness.•Long-term survival and metabolic activity of ASCs are substantially improved in the fast-relaxing hydrogel.•The fast-relaxing hydrogel allows higher rate of cell protrusions formation and matrix remodeling.•ASC differentiation towards an NP-like cell phenotype is promoted in the fast-relaxing hydrogel, with more CD24 positive expression indicating NP committed cell fate.•The expression of TRPV4, a molecular sensor of matrix viscoelasticity, is significantly enhanced in the fast-relaxing hydrogel, indicating ASC sensing matrix viscoelasticity during cell development.•The NP-specific ECM secretion of ASC is considerably influenced by matrix viscoelasticity, where the deposition of aggrecan and type-II collagen are significantly enhanced in the fast-relaxing hydrogel.

Engineered extracellular vesicle-based gene therapy for the treatment of discogenic back pain

Painful musculoskeletal disorders such as intervertebral disc (IVD) degeneration associated with chronic low back pain (termed “Discogenic back pain”, DBP), are a significant socio-economic burden worldwide and contribute to the growing opioid crisis. Yet there are very few if any successful interventions that can restore the tissue's structure and function while also addressing the symptomatic pain. Here we have developed a novel non-viral gene therapy, using engineered extracellular vesicles (eEVs) to deliver the developmental transcription factor FOXF1 to the degenerated IVD in an in vivo model. Injured IVDs treated with eEVs loaded with FOXF1 demonstrated robust sex-specific reductions in pain behaviors compared to control groups. Furthermore, significant restoration of IVD structure and function in animals treated with FOXF1 eEVs were observed, with significant increases in disc height, tissue hydration, proteoglycan content, and mechanical properties. This is the first study to successfully restore tissue function while modulating pain behaviors in an animal model of DBP using eEV-based non-viral delivery of transcription factor genes. Such a strategy can be readily translated to other painful musculoskeletal disorders.

1066 Comparative Outcome Using Expandable Versus Static Cage in Direct Lateral Interbody Fusion for Degenerative Lumbar Disc Disease

INTRODUCTION: Subsidence has been a common concern or complication in patients undergoing TLIF with an expandable cage or standalone DLIF with a static cage. It could lead to further complications such as pseudoarthrosis, lumbar kyphosis, and radiculopathy. Recently, expandable technology has emerged in lateral interbody fusion, which could be delivered through the smaller surgical corridors. Therefore we sought to determine the extent of radiological outcome and subsidence rate in patients with expandable cages. METHODS: A retrospective review of patients who underwent DLIF was performed. Only patients with degenerative lumbar disc disease were included. Baseline demographic and radiographic outcomes such as cage subsidence, anterior and posterior disc height, foraminal dimensions, and other spinopelvic parameters were collected. The primary endpoint was severe cage subsidence (grade 2 and 3) per level according to the classification by Marchi et al. Multivariate Analysis was performed. RESULTS: 59 patients underwent DLIF with expandable (n = 25) and static (n = 34) cages respectively. Both expandable and static groups have comparable baseline demographic such as age, gender, BMI, and medical comorbidities. The average follow-up period was 16 months. Both groups also had a comparable rate of the standalone construct (40% vs 68%, p 0.088). Significant higher cage width and length were used in the expandable group. However, there were no statistically significant differences in the restoration of both anterior and posterior disc heights, foraminal height, and central canal diameter. A significantly lower rate of severe subsidence was observed in the expandable group (4% vs 26.5%, p = 0.023) compared to the static group. CONCLUSIONS: In our study, expandable cages in DLIF patients were observed to have a significantly lower rate of subsidence when compared to those who received static cages.

Transient Receptor Potential Vanilloid 4 Regulates Extracellular Matrix Composition and Mediates Load-Induced Intervertebral Disc Degeneration in a Mouse Model

ObjectiveTransient receptor potential vanilloid 4 (TRPV4) is a multi-modally activated cation channel that mediates mechanotransduction pathways by which musculoskeletal tissues respond to mechanical load and regulate tissue health. Using conditional Trpv4 knockout mice, we investigated the role of Trpv4 in regulating intervertebral disc (IVD) health and injury-induced IVD degeneration. MethodsCol2Cre;Trpv4fl/f (Trpv4 KO) mice were used to knockout Trpv4 in all type 2 collagen-expressing cells. Effects of gene targeting alone was assessed in lumbar spines, using vertebral bone length measurement, histological, immunohistochemistry and gene expression analyses, and mechanical testing. Disc puncture was performed on caudal IVDs of wild-type (WT) and Trpv4 KO mice at 2.5- and 6.5-months-of-age. 6 weeks after puncture (4- and 8-months-of-age at sacrifice), caudal spines were assessed using histological analyses. ResultsWhile loss of Trpv4 did not significantly alter vertebral bone length and tissue histomorphology compared to age-matched WT mice, Trpv4 KO mice showed decreased proteoglycan and PRG4 staining in the AF compared to WT. At the gene level, Trpv4 KO mice showed significantly increased expression of Acan, Bgn, and Prg4 compared to WT. Functionally, loss of Trpv4 was associated with significantly increased neutral zone length in lumbar IVDs. Following puncture, both Trpv4 KO and WT mice showed similar signs of degeneration at the site of injury. Interestingly, loss of Trpv4 prevented mechanically-induced degeneration in IVDs adjacent to sites of injury. ConclusionThese studies suggest a role for Trpv4 in regulating extracellular matrix synthesis and mediating the response of IVD tissues to mechanical stress.