Disc Cells Research Articles

Biology and mechanobiology of the intervertebral disc : Challenges for regenerative therapies

The fibrocartilaginous intervertebral discs between the vertebrae give the spine mobility and flexibility. Age and degeneration contribute to tissue changes that affect the composition and structure of the intervertebral discs and can lead to loss of function and back pain. The intervertebral disc cells are responsible for the formation and maintenance of the tissue and are influenced by the physiological load. Degenerative changes that promote tissue degradation are influenced by cellular responses to overuse, inflammation and nutrient deficiency. The mechanobiology of intervertebral discs deals with the interrelationships of the functional adaptation of this organ down to the cellular and molecular level and contributes to the understanding of the causes and consequences of degeneration. Based on these findings, the challenges for suitable regenerative therapy concepts can be understood.

The proteomic landscape of extracellular vesicles derived from human intervertebral disc cells.

Extracellular vesicles (EVs) function as biomarkers and are crucial in cell communication and regulation, with therapeutic potential for intervertebral disc (IVD)-related low back pain (LBP). EV cargo is often affected by tissue health, which may affect the therapeutic potential. There is currently limited knowledge of how the cargo of IVD cell-derived EVs varies with tissue health and how differences in proteomic profile affect the predicted biological functions. Our study purified EVs from human IVD cell conditioned media by size-exclusion chromatography. Nanoparticle tracking analysis was conducted to measure EV size and concentration. Transmission electron microscopy and Western blot were performed to examine EV structure and markers. Tandem mass tag-mass spectrometry was conducted to determine protein cargo. Most EVs were exosomes and intermediate microvesicles with an increasing amount linked to disease progression. Of the proteins detected, 88.6% were shared across the non-degenerate, mildly-degenerate, and degenerate samples. GO and KEGG analyses revealed that cargo from the mildly-degenerate samples was the most distinct, with the proteins in high abundance strongly associated with extracellular matrix (ECM) organization and structure. Shared proteins, highly expressed in the non-degenerate and degenerate samples, showed strong associations with cell adhesion, ECM-receptor interaction, and vesicle-mediated transport, respectively. Our findings indicate that EVs from IVD cells from tissue with different degrees of degeneration share a majority of the cargo proteins. However, the level of expression differs with degeneration grade. Cargo from the mildly-degenerate samples exhibits the most differences. A better understanding of changes in EV cargo in the degenerative process may provide novel information related to molecular mechanisms underlying IVD degeneration and suggest new potential treatment modalities for IVD-related LBP.

The Role of the Bone Morphogenetic Protein Antagonist Noggin in Nucleus Pulposus Intervertebral Disc Cells.

Low back pain (LBP) is a significant global health issue, contributing to disability and socioeconomic burdens worldwide. The degeneration of the human intervertebral disc (IVD) is a critical factor in the pathogenesis of LBP. Recent studies have emphasized the significance of a specific set of genes and extracellular matrix (ECM) in IVD health. In particular, Noggin has emerged as a critical gene due to its high expression levels in healthy nucleus pulposus cells (NPCs) observed in our previous research. In this study, it was hypothesized that decreased Noggin expression in NPCs is associated with IVD degeneration and contributes to LBP development. A lentivirus-mediated RNAi was applied to knock down Noggin expression in primary NPCs from six human donors. The NPCs after transduction were evaluated through cell viability analysis, XTT assay, and cell apoptosis analyses. After two weeks, a colony formation assay was used to examine the anchor-independent growth ability of transduced cells. At the transcript level, anabolic and catabolic markers were quantified using RT-qPCR. The results demonstrated that lentivirus-mediated downregulation of Noggin significantly inhibited cell proliferation, reduced cell viability, and suppressed colony formation, while inducing apoptosis in human NPCs in vitro. Notably, it disrupted cellular anabolic processes and promoted catabolic activity in human NPCs post-transduction. Our findings indicated that the degeneration of human IVD is possibly related to decreased Noggin expression in NPCs. This research provides valuable insights into the role of Noggin in IVD homeostasis and its implications in LBP treatment.

Unveiling the Gut-Disc Axis: How Microbiome Dysbiosis Accelerates Intervertebral Disc Degeneration.

The gut microbiome (GM), often referred to as the second genome of the human body, plays a crucial role in various metabolic processes and mediates the development of numerous diseases. Intervertebral disc degeneration (IDD) is an age-related degenerative spinal disease characterized by the loss of disc height, hydration, and integrity, leading to pain and reduced mobility. Although the pathogenesis of IDD is not fully understood, recent studies suggest that dysbiosis of the gut microbiome may accelerate the progression of IDD through multiple mechanisms. This article begins by discussing the potential relationship between GM dysbiosis and human diseases, followed by a comprehensive review of the regulatory mechanisms of GM in skeletal diseases within the gut-disc axis framework. Furthermore, it explores three potential pathways through which GM dysbiosis may mediate the development of IDD: immunomodulation, bacterial translocation and colonization, and the decomposition and absorption of intestinal metabolites. These pathways can disrupt disc cell homeostasis and promote degenerative changes. Finally, this paper summarizes for the first time the potential therapeutic approaches for delaying IDD by targeting the gut-disc axis, providing new insights into the pathogenesis and regenerative repair strategies for IDD.

Short Link N Modulates Inflammasome Activity in Intervertebral Discs Through Interaction with CD14.

Intervertebral disc degeneration and pain are associated with the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing 3 (NLRP3) inflammasome activation and the processing of interleukin-1 beta (IL-1β). Activation of thehm inflammasome is triggered by Toll-like receptor stimulation and requires the cofactor receptor cluster of differentiation 14 (CD14). Short Link N (sLN), a peptide derived from link protein, has been shown to modulate inflammation and pain in discs in vitro and in vivo; however, the underlying mechanisms remain elusive. This study aims to assess whether sLN modulates IL-1β and inflammasome activity through interaction with CD14. Disc cells treated with lipopolysaccharides (LPS) with or without sLN were used to assess changes in Caspase-1, IL-1β, and phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB). Peptide docking of sLN to CD14 and immunoprecipitation were performed to determine their interaction. The results indicated that sLN inhibited LPS-induced NFκB and Caspase-1 activation, reducing IL-1β maturation and secretion in disc cells. A significant decrease in inflammasome markers was observed with sLN treatment. Immunoprecipitation studies revealed a direct interaction between sLN and the LPS-binding pocket of CD14. Our results suggest that sLN could be a potential therapeutic agent for discogenic pain by mitigating IL-1β and inflammasome activity within discs.

Type V collagen exhibits distinct regulatory activities in TMJ articular disc versus condylar cartilage during postnatal growth and remodeling

Understanding matrix molecular activities that regulate the postnatal growth and remodeling of the temporomandibular joint (TMJ) articular disc and condylar cartilage will enable the development of effective regenerative strategies targeting TMJ disorders. This study elucidated the distinct roles of type V collagen (collagen V) in regulating these two units. Studying the TMJ of young adult Col5a1+/− mice, we found that loss of collagen V resulted in substantial changes in the proliferation, clustering and density of progenitors in condylar cartilage, but did not have a major impact on disc cells that are more fibroblast-like. Although loss of collagen V led to thickened collagen fibrils with increased heterogeneity in the disc, there were no significant changes in local micromodulus, except for a reduction at the posterior end of the inferior side. Following the induction of aberrant occlusal loading by the unilateral anterior crossbite (UAC) procedure, both wild-type (WT) and Col5a1+/− condylar cartilage exhibited salient remodeling, and Col5a1+/− condyle developed more pronounced degeneration and tissue hypertrophy at the posterior end than the WT. In contrast, neither UAC nor collagen V deficiency induced marked changes in the morphology or biomechanical properties of the disc. Together, our findings highlight the distinct roles of collagen V in regulating these two units during postnatal growth and remodeling, emphasizing its more crucial role in condylar cartilage due to its impact on the highly mechanosensitive progenitors. These results provide the foundation for using collagen V to improve the regeneration of TMJ and the care of patients with TMJ disorders. Statement of significanceSuccessful regeneration of the temporomandibular joint (TMJ) articular disc and condylar cartilage remains a significant challenge due to the limited understanding of matrix molecular activities that regulate the formation and remodeling of these tissues. This study demonstrates that collagen V plays distinct and critical roles in these processes. In condylar cartilage, collagen V is essential for regulating progenitor cell fate and maintaining matrix integrity. In the disc, collagen V also regulates fibril structure and local micromechanics, but has a limited impact on cell phenotype or its remodeling response. Our findings establish collagen V as a key component in maintaining the integrity of these two units, with a more crucial role in condylar cartilage due to its impact on progenitor cell activities.

Protein Kinase C and Matrix Metalloproteinases Expression Using Phorbol Myristate Acetate in Degenerative Intervertebral Disc Cells.

Degeneration of nucleus pulposus (NP) cells involves multiple factors. The relationship between the canonical Wnt/β-catenin signaling pathway and matrix metalloproteinases (MMPs) is important in cellular senescence. Protein kinase C (PKC), an intermediate of the non-canonical Wnt pathway stimulated by phorbol myristate acetate (PMA), possibly prevents NP cell senescence, although not yet demonstrated in human-based studies. This study aimed to investigate the effect of PMA stimulation on the non-canonical and canonical Wnt pathways and MMP expression in human NP cells to ascertain its inhibitory effects on the senescence of NP cells. Human disc tissues of Pfirrmann grades 1 and 2 were collected from patients during spinal surgery and subsequently cultured. Protein and ribonucleic acid (RNA) were isolated from NP cells treated with PMA (400 nM) for 24 hours. Expression of MMP1, MMP13, tissue inhibitor of matrix metalloproteinase 1 (TIMP1), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), transient receptor potential vanilloid 4 (TRPV4), interleukin-6 (IL-6), and β-catenin were detected using western blot analysis. Messenger RNA (mRNA) expression of type II collagen and glycosaminoglycan (GAG) were analyzed using reverse transcription polymerase chain reaction. IL-6 and prostaglandin E2 (PGE2) levels were measured using enzyme-linked immunosorbent assay. Expression of PKC-δ (intermediate of the non-canonical Wnt pathway) and β-catenin (intermediate of the canonical Wnt pathway) was increased by PMA treatment. The mRNA levels of type II collagen and GAG increased; however, their protein levels were not altered. PMA treatment increased the expression of MMP1, TIMP1, ADAMTS5, IL-6, PGE2, and TRPV4; however, the expression of MMP13 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was unaltered. PMA activated PKC-δ, affecting the non-canonical Wnt pathway; however, its effect on β-catenin in the canonical Wnt pathway was limited. β-catenin activation through the TRPV4 channel led to increased expression of MMP1 and ADAMTS5 and that of IL-6 and PGE2 owing to NF-κB expression. Consequently, the degeneration of NP cells was not prevented.

Simplified Polynomial-asymptotic-distribution Actuator Disc (SPAD) method for wind turbine wake simulation based on k-[formula omitted]-[formula omitted] turbulence model

In large wind farms, wake effect has a negative impact on the annual production of wind turbines. As a result, wind turbine wake simulation is important for wind farm micro-sitting to minimize power loss and maximize energy production. Coupled with Reynolds Averaged Navier–Stokes turbulence model, Simplified Uniform-distribution Actuator Disc method is the most widely-used rotor model for wake simulation in engineering practice. The conventional simplified uniform-distribution actuator disc models suffer discrepancies of wake velocity prediction compared with the measurements in the near wake region. The novelty of the current research is to propose a Simplified Polynomial-asymptotic-distribution Actuator Disc method based on k−ϵ−fP turbulence model for cylindrical actuator disc cell region with finite thickness, which is simple for implementation and improves the accuracy of wake simulation compared with conventional method. The proposed method conforms to momentum conservation and is as simple as conventional method because of its polynomial formulation and no requirement for aerodynamics data in Generalized Actuator Disc model. From the verification and validation cases, it can be found that the proposed model has better agreement with both high-fidelity actuator line model and the field test measurements from Lillgrund wind farm compared with conventional model. The proposed actuator disc model has the potential to be applied to the micrositting of large offshore wind farms in the future.

The Expression of Toll-like Receptors in Cartilage Endplate Cells: A Role of Toll-like Receptor 2 in Pro-Inflammatory and Pro-Catabolic Gene Expression.

The vertebral cartilage endplate (CEP), crucial for intervertebral disc health, is prone to degeneration linked to chronic low back pain, disc degeneration, and Modic changes (MC). While it is known that disc cells express toll-like receptors (TLRs) that recognize pathogen- and damage-associated molecular patterns (PAMPs and DAMPs), it is unclear if CEP cells (CEPCs) share this trait. The CEP has a higher cell density than the disc, making CEPCs an important contributor. This study aimed to identify TLRs on CEPCs and their role in pro-inflammatory and catabolic gene expression. Gene expression of TLR1-10 was measured in human CEPs and expanded CEPCs using quantitative polymerase chain reaction. Additionally, surface TLR expression was measured in CEPs grouped into non-MC and MC. CEPCs were stimulated with tumor necrosis factor alpha, interleukin 1 beta, small-molecule TLR agonists, or the 30 kDa N-terminal fibronectin fragment. TLR2 signaling was inhibited with TL2-C29, and TLR2 protein expression was measured with flow cytometry. Ex vivo analysis found all 10 TLRs expressed, while cultured CEPCs lost TLR8 and TLR9 expression. TLR2 expression was significantly increased in MC1 CEPCs, and its expression increased significantly after pro-inflammatory stimulation. Stimulation of the TLR2/6 heterodimer upregulated TLR2 protein expression. The TLR2/1 and TLR2/6 ligands upregulated pro-inflammatory genes and matrix metalloproteases (MMP1, MMP3, and MMP13), and TLR2 inhibition inhibited their upregulation. Endplate resorptive capacity of TLR2 activation was confirmed in a CEP explant model. The expression of TLR1-10 in CEPCs suggests that the CEP is susceptible to PAMP and DAMP stimulation. Enhanced TLR2 expression in MC1, and generally in CEPCs under inflammatory conditions, has pro-inflammatory and pro-catabolic effects, suggesting a potential role in disc degeneration and MC.

Dysregulated lipid metabolism and intervertebral disc degeneration: the important role of ox-LDL/LOX-1 in endplate chondrocyte senescence and calcification

BackgroundLipid metabolism disorders are associated with degeneration of multiple tissues and organs, but the mechanism of crosstalk between lipid metabolism disorder and intervertebral disc degeneration (IDD) has not been fully elucidated. In this study we aim to investigate the regulatory mechanism of abnormal signal of lipid metabolism disorder on intervertebral disc endplate chondrocyte (EPC) senescence and calcification. MethodsHuman intervertebral disc cartilage endplate tissue, cell model and rat hyperlipemia model were performed in this study. Histology and immunohistochemistry were used to human EPC tissue detection. TMT-labelled quantitative proteomics was used to detect differential proteins, and MRI, micro-CT, safranin green staining and immunofluorescence were performed to observe the morphology and degeneration of rat tail intervertebral discs. Flow cytometry, senescence-associated β-galactosidase staining, alizarin red staining, alkaline phosphatase staining, DCFH-DA fluorescent probe, and western blot were performed to detect the expression of EPC cell senescence, senescence-associated secretory phenotype, calcification-related proteins and the activation of cell senescence-related signaling pathways. ResultsOur study found that the highly expressed oxidized low-density lipoprotein (ox-LDL) and Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) in human degenerative EPC was associated with hyperlipidemia (HLP). TMT-labelled quantitative proteomics revealed enriched pathways such as cell cycle regulation, endochondral bone morphogenesis and inflammation. The rat model revealed that HLP could induce ox-LDL, LOX-1, senescence and calcification markers high expression in EPC. Moreover, we demonstrated that ox-LDL-induced EPCs senescence and calcification were dependent on the LOX-1 receptor, and the ROS/P38-MAPK/NF-κB signaling pathway was implicated in the regulation of senescence induced by ox-LDL/LOX-1 in cell model.ConclusionsSo our study revealed that ox-LDL/LOX-1-induced EPCs senescence and calcification through ROS/P38-MAPK/NF-κB signaling pathway, providing information on understanding the link between lipid metabolism disorders and IDD.

A repeated strike loading organ culture model for studying compression-associated chronic disc degeneration.

Mechanical stress has been viewed as one of the key risk factors in accelerating the intervertebral disc degeneration process. The goal of the present study was to employ a repeated strike loading bovine caudal disc system to elucidate the pathophysiological impacts of cumulative mechanical stress on the disc. The discs in the model groups were subjected to two different mechanical stresses: one strike loading or repeated strike loading. The following indices were analyzed: histological morphology, glycosaminoglycan release, disc height, cell viability, apoptosis-related protein expression, and catabolism-related gene expression. Both mechanical stress modes induced degenerative changes in the discs by day 11, such as clefts and delamination of the annulus fibrosus; they increased glycosaminoglycan release. Cell viability was significantly decreased and catabolic gene expression was significantly up-regulated in the degenerative loading group and repeated strike loading group by day 9. These alterations remained evident in the annulus fibrosus tissue of the repeated strike loading group on day 11.Our data suggests that the repeated strike loading model adopted in this study could lead to degenerative changes in the disc organ model. Annulus fibrosus cells displayed a more noticeable response to mechanical stress damage and a slower recovery process, suggesting that the annulus fibrosus serves as a pivotal factor in disc degeneration due to mechanical stress injuries. The study also indicates that due to the gradual self-repair of intervertebral disc cells after injury, it is necessary to apply repeated strike loading on the disc at specific intervals when researching the repair of chronic disc injuries.

Diverse and multifunctional roles for perlecan (HSPG2) in repair of the intervertebral disc.

Perlecan is a widely distributed, modular, and multifunctional heparan sulfate proteoglycan, which facilitates cellular communication with the extracellular environment to promote tissue development, tissue homeostasis, and optimization of biomechanical tissue functions. Perlecan-mediated osmotic mechanotransduction serves to regulate the metabolic activity of cells in tissues subjected to tension, compression, or shear. Perlecan interacts with a vast array of extracellular matrix (ECM) proteins through which it stabilizes tissues and regulates the proliferation or differentiation of resident cell populations. Here we examine the roles of the HS-proteoglycan perlecan in the normal and destabilized intervertebral disc. The intervertebral disc cell has evolved to survive in a hostile weight bearing, acidic, low oxygen tension, and low nutrition environment, and perlecan provides cytoprotection, shields disc cells from excessive compressive forces, and sequesters a range of growth factors in the disc cell environment where they aid in cellular survival, proliferation, and differentiation. The cells in mechanically destabilized connective tissues attempt to re-establish optimal tissue composition and tissue functional properties by changing the properties of their ECM, in the process of chondroid metaplasia. We explore the possibility that perlecan assists in these cell-mediated tissue remodeling responses by regulating disc cell anabolism. Perlecan's mechano-osmotic transductive property may be of potential therapeutic application.

Vaginal Ovule Loaded with Bismuth Lipophilic Nanoparticles and Cetylpyridinium Chloride Inhibits Human Cervical Carcinoma and Candida albicans Growth.

Bismuth lipophilic nanoparticles (BisBAL NPs) and cetylpyridinium chloride (CPC) are antineoplastic and antimicrobial in vitro. As a next pre-clinical step, a clinically viable dosage form for vaginal application was developed. Compendial pharmacopeial tests (mass uniformity, disintegration, and compressive mechanics) and inductively coupled plasma optical emission spectroscopy were conducted on in-house developed glycerinated gelatin (60:15 v/w) vaginal ovules containing BisBAL NP-CPC. The antimycotic activity of BisBAL NP-CPC vaginal ovules was analyzed using disk diffusion and cell viability XTT assays. The antitumor properties of BisBAL NP-CPC vaginal ovules were assessed by cell viability MTT tests. BisBAL NP-CPC and drug-free vaginal ovules deposited into ex vivo porcine vaginas disaggregated without signs of adverse cytotoxicity within the timespan of clinical efficacy. BisBAL NP-CPC vaginal ovules demonstrated antifungal efficacy comparable to miconazole: C. albicans growth inhibition haloes in diffusion tests were 23 ± 0.968 mm (n = 3) for BisBAL NP-CPC and 20.35 ± 0.899 mm (n = 3) for miconazole. Likewise, BisBAL NP-CPC vaginal ovules reduced HeLa cell growth by 81%, outperforming the clinical reference of 500 μM 5-fluouracil, which induced a 70% growth inhibition. BisBAL NP-CPC incorporated into glycerinated gelatin vaginal ovules constitute an innovative drug delivery system for topical antimycotic and anti-cervical carcinoma treatments.

Establishment of a Rabbit Model of Adjacent Intervertebral Disk Degeneration After Lumbar Fusion and Fixation and Evaluation of Autophagy Factor Expression in Nucleus Pulposus Cells.

The objectives of this research were to establish an animal model of adjacent segment degeneration (ASD) bordering lumbar fusion and to investigate the expression of autophagy factors in nucleus pulposus cells of adjacent intervertebral disks. Twenty-four adult New Zealand white rabbits were enrolled and divided into two groups: group A (n=12) and group B (n=12). Posterolateral fusion and fixation were performed after intervertebral disk degeneration occurred in group A, and the rabbits were monitored for 6 months. Group B was the control group and did not undergo fusion surgery. These rabbits were monitored for 6 months. Real-time quantitative polymerase chain reaction and immunohistochemistry were performed to detect the mRNA and protein expressions of PTEN-induced kinase 1 (PINK1), Parkin, ADAMTS-4, and MMP-3. An external database, the GEO database, was used to examine the expression of these genes and analyze them for differential expression. After lumbar fusion in rabbits, the animal model of ASD exhibited gradual degeneration of adjacent intervertebral disks over time. Group A displayed significantly higher mRNA and protein expressions of PINK1 and MMP-3 but lower expression of ADAMTS-4 compared with group B (P<.05). The results analyzed in the GEO database showed that the expression of PINK1 was higher in group A than in group B, while the expression of ADAMTS-4 was lower in group A than in group B. After posterolateral lumbar fusion in rabbits, the animal ASD model showed gradual deterioration of adjacent intervertebral disks with prolonged follow-up. The findings indicate the important role of autophagy in the apoptosis of nucleus pulposus cells in adjacent intervertebral disks. [Orthopedics. 2024;47(4):e167-e173.].

Ras promotes germline stem cell division in Drosophila ovaries

The Ras family genes are proto-oncogenes that are highly conserved from Drosophila to humans. In Drosophila, RasV12 is a constitutively activated form of the Ras oncoprotein, and its function in cell-cycle progression is context dependent. However, how it influences the cell cycle of female germline stem cells (GSCs) still remains unknown. Using both wild-type GSCs and bam mutant GSC-like cells as model systems, here we determined that RasV12 overexpression promotes GSC division, not growth, opposite to that in somatic wing disc cells. Ras performs this function through activating the mitogen-activated protein kinase (MAPK) signaling. This signaling is activated specifically in the M phase of mitotic germ cells, including both wild-type GSCs and bam mutant GSC-like cells. Furthermore, RasV12 overexpression triggers polyploid nurse cells to die through inducing mitotic stress. Given the similarities between Drosophila and mammalian GSCs, we propose that the Ras/MAPK signaling also promotes mammalian GSC division.

Drosophila melanogaster как модель in vivo для оценки цитогенетических эффектов низкоинтенсивного ионизирующего излучения

The most important target of radiation damage is the cell nucleus. Structural and functional changes occurring in the nucleus under the influence of ionizing radiation affect the development of different biological effects at the cellular and organismal levels. In the present study, the Comet assay was used which makes it possible to assess the complex of DNA damage in different somatic cells of the body. The specificity of the cytogenetic effect of irradiation in low doses in Drosophila melanogaster has been established. The observed reactions depended not only on the irradiation dose and genotype but also on the type of DNA damage and tissue. In general, neuroblasts of individuals with low synthesis of cytoplasmic superoxide dismutase (sodn1/+) showed the highest sensitivity to irradiation in low doses. With an increase in the dose of ionizing radiation, the frequency of alkali-labile sites and DNA single-strand breaks in sodn1-genotype cells increased. The repair mutant genotypes, on the contrary, had radiosensitive traits exclusively at the level of DNA double-strand breaks. To a greater extent, an increase in the yield of radiation-induced DNA damage of this type was registered in cells of the imaginal disks of individuals with defect in the mechanisms of DNA double-strand break repair (okrA17-11/+), postreplicative repair, and meiotic recombination (mei-41D5/+). The genetically unstable strains used in the work have radiosensitive features which makes them convenient models for assessing the radioecological situation in the environment.

TNFR1-mediated senescence and lack of TNFR2-signaling limit human intervertebral disc cell repair in back pain conditions.

TNFR1 signaling drives cells towards senesce and muted inflammatory response in painful intervertebral disc degeneration, while limited TNFR2 signaling may limit disc cell repair responses.

A single-cell atlas of pig gastrulation as a resource for comparative embryology

Cell-fate decisions during mammalian gastrulation are poorly understood outside of rodent embryos. The embryonic disc of pig embryos mirrors humans, making them a useful proxy for studying gastrulation. Here we present a single-cell transcriptomic atlas of pig gastrulation, revealing cell-fate emergence dynamics, as well as conserved and divergent gene programs governing early porcine, primate, and murine development. We highlight heterochronicity in extraembryonic cell-types, despite the broad conservation of cell-type-specific transcriptional programs. We apply these findings in combination with functional investigations, to outline conserved spatial, molecular, and temporal events during definitive endoderm specification. We find early FOXA2 + /TBXT- embryonic disc cells directly form definitive endoderm, contrasting later-emerging FOXA2/TBXT+ node/notochord progenitors. Unlike mesoderm, none of these progenitors undergo epithelial-to-mesenchymal transition. Endoderm/Node fate hinges on balanced WNT and hypoblast-derived NODAL, which is extinguished upon endodermal differentiation. These findings emphasise the interplay between temporal and topological signalling in fate determination during gastrulation.

Nuclear factor κB overactivation in the intervertebral disc leads to macrophage recruitment and severe disc degeneration.

Persistent inflammation has been associated with severe disc degeneration (DD). This study investigated the effect of prolonged nuclear factor κB (NF-κB) activation in DD. Using an inducible mouse model, we genetically targeted cells expressing aggrecan, a primary component of the disc extra cellular matrix, for activation of the canonical NF-κB pathway. Prolonged NF-κB activation led to severe structural degeneration accompanied by increases in gene expression of inflammatory molecules (Il1b, Cox2, Il6, and Nos2), chemokines (Mcp1 and Mif), and catabolic enzymes (Mmp3, Mmp9, and Adamts4). Increased recruitment of proinflammatory (F4/80+,CD38+) and inflammatory resolving (F4/80+,CD206+) macrophages was observed within caudal discs. We found that the secretome of inflamed caudal disc cells increased macrophage migration and inflammatory activation. Lumbar discs did not exhibit phenotypic changes, suggestive of regional spinal differences in response to inflammatory genetic overactivation. Results suggest prolonged NF-κB activation can induce severe DD through increases in inflammatory cytokines, chemotactic proteins, catabolic enzymes, and the recruitment and activation of macrophage cell populations.

Allogeneic Disc Progenitor Cells Safely Increase Disc Volume and Improve Pain, Disability, and Quality of Life in Patients With Lumbar Disc Degeneration-Results of an FDA-Approved Biologic Therapy Randomized Clinical Trial.

Progenitor cells derived from intervertebral disc tissue demonstrated immunomodulatory and regenerative properties in preclinical studies. We report the safety and efficacy results of a US Food and Drug Administration-approved clinical trial of these cells for the treatment of symptomatic degenerative disc disease. Sixty patients with symptomatic single-level lumbar degenerative disc disease (mean age 37.9 years, 60% men) were enrolled in a randomized, double-blinded, placebo-controlled Phase I/Phase II study at 13 clinical sites. They were randomized to receive single intradiscal injections of either low-dose cells (N = 20), high-dose cells (N = 20), vehicle alone (N = 10), or placebo (N = 10). The primary endpoint was mean visual analog scale (VAS) pain improvement >30% at 52 weeks. Disc volume was radiologically assessed. Adverse events (AEs), regardless of whether they were related to treatment, were reported. Patients were assessed at baseline and at 4, 12, 26, 52, 78, and 104 weeks posttreatment. At week 52, the high-dose group had a mean VAS percentage decrease from baseline (-62.8%, P = 0.0005), achieving the endpoint of back pain improvement >30%; the mean change was also significantly greater than the minimal clinically important difference of a 20-point decrease (-42.8, P = 0.001). This clinical improvement was maintained at week 104. The vehicle group had a smaller significant decrease in VAS (-52.8%, P = 0.044), while the low-dose and placebo groups showed nonsignificant improvements. Only the high-dose group had a significant change in disc volume, with mean increases of 249.0 mm3 (P = 0.028) at 52 weeks and 402.1 mm3 (P = 0.028) at 104 weeks. A minority of patients (18.3%) reported AEs that were severe. Overall, 6.7% of patients experienced serious AEs, all in the vehicle (n = 1) or placebo (n = 3) groups, none treatment related. High-dose allogeneic disc progenitor cells produced statistically significant, clinically meaningful improvements in back pain and disc volume at 1 year following a single intradiscal injection and were safe and well tolerated. These improvements were maintained at 2 years post-injection. NCT03347708-Study to Evaluate the Safety and Preliminary Efficacy of Injectable Disc Cell Therapy, a Treatment for Symptomatic Lumbar Intervertebral Disc Degeneration.