Intervertebral disc (IVD) degeneration is a major contributor to low back pain, yet its initiating factors remain unclear. While the individual effects of pro-inflammatory cytokines and mechanical loading on IVDs have been studied, their combined impact is poorly understood. This study investigated how dynamic compression and torsion interact with interleukin-1 beta (IL-1β) and its inhibitor, interleukin-1 receptor antagonist (IL-1Ra), using bovine IVDs in an ex vivo organ culture system.
Whole bovine caudal IVDs were cultured for one week in a custom bioreactor applying diurnal dynamic compression (0.1–0.5 MPa) and torsion (±6°) under three media conditions: physiological, catabolic (10 ng/mL IL-1β), and inhibitory (10 ng/mL IL-1Ra). Static compression (0.1 MPa) served as control. 3 T magnetic resonance imaging (MRI) was used pre- and post-culture for imaging and segmentation using 3DSlicer. Subject-personalized finite element (FE) models were generated via morphing algorithms and coupled with a parallel network (PN) model to analyze metabolite transport and its impact on gene expression. Outcomes included disc height, glycosaminoglycan (GAG) content, qPCR, and cell metabolic activity.
Degenerative changes were detected in all treatment groups. Results of decreased disc height, hydration, and ACAN expression, alongside increased MMP-13, indicated that the applied loading was supraphysiological and induced catabolic responses. IL-1Ra, at the given dose, did not counteract degeneration. MRI-based FE modeling effectively captured patterns of tissue consolidation and degeneration, providing valuable insights into IVD responses under combined mechanical and inflammatory stress. This integrative platform highlights the importance of modeling complex IVD environments and may inform the design of improved anti-catabolic therapies.
The intervertebral disc (IVD) microenvironment plays a crucial role in cellular function and viability. Although the precise cause of IVD degeneration remains unclear, it is associated with progressive disruption of nutrient, metabolite, and pH homeostasis. Despite growing interest in regenerative therapies, the complex IVD microenvironment is often overlooked in preclinical development. This study investigates the effects of clinically relevant combinations of oxygen, glucose, pH, and osmolarity on the metabolic activity and matrix synthesis of goat nucleus pulposus (NP) cells.
Goat NP cells were embedded in 3D alginate beads and exposed to 24 distinct microenvironments across four factors in combination: oxygen (2% and 5%), glucose (0.5 and 1.0 mM), pH (6.5, 6.8, and 7.1), and osmolarity (350 and 500 mOsm). Alginate beads were primed for 10 days before subjection to altered microenvironmental conditions for a further 14 days. Cell viability, DNA content, glycosaminoglycan (GAG), and collagen synthesis, as well as oxygen consumption and lactate production rates, were quantified. Experimental data informed in silico modeling of a goat IVD, profiling nutrient and metabolite gradients and GAG accumulation to determine the effects of microenvironmental changes at the whole-organ level.
pH was the most influential factor, significantly reducing cell viability, DNA content, and GAG production under degenerated conditions at pH 6.5. Collagen production remained unchanged. Oxygen and glucose significantly affected metabolic rates. Combined analysis revealed the interdependent nature of these factors, better reflecting in vivo interactions. In silico modeling demonstrated that microenvironment-driven changes directly altered disc-wide nutrient profiles and long-term GAG accumulation.
These findings highlight the critical role of pH in regulating NP cell function and show that interactions between microenvironmental factors impact cell behavior more than isolated effects. Incorporating physiologically relevant microenvironments may improve regenerative therapy development and enhance translation from preclinical models to clinical application.
Intervertebral disc (IVD) degeneration is a major contributor to back pain and disability. The cause of IVD degeneration is multifactorial, with no disease-modifying treatments. Sex steroids, primarily testosterone and its derivatives, are becoming increasingly common in the clinic for the treatment of low back pain and continue to be used as ergogenic aids in sport. While outcomes at the level of pain and athletic performance are promising, little research has investigated the effects of these hormones on the biology of the IVD and how sex hormones may directly influence joint health and homeostasis.
Primary bovine nucleus pulposus (NP) and annulus fibrosus (AF) cells were isolated from 18-month-old female bovine caudal IVDs for primary cell culture. These cells were subjected to sex hormone stimulation (5α-dihydrotestosterone or 17β-estradiol) at increasing doses (0, 25, 50, 75, 100, 125 nM) with or without a pro-inflammatory stimulus (IL-1β; 10 ng/mL or TNFα; 25 ng/mL) to model healthy and pro-inflammatory environments, respectively. Cells were harvested for analysis of gene expression, cytokine secretion, and to assess NF-κB signaling.
In both NP and AF cells (dihydro)testosterone and 17β-estradiol decreased proinflammatory gene expression and cytokine release. Changes induced by sex hormones were cell-type dependent and specific to the inflammatory stimulus used. NP cells displayed a robust inflammatory response to IL-1β compared to TNFα, while AF cells responded to TNFα only, but only at the level of gene expression. Attenuation of inflammatory gene expression by sex hormone exposure was not associated with changes in p65 phosphorylation or NF-κB pathway associated gene expression.
Sex hormones such as dihydrotestosterone and estrogen play an important role mediating inflammatory signaling in cells of the IVD, finding which could lead to novel therapeutics for IVD degeneration.
This study investigated the effect of bone metastasis on the biomechanical environment of human vertebrae in patients with metastatic spine disease through the metric of load-to-strength ratio (LSR). Specifically, we compared the patients' LSRs to age and sex-similar noncancer controls from the Framingham Heart Study.
Derived from clinical CT data of 135 metastatic spine disease patients planned for radiotherapy and 246 normative controls from the Framingham Heart Study, individualized spinal musculoskeletal models and vertebral strength estimates were used to compute level-specific LSR under natural standing and three weight-holding conditions (standing + weight, flexion + weight, and lateral bending + weight).
Adjusted for age, BMI, and spinal region, osteosclerotic and mixed lesion vertebrae had higher strength than osteolytic and control vertebrae. The musculoskeletal models suggested breast, prostate, and male lung cancer patients had higher compressive vertebral loading, and female lung cancer patients had lower compressive vertebral loading than controls. Male patients had higher standardized LSRs in natural standing, while female patients had lower LSRs for all activities than controls. Independent of sex, vertebrae with osteosclerotic and mixed bone metastasis had lower LSRs than controls, while, for osteolytic bone lesions, males had higher and females lower LSRs than controls. Vertebrae with no observed lesion on CT had higher LSRs than controls in males and lower LSRs in females.
Our findings highlighted that primary cancer and lesion type differentially affected task-specific vertebral loading and strength, thus modifying the vertebral LSRs. Sex-mediated differences in LSRs between FHS controls and vertebrae with no observed metastatic lesions suggest that considering the latter as “normal” should be taken with care. Our initial assessment supports further examination of whether vertebral LSR measurements are associated with vertebral risk and, if so, what threshold values indicate risk.
3.
Ex vivo, multiscale analysis of disc strain using ultrahigh-field MRI-based digital volume correlation (MRI-DVC) and differential interference contrast (DIC) microscopy.
To evaluate the relationship between three-dimensional strain distributions and collagen fiber recruitment in porcine cervical intervertebral discs under flexion and lateral bending.
Flexion combined with lateral bending is often linked to disc herniation, yet the strain patterns and fiber-level changes in the annulus fibrosus are not well understood. Multiscale characterization is essential to uncovering failure mechanisms.
Four porcine cervical motion segments were scanned in neutral and anterolaterally (AL)-bent postures using 9.4T MRI, with 3D strains calculated via DVC. Samples were sectioned and imaged with DIC microscopy to quantify collagen fiber recruitment based on fiber crimp patterns, using a crimp grading scale (0 = fully straight, 1 = semi-crimped, 2 = uncrimped).
MRI-DVC revealed an inhomogeneous strain distribution in AL-bent discs, with higher magnitudes compared to the neutral discs. Fiber uncrimping was greater in the AL-bent discs (mean crimp grade: 0.44, mostly straight) compared with the neutral discs (1.56, predominantly crimped). Across the bending axis, the anterior-right region exhibited higher strains than the posterior-left (minimum principal strain ~25% greater), which correlated with the presence of sequential lamellae having straight and fully-crimped fibers. A greater amount of fiber uncrimping was observed in the posterior-left than anterior-right disc regions.
This study confirms the suitability of MRI-DVC combined with DIC microscopy for relating macroscopic strains to microscopic fiber crimp, and for identifying regions of high strain across multiple length scales. Under AL-bending, this methodology revealed that the disc's posterior region exhibited taut fibers, which may contribute to its susceptibility to herniation.
Extracellular vesicles (EVs) represent a promising cell-free regenerative therapy. Deciphering their mode and mechanism of action comes with technical and biological challenges. This scoping review presents a complementary perspective to reviews that synthesized EV therapeutic strategies in intervertebral disc (IVD) degeneration. It intends to create awareness of the minimal experimental requirements defined by the International Society for Extracellular Vesicles (MISEV). These have been established to facilitate robust and reproducible protocols in the rapidly expanding EV field, aiming to allow comparative studies, improve reproducibility, and interpretability.
The MISEV were tailored with IVD-related considerations. Within the timeframe 2016–2025, 129 articles studying EVs in the context of IVD were identified on PubMed. From each article, experimental information on EV isolation and characterization studies, and on functional studies was reviewed for compliance to the IVD-tailored MISEV.
The information reporting rates were 57% for EV characterization studies and 67% for EV functional studies. Information on EV nomenclature, storage, quantification, and methodological controls for functional studies specifically needs better reporting. Most studies explore EV functionality through conditioned media processed to be enriched for EVs. These EV-enriched media represent the secretome, the entire collection of secreted molecules, including EVs and co-isolates. In functional studies, intending to study biological effects driven by the EV-cargo, inclusion of key methodological MISEV controls is essential.
Here, we sketch and discuss the consolidated “EV-idence” of EV-mediated IVD tissue regeneration with studies that have specifically included the minimal MISEV requirements, i.e., (1) EV-depletion of serum when supplemented in culture medium and (2) inclusion of EV-depleted conditioned medium as a negative control. Although in several studies, EVs showed homeostatic effects and halted IVD degeneration, solid conclusions are constrained by the limited number of studies complying with the MISEV guidelines.
In addition to being highly prevalent and variable in its presentation, chronic low back pain (cLBP) has the unique challenge of having multi-faceted barriers to recovery [1-3]. This has resulted in high costs of care for people with cLBP, largely without associated improvements in pain, disability, and quality of life [4]. In fact, LBP is the 4th leading cause of global disability adjusted life years in individuals 25–49 years of age and 8th in those 50–74 years [5, 6]. While previous research has aimed to collect large datasets to identify key characteristics of persons with cLBP [7-10], most focused only on a few data domains. None have comprehensively compiled aspects from various research domains within the same individual. Given the multidimensional nature of cLBP, it is imperative to collect data on all of the features of cLBP and understand the key co-contributors to the experience of cLBP and potential barriers to recovery to optimize treatment approaches.
Together, these measurements, led by domain experts in their respective fields, have yielded an unprecedented dataset to facilitate understanding of the diverse characteristics contributing to the experience of cLBP. Moreover, by collecting this broad set of data from different scientific perspectives (biological, biomechanical, and behavioral) within the same participants, this work will facilitate examination of the interactions of these various components of cLBP to allow a more comprehensive assessment of cLBP.
Acknowledging the value to the community of this unique set of comprehensive characteristics collected for our cohort of persons with cLBP, herein we present the baseline features of our participants, and report data from the enrollment visits in domains including demographics and clinical characteristics, patient-reported outcomes, quantitative sensory testing, behaviors and activity, physical exam and performance, kinematics, and circulating inflammatory mediators. Future work will follow this valuable cohort longitudinally, collecting data on treatments experienced by our participants and patient-reported outcomes, and proposing advanced modeling to identify distinct cLBP subgroups or “phenotypes,” to be evaluated in future studies for their ability to predict response to treatment. The data will also be made publicly available through the HEAL data repository [12] to facilitate additional hypothesis testing and future study designs. It is hoped that sharing these data with the research, clinical, and stakeholder community will be catalytic in multi-disciplinary efforts to improve care for this important and widespread condition.
This work was supported by the National Institutes of Health, U19AR076725-01.
Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.
The natural environment within the nucleus pulposus (NP) is hypoxic, acidic, low in nutrition, and exerts a high osmotic pressure. NP cells have adapted to this harsh environment; however, in vitro conditions often fail to recapitulate this environment. Hence, this study aimed to develop media to mimic the conditions of the native NP, with regards to pH, osmolality, glucose, combined with culture in physioxia (5% O2), and determine their effects upon human NP cells and tissue.
All media utilized low glucose DMEM/serum free conditions with supplements supporting matrix synthesis, based on media recommended for alginate culture (standard media). Healthy media modulated osmolarity (425 mOsm/kg) and pH 7.2; degenerate media consisted of 325 mOsm/kg and pH 6.8. The latter was further supplemented with 100 pg/mL IL-1β (degenerate+IL-1β media). NP cells in 3D alginate and NP tissue explants were cultured in these media for up to 2 weeks in physioxia (5% O2) to determine effects on viability, mitochondrial activity, protein expression, and secretome.
Media osmolarity and pH remained stable and cell viability was not altered by any media composition. Mitochondrial activity was increased during short-term cultures, whilst a decrease was seen following 14 days in degenerate media. The secretome of NP cells was differentially affected in healthy or degenerate media, with most increases in catabolic cytokines observed following the addition of IL-1β. Tissue explants showed stability of protein expression of matrix components in both healthy and degenerate+IL-1β media, with limited effects seen on the secretome.
The media formulations developed here can provide more appropriate environmental conditions in vitro, mimicking more closely the in vivo conditions observed within healthy and degenerate IVDs. The application of which can provide more appropriate culture conditions to test potential therapeutic approaches and understand more fully the pathogenesis of disease using in vitro and ex vivo models.
Low back pain (LBP) is a leading cause of disability, often progressing to chronic low back pain (CLBP), which often involves facet joint degeneration. The Weishaupt grading system is widely used to evaluate facet joint degeneration, but precise, quantitative methods for early diagnosis are lacking. This study aims to develop a predictive model for facet joint degeneration using magnetic resonance imaging (MRI)-derived curve fitting and some radiographic parameters, enhancing early, quantitative assessment and providing more accurate analysis for effective treatment planning.
This study included 48 patients (161 joints), aged 20–80 years. Imaging parameters such as intervertebral space height (ISH), lumbar range of motion (ROM-L), intervertebral disc degeneration, facet joint degeneration, facet joint cross-sectional area (FJCSA), vertebral bone quality (VBQ) scores, subcutaneous fat tissue thickness (SFTT) and grayscale values of lumbar facet joint were analyzed. Statistical correlations were evaluated using spearman rank correlation and ordinal logistic regression. Curve fitting was performed to analyze and model the grayscale value changes in lumbar facet joints.
Correlation analysis revealed positive correlations between facet joint degeneration and intervertebral disc degeneration, FJCSA and SFTT, while negative correlations were observed with ISH and ROM-L. Ordinal logistic regression identified ROM-L and FJCSA as significant factors influencing degeneration. The locally estimated scatterplot smoothing (LOESS) curve fitting method of grayscale value for facet joint degeneration provided a more accurate predictive model, refining the joint degeneration grading system for improved quantitative assessment.
The study identified some radiographic factors, including ISH, FJCSA, ROM-L, SFTT and intervertebral disc degeneration, associated with facet joint degeneration. This study refined the joint degeneration grading system using LOESS curve fitting, providing a more quantitative approach for evaluating facet joint degeneration. This grading system offered greater precision and reliability in clinical assessments, supporting better diagnostic accuracy for patients with facet joint-related CLBP.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：