Molecular pathogenic factors in symptomatic disc degeneration

FOXO3-Activated HOTTIP Sequesters miR-615-3p away from COL2A1 to Mitigate Intervertebral Disc Degeneration

In this study, knockout of FOXO3 was found to impair intervertebral disc maturation and homeostasis in postnatal mice as well as facilitating extracellular matrix degradation. RNA sequencing can uncover disease-related gene expression and investigate disease pathophysiology. High-throughput transcriptome sequencing and experimental validations were used to identify the essential gene and mechanism involved in intervertebral disc degeneration (IDD). Nucleus pulposus (NP) tissue samples were collected from the mice with conditional knockout of FOXO3 (FOXO3 KO) for high-throughput sequencing, followed by screening of differentially expressed lncRNAs and mRNAs. The mRNAs were subjected to GO and KEGG enrichment analyses. Interactions among FOXO3, HOTTIP, miR-615-3p, and COL2A1 were analyzed. NP cells were subjected to a series of mimics, inhibitors, overexpression plasmids, and shRNAs to validate the mechanisms of FOXO3 in controlling HOTTIP/miR-615-3p/COL2A1 in IDD. Mechanistically, FOXO3 transcriptionally activated HOTTIP, facilitated the competitive HOTTIP binding to miR-615-3p, and increased the expression of the miR-615-3p target gene COL2A1. Thus, NP cell proliferation was induced, cell apoptosis was diminished, resulting in delayed development of IDD. Based on these data, the transcription factor FOXO3 may decrease miR-615-3p binding to COL2A1 and up-regulate COL2A1 expression by activating HOTTIP transcription, which in turn inhibits NP cell apoptosis and promotes its proliferation, to prevent the degradation of intervertebral disc matrix and maintain the normal physiological function of intervertebral disc, thereby preventing the occurrence and development of IDD.

Role of Apparent Diffusion Coefficient in Evaluating Degeneration of the Intervertebral Disc: A Narrative Review

Degeneration of the lumbar intervertebral disc is the most common cause of lower back pain. It is directly related to daily activities, mechanical stress, and other biological factors. We use imaging modalities to assess the degree of disc degeneration, out of which magnetic resonance imaging (MRI) is the most popular non-invasive modality. It is believed that early changes in disc degeneration are due to the biochemical events in the disc and can be evaluated by sequences in MRI involving the diffusion of water molecules. The apparent diffusion coefficient (ADC) is one such sequence that captures the signals based on the diffusion of water molecules. Ten articles were chosen from PubMed and Google Scholar using the MeSH terms 'lumbar spine degeneration' and 'apparent diffusion coefficient'. This review article has summarized various studies intending to gain a better understanding of the biochemical events leading to the development of disc degeneration. This study has also gathered the role of various sequences in MRI that can quantitatively assess disc degeneration.

The impact of matrix age on intervertebral disc regeneration

With the lack of effective treatments for low back pain, the use of extracellular matrix (ECM)-based biomaterials have emerged with undeniable promise for IVD regeneration. Decellularized scaffolds can recreate an ideal microenvironment inducing tissue remodeling and repair. In particular, fetal tissues have a superior regenerative capacity given their ECM composition. In line with this, we unraveled age-associated alterations of the nucleus pulposus (NP) matrisome. Thus, the aim of the present work was to evaluate the impact of ECM donor age on IVD de/regeneration. Accordingly, we optimized an SDS (0.1 %, 1 h)-based decellularization protocol that preserves ECM cues in bovine NPs from different ages. After repopulation with adult NP cells, younger matrices showed the highest repopulation efficiency. Most importantly, cells seeded on younger scaffolds produced healthy ECM proteins suggesting an increased capacity to restore a functional IVD microenvironment. In vivo, only fetal matrices decreased neovessel formation, showing an anti-angiogenic potential. Our findings demonstrate that ECM donor age has a strong influence on angiogenesis and ECM de novo synthesis, opening new avenues for novel therapeutic strategies for the IVD. Additionally, more appropriate 3D models to study age-associated IVD pathology were unveiled.

Comparisons between needle puncture and chondroitinase ABC to induce intervertebral disc degeneration in rabbits

PURPOSE

This study aimed to compare the effect of needle puncture and chondroitinase ABC (ChABC) injection on inducing intervertebral disc (IVD) degeneration (IVDD) in rabbits.

METHODS

Sixteen New Zealand white rabbits were used in this study. Briefly, the rabbits were divided into four groups. In the annulus fibrosis (AF) needle puncture group, a 16-G needle was used to puncture the L5-6 and L6-7 IVDs, while in the sham group, these IVDs were not punctured. In the ChABC group, 30 μL 0.5 Unit/mL ChABC was injected into L5-6 and L6-7 IVDs using a 26-G needle, while in the vehicle group, these IVDs were injected with 30 μL phosphate-buffered saline (PBS). X-ray and MRI scans were performed at the 4th, 12th and 16th weeks postoperatively. Histological, immunohistochemical and biochemical analyses were performed at the 16th week postoperatively.

RESULTS

Both needle puncture and ChABC successfully established IVDD in rabbits at 4th, 12th and 16th weeks, confirmed by X-ray and MRI scan. The progression of IVDD went in a time-dependent manner. The IVDD in the ChABC group was less severe than in the needle puncture group throughout the study. Aggrecan and type II collagen significantly decreased, while tumor necrosis factor-α and superoxide dismutase 2 increased in the needle puncture and ChABC groups, compared with the sham and PBS groups.

CONCLUSIONS

Both AF needle puncture and ChABC injection can successfully induce IVDD in rabbits. Compared with ChABC injection, AF needle puncture can induce more severe IVDD.

Single Impact Injury of Vertebral Endplates Without Structural Disruption, Initiates Disc Degeneration Through Piezo1 Mediated Inflammation and Metabolism Dysfunction

STUDY DESIGN

In vitro experimental study.

OBJECTIVE

To establish an axial impact injury model of intervertebral disc (IVD) and to investigate if a single impact injury without endplate structural disruption could initiate intervertebral disc degeneration (IDD), and what is the roles of Piezo1 in this process.

SUMMARY OF BACKGROUND DATA

Although IDD process has been confirmed to be associated with structural failures such as endplate fractures, whether a single impact injury of the endplates without structural disruption could initiate IDD remains controversial. Previous studies reported that Piezo1 mediated inflammation participated in the progression of IDD induced by mechanical stretch; however, the roles of Piezo1 in IVD impact injury remain unknown.

METHODS

Rats spinal segments were randomly assigned into Control, Low, and High Impact groups, which were subjected to pure axial impact loading using a custom-made apparatus, and cultured for 14 days. The degenerative process was investigated by using histomorphology, real-time Polymerase Chain Reaction(PCR), western-blot, immunofluorescence, and energy metabolism of IVD cell. The effects of Piezo1 were investigated by using siRNA transfection, real-time PCR, western-blot, and immunofluorescence.

RESULTS

The discs in both of the impact groups presented degenerative changes after 14 days, which showed significant up-regulation of Piezo1, NLRP3 inflammasome, the catabolic (MMP-9, MMP-13), and pro-inflammatory gene (IL-1β) expression than that of the control group (P < 0.05), accompanied by significantly increased release of ATP, lactate, nitric oxide (NO), and glucose consumption of IVD cells at first 7 days. Silencing Piezo1 reduced the activation of NLRP3 inflammasome and IL-1β expression in the nucleus pulposus induced by impact injury.

CONCLUSION

It demonstrated that not only fracture of the endplate but also a single impact injury without structural impairment could also initiate IDD, which might be mediated by activation of Piezo1 induced inflammation and abnormal energy metabolism of IVD cells.Level of Evidence: N/A.

Exogenous Parathyroid Hormone Alleviates Intervertebral Disc Degeneration through the Sonic Hedgehog Signalling Pathway Mediated by CREB

As an important hormone that regulates the balance of calcium and phosphorus, parathyroid hormone (PTH) has also been found to have an important function in intervertebral disc degeneration (IVDD). Our aim was to investigate the mechanism by which PTH alleviates IVDD. In this study, the PTH 1 receptor was found to be highly expressed in severely degenerated human nucleus pulposus (NP) cells. We found in the mouse model of IVDD that supplementation with exogenous PTH alleviated the narrowing of the intervertebral space and the degradation of the extracellular matrix (ECM) caused by tail suspension (TS). In addition, inflammation, oxidative stress, and apoptosis levels were significantly increased in the intervertebral disc tissues of TS-induced mice, and the activity of NP cells was decreased. TS also led to the downregulation of Sonic hedgehog (SHH) signalling pathway-related signal molecules in NP cells such as SHH, Smoothened, and GLI1. However, supplementation with exogenous PTH can reverse these changes. In vitro, PTH also promotes the activity of NP cells and the secretion of ECM. However, the antagonist of the SHH signalling pathway can inhibit the therapeutic effect of PTH on NP cells. In addition, a cAMP-response element-binding protein, as an important transcription factor, was found to mediate the promotion of PTH on the SHH signalling pathway. Our results revealed that PTH can alleviate IVDD by inhibiting inflammation, oxidative stress, and apoptosis and improving the activity of NP cells via activating the SHH signalling pathway.

The Roles of circRNAs in Intervertebral Disc Degeneration: Inflammation, Extracellular Matrix Metabolism, and Apoptosis

Low back pain (LBP) is seriously harmful to human health and produces heavy economic burden. And most scholars hold that intervertebral disc degeneration (IDD) is the primary cause of LBP. With the study of IDD, aberrant expression of gene has become an important pathogenic factor of IDD. Circular RNAs (circRNAs), as a kind of noncoding RNA (ncRNA), participate in the regulation of genetic transcription and translation and further affect the expression of inflammatory cytokine, metabolism of extracellular matrix (ECM), the proliferation and apoptosis of cells, etc. Therefore, maybe it will become a new therapeutic target for IDD. At present, our understanding of the mechanism of circRNAs in IDD is limited. The purpose of this review is to summarize the mechanism and related signaling pathways of circRNAs in IDD reported in the past. Particularly, the roles of circRNAs in inflammation, ECM metabolism, and apoptosis are emphasized.

A new immunometabolic perspective of intervertebral disc degeneration

Intervertebral disc (IVD) degeneration is a common finding on spine imaging that increases in prevalence with age. IVD degeneration is a frequent cause of low back pain, which is a leading cause of disability. The process of IVD degeneration consists of gradual structural change accompanied by severe alterations in metabolic homeostasis. IVD degeneration, like osteoarthritis, is a common comorbidity in patients with obesity and type 2 diabetes mellitus, two metabolic syndrome pathological conditions in which adipokines are important promoters of low-grade inflammation, extracellular matrix degradation and fibrosis. Impairment in white adipose tissue function, due to the abnormal fat accumulation in obesity, is characterized by increased production of specific pro-inflammatory proteins such as adipokines by white adipose tissue and of cytokines such as TNF by immune cells of the stromal compartment. Investigations into the immunometabolic alterations in obesity and type 2 diabetes mellitus and their interconnections with IVD degeneration provide insights into how adipokines might affect the pathogenesis of IVD degeneration and impair IVD function and repair. Toll-like receptor-mediated signalling has also been implicated as a promoter of the inflammatory response in the metabolic alterations associated with IVD and is thus thought to have a role in IVD degeneration. Pathological starvation, obesity and adipokine dysregulation can result in immunometabolic alterations, which could be targeted for the development of new therapeutics.

Fundamentals of Intervertebral Disc Degeneration

Lumbar disc degeneration is one of the leading causes of chronic low back pain. The degenerative cascade is often initiated by an imbalance between catabolic and anabolic processes in the intervertebral discs. As a consequence of extracellular matrix degradation, neoinnervation and neovascularization take place. Ultimately, this degenerative process results in disc bulging and loss of nucleus pulposus and water content and subsequent loss of disc height. Most patients respond to conservative management and surgical interventions well initially, yet a significant number of patients continue to suffer from chronic low back pain. Because of the high prevalence of long-term discogenic pain, regenerative biological therapies, including gene therapies, growth factors, cellular-based injections, and tissue-engineered constructs, have attracted significant attention in light of their potential to directly address the degenerative process. Understanding the pathophysiology of degenerative disc disease is important in both refining existing technologies and developing innovative techniques to reverse the degenerative processes in the discs. In this review, we aimed to cover the underlying pathophysiology of degenerative disc disease as well as its associated risk factors and give a comprehensive summary about the developmental, structural, radiological, and biomechanical properties of human intervertebral discs.

Comparison of the differentiation abilities of bone marrow-derived mesenchymal stem cells and adipose-derived mesenchymal stem cells toward nucleus pulposus-like cells in three-dimensional culture

Nucleus pulposus cell (NPC) transplantation can be a potential therapeutic approach for intervertebral disc degeneration (IDD). However, low cell viability has restricted the therapeutic capacity of NPCs, and sources of natural NPCs are limited. Bone marrow-derived mesenchymal stem cells (BMSCs) and adipose-derived mesenchymal stem cells (ADSCs) can be differentiated toward NPC-like cells. However, it is unknown whether there are differences in the abilities of these two cell types to differentiate into NPC-like cells, or which cell type exhibits the best differentiation ability. The present study compared the abilities of BMSCs and ADSCs to differentiate toward NPC-like cells with or without a 3D culture system to lay a foundation for stem cell transplantation therapy for IDD. BMSCs were isolated from the rat whole bone marrow cell using the repeated adherent culture method. ADSCs were isolated from rat adipose tissues in the subcutaneous inguinal region using the enzyme digestion method. Cells were identified using flow cytometry. Cell viability was assessed via Cell Counting Kit-8 assays, and reverse transcription-quantitative PCR and western blotting were carried out to evaluate the expression of NPC markers and chondrocyte-specific genes. Glycosaminoglycans (GAGs) and proteoglycans were examined via Alcian blue and safranin O staining, respectively. ADSCs in 3D culture displayed the highest cell proliferative ability, compared with the 2D culture system and BMSC culture. In addition, ADSCs in 3D culture exhibited increased GAG and proteoglycan synthesis than BMSCs. Compared with BMSCs in 3D culture, ADSCs in 3D culture exhibited higher mRNA and protein expression of NPC marker genes (hypoxia-inducible factor 1-α, glucose transporter 1) and chondrocyte-specific genes (Sox-9, aggrecan and type II collagen). The present findings indicated that ADSCs exhibited a better ability to differentiate into NPC-like cells in 3D culture compared with BMSCs, which may be of value for the regeneration of intervertebral discs using cell transplantation therapy.

Pathomechanism and Biomechanics of Degenerative Disc Disease: Features of Healthy and Degenerated Discs

The human intervertebral disc (IVD) is a complex organ composed of fibrous and cartilaginous connective tissues, and it serves as a boundary between 2 adjacent vertebrae. It provides a limited range of motion in the torso as well as stability during axial compression, rotation, and bending. Adult IVDs have poor innate healing potential due to low vascularity and cellularity. Degenerative disc disease (DDD) generally arises from the disruption of the homeostasis maintained by the structures of the IVD, and genetic and environmental factors can accelerate the progression of the disease. Impaired cell metabolism due to pH alteration and poor nutrition may lead to autophagy and disruption of the homeostasis within the IVD and thus plays a key role in DDD etiology. To develop regenerative therapies for degenerated discs, future studies must aim to restore both anatomical and biomechanical properties of the IVDs. The objective of this review is to give a detailed overview about anatomical, radiological, and biomechanical features of the IVDs as well as discuss the structural and functional changes that occur during the degeneration process.

Danshen Attenuates Intervertebral Disc Degeneration via Antioxidation in SD Rats

Objective

To investigate the effects of Danshen on the imaging and histological parameters, expression levels of ECM-associated proteins and inflammatory factors, and antioxidative activity in the degenerated intervertebral disc (IVD) of SD rats.

Methods

Sixty male rats were randomly divided into three groups (control, IDD, and Danshen IDD). Percutaneous needle puncture in Co8-9 intervertebral disc was conducted in all rats of the IDD and Danshen IDD groups to induce intervertebral disc degeneration (IDD). After operation, animals of the Danshen IDD group were administrated with Danshen granules (3 g/kg body weight ) by gavage once a day. Four weeks later, the coccygeal vertebrae were harvested and used for imaging (disc height and MR signal), histological, immunohistochemical, and biochemical [water content, glycosaminoglycans (GAG), superoxide dismutase (SOD2), glutathione (GSH), and malondialdehyde (MDA)] analyses.

Results

The puncture induced significant decreased IVD space and MR T2 signal at both 2 and 4 weeks, which were attenuated by Danshen treatment. The disc degeneration in the IDD group (HE and Safranin O-Fast Green histological staining was markedly more serious compared with that in the control group. Four weeks of Danshen treatment significantly alleviated this degeneration compared with the IDD group. Needle puncture resulted in the upregulation of IL-1β and TNF-α, MMP-3, and downregulation of COL2 and aggrecan in the IDD group. However, this change was significantly weakened by Danshen treatment. Significantly lower water and GAG content, as well as the SOD2 and GSH levels, in the IDD group were found compared with those in the control group. However, the above parameters of the Danshen IDD group were significantly higher than those of the IDD group. Danshen treatment significantly decreased the content of MDA which was increased by needle puncture in the IDD group.

Conclusion

Danshen can attenuate intervertebral disc degeneration in SD rats by suppressing the oxidation reaction.

Perspectives on the Treatment of Lumbar Disc Degeneration: The Value Proposition for a Cell-Based Therapy, Immunomodulatory Properties of Discogenic Cells and the Associated Clinical Evaluation Strategy

Low back pain (LBP) is a serious medical condition that affects a large percentage of the population worldwide. One cause of LBP is disc degeneration (DD), which is characterized by progressive breakdown of the disc and an inflamed disc environment. Current treatment options for patients with symptomatic DD are limited and are often unsuccessful, so many patients turn to prescription opioids for pain management in a time when opioid usage, addiction, and drug-related deaths are at an all-time high. In this paper, we discuss the etiology of lumbar DD and currently available treatments, as well as the potential for cell therapy to offer a biologic, non-opioid alternative to patients suffering from the condition. Finally, we present an overview of an investigational cell therapy called IDCT (Injectable Discogenic Cell Therapy), which is currently under evaluation in multiple double-blind clinical trials overseen by major regulatory agencies. The active ingredient in IDCT is a novel allogeneic cell population known as Discogenic Cells. These cells, which are derived from intervertebral disc tissue, have been shown to possess both regenerative and immunomodulatory properties. Cell therapies have unique properties that may ultimately lead to decreased pain and improved function, as well as curb the numbers of patients pursuing opioids. Their efficacy is best assessed in rigorous double-blinded and placebo-controlled clinical studies.

Holistic Approach of Swiss Fetal Progenitor Cell Banking: Optimizing Safe and Sustainable Substrates for Regenerative Medicine and Biotechnology

Safety, quality, and regulatory-driven iterative optimization of therapeutic cell source selection has constituted the core developmental bedrock for primary fetal progenitor cell (FPC) therapy in Switzerland throughout three decades. Customized Fetal Transplantation Programs were pragmatically devised as straightforward workflows for tissue procurement, traceability maximization, safety, consistency, and robustness of cultured progeny cellular materials. Whole-cell bioprocessing standardization has provided plethoric insights into the adequate conjugation of modern biotechnological advances with current restraining legislative, ethical, and regulatory frameworks. Pioneer translational advances in cutaneous and musculoskeletal regenerative medicine continuously demonstrate the therapeutic potential of FPCs. Extensive technical and clinical hindsight was gathered by managing pediatric burns and geriatric ulcers in Switzerland. Concomitant industrial transposition of dermal FPC banking, following good manufacturing practices, demonstrated the extensive potential of their therapeutic value. Furthermore, in extenso, exponential revalorization of Swiss FPC technology may be achieved via the renewal of integrative model frameworks. Consideration of both longitudinal and transversal aspects of simultaneous fetal tissue differential processing allows for a better understanding of the quasi-infinite expansion potential within multi-tiered primary FPC banking. Multiple fetal tissues (e.g., skin, cartilage, tendon, muscle, bone, lung) may be simultaneously harvested and processed for adherent cell cultures, establishing a unique model for sustainable therapeutic cellular material supply chains. Here, we integrated fundamental, preclinical, clinical, and industrial developments embodying the scientific advances supported by Swiss FPC banking and we focused on advances made to date for FPCs that may be derived from a single organ donation. A renewed model of single organ donation bioprocessing is proposed, achieving sustained standards and potential production of billions of affordable and efficient therapeutic doses. Thereby, the aim is to validate the core therapeutic value proposition, to increase awareness and use of standardized protocols for translational regenerative medicine, potentially impacting millions of patients suffering from cutaneous and musculoskeletal diseases. Alternative applications of FPC banking include biopharmaceutical therapeutic product manufacturing, thereby indirectly and synergistically enhancing the power of modern therapeutic armamentariums. It is hypothesized that a single qualifying fetal organ donation is sufficient to sustain decades of scientific, medical, and industrial developments, as technological optimization and standardization enable high efficiency.

Expression and role of Sphingosine 1-phosphate receptors in intervertebral disc degeneration

BACKGROUND

IVD degeneration is a widespread problem all over the world, which a variety of inflammatory cytokines have been implicated in, while Sphingosine 1-phosphate (S1P) is an important lipid mediator that may play a role in IVD degeneration.

OBJECTIVE

To study the expression and role of S1PRs in the intervertebal disc (IVD) degeneration to enhance understanding of disc degeneration.

METHODS

Degenerated and normal IVD were harvested from patients through surgery. Expression of S1P receptor subtypes was evaluated using real-time PCR, immunohistochemistry, and western blotting. The effect of S1PR on inflammation induced by interleukin-1β in nucleus pulposus (NP) cells was also assessed by real time PCR and western blotting.

RESULTS

The nucleus pulposus mainly expressed the S1PR1/2/3, and the expression decreased in the severe degenerated nucleus pulposus cells. The ligand, S1P, inhibited the up-regulation of matrix metallopeptidase-3 (MMP-3) and ADAM metallopeptidase with thrombospondin type 1 motif 4 (ADAMTS4) induced by IL-1β.

CONCLUSIONS

The results show that an the expression of S1PRs in degenerative discs is down-regulated as degeneration, and S1P can inhibit the inflammation response induced by IL-1β in NP cells, implicating that S1P/S1PR may contribute to IVD degeneration.

MiR-96 promotes apoptosis of nucleus pulpous cells by targeting FRS2

This study aimed to investigate the molecular mechanism by which microRNA (miR)-96 regulates the progression of intervertebral disc degeneration (IDD). The expression of miR-96 in normal intervertebral discs and in IDD was detected by performing reverse transcription-quantitative PCR. CCK8 assay was applied to examine the proliferation of nucleus pulpous (NP) cells and flow cytometry was used to evaluate the cell apoptosis and cell cycle profile. In addition, the immunofluorescence analysis was employed to detect cell proliferation. The expressions of proteins were assessed by western blot analysis. TargetScan and miRDB were used to predict the target genes of miR-96. The results indicated that miR-96 expression was upregulated in IDD compared with normal intervertebral discs. Overexpression of miR-96 could significantly inhibit the proliferation of NP cells via inducing apoptosis and G1 arrest. In addition, fibroblast growth factor receptor substrate 2 (FRS2) was identified as the target of miR-96 and overexpression of FRS2 could revere the effect of miR-96 mimics in NP cells. Therefore, these findings demonstrated that miR-96 plays a critical role during the progression of IDD and miR-96 may serve as a target for the treatment of IDD.

Intervertebral disc ageing and degeneration: The antiapoptotic effect of oestrogen

As an important part of the spinal column, the intervertebral disc (IVD) plays an important role in the intervertebral juncture and spinal movement in general. IVD degeneration (IVDD), which mimics disc ageing but at an accelerated rate, is a common and chronic process that results in severe spinal symptoms, such as lower back pain. It is generally assumed that lower back pain caused by IVDD can also develop secondary conditions, including spinal canal stenosis, spinal segmental instability, osteophyte formation, disc herniation and spinal cord and nerve root compression. Over the past few years, many researchers around the world have widely studied the relevance between oestrogen and IVDD, indicating that oestrogen can effectively alleviate IVDD development by inhibiting the apoptosis of IVD cells. Oestrogen can decrease IVD cell apoptosis in multiple ways, including the inhibition of the inflammatory cytokines IL-1β and TNF-α, reducing catabolism because of inhibition of matrix metalloproteinases, upregulating integrin α₂β₁ and IVD anabolism, activating the PI3K/Akt pathway, decreasing oxidative damage and promoting autophagy. In this article, we perform an overview of the literature regarding the antiapoptotic effect of oestrogen in IVDD.

Learning curve and clinical outcomes of percutaneous endoscopic transforaminal decompression for lumbar spinal stenosis

PURPOSE

To define and analyze the learning curve of percutaneous endoscopic transforaminal decompression (PETD) for lumbar spinal stenosis (LSS).

METHODS

From July 2015 to September 2016, 78 patients underwent PETD; one of whom was converted to open surgery, two were lost, and 75 were included in this study. Clinical results were assessed by using the Oswestry Disability Index (ODI) and visual analog scale (VAS). The learning curve was assessed by a logarithmic curve-fitting regression analysis. Of these 75 patients, 35 were defined as the "early" group, and 40 were defined as the "late" group for comparison.

RESULTS

The mean follow-up was 25.37 ± 4.71 months. The median operative time gradually decreased from 95 (interquartile range, IQR, 85-110) minutes for the early group to 70 (IQR, 60-80) minutes for the late group (P < .000), and an asymptote was reached after approximately 35 cases. After surgery, the VAS for leg pain (LP) and ODI decreased significantly and remained constant during the follow-up. However, the VAS of low back pain (LBP) increased mildly. The total complication rate was 6.6%. ODI, VAS of LP and of LBP, and complication rate did not significantly differ between two groups. Early ambulation and short hospital stay after surgery were achieved.

CONCLUSION

The learning curve of PETD for LSS was assessed and good clinical results were achieved. The surgeon's experience with this technique correlated with reduced operation time. Proper patient selection, familiarity with pathological anatomy, and manipulation under endoscopic view may shorten the learning curve and decrease complications.

Evaluation of Anti-inflammatory and Regenerative Efficiency of Naringin and Naringenin in Degenerated Human Nucleus Pulposus Cells: Biological and Molecular Modeling Studies

Study Design

Development of an in vitro model for assessing the anti-inflammatory efficacies of naringin (Nar) and naringenin (NG).

Purpose

To evaluate the efficacy of natural flavonoids as therapeutic drugs against anti-inflammatory processes in the nucleus pulposus (NP) cells using in-vitro and in-silico methods.

Overview of Literature

Intervertebral disc (IVD) disease is a common cause of low back pain. Chronic inflammation and degeneration play a significant role in its etiopathology. Thus, a better understanding of anti-inflammatory agents and their role in IVD degeneration and pro-inflammatory cytokines expression is necessary for pain management and regeneration in IVD.

Methods

We performed primary cell culture of NP cells; immunocytochemistry; gene expression studies of cytokines, metalloproteases, extracellular proteins, and apoptotic markers using quantitative polymerase chain reaction and reverse transcription-polymerase chain reaction (RT-PCR); cytotoxicity assay (MTT); and molecular docking studies using AutoDock 4.2 software (Molecular Graphics Laboratory, La Jolla, CA, USA) to confirm the binding mode of proteins and synthesized complexes. We calculated the mean±standard deviation values and performed analysis of variance and t-test using SPSS ver. 17.0 (SPSS, Inc., Chicago, IL, USA).

Results

Molecular docking showed that both Nar and NG bind to the selected genes of interest. Semi-quantitative RT-PCR analysis reveals differential gene expression of collagen (COL)9A1, COL9A2, COL9A3, COL11A2, COMT (catechol-O-methyltransferase), and THBS2 (thrombospondin 2); up regulation of ACAN (aggrecan), COL1A1, COL11A1, interleukin (IL)6, IL10, IL18R1, IL18RAP, metalloprotease (MMP)2, MMP3, MMP9, ADAMTS5 (a disintegrin and metalloproteinase with thrombospondin motifs 5), IGF1R (insulin-like growth factor type 1 receptor), SPARC (secreted protein acidic and cysteine rich), PARK2 (parkin), VDR (vitamin D receptor), and BCL2 (B-cell lymphoma 2); down regulation of IL1A, CASP3 (caspase 3), and nine genes with predetermined concentrations of Nar and NG.

Conclusions

The present study evaluated the anti-inflammatory and regenerative efficiencies of Nar and NG in degenerated human NP cells. Altered gene expressions of cytokines, metalloproteases, extracellular proteins, apoptotic genes were dose responsive. The molecular docking (in silico) studies showed effective binding of these native ligands (Nar and NG) with genes identified as potent inhibitors of inflammation. Thus, these natural flavonoids could serve as anti-inflammatory agents in the treatment of low back pain and sciatica.

Lessons learned from intervertebral disc pathophysiology to guide rational design of sequential delivery systems for therapeutic biological factors

Intervertebral disc (IVD) degeneration has been associated with low back pain, which is a major musculoskeletal disorder and socio-economic problem that affects as many as 600 million patients worldwide. Here, we first review the current knowledge of IVD physiology and physiopathological processes in terms of homeostasis regulation and consecutive events that lead to tissue degeneration. Recent progress with IVD restoration by anti-catabolic or pro-anabolic approaches are then analyzed, as are the design of macro-, micro-, and nano-platforms to control the delivery of such therapeutic agents. Finally, we hypothesize that a sequential delivery strategy that i) firstly targets the inflammatory, pro-catabolic microenvironment with release of anti-inflammatory or anti-catabolic cytokines; ii) secondly increases cell density in the less hostile microenvironment by endogenous cell recruitment or exogenous cell injection, and finally iii) enhances cellular synthesis of extracellular matrix with release of pro-anabolic factors, would constitute an innovative yet challenging approach to IVD regeneration.

Assessment of changes in the micro-nano environment of intervertebral disc degeneration based on Pfirrmann grade

BACKGROUND CONTEXT

Pfirrmann grading can be used to assess intervertebral disc degeneration (IVDD). There is growing evidence that IVDD is not simply a structural disorder but also involves changes to the substructural characteristics of the disc. Whether Pfirrmann grade can accurately represent these micro-nano environmental changes remains unclear.

PURPOSE

We aimed to assess the micro-nano structural characteristics of the degenerative disc to provide more specific biomechanical information than the Pfirrmann score.

STUDY DESIGN

A micro- and nano-level structural analysis of degenerative discs of rat tails.

METHODS

In this study, 12-week-old adult male Sprague-Dawley rats were divided randomly into five groups: control (no intervention to the intervertebral disc of the tail) and four intervention groups that all had caudal vertebrae immobilized using a custom-made external device to fix four caudal vertebrae (Co7-Co10) but with variable subsequent compression of Co8 and Co9 for 2, 4, 6, or 8 weeks. Magnetic resonance imaging detection of rat coccygeal vertebrae was conducted at each time node of the experiment, and the T2 signal intensity and disc space were evaluated. Animals were euthanized and the caudal vertebrae were harvested for further analysis. Histopathology, glycosaminoglycan (GAG) content, histologic score, end plate structure, and elastic modulus of the intervertebral discs were evaluated.

RESULTS

IVDD was observed at an earlier Pfirrmann grade (Pfirrmann II) under the microscope. With an increase in Pfirrmann grade to III-V, the pore structure of the bony end plate changed significantly and the number of pores decreased gradually. Furthermore, the total GAG content of the nucleus pulposus decreased from an average of 640.33 μg GAG/ng DNA in Pfirrmann grade I to 271.33 μg GAG/ng DNA in Pfirrmann grade V (p < .0001). At the early stage of clinical degeneration of intervertebral discs (Pfirrmann grades II and III), there were significant changes in mechanical properties of the outer annulus fibrosus compared with the inner layer (p < .05). Further, the fibril diameters exhibited significant changes compared with the control group (p < .05).

CONCLUSIONS

Our study found that the Pfirrmann grading system combined with intervertebral disc micro-nano structural changes more comprehensively reflected the extent of disc degeneration. These data may help improve our understanding of the pathogenesis and process of clinical disc degeneration.

Controlled immobilization-traction based on intervertebral stability is conducive to the regeneration or repair of the degenerative disc: an in vivo study on the rat coccygeal model

BACKGROUND CONTEXT

Previous studies have shown the potential for intervertebral disc tissue regeneration is very limited. While in vivo and in vitro studies have shown that traction can restore disc height and internal pressure, in many clinical studies it was shown that axial mechanical traction for the treatment of low back pain is ineffective.

PURPOSE

The aim of this study was to identify how the disc could be distracted, how to define the state of traction, and to further examine the feasibility of regenerating or restoring the degenerative disc by means of traction.

STUDY DESIGN

A macro- and microlevel structural analysis of degenerative discs of rat tail before and after controlled immobilization-traction.

METHODS

In this study, 49 6-month-old male Sprague-Dawley rats were randomly assigned to one of seven groups. Group A was the sham control group in which caudal vertebrae were instrumented with K-wires only. In Group B (model group), caudal vertebrae were immobilized using a custom-made external device to fix four caudal vertebrae (Co7-Co10) and Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration. In Group C, vertebrae Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration, followed by removal of the external apparatus. Rats in the other four groups (Groups D-G), Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration followed by 2 weeks, 4 weeks, 6 weeks, and 8 weeks of distraction, respectively. Caudal vertebrae were harvested and disc height, T2 signal intensity of the discs, disc morphology, total glycosaminoglycan content of the nucleus pulposus and the structure of the Co8-Co9 end plate were evaluated.

RESULTS

After 4 weeks of compression, the intervertebral height and T2 signal intensity of Co8-Co9 vertebrae of rats in Groups B to G were significantly reduced compared with Group A (sham group, all p<.0001). Histological scores of rats in Group B averaged 10.14 and the total glycosaminoglycan (GAG) of nucleus pulposus averaged 238.21μg GAG/ng DNA. The bony end plate structure showed significant changes in comparison with the control Group. After 2 weeks to 8 weeks of traction, the disc space and T2 signal intensity of Co8-Co9 vertebrae in Group E were significantly recovered compared to that of rats in Group B (p<.0001), and the intervertebral height of the Co8-Co9 in Group D, Group F, and Group G when compared with Group B (p<.0001). Meanwhile, the T2 signal intensity of Co8-Co9 in Group D, F, and G when compared with Group B (p<.001). Histological scores dropped from an average of 10.14 in Group B to 5.57 in Group E, and 5.86 in Group F (all p<.0001). Furthermore, the total GAG content of the nucleus pulposus increased from an average of 238.21μg GAG/ng DNA in Group B to 601.02μg GAG/ng DNA in Group E (p<.0001). The number of pores of end plates in rats in Groups D and E both were significantly increased when compared to that of rats in Group B (Groups D vs Groups B, p<.05; Groups E vs Groups B, p<.0001).

CONCLUSIONS

A mechanical degenerative model was successfully established by using a custom-made device. We demonstrated that disc degeneration is a cascade of biochemical, mechanical, and structural changes mediated by cells in an abnormal mechanical environment. Not all levels of disc degeneration can be regenerated or repaired. Regeneration or recovery of disc degeneration requires specific conditions. Based on the immobilization-traction mode, the cascade cycle of disc degeneration is interrupted. Traction of 2 to 6 weeks is a sensitive period for regeneration of the degenerative disc. Moreover, the duration and extent of the traction loading must be moderately controllable, and beyond the limits that can lead to significant degeneration. These data may help improve our understanding of the pathogenesis of clinical disc degeneration and how to optimize the use of traction devices for possible regeneration.

Computed tomography-guided sub-end plate injection of pingyangmycin for a novel rabbit model of slowly progressive disc degeneration

BACKGROUND CONTEXT

Different animal models are used in disc degenerative disease research by now. To our knowledge, a functional animal model that mimics ischemic and slowly progressive disc degeneration of humans does not exist.

STUDY DESIGN

This is an experimental animal study of disc degeneration.

PURPOSE

The purpose of this study was to establish an ischemic and slowly progressive intervertebral disc (IVD) degeneration model with an injection of pingyangmycin (PYM) into subchondral bone adjacent to the disc, using bone marrow needle guided by computed tomography (CT) scan.

METHODS

The subchondral bone adjacent to the lumbar IVDs (from L3-L4 to L5-L6) of 18 rabbits was randomly injected with 3 mL PYM solution (1.5 mg/mL PYM), 3 mL phosphate-buffered saline (vehicle control), or exteriorized but not injected with anything (sham), with using bone marrow needle guided by CT scan. The degenerative process was investigated by using radiography and magnetic resonance imaging at 1, 3, and 6 months postoperatively, combined with histological scoring, immunohistochemistry, and real-time polymerase chain reaction analysis.

RESULTS

Significant disc space narrowing was observed at 6 months in the discs adjacent to the subchondral bone injected with PYM, compared with the control groups (p<.05). The magnetic resonance imaging assessment also demonstrated a progressive loss of T2-weighted signal intensity postoperatively. The histological score increased significantly compared with that of the control groups from 3 months to the end point (p<.05). The bone tissue area of the end plate increased significantly at the end point, compared with that of the control groups (p<.05). The results of molecular analysis showed significant increase of matrix metalloproteinase-3, a disintegrin and metalloproteinase with thrombospondin motif-5, and marked reduction of aggrecan and Type II collagen after 3 months at the messenger RNA levels in the discs of PYM group (p<.05). The von Willebrand factor expression of PYM group also showed a significant reduction after 1 month (p<.05).

CONCLUSIONS

Percutaneous injection of PYM into the subchondral bone adjacent to the lumbar IVDs of rabbits, using bone marrow needle guided by CT scan, can result in ischemic and slowly progressive disc degeneration model, which mimics the onset of human disc degeneration.

Nano and micro biomechanical alterations of annulus fibrosus after in situ immobilization revealed by atomic force microscopy

Annulus fibrosus is critical to bear loads and resist fluid flow in the intervertebral disc. However, the detailed biomechanical mechanism of annulus fibrosus under abnormal loading is still ambiguous, especially at the micro and nano scales. This study aims to characterize the alterations of modulus at the nano scale of individual collagen fibrils in annulus fibrosus after in-situ immobilization, and the corresponding micro-biomechanics of annulus fibrosus. An immobilization model was used on the rat tail with an external fixation device. The elastic modulus of annulus fibrosus at both the nano- and micro-scale was examined using atomic force microscopy after fixation for 4 and 8 weeks, respectively. The fibrils in inner layer showed an alteration in elastic modulus from 91.38 ± 20.19 MPa in the intact annulus fibrosus to 110.64 ± 15.58 MPa (p < 0.001) at the nano scale after immobilization for 8 weeks, while the corresponding modulus at the micro scale also underwent a change from 0.33 ± 0.04 MPa to 0.47 ± 0.04 MPa (p < 0.001). The fibril disorder after immobilization was observed by hematoxylin/eosin staining. The gene expression of annulus fibrosus was also measured by real-time reverse transcription-polymerase chain reaction, which showed the upregulation of collagen II (p = 0.003) after immobilization. The results indicated that the immobilization not only influenced the individual fibril at the nanoscale, but also the micro-biomechanical property of annulus fibrosus which is critical to define the cell response to surrounding biomechanical environment. These alterations may also lead to the change in the mechanical property of the whole disc and the load-bearing function. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-7, 2018.

Evaluation of Common Variants in Matrix Metalloproteinase-9 Gene with Lumbar Disc Herniation in Han Chinese Population

OBJECTIVE

Lumbar disc herniation (LDH) is a common and frequent orthopedic disease with strong genetic determinants. The disruption of the intervertebral disc extracellular matrix has been found to play a key role in the development of LDH, suggesting that abnormal matrix metalloproteinases (MMPs) may promote the degradation of the disc matrix. MMP-9, an important member of the MMP family, is a good candidate for the LDH susceptibility gene. The present study aimed to investigate the association of common variants in the MMP-9 gene with the risk, severity, and clinical characteristic variables of LDH.

MATERIALS AND METHODS

Fourteen tag single nucleotide polymorphisms (SNPs) entirely covering the region of the MMP-9 gene were analyzed in a sample of 845 patients and 1751 healthy controls.

RESULTS

The SNP rs17576 was found to be significantly associated with susceptibility to LDH (OR = 0.77, p = 0.0002), which was also confirmed by haplotype-based analyses (rs79845319-rs17576-rs45437897, global p < 0.001). Our results indicated that the A allele of rs17576 reduced the risk of LDH by ∼23% on average. Furthermore, the G allele of rs17576 was found to correlate with more severe grades of disc degeneration.

CONCLUSION

Our results provide additional evidence supporting an important role of the MMP-9 gene in the pathogenesis of LDH.

FOXO are required for intervertebral disk homeostasis during aging and their deficiency promotes disk degeneration

Intervertebral disk (IVD) degeneration is a prevalent age-associated musculoskeletal disorder and a major cause of chronic low back pain. Aging is the main risk factor for the disease, but the molecular mechanisms regulating IVD homeostasis during aging are unknown. The aim of this study was to investigate the function of FOXO, a family of transcription factors linked to aging and longevity, in IVD aging and age-related degeneration. Conditional deletion of all FOXO isoforms (FOXO1, 3, and 4) in IVD using the Col2a1Cre and AcanCreER mouse resulted in spontaneous development of IVD degeneration that was driven by severe cell loss in the nucleus pulposus (NP) and cartilaginous endplates (EP). Conditional deletion of individual FOXO in mature mice showed that FOXO1 and FOXO3 are the dominant isoforms and have redundant functions in promoting IVD homeostasis. Gene expression analyses indicated impaired autophagy and reduced antioxidant defenses in the NP of FOXO-deficient IVD. In primary human NP cells, FOXO directly regulated autophagy and adaptation to hypoxia and promoted resistance to oxidative and inflammatory stress. Our findings demonstrate that FOXO are critical regulators of IVD homeostasis during aging and suggest that maintaining or restoring FOXO expression can be a therapeutic strategy to promote healthy IVD aging and delay the onset of IVD degeneration.

Active discopathy: a clinical reality

In the late 1980s, the description by Modic and colleagues of elementary discovertebral changes detected on MRI (Modic classification) suggested for the first time a possible correlation between anatomical and clinical features in a subgroup of patients with non-specific chronic low back pain. Degenerative disc disease is frequent and usually asymptomatic, but Modic 1 changes in the vertebral endplates adjacent to a degenerated disc are associated with inflammatory-like chronic low back pain and low-grade local and systemic inflammation, which led to the concept of ‘active discopathy’. Active discopathy shares some similarities with acute flares of peripheral osteoarthritis. Likewise, what triggers disc activation and how it self-limits remain unknown. A better understanding of mechanisms underlying disc activation and its self-limitation is of clinical relevance because it may enable the design of more targeted pharmacological and non-pharmacological interventions for the subgroup of patients with chronic low back pain and active discopathy. Here, we narratively review current disc-centred biomechanical and biochemical hypotheses of disc activation and discuss evidence of interactions with adverse personal and environmental factors.

The Effect of Pregabalin and Metformin on Subacute and Chronic Radiculopathy

Background:

Radicular pain is one of the most common forms of chronic pain in the world, which has challenges about effective medical therapy. The aim of this study was to evaluate the effect of pregabalin (PGB) and metformin (Met) on subacute and chronic radiculopathy.

Materials and Methods:

This double-blind prospective clinical trial was performed on 71 patients with subacute and chronic cervical and lumbosacral radiculopathy. Group A was treated with PGB 75 mg daily while Group B was treated with PGB 75 mg daily and Met 500 mg daily for 3 months. Finally, the pain score in both groups was evaluated based on visual analog scale (VAS) and numerical scale pain.

Results:

The results showed a significant reduction in VAS and pain severity in both groups but this reduction in the terms of VAS (47.79% vs. 46.48%, P = 0.125) and pain severity (47.1% vs. 39.2%, P = 0.264) was more in treated patients with PGB and Met as compared to PGB group while total pain experience (53.5% vs. 49.1%, P = 0.464) and interference with daily function (57.1% vs. 50.61%, P = 0.726) were more in patients treated with PGB alone.

Conclusion:

Our results showed that PGB and PGB + Met reduced pain intensity and interference with daily function while we did not observe significant differences between two groups. PGB alone would have the potentiality to become a simple and economic means to decrease radicular pain.

Comparison of the biochemical and radiological criteria for lumbar disc degeneration

BACKGROUND

The relationship between radiological degeneration criteria on lumbar magnetic resonance imaging (MRI) and both the keratan sulfate (KS) and chondroitin sulfate (ChS) levels was examined in disc material taken from patients undergoing lumbar disc herniation (LDH) surgery. To examine whether the biochemical and radiological degeneration criteria testing the reliability of radiological degeneration findings agreed and to evaluate the contribution of the KS/ChS ratio to disc form (protruding or extruding).

METHODS

This was a prospective experimental cohort study. Using enzyme-linked immunosorbent assay, KS and ChS levels were measured in the degenerate nucleus pulposus taken from 71 patients with a diagnosis of LDH who underwent surgery. The degeneration levels and disc form (protruding or extruding) were determined according to the Pfirrmann five-stage grading system on preoperative T2-weighted lumbar MRIs. According to the Pfirrmann system, 28 patients were grade III and 43 were grade IV. The relationship between radiological criteria and the KS/ChS ratio was statistically evaluated.

RESULTS

The KS levels (p=0.046) and the KS/ChS ratio (p=0.001) were significantly higher in grade IV patients than in grade III patients. However, there was no difference between the KS and ChS levels and the KS/ChS ratio when patients were classified as protruding or extruding according to their disc structure. Disc structure and biochemical degeneration indicators were not correlated.

CONCLUSIONS

The KS level and the KS/ChS ratio were high in patients with marked radiological degeneration on lumbar MRI, demonstrating the sensitivity and reliability of the Pfirrmann five-stage grading system for showing radiological degeneration.

Thermo-sensitive injectable glycol chitosan-based hydrogel for treatment of degenerative disc disease

The use of injectable hydrogel formulations have been suggested as a promising strategy for the treatment of degenerative disc disease to both restore the biomechanical function and reduce low back pain. In this work, a new thermo-sensitive injectable hydrogels with tunable thermo-sensitivity and enhanced stability were developed with N-hexanoylation of glycol chitosan (GC) for treatment of degenerative disc disease, and their physico-chemical and biological properties were evaluated. The sol-gel transition temperature of the hydrogels was controlled in a range of 23-56 °С, depending on the degree of hexanoylation and the polymer concentration. In vitro and in vivo tests showed no cytotoxicity and no adverse effects in a rat model. The hydrogel filling of the defective IVD site in an ex vivo porcine model maintained its stability for longer than 28 days. These results suggest that the hydrogel can be used as an alternative material for treatment of disc herniation.

Age-related reduction in the expression of FOXO transcription factors and correlations with intervertebral disc degeneration

Aging is a main risk factor for intervertebral disc (IVD) degeneration, the main cause of low back pain. FOXO transcription factors are important regulators of tissue homeostasis and longevity. Here, we determined the expression pattern of FOXO in healthy and degenerated human IVD and the associations with IVD degeneration during mouse aging. FOXO expression was assessed by immunohistochemistry in normal and degenerated human IVD samples and in cervical and lumbar IVD from 6-, 12-, 24-, and 36-month-old C57BL/6J mice. Mouse spines were graded for key histological features of disc degeneration in all the time points and expression of two key FOXO downstream targets, sestrin 3 (SESN3) and superoxide dismutase (SOD2), was assessed by immunohistochemistry. Histological analysis revealed that FOXO proteins are expressed in all compartments of human and mouse IVD. Expression of FOXO1 and FOXO3, but not FOXO4, was significantly deceased in human degenerated discs. In mice, degenerative changes in the lumbar spine were seen at 24 and 36 months of age whereas cervical IVD showed increased histopathological scores at 36 months. FOXO expression was significantly reduced in lumbar IVD at 12-, 24-, and 36-month-old mice and in cervical IVD at 36-month-old mice when compared with the 6-month-old group. The reduction of FOXO expression in lumbar IVD was concomitant with a decrease in the expression of SESN3 and SOD2. These findings suggest that reduced FOXO expression occurs in lumbar IVD during aging and precedes the major histopathological changes associated with lumbar IVD degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2682-2691, 2017.

Knockout of Apolipoprotein E in rabbit promotes premature intervertebral disc degeneration: A new in vivo model for therapeutic approaches of spinal disc disorders

Intervertebral disc (IVD) degeneration that accelerates the loss of disc structural and functional integrities is recognized as one of the major factors of chronic back pain. Cardiovascular risk factors, such as deficits of apolipoproteins that elevate the levels of cholesterol and triglycerides, are considered critical for the progress of atherosclerosis; notably in the abdominal aorta and its lumbar branching arteries that supply lumbar vertebrae and IVDs. Obstruction of the lumbar arteries by atherosclerosis is presumed to promote lumbar disc degeneration and low back pain. APOE-knockout rabbits have recently been shown to generate hyperlipidemia with increased levels of cholesterol and triglycerides that mimic the symptoms of atherosclerosis in humans. Here, we analysed IVD degeneration in the lumbar spines of ten homozygous APOE-knockout and four wild-type New Zealand White rabbits of matching age to prove accelerated IVD degeneration in APOE-knockout rabbits, since APOE-knockout rabbits could be a beneficial model for therapeutic approaches of degenerative IVD disorders. Experiments were performed using T1/T2-weighted magnetic resonance imaging, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, glucose-oxidase assay, enzyme-linked immunosorbent assay, quantitative reverse transcription PCR and western blot. APOE-knockout lumbar spines showed more advanced IVD degeneration, obstructed lumbar arteries and lower enhancement of contrast agent in IVDs. Moreover, lower concentration of glucose, lower number of viable cells and lower concentrations of aggrecan, collagen II and higher concentration of collagen I were detected in APOE-knockout IVDs (p < 0.0001). APOE-knockout in rabbits could induce structurally deteriorating premature IVD degeneration that mimics the symptoms of accelerated IVD degeneration in humans. APOE-knockout rabbits could be used as beneficial model, as they can bypass the standard surgical interventions that are commonly applied in research animals for the induction of enhanced IVD degeneration. Their parallel use in therapeutic approaches of IVD disorders and atherosclerosis could reduce the number of research animals to be used and contribute to the principles of 3Rs (Replacement, Reduction and Refinement).

Individual Collagen Fibril Thickening and Stiffening of Annulus Fibrosus in Degenerative Intervertebral Disc

STUDY DESIGN

In vitro study using rat intervertebral discs (IVDs).

OBJECTIVE

To explore the alteration of annulus fibrosus collagen fibrils after loading on IVD and to investigate the degeneration pathogenesis at the nanoscale.

SUMMARY OF BACKGROUND DATA

Abnormal loading can lead to IVD degeneration, but the precise mechanism has been hitherto elusive, especially at the nanoscale.

METHODS

A rat IVD loading model was used, which combined bending of the tail by 40° with compressive loading of 1.8, 4.5, and 7.2 N of the rat tail using an external fixation device. The structure and the elastic modulus of individual collagen fibrils within IVD Co8-Co9 was examined 2 weeks after loading at the nanoscale using atomic force microscopy.

RESULTS

Significant fibril disorder and a decrease in cell number within the annulus fibrosus after loading was observed at the microscale as judged by hematoxylin/eosin staining, suggesting initiation of rupture of the structure and degradation of the IVD. The annulus fibrosus collagen fibrils underwent a change in diameter and elastic modulus from 170 ± 18 to 310 ± 24 nm (P < 0.001) and 0.86 ± 0.12 to 1.27 ± 0.30 GPa (P = 0.003), respectively when measured on the concave side after a loading of 7.2 N. Thus the loading process resulted in a thickening and stiffening of collagen fibrils with a difference between the inner and outer layers.

CONCLUSION

The results of the present study indicated that abnormal loading was not only associated with disorder at the microscale, but also alteration of the collagen fibrils at the nanoscale, possibly leading to changes in the mechanical and physiological environment around the cells of the annulus fibrosus.

LEVEL OF EVIDENCE

N/A.

Matrisome Profiling During Intervertebral Disc Development And Ageing

Intervertebral disc (IVD) degeneration is often the cause of low back pain. Degeneration occurs with age and is accompanied by extracellular matrix (ECM) depletion, culminating in nucleus pulpous (NP) extrusion and IVD destruction. The changes that occur in the disc with age have been under investigation. However, a thorough study of ECM profiling is needed, to better understand IVD development and age-associated degeneration. As so, iTRAQ LC-MS/MS analysis of foetus, young and old bovine NPs, was performed to define the NP matrisome. The enrichment of Collagen XII and XIV in foetus, Fibronectin and Prolargin in elder NPs and Collagen XI in young ones was independently validated. This study provides the first matrisome database of healthy discs during development and ageing, which is key to determine the pathways and processes that maintain disc homeostasis. The factors identified may help to explain age-associated IVD degeneration or constitute putative effectors for disc regeneration.

Physiological effects of physical therapy interventions on lumbar intervertebral discs: A systematic review

BACKGROUND CONTEXT

The use of physical therapy has been recommended in the treatment of low back pain based on primarily mechanical and neurophysiological effects. Recent studies have measured the physiological effects of physical therapy interventions, including manual therapy and traction, on the intervertebral discs (IVD), and these findings may have implications for the long-term management or even prevention of low back pain.

PURPOSE

The objective of this systematic review is to investigate the literature regarding possible physiological effects of physical therapy interventions on the intervertebral disc (IVD).

STUDY DESIGN

Systematic Review.

METHODS

A literature search of published articles through December 2014 resulted in the retrieval of 8 clinical studies assessing the influence of physical therapy interventions on the physiology of the IVD.

RESULTS

Three studies, including two using animal models, investigated the effects of 30-minute intermittent traction on disc height. One in vivo animal study and two studies using human subjects assessed changes of disc height associated with static traction. Three studies investigated the effects of lumbar spine manipulation and mobilization on changes in water diffusion within the IVD. All studies confirmed, either directly or indirectly, that their respective intervention influenced disc physiology primarily through water flow.

CONCLUSION

Physical therapy interventions may have an effect on the physiology of the IVD, primarily through water diffusion and molecular transport, which are important for the health of the IVD.

A Histopathological Scheme for the Quantitative Scoring of Intervertebral Disc Degeneration and the Therapeutic Utility of Adult Mesenchymal Stem Cells for Intervertebral Disc Regeneration

The purpose of this study was to develop a quantitative histopathological scoring scheme to evaluate disc degeneration and regeneration using an ovine annular lesion model of experimental disc degeneration. Toluidine blue and Haematoxylin and Eosin (H&E) staining were used to evaluate cellular morphology: (i) disc structure/lesion morphology; (ii) proteoglycan depletion; (iii) cellular morphology; (iv) blood vessel in-growth; (v) cell influx into lesion; and (vi) cystic degeneration/chondroid metaplasia. Three study groups were examined: 5 × 5 mm lesion; 6 × 20 mm lesion; and 6 × 20 mm lesion plus mesenchymal stem cell (MSC) treatment. Lumbar intervertebral discs (IVDs) were scored under categories (i-vi) to provide a cumulative score, which underwent statistical analysis using STATA software. Focal proteoglycan depletion was associated with 5 × 5 mm annular rim lesions, bifurcations, annular delamellation, concentric and radial annular tears and an early influx of blood vessels and cells around remodeling lesions but the inner lesion did not heal. Similar features in 6 × 20 mm lesions occurred over a 3-6-month post operative period. MSCs induced a strong recovery in discal pathology with a reduction in cumulative histopathology degeneracy score from 15.2 to 2.7 (p = 0.001) over a three-month recovery period but no recovery in carrier injected discs.

The Association Between Atherosclerosis and Low Back Pain: A Systematic Review

OBJECTIVE

To assess the evidence of association between atherosclerosis and low back pain (LBP). TYPE: Focused systematic review.

LITERATURE SURVEY

PubMed, Web of Science, CINAHL, and EMBASE were searched for original research articles, not limited by language, from January 1, 1990, to October 31, 2016.

METHODOLOGY

Titles and then abstracts were identified using predefined search terms and excluded based on lack of relevancy. This was followed by full-text reviews. Two authors independently assessed methodological quality based on Cochrane Handbook for Systematic Reviews of Interventions.

SYNTHESIS

A total of 26 studies met the inclusion criteria. The quality of the studies was low to moderate. There was significant heterogeneity across articles with respect to methodology. There was insufficient evidence to support an association between ischemia and low back pain.

CONCLUSIONS

The cause of LBP remains poorly understood. Better insight into how intervertebral disk changes relate to LBP is needed to guide future research. High-quality prospective studies are needed to answer the question of whether atherosclerosis is a risk factor for LBP.

LEVEL OF EVIDENCE

II.

ISSLS PRIZE IN CLINICAL SCIENCE 2017: Is infection the possible initiator of disc disease? An insight from proteomic analysis

STUDY DESIGN

Proteomic and 16S rDNA analysis of disc tissues obtained in vivo.

OBJECTIVE

To address the controversy of infection as an aetiology for disc disorders through protein profiling. There is raging controversy over the presence of bacteria in human lumbar discs in vivo, and if they represent contamination or infection. Proteomics can provide valuable insight by identifying proteins signifying bacterial presence and, also host defence response proteins (HDRPs), which will confirm infection.

METHODS

22 discs (15-disc herniations (DH), 5-degenerate (DD), 2-normal in MRI (NM) were harvested intraoperatively and immediately snap frozen. Samples were pooled into three groups and proteins extracted were analysed with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Post identification, data analysis was performed using Uniprotdb, Pantherdb, Proteome discoverer and STRING network. Authentication for bacterial presence was performed by PCR amplification of 16S rDNA.

RESULTS

LC-MS/MS analysis using Orbitrap showed 1103 proteins in DH group, compared to 394 in NM and 564 in DD. 73 bacterial specific proteins were identified (56 specific for Propionibacterium acnes; 17 for Staphylococcus epidermidis). In addition, 67 infection-specific HDRPs, unique or upregulated, such as Defensin, Lysozyme, Dermcidin, Cathepsin-G, Prolactin-Induced Protein, and Phospholipase-A2, were identified confirming presence of infection. Species-specific primers for P. acnes exhibited amplicons at 946 bp (16S rDNA) and 515 bp (Lipase) confirming presence of P. acnes in both NM discs, 11 of 15 DH discs, and all five DD discs. Bioinformatic search for protein-protein interactions (STRING) documented 169 proteins with close interactions (protein clustering co-efficient 0.7) between host response and degenerative proteins implying that infection may initiate degradation through Ubiquitin C.

CONCLUSION

Our study demonstrates bacterial specific proteins and host defence proteins to infection which strengthen the hypothesis of infection as a possible initiator of disc disease. These results can lead to a paradigm shift in our understanding and management of disc disorders.

Joint analysis of IVD herniation and degeneration by rat caudal needle puncture model

Intervertebral disc (IVD) degeneration is responsible for various spine pathologies and present clinical treatments are insufficient. Concurrently, the mechanisms behind IVD degeneration are still not completely understood, so as to allow development of efficient tissue engineering approaches. A model of rat IVD degeneration directly coupled to herniation is here proposed in a pilot study. Disc injury is induced by needle puncture, using two different needles gauges: a low caliber 25-G needle and a high caliber 21-G needle. Histological, biochemical, and radiographic degeneration was evaluated at 2 and 6 weeks post-injury. We show that the larger caliber needle results in a more extended histological and radiographic degeneration within the IVD, compared to the smaller one. TUNEL quantification indicates also increased cell death in the 21-G group. Analyses of collagen type I (Picrosirius red staining), collagen type II (immunofluorescence), and GAG content (Blyscan assay) indicate that degeneration features spontaneously recover from 2 to 6 weeks, for both needle types. Moreover, we show the occurrence of hernia proportional to the needle gauge. The number of CD68+ macrophages present, as well as cell apoptosis within the herniated tissue are both proportional to hernia volume. Moreover, hernias formed after lesion tend to spontaneously diminish in volume after 6 weeks. Finally, MMP3 is increased in the hernia in the 21-G group at 2 weeks. This model, by uniquely combining IVD degeneration and IVD herniation in the same animal, may help to understand mechanisms behind IVD pathophysiology, such as hernia formation and spontaneous regression. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:258-268, 2017.

Inflammation in low back pain may be detected from the peripheral blood: suggestions for biomarker

The results of our study provides novel insights into the mechanisms of low back pain, as well as provide suggestions of the possibility that these assays may be used as biomarkers for low back pain.

Biomarker for prediction of development of low back pain, and disease progression in chronic conditions are virtually non-existent. In the present study, we examined evidence of inflammation in the peripheral blood and demonstrated significant changes in neuroinflammation markers in subjects with chronic low back pain in comparison with control subjects. The present study was performed using peripheral blood from subjects with chronic low back pain and age-matched control subjects. Western blotting, real-time RT-PCR, cell culture and in vitro assays were incorporated to perform the current study. We obtained evidence that the balance between proinflammatory and anti-inflammatory cytokines is misaligned, with decrease in interleukin-10 (IL-10) expression and increase in interleukin-6 (IL-6) expression. Furthermore, we demonstrated increase in CD16 monocyte expression. Cells were cultured under differential conditions to generate M1/M2 macrophages. In the macrophages, opioid secretory capacity was shown to be diminished. Finally, Dragon (repulsive guidance molecule b, RGMb) expression was shown diminished in M1 macrophages, which serves as a key transcriptional inhibitor of IL-6 expression. These biochemical and cellular alterations in chronic low back pain can serve as potential biomarkers for assessing disease initiation, intensity and progression.

A prospective multicenter phase I/II clinical trial to evaluate safety and efficacy of NOVOCART Disc plus autologous disc chondrocyte transplantation in the treatment of nucleotomized and degenerative lumbar disc to avoid secondary disease: study protocol for a randomized controlled trial

Background

Intervertebral disc degeneration is emphasized as an important cause of low back pain. Current surgical treatment provides relief to the accompanying pain and disability but does not restore the biological function of the intervertebral disc. NOVOCART™ Disc plus, an autologous cell compound for autologous disc chondrocyte transplantation, was developed to reduce the degenerative sequelae after lumbar disc surgery or to prophylactically avoid degeneration in adjacent discs.

Methods/design

This is a multicenter, randomized, controlled, clinical phase I/II combination study. A total of 120 adult patients are allocated in a ratio of 2:1:1. Sample size and power calculations were performed to detect the minimal clinically important difference of 10 units, with an expected standard deviation of 12 in the Oswestry Disability Index, which is the primary outcome parameter. Secondary outcome parameters include the visual analog scale and the EQ-5D questionnaire. Changes in physical and mental health are evaluated using the Short Form-12 (SF-12). Moreover, radiological and functional outcomes are evaluated. The major inclusion criterion is a single lumbar disc herniation that requires sequestrectomy. Transplantation is performed 90 days thereafter. Study data generation (study sites) and data storage, processing, and statistical analysis are clearly separated.

Discussion

In this phase-I/II study, NDplus is being investigated for its clinical applicability, safety, and efficacy in the repair of herniated, nucleotomized discs, and of adjacent degenerated discs, if present. To date, autologous disc chondrocytes have not been transplanted into degenerative discs without previous disc herniation. As such, this is the first study to investigate a therapeutic as well as a prophylactic approach to treat degenerative discs of the lumbar spine.

Trial registration

EudraCT No: 2010-023830-22, ID NCT01640457, 8 November 2010

Autologous Conditioned Serum as a Novel Alternative Option in the Treatment of Unilateral Lumbar Radiculopathy: A Prospective Study

Study Design

The study was conducted on patients who received autologous conditioned serum (ACS) as a line of treatment at the Orthopedics outpatient department of Post Graduate Institute of Medical Education and Research (PGIMER, Chandigarh) from January 2011 to June 2012. Of the 1,224 patients, 20 males or females were included in the study based on the inclusion and exclusion criteria. The institutional board of PGIMER approved the study before it was initiated.

Purpose

To study the efficacy of ACS in the treatment of unilateral lumbar radiculopathy.

Overview of Literature

Interleukin (IL)-1 appears to be of special importance among the cytokines identified in orthopedic diseases. ACS contains high concentrations of IL-1 receptor antagonist, antagonist to IL-1 in that is a biochemical 'sensitizer' of nerve roots in radiculopathy.

Methods

We included 20 patients with unilateral lumbar radiculopathy after obtaining informed consent. We prepared ACS as described by Meijer et al. Under bi-planar fluoroscopic imaging in anterior-posterior and lateral views, ACS was administered via epidural perineural technique. Patients in both groups were evaluated by quadruple visual analogue scale, straight leg raising test, revised Oswestry disability index, and 12-Item Short Form of Health Survey before and after epidural injections at 3 weeks, 3 months, and 6 months.

Results

There was a statistically significant change in all parameters from pre-injection to first, second, and third follow-up (p<0.001).

Conclusions

ACS can modify the disease course in addition to reducing pain, disability and improving general health.

Survivin is expressed in degenerated nucleus pulposus cells and is involved in proliferation and the prevention of apoptosis in vitro

Survivin is a unique inhibitor of apoptosis, which is frequently present within degenerated human nucleus pulposus (NP) cells. Survivin has been extensively investigated using proliferation and apoptosis assays in tumor cells; however, studies conducted on survivin in degenerative NP cells remain limited to date. The aim of the present study was to investigate survivin expression and its effects on the proliferation and apoptosis of degenerated NP cells in vitro. The expression levels of survivin in the NP cells of patients (>45 years) with lumbar disc degenerative disease and the NP cells of patients (<25 years) with lumbar vertebra fracture were assessed by reverse transcription‑quantitative polymerase chain reaction. The effects on in vitro proliferation and apoptosis were investigated through transfection with a specific small interfering (si)RNA. The results of the present study demonstrated that survivin was expressed in the degenerated NP cells, but was undetectable in normal NP cells at the mRNA level. Survivin suppression following transfection with a specific survivin‑siRNA reduced the proliferation rate of NP cells and enhanced sensitization to pro‑apoptotic stimuli. Therefore, survivin was shown to be expressed and exhibit an important role in the proliferation and prevention of apoptosis of degenerated NP cells. Studies on survivin in NP cells may aid in increasing the understanding of the complex processes underlying NP cell degeneration, and could provide fundamental information for gene therapy to inhibit this degeneration in vitro.

Effect of lentivirus-mediated survivin transfection on the morphology and apoptosis of nucleus pulposus cells derived from degenerative human disc in vitro

Lower back pain is a common concern, and 40% of all cases involve the degeneration of the intervertebral disc (IVD). However, the excessive apoptosis of disc cells plays an important role in IVD degeneration, particularly in the nucleus pulposus (NP). Thus, anti-apoptotic gene therapy to attenuate or reverse the degenerative process within the NP is being developed. Survivin is a unique inhibitor of apoptosis (IAP) and has been extensively investigated in cancer cells. However, little is known of the effects of survivin transfection on NP cells derived from degenerative human disc. In this study, we aimed to investigate the effects of lentivirus (LV)-mediated survivin transfection on the morphology and apoptosis of NP cells derived from degenerative human disc in vitro. NP cells were transfected with LV-mediated survivin. Subsequently, cell morphology was observed and the survivin mRNA expression levels were measured by RT-qPCR. Apoptosis was analyzed by flow cytometry and by measuring caspase-3 activity. The results revealed that the morphology of the NP cells derived from degenerative human disc transfected with LV-mediated survivin was significantly altered as evidenced by cytomorphosis, the reduction of the cytoplasm and cell shrinkage. Following transfection, survivin gene expression significantly increased in the transfected cells and subsequent generation cells; however, no significant differences in the cell apoptotic rate and caspase-3 activity were observed. We found that transfection of the survivin gene into NP cells led to the stable expression of survivin and induced marked changes in cell morphology. Furthermore, no significant anti-apoptotic effects were observed following LV-mediated survivin transfection. Overall, our findings demonstrate that LV carrying surviving may be used to successfully enforce the expression of survivin in NP cells. However, cell morphology was evidently altered, whereas the apoptotic rate did not decrease. Comprehensive studies on the feasibility of using survivin in gene therapy in an aim to attenuate disc degeneration are warranted. Further research on the mechanisms responsible for the changes in cell morphology and cell function are also required.

Effect of coculturing canine notochordal, nucleus pulposus and mesenchymal stromal cells for intervertebral disc regeneration

Introduction

Early degenerative changes in the nucleus pulposus (NP) are observed after the disappearance of notochordal cells (NCs). Thus, it has been suggested that NCs play an important role in maintaining the NP and may have a regenerative potential on other cells of the NP. As the number of resident NP cells (NPCs) decreases in a degenerating disc, mesenchymal stromal (stem) cells (MSCs) may be used for cell supplementation. In this study, using cells of one species, the regenerative potential of canine NCs was assessed in long-term three-dimensional coculture with canine NPCs or MSCs.

Methods

Canine NCs and canine NPCs or MSCs were cocultured in alginate beads for 28 days under hypoxic and high-osmolarity conditions. Cell viability, cell morphology and DNA content, extracellular matrix production and expression of genes related to NC markers (Brachyury, KRT18) and NP matrix production (ACAN, COL2A1, COL1A1) were assessed after 1, 15 and 28 days of culture.

Results

NCs did not completely maintain their phenotype (morphology, matrix production, gene expression) during 28 days of culture. In cocultures of NPCs and NCs, both extracellular matrix content and anabolic gene expression remained unchanged compared with monoculture groups, whereas cocultures of MSCs and NCs showed increased glycosaminoglycan/DNA. However, the deposition of these proteoglycans was observed near the NCs and not the MSCs. Brachyury expression in the MSC and NC coculture group increased in time. The latter two findings indicate a trophic effect of MSCs on NCs rather than vice versa.

Conclusions

No regenerative potential of canine NCs on canine NPCs or MSCs was observed in this study. However, significant changes in NC phenotype in long-term culture may have resulted in a suboptimal regenerative potential of these NCs. In this respect, NC-conditioned medium may be better than coculture for future studies of the regenerative potential of NCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0569-6) contains supplementary material, which is available to authorized users.

Pingyangmycin-induced in vivo lumbar disc degeneration model of rhesus monkeys

STUDY DESIGN

Animal experimental study.

OBJECTIVE

To establish a slowly progressive and reproducible intervertebral disc degeneration model and determine the performance of T1ρ magnetic resonance imaging in the evaluation of disc degeneration.

SUMMARY OF BACKGROUND DATA

Recently, one of the hotspots of research efforts was related to management of early stage of disc degeneration. To our knowledge, a functional animal model that mimics ischemic and slowly progressive disc degeneration of humans does not exist.

METHODS

The subchondral bone adjacent to the lumbar intervertebral discs (from L3-L4 to L6-L7) of 8 rhesus monkeys was randomly injected with 4 mL of Pingyangmycin (PYM) solution (1.5 mg/mL, PYM), or 4 mL of phosphate buffered saline (Vehicle control), or exteriorized but not injected anything (Sham), respectively. The degenerative process was investigated by using radiography and T1ρ magnetic resonance imaging at 1, 3, 6, 9, 12, and 15 months postoperatively. Histological scoring, immunohistochemistry, and real-time polymerase chain reaction were performed at 15 months.

RESULTS

The mean T1ρ values of nucleus pulposus and annulus fibrosus in the PYM group significantly decreased after 3 and 6 months, respectively, followed by slow decrease, and the histological score was significantly higher at 15 months, compared with the control groups. The results of molecular analysis revealed a significant increase matrix metalloprotease-3, A disintegrin and metalloproteinase with thrombospondin motifs -5, tumor necrosis factor α, interleukin-1β, interleukin-6 expressions, and marked reduction in aggrecan, type II collagen, von Willebrand factor expressions at the messenger RNA levels in the PYM group. Spearman correlation analysis of Pfirrmann grades showed significantly inverse correlation with T1ρ values of nucleus pulposus and annulus fibrosus (r = -0.634, -0.617, respectively, P < 0.01).

CONCLUSION

Injection of PYM into the subchondral bone adjacent to the lumbar intervertebral discs of rhesus monkeys can results in mild, slowly progressive disc degeneration, which mimics the onset of human disc degeneration, and the T1ρ magnetic resonance imaging is suited for evaluating intervertebral disc degeneration.

LEVEL OF EVIDENCE

N/A.