Spontaneous Intervertebral Disc Degeneration Research Articles

Chronic spinal cord compression associated with intervertebral disc degeneration in SPARC-null mice.

Chronic spinal cord compression (CSCC) is induced by disc herniation and other reasons, leading to movement and sensation dysfunction, with a serious impact on quality of life. Spontaneous disc herniation rarely occurs in rodents, and therefore establishing a chronic spinal cord compression (CSCC) animal model is of crucial importance to explore the pathogenesis and treatment of CSCC. The absence of secreted protein, acidic, and rich in cysteine (SPARC) leads to spontaneous intervertebral disc degeneration in mice, which resembles human disc degeneration. In this study, we evaluated whether SPARC-null mice may serve as an animal model for CSCC. We performed rod rotation test, pain threshold test, gait analysis, and Basso Mouse Scale score. Our results showed that the motor function of SPARC-null mice was weakened, and magnetic resonance images revealed compression at different spinal cord levels, particularly in the lumbar segments. Immunofluorescence staining and western blot assay showed that the absence of SPARC induced apoptosis of neurons and oligodendrocytes, activation of microglia/macrophages with M1/M2 phenotype and astrocytes with A1/A2 phenotype; it also activated the expression of the NOD-like receptor protein 3 inflammasome and inhibited brain-derived neurotrophic factor/tyrosine kinase B signaling pathway. Notably, these findings are characteristics of CSCC. Therefore, we propose that SPARC-null mice may be an animal model for studying CSCC caused by disc herniation.

Case Report: Successful Therapy of Spontaneously Occurring Canine Degenerative Lumbosacral Stenosis Using Autologous Adipose Tissue-Derived Mesenchymal Stem Cells

The management of degenerative lumbosacral stenosis (DLSS) in dogs usually requires aggressive, costly surgical treatments that may themselves present complications, while do not fully resolve the symptoms of the disease. In this study, the dog diagnosed with severe DLSS, with hind limb paresis, was treated using a new and least invasive treatment. Cultured autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs) were injected bilaterally at the level of L7-S1, in the vicinity of the external aperture of the intervertebral foramen of DLSS patient. In the previously described treatments of spontaneous intervertebral disc degeneration in dogs, intradiscal injections of MSCs did not lead to positive effects. Here, we report a marked improvement in clinical outcome measures related to the ability of a dog to walk and trot, which were expressed by a numeric rating scale based on a veterinary assessment questionnaire. The improved status persisted throughout the observed time course of 4.5 years after the AT-MSC transplantation. To the best of our knowledge, this is the first case of successful therapy, with long-term positive effect, of spontaneously occurring canine DLSS using presented treatment that, we believe, represents a contribution to current knowledge in this field and may shape both animal and human DLSS treatment options.

Chondroitin synthase-3 regulates nucleus pulposus degeneration through actin-induced YAP signaling.

Loss of chondroitin sulfate (CS) has been reported to play a key role during intervertebral disc degeneration (IDD). However, the detailed mechanism of CS and its synthases have not been elucidated. Since CS is mainly synthesized by chondroitin synthases 3 (Chsy3), here, the Chsy3 knockout mice are generated by using CRISPR-Cas9 and semi-cloning technology to study its mechanism during IDD. We find that CS and Chsy3 expression are decreased during IDD both in human and mice nucleus pulposus (NP) tissue, and knockout of Chsy3 shows that spontaneous IDD phenotype resembles that of human samples in the Chsy3-/- mice. Taking advantage of RNA-Seq data, we confirm increased catabolic and decreased anabolic changes in Chsy3-/- NP cells. By using bioinformatic analysis and validation, we find that Hippo signaling pathway is significantly downregulated, and the activation of Yap1 is mainly affected in Chsy3-/- NP cells. Furthermore, functional analyses have shown that Chsy3 could regulate NP cell degeneration by Actin tension mediated activation of Yap1, which is independent of Hippo/Lats signaling. In summary, our findings reveal a novel mechanism that depletion of CS-related Chsy3 can cause spontaneous intervertebral disc degeneration by mediating Yap activation through CS-related actin-tension in NP cells.

Dysregulation of the Inflammatory Mediators in the Multifidus Muscle After Spontaneous Intervertebral Disc Degeneration SPARC-null Mice is Ameliorated by Physical Activity.

A longitudinal case-control animal model. The aim of this study was to investigate the inflammatory pathways active in the multifidus muscle after spontaneous intervertebral disc degeneration (IDD), and whether these IDD-related muscle changes can be ameliorated by exercise. A pro-inflammatory response is present in the multifidus muscle after an intervertebral disc lesion and has been proposed to drive the structural alterations present during low back pain. However, it is not known whether spontaneous IDD produces an inflammatory response. Furthermore, exercise/physical activity produces a strong anti-inflammatory response, but its effectiveness in ameliorating inflammation in the multifidus is unknown. We assessed the inflammatory profile of the multifidus and the effectiveness of physical activity as a treatment using an animal model of spontaneous model of IDD. Wild-type and SPARC null mice that were sedentary or housed with a running wheel were used in this study. Multifidus muscle segments were harvested from L2-L6 from the mice at 9 months of age after they had undergone a magnetic resonance imaging (MRI) scan to determine levels with IDD. The inflammatory profile of the multifidus was examined using quantitative polymerase chain reaction (PCR) assays. Spontaneous IDD in the SPARC-null mice caused a dysregulation of interleukin (IL)-1β, IL6, transforming growth factor-beta (TGFβ1), and adiponectin expression. More specifically, the proximity and degree of IDD was related to levels of IL-1β expression. Physical activity reduced the pro-inflammatory response to IDD in the multifidus. IL-1β, tumor necrosis factor (TNF), IL-10, adiponectin, and leptin levels were lower in the physically active group. These results reveal that spontaneous IDD causes dysregulation of the inflammatory pathways active in the multifidus muscle. These alterations were related to the severity of IDD and were prevented by physical activity. N/A.

Age-related spontaneous lumbar intervertebral disc degeneration in a mouse model.

The pathogenesis of intervertebral disc degeneration is unclear, but it is a major cause of several spinal diseases. Animal models have historically provided an appropriate benchmark for understanding the human spine. However, there is little information about when intervertebral disc degeneration begins in the mouse or regarding the relationship between magnetic resonance imaging and histological findings. The aim for this study was to obtain information about age-related spontaneous intervertebral disc degeneration in the mouse lumbar spine using magnetic resonance imaging and a histological score regarding when the intervertebral disc degeneration started and how rapidly it progressed, as well as how our histological score detected the degeneration. The magnetic resonance imaging index yielded a moderate correlation with our Age-related model score. The Pfirrmann grade and magnetic resonance imaging index had moderate correlations with age. However, our Age-related model score had a high correlation with age. Intervertebral disc level was not a significant variable for the severity of disc degeneration. Both Pfirrmann grade and the Age-related model score were higher in the ≥14-month-old group than in the 6-month-old group. The present results indicated that mild but significant intervertebral disc degeneration occurred in 14-month-old mice, and the degree of degeneration progressed slowly, reaching a moderate to severe condition for 22-month-old mice. At least a 14-month follow-up is mandatory for evaluating spontaneous age-related mouse intervertebral disc degeneration. The histological classification score can precisely detect the gradual progression of age-related spontaneous intervertebral disc degeneration in the mouse lumbar spine, and is appropriate for evaluating it. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:224-232, 2018.

MRI evaluation of spontaneous intervertebral disc degeneration in the alpaca cervical spine.

Animal models have historically provided an appropriate benchmark for understanding human pathology, treatment, and healing, but few animals are known to naturally develop intervertebral disc degeneration. The study of degenerative disc disease and its treatment would greatly benefit from a more comprehensive, and comparable animal model. Alpacas have recently been presented as a potential large animal model of intervertebral disc degeneration due to similarities in spinal posture, disc size, biomechanical flexibility, and natural disc pathology. This research further investigated alpacas by determining the prevalence of intervertebral disc degeneration among an aging alpaca population. Twenty healthy female alpacas comprised two age subgroups (5 young: 2-6 years; and 15 older: 10+ years) and were rated according to the Pfirrmann-grade for degeneration of the cervical intervertebral discs. Incidence rates of degeneration showed strong correlations with age and spinal level: younger alpacas were nearly immune to developing disc degeneration, and in older animals, disc degeneration had an increased incidence rate and severity at lower cervical levels. Advanced disc degeneration was present in at least one of the cervical intervertebral discs of 47% of the older alpacas, and it was most common at the two lowest cervical intervertebral discs. The prevalence of intervertebral disc degeneration encourages further investigation and application of the lower cervical spine of alpacas and similar camelids as a large animal model of intervertebral disc degeneration.

Intradiscal application of rhBMP-7 does not induce regeneration in a canine model of spontaneous intervertebral disc degeneration.

IntroductionStrategies for biological repair and regeneration of the intervertebral disc (IVD) by cell and tissue engineering are promising, but few have made it into a clinical setting. Recombinant human bone morphogenetic protein 7 (rhBMP-7) has been shown to stimulate matrix production by IVD cells in vitro and in vivo in animal models of induced IVD degeneration. The aim of this study was to determine the most effective dose of an intradiscal injection of rhBMP-7 in a spontaneous canine IVD degeneration model for translation into clinical application for patients with low back pain.MethodsCanine nucleus pulposus cells (NPCs) were cultured with rhBMP-7 to assess the anabolic effect of rhBMP-7 in vitro, and samples were evaluated for glycosaminoglycan (GAG) and DNA content, histology, and matrix-related gene expression. Three different dosages of rhBMP-7 (2.5 μg, 25 μg, and 250 μg) were injected in vivo into early degenerated IVDs of canines, which were followed up for six months by magnetic resonance imaging (T2-weighted images, T1rho and T2 maps). Post-mortem, the effects of rhBMP-7 were determined by radiography, computed tomography, and macroscopy, and by histological, biochemical (GAG, DNA, and collagen), and biomolecular analyses of IVD tissue.ResultsIn vitro, rhBMP-7 stimulated matrix production of canine NPCs as GAG deposition was enhanced, DNA content was maintained, and gene expression levels of ACAN and COL2A1 were significantly upregulated. Despite the wide dose range of rhBMP-7 (2.5 to 250 μg) administered in vivo, no regenerative effects were observed at the IVD level. Instead, extensive extradiscal bone formation was noticed after intradiscal injection of 25 μg and 250 μg of rhBMP-7.ConclusionsAn intradiscal bolus injection of 2.5 μg, 25 μg, and 250 μg rhBMP-7 showed no regenerative effects in a spontaneous canine IVD degeneration model. In contrast, intradiscal injection of 250 μg rhBMP-7, and to a lesser extent 25 μg rhBMP-7, resulted in extensive extradiscal bone formation, indicating that a bolus injection of rhBMP-7 alone cannot be used for treatment of IVD degeneration in human or canine patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0625-2) contains supplementary material, which is available to authorized users.

Potential regenerative treatment strategies for intervertebral disc degeneration in dogs

Pain due to spontaneous intervertebral disc (IVD) disease is common in dogs. In chondrodystrophic (CD) dogs, IVD disease typically develops in the cervical or thoracolumbar spine at about 3–7 years of age, whereas in non-chondrodystrophic (NCD) dogs, it usually develops in the caudal cervical or lumbosacral spine at about 6–8 years of age. IVD degeneration is characterized by changes in the biochemical composition and mechanical integrity of the IVD. In the degenerated IVD, the content of glycosaminoglycan (GAG, a proteoglycan side chain) decreases and that of denatured collagen increases. Dehydration leads to tearing of the annulus fibrosus (AF) and/or disc herniation, which is clinically characterized by pain and/or neurological signs. Current treatments (physiotherapy, anti-inflammatory/analgesic medication, surgery) for IVD disease may resolve neurological deficits and reduce pain (although in many cases insufficient), but do not lead to repair of the degenerated disc. For this reason, there is interest in new regenerative therapies that can repair the degenerated disc matrix, resulting in restoration of the biomechanical function of the IVD. CD dogs are considered a suitable animal model for human IVD degeneration because of their spontaneous IVD degeneration, and therefore studies investigating cell-, growth factor-, and/or gene therapy-based regenerative therapies with this model provide information relevant to both human and canine patients. The aim of this article is to review potential regenerative treatment strategies for canine IVD degeneration, with specific emphasis on cell-based strategies.

The Dog as an Animal Model for Intervertebral Disc Degeneration?

Prospective observational and analytic study. To investigate whether spontaneous intervertebral disc degeneration (IVDD) occurring in both chondrodystrophic (CD) and nonchondrodystrophic dogs (NCD) can be used as a valid translational model for human IVDD research. Different animal models are used in IVDD research, but in most of these models IVDD is induced manually or chemically rather than occurring spontaneously. A total of 184 intervertebral discs (IVDs) from 19 dogs of different breeds were used. The extent of IVDD was evaluated by macroscopic grading, histopathology, glycosaminoglycan content, and matrix metalloproteinase 2 activity. Canine data were compared with human IVD data acquired in this study or from the literature. Gross pathology of IVDD in both dog types (CD and NCD) and humans showed many similarities, but the cartilaginous endplates were significantly thicker and the subchondral cortices significantly thinner in humans than in dogs. Notochordal cells were still present in the IVDs of adult NCD but were not seen in the CD breeds or in humans. Signs of degeneration were seen in young dogs of CD breeds (<1 year of age), whereas this was only seen in older dogs of NCD breeds (5-7 years of age). The relative glycosaminoglycan content and metalloproteinase 2 activity in canine IVDD were similar to those in humans: metalloproteinase 2 activity increased and glycosaminoglycan content decreased with increasing severity of IVDD. IVDD is similar in humans and dogs. Both CD and NCD breeds may therefore serve as models of spontaneous IVDD for human research. However, as with all animal models, it is important to recognize interspecies differences and, indeed, the intraspecies differences between CD and NCD breeds (early vs. late onset of IVDD, respectively) to develop an optimal canine model of human IVDD.