An Animal Model of Modic Changes by Embedding Autogenous Nucleus Pulposus inside Subchondral Bone of Lumbar Vertebrae

Cartilaginous Endplate Damage May be a Root Pathology Underlying Modic Changes on Lumbar Spine MR Images

STUDY DESIGN

Rabbit model study.

OBJECTIVE

To examine whether cartilaginous endplate (CEP) destruction leads to endplate and vertebral marrow signal changes (Modic changes, MCs) on MR images.

METHODS

Sixteen adult rabbits were used in the study and underwent an anterolateral procedure to expose the L2-6 intervertebral discs. The L4/5, L3/4 and L2/3 discs underwent annulotomy, annulotomy and CEP curettage, or annulotomy and chemonucleolysis, respectively, while the L5/6 disc served as a shame control. MR imaging was performed preoperatively and at 1, 3, and 6 months postoperatively to evaluate the presence or absence of MCs. After the last imaging, animals were sacrificed for histological study, focusing on endplate pathologies and their associations with MCs.

RESULTS

Among the 64 endplates that underwent CEP curettage or were exposed to chemonucleolysis, there were 6 (9.4%), 19 (29.7%), and 32 (50%) endplates with MCs at 1, 3 and 6 months, respectively. No MCs developed in the sham controls. Both surgical curettage and chymopapain injection successfully induced CEP destruction. Endplates with full layer CEP defects were most likely to develop MCs (59.6% vs 11.4%, P < 0.001). Moreover, endplates with MCs had a greater histological degeneration score than those without (8.97 ± 1.92 vs 5.35 ± 2.28, P < 0.001) and higher expression levels of inflammatory factors (IL-1β, TNF-α, and IL-6, P < 0.05 for all) in the subchondral vertebral marrow.

CONCLUSIONS

CEP destruction, induced either by physical curettage or chemical lysis, can lead to long-lasting inflammation in the vertebral marrow and Modic-like signal changes on MR images. CEP destruction may be a root pathology underlying MCs.

What can be observed in intervertebral cartilage endplate with aging? An animal model study of excessive axial mechanical loading

Introduction

The cartilage endplate (CEP) plays a crucial role as both a mechanical barrier and nutrient channel for the intervertebral disc, but it is vulnerable to excessive axial loading. We modified the Ilizarov external fixator and applied it to the CEP of the rat tail to impose diurnal, controllable excess axial loading. The objective was to measure morphological changes in the CEP when subjected to loading during the aging process.

Methods

Two Kirschner wires were, respectively, inserted into the center of the eighth and ninth coccygeal vertebrae (Co8/9) of rat (n = 54) to apply axial loading to the CEP. A remote control device was used to establish the diurnal loading schedule. At the end of 4, 8, and 12-week periods, the Co8/9 CEPs in each group were analyzed using MRI, histological staining, and immunohistochemical staining techniques.

Results

The novel Ilizarov model that we modified successfully induced degeneration of the rat coccygeal CEP. MRI analysis revealed significant degenerative changes in the loaded Co8/9 CEP, including decreased signal intensity and the formation of Schmorl's nodes at 8 and 12 weeks. Histological examination showed progressive CEP degeneration (CEPD), characterized by decreased microporosity, thinning, and structural irregularities. Immunohistochemical analysis demonstrated a significant reduction in Aggrecan and Collagen II expression in the CEP and nucleus pulposus over time. Control and sham groups maintained normal CEP structure and composition throughout the study period.

Conclusion

Excessive axial loading induced CEPD in the rat tail, primarily characterized by the formation of Schmorl's nodes and a reduction in CEP microporosity in this study. Our modified Ilizarov rat tail compression model, featuring stable and controllable axial loading capabilities, provided an alternative experimental paradigm for further investigation into CEPD.

Molybdenum disulfide, exfoliation methods and applications to photocatalysis: a review

This review provides a deep analysis of the mechanical and optoelectronic characteristics of MoS2. It offers a comprehensive assessment of diverse exfoliation methods, encompassing chemical, liquid-phase, mechanical, and microwave-driven techniques. The review also explores MoS2's versatile applications across various domains and meticulously examines its significance as a photocatalyst. Notably, it highlights key factors influencing the photocatalytic process. Indeed, the enhanced visible light responsiveness of materials like MoS2 holds immense potential across a wide range of applications. MoS2's remarkable photocatalytic response to visible light, coupled with its notable stability, opens up numerous possibilities in various fields. This unique combination makes MoS2 a promising candidate for applications that require efficient and stable photocatalytic processes, such as environmental remediation, water purification, and energy generation. Its attributes contribute significantly to addressing contemporary challenges and advancing sustainable technologies.

Lumbar endplate microfracture injury induces Modic-like changes, intervertebral disc degeneration and spinal cord sensitization - an in vivo rat model

BACKGROUND CONTEXT

Endplate (EP) injury plays critical roles in painful IVD degeneration since Modic changes (MCs) are highly associated with pain. Models of EP microfracture that progress to painful conditions are needed to better understand pathophysiological mechanisms and screen therapeutics.

PURPOSE

Establish in vivo rat lumbar EP microfracture model and assess crosstalk between IVD, vertebra and spinal cord.

STUDY DESIGN/SETTING

In vivo rat EP microfracture injury model with characterization of IVD degeneration, vertebral remodeling, spinal cord substance P (SubP), and pain-related behaviors.

METHODS

EP-injury was induced in 5 month-old male Sprague-Dawley rats L4-5 and L5-6 IVDs by puncturing through the cephalad vertebral body and EP into the NP of the IVDs followed by intradiscal injections of TNFα (n=7) or PBS (n=6), compared with Sham (surgery without EP-injury, n=6). The EP-injury model was assessed for IVD height, histological degeneration, pain-like behaviors (hindpaw von Frey and forepaw grip test), lumbar spine MRI and μCT, and spinal cord SubP.

RESULTS

Surgically-induced EP microfracture with PBS and TNFα injection induced IVD degeneration with decreased IVD height and MRI T2 signal, vertebral remodeling, and secondary damage to cartilage EP adjacent to the injury. Both EP injury groups showed MC-like changes around defects with hypointensity on T1-weighted and hyperintensity on T2-weighted MRI, suggestive of MC type 1. EP injuries caused significantly decreased paw withdrawal threshold, reduced axial grip, and increased spinal cord SubP, suggesting axial spinal discomfort and mechanical hypersensitivity and with spinal cord sensitization.

CONCLUSIONS

Surgically-induced EP microfracture can cause crosstalk between IVD, vertebra, and spinal cord with chronic pain-like conditions.

CLINICAL SIGNIFICANCE

This rat EP microfracture model was validated to induce broad spinal degenerative changes that may be useful to improve understanding of MC-like changes and for therapeutic screening.

Lumbar endplate microfracture injury induces Modic-like changes, intervertebral disc degeneration and spinal cord sensitization - An In Vivo Rat Model

BACKGROUND CONTEXT : Endplate (EP) injury plays critical roles in painful IVD degeneration since Modic changes (MCs) are highly associated with pain. Models of EP microfracture that progress to painful conditions are needed to better understand pathophysiological mechanisms and screen therapeutics. PURPOSE : Establish in vivo rat lumbar EP microfracture model with painful phenotype. STUDY DESIGN/SETTING : In vivo rat study to characterize EP-injury model with characterization of IVD degeneration, vertebral bone marrow remodeling, spinal cord sensitization, and pain-related behaviors. METHODS : EP-driven degeneration was induced in 5-month-old male Sprague-Dawley rats L4-5 and L5-6 IVDs through the proximal vertebral body injury with intradiscal injections of TNFα (n=7) or PBS (n=6), compared to Sham (surgery without EP-injury, n=6). The EP-driven model was assessed for IVD height, histological degeneration, pain-like behaviors (hindpaw von Frey and forepaw grip test), lumbar spine MRI and μCT analyses, and spinal cord substance P (SubP). RESULTS : EP injuries induced IVD degeneration with decreased IVD height and MRI T2 values. EP injury with PBS and TNFα both showed MC type1-like changes on T1 and T2-weighted MRI, trabecular bone remodeling on μCT, and damage in cartilage EP adjacent to the injury. EP injuries caused significantly decreased paw withdrawal threshold and reduced grip forces, suggesting increased pain sensitivity and axial spinal discomfort. Spinal cord dorsal horn SubP was significantly increased, indicating spinal cord sensitization. CONCLUSIONS : EP microfracture can induce crosstalk between vertebral bone marrow, IVD and spinal cord with chronic pain-like conditions. CLINICAL SIGNIFICANCE : This rat EP microfracture model of IVD degeneration was validated to induce MC-like changes and pain-like behaviors that we hope will be useful to screen therapies and improve treatment for EP-drive pain.

Immune exposure: how macrophages interact with the nucleus pulposus

Intervertebral disc degeneration (IDD) is a primary contributor to low back pain. Immune cells play an extremely important role in modulating the progression of IDD by interacting with disc nucleus pulposus (NP) cells and extracellular matrix (ECM). Encased within the annulus fibrosus, healthy NP is an avascular and immune-privileged tissue that does not normally interact with macrophages. However, under pathological conditions in which neovascularization is established in the damaged disc, NP establishes extensive crosstalk with macrophages, leading to different outcomes depending on the different microenvironmental stimuli. M1 macrophages are a class of immune cells that are predominantly pro-inflammatory and promote inflammation and ECM degradation in the NP, creating a vicious cycle of matrix catabolism that drives IDD. In contrast, NP cells interacting with M2 macrophages promote disc tissue ECM remodeling and repair as M2 macrophages are primarily involved in anti-inflammatory cellular responses. Hence, depending on the crosstalk between NP and the type of immune cells (M1 vs. M2), the overall effects on IDD could be detrimental or regenerative. Drug or surgical treatment of IDD can modulate this crosstalk and hence the different treatment outcomes. This review comprehensively summarizes the interaction between macrophages and NP, aiming to highlight the important role of immunology in disc degeneration.

Schmorl's nodes: demystification road of endplate defects-a critical review

BACKGROUND

Schmorl's nodes (SN) were the first vertebral endplate defects described. Debate continues about their epidemiology, physiopathology, and clinical significance. The purpose of this work was to summarize and discuss available literature about SN.

METHODS

We have searched for relevant papers about SN until April 2020, with 104 articles have been reviewed.

RESULTS

More than half of the available literature described the epidemiological aspects of SN or reported rare clinical presentations and treatment options. The lack of a consensual definition of SN, among other endplate defects, contributed to difficulties in literature results' interpretation. Summing up, SN is a frequent vertebral defect at the thoracolumbar juncture, with ethnic and gender influence. Lumbar Schmorl's nodes were frequently associated with disc degenerative disease and back pain. Their physiopathology remains unknown. However, strain energy changes in the spine along with morphological aspects of the vertebra, the genetic background, and the osteoimmunology may constitute possible clues. New SN could be confused in malignancy context with bone metastasis. The literature describes some imaging techniques to differentiate them, avoiding invasive approaches. Treatment options for rare painful presentations remain few with low evidence. Further studies are needed to establish a consensual definition for SN, understand clinical aspects, and provide adequate therapeutic strategies.

Cartilaginous endplate avulsion is associated with modic changes and endplate defects, and residual back and leg pain following lumbar discectomy

OBJECTIVE

While cartilaginous endplate (CEP) avulsion is a common finding in discectomy due to lumbar disc herniation, its roles in residual back and leg pain, associations with Modic changes (MCs) and endplate defects (EPD) remain unknown.

DESIGN

Patients with a single-level lumbar disc herniation who underwent endoscopic discectomy were studied. On MR images, the adjacent endplates of the herniated disc were assessed for MCs and EPD. The presence of CEP avulsion was examined under endoscopic and visualized inspection. Back and leg pain were evaluated by a numeric rating scale (NRS) and the Oswestry Disability Index. Associations of CEP avulsion with adjacent MCs, EPD, and residual back and leg pain were examined. In addition, histological features of avulsed CEP were determined using gross staining and immunohistochemical methods.

RESULTS

A total of 386 patients were included. CEP avulsion was found in 166 (43%) patients, and adjacent MCs and EPD were observed in 117 (30.3%) and 139 (36%) patients. The presence of CEP avulsion was associated with greater age, adjacent MCs (OR = 2.60, 95%CI [1.61-4.19]) and EPD (OR = 1.63, 95%CI [1.03-2.57]). Among the 187 patients with ≥2 years follow-up, CEP avulsion was associated with residual back pain (OR = 2.49, 95%CI [1.29-4.82]) and leg pain (OR = 2.25, 95%CI [1.04-4.84]). Histologically, the avulsed CEP was characterized by multiple defects, apparent inflammation, and nucleus invasion, as well as the upregulation of IL-1β, caspase-1, and NLRP3 inflammasome.

CONCLUSION

CEP avulsion was associated with MCs, EPD, and residual back and leg pain after discectomy, which may be attributed to NLRP3 inflammasome related inflammations.

IFN-γ Correlations with Pain Assessment, Radiological Findings, and Clinical Intercourse in Patient after Lumbar Microdiscectomy: Preliminary Study

Objectives

We investigated the influence of pain decrease after lumbar microdiscectomy on the interferon gamma (IFN-γ) serum level in patients with lumbar disc herniations. The study challenges the mechanism of sciatica pain and the role of IFN-γ in radicular pain development. Material and Methods. We performed clinical and immunoenzymatic assessment in a group of 27 patients with lumbar radicular pain due to disc herniations before and 3 months after surgery. Clinical status was assessed with the use of the Numeric Rating Scale (NRS), the Pain Rating Index and Pain Intensity Index of McGill Pain Questionnaire (SF-MPQ), the Oswestry Disability Index (ODI), and Beck Depression Inventory (BDI). The plasma concentrations of IFN-γ were ascertained by an immunoenzymatic method.

Results

We observe significant correlations between the results of the pain in the back region assessment NRS back scale after the surgery with the level of IFN-γ before the procedure (r_s = 0.528; p = 0.008) and after the procedure (r_s = 0.455; p = 0.025). These are moderate and positive correlations—the decrease in pain is correlated with the lower IFN-γ level. Additionally, there are significant correlations between the results of the PRI scale and the IFN-γ level. The PRI score before surgery correlates positively with IFN-γ after surgery (r_s = 0.462; p = 0.023), and the PRI score after surgery correlates positively with IFN before surgery (r_s = 0.529; p = 0.005) and after surgery (r_s = 0.549; p = 0.003). All correlations are moderate in severity—severe pain before surgery correlates with a higher level of IFN-γ after surgery and also higher IFN-γ before surgery. There were significant differences in the IFN-γ level before (Z = −2.733; p = 0.006) and after (Z = −2.391; p = 0.017) surgery in the groups of patients with and without nerve compression. In the group of patients with nerve compression, the level of IFN-γ before and after surgery was lower.

Conclusions

Less pain ratio after operation correlates with the level of IFN-γ. In the group of patients without significant nerve compression confirmed by MRI scans, the level of IFN-γ before and after surgery was higher than that in the group with nerve root compression.

Potential of Human Nucleus Pulposus-Like Cells Derived From Umbilical Cord to Treat Degenerative Disc Disease

BACKGROUND

Degenerative disc disease (DDD) is a common spinal disorder that manifests with neck and lower back pain caused by the degeneration of intervertebral discs (IVDs). Currently, there is no treatment to cure this debilitating ailment.

OBJECTIVE

To investigate the potential of nucleus pulposus (NP)-like cells (NPCs) derived from human umbilical cord mesenchymal stem cells (MSCs) to restore degenerated IVDs using a rabbit DDD model.

METHODS

NPCs differentiated from MSCs were characterized using quantitative real-time reverse transcription polymerase chain reaction and immunocytochemical analysis. MSCs and NPCs were labeled with fluorescent dye, PKH26, and transplanted into degenerated IVDs of a rabbit model of DDD (n = 9 each). Magnetic resonance imaging of the IVDs was performed before and after IVD degeneration, and following cell transplantation. IVDs were extracted 8 wk post-transplantation and analyzed by various biochemical, immunohistological, and molecular techniques.

RESULTS

NPC derivatives of MSCs expressed known NP-specific genes, SOX9, ACAN, COL2, FOXF1, and KRT19. Transplanted cells survived, dispersed, and integrated into the degenerated IVDs. IVDs augmented with NPCs showed significant improvement in the histology, cellularity, sulfated glycosaminoglycan and water contents of the NP. In addition, expression of human genes, SOX9, ACAN, COL2, FOXF1, KRT19, PAX6, CA12, and COMP, as well as proteins, SOX9, ACAN, COL2, and FOXF1, suggest NP biosynthesis due to transplantation of NPCs. Based on these results, a molecular mechanism for NP regeneration was proposed.

CONCLUSION

The findings of this study demonstrating feasibility and efficacy of NPCs to regenerate NP should spur interest for clinical studies to treat DDD using cell therapy.

Lumbar Vertebral Endplate Defects on Magnetic Resonance Images: Classification, Distribution Patterns, and Associations with Modic Changes and Disc Degeneration

STUDY DESIGN

A cross-sectional magnetic resonance (MR) imaging study.

OBJECTIVE

To classify and characterize endplate defects using routine lumbar MR images and to determine associations of endplate defects with Modic changes (MCs) and disc degeneration.

SUMMARY OF BACKGROUND DATA

Previously, a cadaveric study revealed that endplate lesions were common and associated with back pain history. New in vivo approaches appropriate for clinical studies are needed to further this potentially important line of research on the clinical significance of endplate lesions, including their relation with MCs, disc degeneration, and back pain.

METHODS

Using a MRI archive, 1564 endplates of 133 subjects (59 men and 74 women, mean age 58.9 ± 11.9 years) with the presence of MCs were retrospectively collected from April of 2014 to June of 2015. On the basis of morphological characteristics, a protocol was proposed to identify three distinct types of endplate defects, including focal, corner, and erosive defects. The location, size, and distribution patterns of various endplate lesions were characterized. MCs and disc degeneration were measured to examine their associations with endplate defects.

RESULTS

Endplate defects were observed in 27.8% of endplates studied. Greater age was associated with the presence of endplate defects. Focal defects were the most common (13.5%), followed by erosive defects (11.1%) and corner defects (3.2%). Defect types also differed in size and distribution patterns. Endplate defects and MCs had similar distribution patterns in the lumbar spine. The presence of endplate defects were associated with the presence of MCs (odds ratio = 4.29, P < 0.001), and associated with less disc signal intensity and disc height, and greater disc bulging (P < 0.05).

CONCLUSION

The three endplate defects identified on routine MR images appear to represent different pathologies and may play a key role in the pathogenesis of MCs. This classification system may facilitate clinical studies on endplate defects.

LEVEL OF EVIDENCE

4.

Modic type 1 change is an autoimmune response that requires a proinflammatory milieu provided by the 'Modic disc'

BACKGROUND CONTEXT

Modic changes (MCs) are magnetic resonance imaging (MRI) evidence of inflammatory and fibrotic vertebral bone marrow lesions that associate with adjacent disc degeneration and end plate damage. Although MC etiology is uncertain, historical data suggest a linkage to an autoimmune response of bone marrow triggered by the nucleus pulposus (NP).

PURPOSE

The aim of this study was to test whether bone marrow has an autoimmune response to NP cells that is amplified by an inflammatory milieu and ultimately leads to MC development in vivo. We hypothesized that an inflammatory co-stimulus is required for bone marrow/NP crosstalk to stimulate MC.

STUDY DESIGN

This is an in-vitro cell co-culture study plus in-vivo experiments in rat caudal vertebrae.

METHODS

In in-vitro study, bone marrow mononuclear cells (BMNCs) and NP cells (NPCs) from rats were co-cultured with and without interleukin (IL)-1α stimulation. Cell viability (n=3) of BMNCs and NPCs and gene expression (n=7) were analyzed. In in-vivo study, proinflammatory lipopolysaccharide (LPS) and control disc nucleus surrogates (NP micromass pellets) were generated in vitro from rat NPCs and implanted into rat tail vertebrae, and the response was compared with sham surgery (n=12 each). Tissue changes were investigated with T1w and T2w MRI (7T), histology, and immunohistochemistry (tumor necrosis factor, CD3) 1 (n=6) and 2 weeks (n=6) after implantation.

RESULTS

BMNC/NPC co-culture significantly increased lymphocyte viability (42%-69%, p<.05) and reduced NPC viability (96%-88%, p<.001), indicating immunogenicity of NPC. However, IL-1α was required to cause significant transcriptional upregulation of IL-1, IL-6, IL-10, and tropomyosin receptor kinase A. Therefore, an inflammatory activation is required to amplify the immune response. Immunogenicity of the NP was corroborated in vivo by CD3 cell accumulation around LPS and control disc surrogates at Day 7. However, only the LPS disc surrogate group demonstrated infiltration of CD3 cells at Day 14. Furthermore, end plate defects (p<.05, LPS: n=4/6, Ctrl: n=0/6, sham: n=0/6) and MC1-like MRI changes (T2w hyperintensity, p<.05) were only seen with LPS disc surrogates.

CONCLUSIONS

NPCs are immunogenic but cannot trigger MC without an additional proinflammatory stimulus. Our data suggest that MC requires end plate defects that allow marrow/NPC co-mingling plus an adjacent inflammatory "MC disc" that can amplify the immune response.

Effect of Liuweibuqi capsules on the balance between MMP-9 and TIMP1 and viability of alveolar macrophages in COPD

The present study aims to investigate the effect of Liuweibuqi (LWBQ) capsules on the expression of matrix metalloproteinase (MMP)-9 and TIMP1 and cell viability of alveolar macrophages (AMs) in chronic obstructive pulmonary disease (COPD). Rats were randomly divided into normal control (NC) group, model control (MC) group, Jinshuibao (JSB) group, spleen aminopeptidase (PAT) group, and low dose of LWBQ (LWBQ low), mid dose of LWBQ (LWBQ mid), and high dose of LWBQ (LWBQ high) group (n=10). Lung function was measured with a spirometer. Serum cytokines including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected using ELISA. The expressions of MMP-9 and TIMP1 were detected by quantitative real-time PCR (qRT-PCR) and Western blot. MTT assay and flow cytometry were used to measure cell viability and apoptosis. Compared with the NC group, body weight and lung function were reduced in the MC group. In addition, the serum levels of IL-6 and TNF-α were higher in the MC group than those in the NC group. The expression of MMP-9 protein in the AMs from rats was higher, and TIMP1 protein was lower in the MC group compared with the NC group. After LWBQ capsules treatment, compared with the MC group, the expression of inflammatory cytokines and MMP-9 were lower and TIMP1 was higher. Moreover, after LWBQ-medicated serum treatment, the release of inflammatory cytokines was reduced from AMs. Besides, LWBQ-medicated serum decreased the expression of MMP-9 and increased the expression of TIMP1 and cell viability compared with those in MC group. In conclusion, LWBQ capsules can inhibit the release of inflammatory cytokines, promote cell viability in AMs, and regulate the expression of MMP-9 and TIMP1.