Cervical intervertebral disc degeneration induced by unbalanced dynamic and static forces: a novel in vivo rat model

Trigeminal neuralgia as a presentation of high cervical stenosis: a systematic review of the literature

PURPOSE

An atypical presentation of cervical spondylopathy (CS), trigeminal neuralgia (TN) is attributable to the extension of trigeminal nuclei into the spinal cord and is frequently overlooked, leading to limited discussion with patients regarding potential anterior cervical surgery. Our systematic review assesses the effectiveness of cervical surgery for concurrent trigeminal neuralgia in cases of cervical spondylopathy.

METHODS

A systematic review exploring cases of trigeminal neuralgia related to cervical spondylopathy was conducted searching on PubMed, Scopus and Embase databases for article in English. The authors excluded literature reviews and paediatric studies. Abstracts from articles were initially screened, followed by a detailed review of full-text papers. We included studies that documented cases of trigeminal neuralgia unrelated to cranial pathologies in patients with cervical spondylopathy.

RESULTS

Following the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) protocol, 6 studies were included covering 30 patients (20 male, 10 female) with a mean age of 60.75 years and average symptom duration was 18 months. The most affected branches were V2 (41%) and V3 (49%), evenly distributed between left and right sides (55% vs 45%). Motor weakness (60%) and paresthesia (27%) were common non-trigeminal symptoms. The predominant compression levels were C2-C3 (38%) and C3-C4 (34%). After anterior cervical surgery (30% of patients), 100% experienced immediate resolution of trigeminal neuralgia, with no recrudescence at an average 7-month follow-up.

CONCLUSION

Besides common manifestations, high cervical stenosis can cause trigeminal neuralgia. This case report and systematic review confirms spinal decompression and fusion surgery may be effective in select cases. Surgeons should raise the possibility of cervical spine involvement when counseling patients with this disease.

Tuina Promotes Repair of Chronic Cervical Muscle Injury by Regulating Satellite Cell Proliferation and Differentiation and Inhibiting Myocyte Apoptosis

Purpose

Chronic cervical muscle injury is the first common cause of the development of cervical spondylosis, and Tuina can effectively promote the repair of chronic cervical muscle injury and alleviate neck pain, but the mechanism behind its efficacy is still unknown. The proliferation and differentiation of muscle satellite cells and the apoptosis of cervical myocytes play important roles in the repair of chronic cervical muscle injuries; therefore, this study aimed to explore the potential mechanisms of Tuina to promote the repair of cervical muscle injuries in terms of the proliferation and differentiation of satellite cells and the apoptosis of myocytes.

Patients and Methods

Twenty-eight Wistar rats were randomly divided into control group, model group, Tuina group, and meloxicam group, with 7 rats in each group. Except for the control group, each group were establish a chronic cervical muscle injury model (CCMI). Meloxicam (0.79 mg/kg) was administered by gavage, and in the Tuina group, pressure was applied to the Fengchi acupoint on the affected side once a day. Morphological changes of cervical muscle tissues were detected by ultrasonic diagnostic instrument and HE staining, electrophysiological recordings of electromyographic changes, apoptosis rate was detected by TUNEL staining, and positive expression of Bax, Bcl-2, IGF-1, MyoD, and Pax-7 were detected by Immunohistochemistry and Western blot.

Results

In CCMI model rats, we observed that the cervical muscle fibers were disorganized, with irregular morphology, and the amplitude of electromyography was significantly weakened, while Tuina could significantly improve these symptoms and effectively promote the repair of chronic cervical muscle injury. Meanwhile, compared with the model group, Tuina could significantly increase the expression levels of IGF-1 (P<0.01) and MyoD (P<0.05) and decrease the expression level of Pax7 (P<0.05). In addition, we found that the number of apoptotic cells in cervical myocytes was reduced after Tuina intervention (P<0.05), and Tuina inhibited the expression of pro-apoptotic factor Bax (P<0.01) and promoted the expression of anti-apoptotic factor Bcl-2 (P<0.05).

Conclusion

Tuina can promote the proliferation and differentiation of satellite cells to repair chronic cervical muscle injury by regulating the expression of Pax7, MyoD, and IGF-1, as well as inhibiting the expression of Bax and promoting the expression of Bcl-2 to ameliorate the apoptosis of cervical myocytes in CCMI model rats.

Atypical cervical spondylotic radiculopathy resulting in a hypertensive emergency during cervical extension: A case report and review of literature

BACKGROUND

Extensive research revealed the absence of reports documenting hypertensive emergencies precipitated by changes in the cervical spine posture.

CASE SUMMARY

We here present a 57-year-old woman diagnosed as having cervical spondylotic radiculopathy (CSR) who was scheduled for anterior cervical decompression and fusion. During post-anesthetic positioning, a sudden hypertensive surge was observed when the patient was in a supine position with the neck being slightly extended. This surge was promptly reversed through cervical flexion and head elevation. This event however required an alternate surgical approach for recovery—posterior laminoplasty and endoscopy-assisted nucleus pulposus removal. Following the 6-month outpatient follow-up period, cervical flexion and extension activities substantially improved in the patient without any episodes of increase in acute blood pressure.

CONCLUSION

Maintaining a safe hypotensive posture and performing rapid, thorough decompression surgery may serve as effective interventions for patients presenting symptoms similar to those of CSR accompanied by hypertensive emergencies (HE). This would mitigate the underlying causes of these HEs.

ARRB1 inhibits extracellular matrix degradation and apoptosis of nucleus pulposus cells by promoting autophagy and attenuates intervertebral disc degeneration

OBJECTIVE

Intervertebral disc degeneration (IVDD) is the leading cause of lower back pain (LBP). β-arrestin 1 (ARRB1) is a multifunctional protein that regulates numerous pathological processes. The aim of this study was to investigate the role of ARRB1 in IVDD.

METHODS

The expression of ARRB1 in nucleus pulposus (NP) of rats with IVDD was assayed. Next, rat nucleus pulposus cells (NPCs) were infected with lentiviruses containing shArrb1 (LV-shArrb1) and overexpressing Arrb1 (LV-oeArrb1). The roles of Arrb1 in serum-deprived NPCs were investigated by measuring apoptosis, extracellular matrix degradation, and autophagic flux. For experiments in vivo, LV-oeArrb1 lentivirus was injected into the NP tissues of IVDD rats to evaluate the effects of Arrb1 overexpression on NP.

RESULTS

In the NP tissues of IVDD rats, ARRB1 and cleaved caspase-3 expression increased, and the ratio of LC3II/LC3I protein expression was upregulated. Arrb1 knockdown aggravated extracellular matrix degradation, cellular apoptosis, and impairment of autophagic flux in rat NPCs under serum-deprived conditions, whereas Arrb1 overexpression significantly reversed these effects. ARRB1 interacted with Beclin 1, and Arrb1 knockdown suppressed the formation of the Beclin1-PIK3C3 core complex. The autophagy inhibitor 3-methyladenine (3-MA) offset the protective effects of Arrb1 overexpression in serum-deprived NPCs. Furthermore, Arrb1 overexpression inhibited apoptosis and extracellular matrix degradation, promoted autophagy in NP, and delayed the development of IVDD in rats.

CONCLUSION

ARRB1 prevents extracellular matrix degradation and apoptosis of NPCs by upregulating autophagy and ameliorating IVDD progression, presenting an innovative strategy for the treatment of IVDD.

Electroacupuncture improves apoptosis of nucleus pulposus cells via the IL-22/JAK2-STAT3 signaling pathway in a rat model of cervical intervertebral disk degeneration

BACKGROUND

Cervical spondylosis (CS) is a prevalent disorder that can have a major negative impact on quality of life. Traditional conservative treatment has limited efficacy, and electroacupuncture (EA) is a novel treatment option. We investigated the application and molecular mechanism of EA treatment in a rat model of cervical intervertebral disk degeneration (CIDD).

METHODS

The CIDD rat model was established, following which rats in the electroacupuncture (EA) group received EA. For overexpression of IL-22 or inhibition of JAK2-STAT3 signaling, the rats were injected intraperitoneally with recombinant IL-22 protein (p-IL-22) or the JAK2-STAT3 (Janus kinase 2-signal transducer and activator of transcription protein 3) inhibitor AG490 after model establishment. Rat nucleus pulposus (NP) cells were isolated and cultured. Cell counting kit-8 and flow cytometry were used to analyze the viability and apoptosis of the NP cells. Expression of IL-22, JAK2 and STAT3 was determined using RT-qPCR. Expression of IL-22/JAK2-STAT3 pathway and apoptosis related proteins was detected by Western blotting (WB).

RESULTS

EA protected the NP tissues of CIDD rats by regulating the IL-22/JAK2-STAT3 pathway. Overexpression of IL-22 significantly promoted the expression of tumor necrosis factor (TNF)-α, IL-6, IL-1β, matrix metalloproteinase (MMP)3 and MMP13 compared with the EA group. WB demonstrated that the expression of IL-22, p-JAK2, p-STAT3, caspase-3 and Bax in NP cells of the EA group was significantly reduced and Bcl-2 elevated compared with the model group. EA regulated cytokines and MMP through activation of IL-22/JAK2-STAT3 signaling in CIDD rat NP cells.

CONCLUSION

We demonstrated that EA affected apoptosis by regulating the IL-22/JAK2-STAT3 pathway in NP cells and reducing inflammatory factors in the CIDD rat model. The results extend our knowledge of the mechanisms of action underlying the effects of EA as a potential treatment approach for CS in clinical practice.

The mitochondrial UPR induced by ATF5 attenuates intervertebral disc degeneration via cooperating with mitophagy

Intervertebral disc degeneration (IVDD) is an aging disease that results in a low quality of life and heavy socioeconomic burden. The mitochondrial unfolded protein response (UPRmt) take part in various aging-related diseases. Our research intents to explore the role and underlying mechanism of UPRmt in IVDD. Nucleus pulposus (NP) cells were exposed to IL-1β and nicotinamide riboside (NR) served as UPRmt inducer to treat NP cells. Detection of ATP, NAD + and NADH were used to determine the function of mitochondria. MRI, Safranin O-fast green and Immunohistochemical examination were used to determine the degree of IVDD in vivo. In this study, we discovered that UPRmt was increased markedly in the NP cells of human IVDD tissues than in healthy controls. In vitro, UPRmt and mitophagy levels were promoted in NP cells treated with IL-1β. Upregulation of UPRmt by NR and Atf5 overexpression inhibited NP cell apoptosis and further improved mitophagy. Silencing of Pink1 reversed the protective effects of NR and inhibited mitophagy induced by the UPRmt. In vivo, NR might attenuate the degree of IDD by activating the UPRmt in rats. In summary, the UPRmt was involved in IVDD by regulating Pink1-induced mitophagy. Mitophagy induced by the UPRmt might be a latent treated target for IVDD.

Aberrant mechanical loading induces annulus fibrosus cells apoptosis in intervertebral disc degeneration via mechanosensitive ion channel Piezo1

BACKGROUND

Intervertebral disc degeneration (IVDD) is closely associated with the structural damage in the annulus fibrosus (AF). Aberrant mechanical loading is an important inducement of annulus fibrosus cells (AFCs) apoptosis, which contributes to the AF structural damage and aggravates IVDD, but the underlying mechanism is still unclear. This study aims to investigate the mechanism of a mechanosensitive ion channel protein Piezo1 in aberrant mechanical loading-induced AFCs apoptosis and IVDD.

METHODS

Rats were subjected to lumbar instability surgery to induce the unbalanced dynamic and static forces to establish the lumbar instability model. MRI and histological staining were used to evaluate the IVDD degree. A cyclic mechanical stretch (CMS)-stimulated AFCs apoptosis model was established by a Flexcell system in vitro. Tunel staining, mitochondrial membrane potential (MMP) detection, and flow cytometry were used to evaluate the apoptosis level. The activation of Piezo1 was detected using western blot and calcium fluorescent probes. Chemical activator Yoda1, chemical inhibitor GSMTx4, and a lentiviral shRNA-Piezo1 system (Lv-Piezo1) were utilized to regulate the function of Piezo1. High-throughput RNA sequencing (RNA-seq) was used to explore the mechanism of Piezo1-induced AFCs apoptosis. The Calpain activity and the activation of Calpain2/Bax/Caspase3 axis were evaluated by the Calpain activity kit and western blot with the siRNA-mediated Calapin1 or Calpain2 knockdown. Intradiscal administration of Lv-Piezo1 was utilized to evaluate the therapeutic effect of Piezo1 silencing in IVDD rats.

RESULTS

Lumbar instability surgery promoted the expression of Piezo1 in AFCs and stimulated IVDD in rats 4 weeks after surgery. CMS elicited distinct apoptosis of AFCs, with enhanced Piezo1 activation. Yoda1 further promoted CMS-induced apoptosis of AFCs, while GSMTx4 and Lv-Piezo1 exhibited opposite effects. RNA-seq showed that knocking down Piezo1 inhibited the calcium signaling pathway. CMS enhanced Calpain activity and elevated the expression of BAX and cleaved-Caspase3. Calpain2, but not Calpain1 knockdown, inhibited the expression of BAX and cleaved-Caspase3 and alleviated AFCs apoptosis. Lv-Piezo1 significantly alleviated the progress of IVDD in rats after lumbar instability surgery.

CONCLUSIONS

Aberrant mechanical loading induces AFCs apoptosis to promote IVDD by activating Piezo1 and downstream Calpain2/BAX/Caspase3 pathway. Piezo1 is expected to be a potential therapeutic target in treating IVDD.

Facet joint degeneration-An initial procedure of the cervical spine degeneration

Objective

This study aims to emphasize the initiating role of facet joint (FJ) degeneration in the process of cervical spine degeneration induced by tangential load, and we further validate it in a novel cervical spine degeneration animal model.

Methods

The characteristics of cervical degeneration in patients of different ages were summarized through case collection. In the rat models, Hematoxylin-Eosin, Safranin O staining, and micro-computed tomography were used to show the histopathological changes and bone fiber structure of FJ and the height of intervertebral disc (IVD) space. The ingrowth of nociceptive sensory nerve fibers was observed by immunofluorescence staining.

Results

FJ degeneration without IVDs degeneration was more common in people with cervical spondylosis in young patients. The obvious degeneration phenotypes of the FJs preceded the IVDs at the same cervical segment in our animal model. The SP+ and CGRP+ sensory nerve fibers were observed in the articular subchondral bone of degenerated FJs and porous endplates of degenerated IVDs.

Conclusion

The FJ degeneration may act as the major contributor to cervical spine degeneration in young people. The dysfunction of functional unit of spine, not a certain part of IVD tissue, results in the occurrence of cervical degeneration and neck pain.

Anterior cervical discectomy and fusion is more effective than cervical arthroplasty in relieving atypical symptoms in patients with cervical spondylosis

BACKGROUND AND PURPOSE

Patients with cervical spondylosis often present with concurrent 'atypical symptoms' of unknown etiology that have been associated with cervical spondylotic disease, including dizziness, headache, nausea, tinnitus, blurred vision, palpitations, and memory and gastrointestinal disturbances. Few studies have addressed whether surgical intervention to treat classic symptoms of cervical spondylosis can also effectively alleviate atypical symptoms. Accordingly, the purpose of this study is to compare the ability of cervical arthroplasty (CA) and anterior cervical discectomy and fusion (ACDF) to alleviate atypical symptoms associated with cervical spondylosis.

MATERIALS AND METHODS

A retrospective analysis of 140 patients with cervical spondylosis and associated atypical symptoms was performed. Atypical symptoms were defined vertigo, headache, nausea and vomiting, tinnitus, blur vision, palpitation, hypomnesia, and gastroenteric disturbances not otherwise explained by medical comorbidities. Seventy-eight patients (55.7%) underwent ACDF and 62 (44.3%) patients underwent CA. Demographics, surgical characteristics, patient reported outcome measures (PROMs), radiographs, complication rates, and resolution in atypical symptoms were recorded and compared between groups. Atypical symptoms were assessed using a 20-point system. All the patients had a minimum of five years follow-up.

RESULTS

VAS, SF-36, JOA, and NDI scores improved significantly in all the patients (p < 0.001). At the last follow-up, the fusion rate was 97% in the ACDF group. Atypical symptoms improved in both groups (p < 0.001), although the ACDF group demonstrated greater improvement in headache and vertigo resolution compared to the CA group (p < 0.0001).

CONCLUSIONS

While both ACDF and CA are effective in alleviating atypical symptoms associated with cervical spondylosis, ACDF demonstrated greater improvements in atypical symptoms.

MFG-E8 alleviates intervertebral disc degeneration by suppressing pyroptosis and extracellular matrix degradation in nucleus pulposus cells via Nrf2/TXNIP/NLRP3 axis

Intervertebral disc degeneration (IVDD) is a chronic age-related degenerative disease accompanied by complex pathophysiological mechanisms. Increasing evidence indicates that NLRP3 inflammasome mediated pyroptosis of nucleus pulposus (NP) cells displays an important role in the pathological progression of IVDD. Milk fat globule-EGF factor-8 (MFG-E8) is an endogenously secreted glycoprotein with beneficial effects of anti-inflammatory, antioxidant, and modulation of NLRP3 inflammasome. However, the effect of MFG-E8 on IVDD remains unclear. In this study, our purpose is to clarify the expression changes of MFG-E8 in the IVDD process and explore the role and mechanism of MFG-E8. We found that MFG-E8's expression was reduced in degraded nucleus pulposus tissues of humans and rats as well as hydrogen peroxide (H2O2)-treated NP cells. Exogenous supplementation of MFG-E8 could rescue H2O2-induced oxidative stress, mitochondrial dysfunction, and NLRP3 inflammasome activation and protect NP cells from pyroptosis and extracellular matrix (ECM) degradation. Mechanistically, Nrf2/TXNIP/NLRP3 axis plays a crucial role in MFG-E8-mediated suppression of the above-pathological events. In vivo, we established a rat intervertebral disc acupuncture model and found that MFG-E8 administration effectively alleviated IVDD development by imageological and histomorphological evaluation. Overall, our findings revealed the internal mechanisms underlying MFG-E8 regulation in NP cells and its intrinsic value for IVDD therapy.

N(6)-methyladenosine RNA methyltransferase like 3 inhibits extracellular matrix synthesis of endplate chondrocytes by downregulating sex-determining region Y-Box transcription factor 9 expression under tension

OBJECTIVE

Tension stimulation is an important inducer of endplate cartilage degeneration, but the specific regulatory mechanism remains unclear. This study was the first to reveal the mechanism by which methyltransferase-like 3 (METTL3)-mediated N(6)-methyladenosine (m6A) modification affected the extracellular matrix anabolism by tension-induced endplate chondrocytes.

METHOD

We examined the differences in METTL3 expression and m6A methylation levels in human endplate chondrocytes and human cartilage endplate tissues under in vitro tension. The effect on endplate cartilage degeneration was evaluated by manipulating m6A methylation mediated by METTL3 in vivo and in vitro. The effect of METTL3-mediated m6A methylation on the stability of sex-determining region Y-box transcription factor 9 (SOX9) gene expression was determined experimentally.

RESULTS

METTL3 expression and m6A methylation levels were significantly increased in degenerative human endplate cartilage tissue. Similarly, tension stimulation inhibited the ability of human endplate chondrocytes to synthesize extracellular matrix, which was accompanied by an increase in METTL3-mediated m6A methylation. The ability of endplate chondrocytes to resist tension was significantly enhanced by inhibiting METTL3 expression and subsequently downregulating m6A methylation in vitro and in vivo, thereby reducing intervertebral disc degeneration. Furthermore, METTL3 mediated SOX9 RNA methylation and disrupted SOX9 mRNA stability, thereby inhibiting the gene expression of the downstream collagen type II alpha 1 chain.

CONCLUSION

Tension stimulation downregulated SOX9 expression through METTL3-mediated m6A methylation, thereby inhibiting the synthesis of extracellular matrix in endplate chondrocytes.

Naringin Inhibits Apoptosis Induced by Cyclic Stretch in Rat Annular Cells and Partially Attenuates Disc Degeneration by Inhibiting the ROS/NF-κB Pathway

Oxidative stress and apoptosis play important roles in the pathogenesis of various degenerative diseases. Previous studies have shown that naringin can exert therapeutic effects in multiple degenerative diseases by resisting oxidative stress and inhibiting apoptosis. Although naringin is effective in treating degenerative disc disease, the underlying mechanism remains unclear. This study is aimed at investigating the effects of naringin on oxidative stress, apoptosis, and intervertebral disc degeneration (IVDD) induced by cyclic stretch and the underlying mechanisms in vitro and in vivo. Abnormal cyclic stretch was applied to rat annulus fibrosus cells, which were then treated with naringin, to observe the effects of naringin on apoptosis, oxidative stress, mitochondrial function, and the nuclear factor- (NF-) κB signaling pathway. Subsequently, a rat model of IVDD induced by dynamic and static imbalance was established to evaluate the effects of naringin on the degree of degeneration (using imaging and histology), apoptosis, and oxidative stress in the serum and the intervertebral disc. Naringin inhibited the cyclic stretch-induced apoptosis of annulus fibrosus cells, reduced oxidative stress, improved mitochondrial function, enhanced the antioxidant capacity, and suppressed the activation of the NF-κB signaling pathway. Additionally, it reduced the degree of IVDD (evaluated using magnetic resonance imaging) and the level of oxidative stress and inhibited apoptosis and p-P65 expression in the intervertebral discs of rats. Thus, naringin can inhibit cyclic stretch-induced apoptosis and delay IVDD, and the underlying mechanism may be related to the inhibition of oxidative stress and activation of the NF-κB signaling pathway. Naringin may be an effective drug for treating degenerative disc disease.

Endoplasmic reticulum stress associates with the development of intervertebral disc degeneration

Endoplasmic reticulum (ER) is an important player in various intracellular signaling pathways that regulate cellular functions in many diseases. Intervertebral disc degeneration (IDD), an age-related degenerative disease, is one of the main clinical causes of low back pain. Although the pathological development of IDD is far from being fully elucidated, many studies have been shown that ER stress (ERS) is involved in IDD development and regulates various processes, such as inflammation, cellular senescence and apoptosis, excessive mechanical loading, metabolic disturbances, oxidative stress, calcium homeostasis imbalance, and extracellular matrix (ECM) dysregulation. This review summarizes the formation of ERS and the potential link between ERS and IDD development. ERS can be a promising new therapeutic target for the clinical management of IDD.

Comparison of Dorsal-to-Ventral Ratios of the Cervical Paraspinal Musculature in French Bulldogs With and Without Cervical Intervertebral Disk Disease and Two Other Breeds Based on CT Scan Measurements

Objective: To objectively assess the cervical paraspinal musculature of French bulldogs (FBs) using computed tomography (CT) scan-based measurements, outline differences in other breeds published in the literature, and investigate the potential influence of its cervical paraspinal musculature on predisposed sites for intervertebral disk disease.

Animals: Thirty FBs that underwent CT scans of the cervical spine from the skull to C7/T1 were enrolled. Fifteen dogs were patients suffering from intervertebral disk herniation (IVDH group), and 15 dogs underwent CT scans due to brachycephalic obstructive airway syndrome (BOAS group).

Methods: At the level of each cervical intervertebral disk from C2/C3 to C7/T1, measurements were performed and statistically analyzed. On the sagittal CT scan reconstruction, the height ratio of the dorsal to ventral paraspinal musculature and the angle of the disk axis to vertebral body length were assessed. On the transverse plane, the area ratio of the dorsal and ventral paraspinal musculature and the ratio of force moments were determined at each intervertebral disk level. Finally, ratios were compared to the values of Labrador retrievers and dachshunds published by Hartmann et al. (1).

Results: Comparing the two FB groups, one significant difference was detected in the mean height ratio of the dorsal to ventral paraspinal musculature at the level of C5/C6 (P = 0.0092) and C6/C7 (P = 0.0076), with IVDH FBs having the more prominent dorsal paraspinal musculature. At the level of C3/C4, a significantly less prominent dorsal paraspinal musculature in FBs than in dachshunds (P = 0.0058) and a significantly steeper disk to vertebral body angulation were observed (P = 0.0005).

Conclusion: Although some incidental differences were found, most parameters did not significantly differ between the BOAS and IVDH FBs. Significant conformational differences in the cervical paraspinal musculature and disk to vertebral body length angulation were found between FBs and two other breeds (chondrodystrophic and non-chondrodystrophic). This study's findings suggest that the paraspinal musculature is an additional biomechanical influencing factor on the preferential sites of IVDH in the cervical spine and that other major factors exist in IVDH development, especially in FBs.

Effect of Cervical Decompression on Atypical Symptoms Cervical Spondylosis-A Narrative Review and Meta-Analysis

BACKGROUND

Atypical symptoms of cervical spondylosis refer to symptoms other than the typical symptoms of cervical spondylosis and include headache, nausea, gastrointestinal discomfort, blurred vision, tinnitus, hypomnesia, and palpitations. The role of cervical decompression in mitigating atypical symptoms of cervical spondylosis is still unclear.

METHODS

A comprehensive search of different databases was performed to retrieve articles that studied the effect of cervical decompression on associated atypical symptoms. The data were analyzed to obtain pooled improvement in the various atypical symptoms after cervical decompression.

RESULTS

Twenty-seven studies were included in the meta-analysis. Our analysis showed that cervical decompression was associated with significant improvement in Neck Disability Index-Headache Component (standardized mean difference [SMD], -0.84; 95% confidence interval [CI], -0.94 to -0.74; P < 0.0001), visual analog scale (SMD, -1.47; 95% CI, -1.73 to -1.21; P = 0.0004) and cervicogenic headache (odds ratio [OR], 0.19; 95% CI, 0.06-0.63; P = 0.01). Significant improvement was also observed in vertigo (OR, 0.27; 95% CI, 0.10-0.77; P = 0.02), tinnitus (OR, 0.54; 95% CI, 0.35-0.83; P = 0.02), and nausea (OR, 0.25; 95% CI, 0.13-0.47; P = 0.006) after cervical decompression. Nonsignificant improvement was noticed in the rates of blurred vision, hypomnesia, giddiness, gastrointestinal discomfort, palpitations, and hypertension.

CONCLUSIONS

Our analysis showed that cervicogenic headache, tinnitus, and nausea were significantly relieved after cervical decompression. There was no significant effect of cervical decompression on blurred vision, hypomnesia, giddiness gastrointestinal discomfort, palpitations, and hypertension.

Cervical spinal instability causes vertebral microarchitecture change and vertebral endplate lesion in rats

Background

The vertebral endplate (VEP) was damaged after spinal instability induced by cervical muscle section (CMS). Whether CMS induces bone formation and mechanical loading change in the vertebra is still obscure. This study was aimed to explore mechanical loading change and endplate damage after CMS.

Methods

Forty-eight rats were randomly divided into the CMS group and the sham group. The C6/7 segments were harvested at 4, 8, and 12 weeks after surgery. The microarchitectures of the C6 vertebra ​and the vertebral endplate lesions and intervertebral disc height of C6/7 were measured by micro-computed tomography. Micro-finite element analysis was used to evaluate biomechanical properties of the C6 vertebra. Bone remodelling of the C6 vertebra ​and the endplate ​sclerosis and intervertebral disc degeneration of C6/7 were evaluated by histological and immunohistochemical analyses.

Results

CMS significantly induced bone formation of the C6 ventral vertebra ​and increased the biomechanical properties of mainly the ventral side at 4 weeks, which was gradually rebalanced throughout the rest of the study. CMS also significantly increased protein expression of transforming growth factor-β1 (TGF-β1) and phosphorylated small mothers against decapentaplegic (pSmad)2/3 ​at 4 weeks. Moreover, tartrate-resistant acid phosphatase staining showed that osteoclast-positive cells were slightly in number decreased at 4 weeks, but were obviously increased at 8 weeks. The VEP of the ventral side was abraded earlier followed by calcification in situ later after CMS, consistent with the biomechanical enhancements observed. The degree of endplate degeneration was aggravated with time. Finally, CMS decreased intervertebral disc height and increased disc degeneration scores with time.

Conclusions

Spinal instability induced by CMS increases bone mass and biomechanical loading of the ventral side of vertebra in the early stage, which might initiate VEP damage and cause intervertebral disc degeneration.

The translational potential of this article

Our study indicates that vertebral trabecular changes may involve in intervertebral disc degeneration induced by spinal instability. This may help to elucidate the mechanisms by which disc degeneration occur.

LncRNA MALAT1 exhibits positive effects on nucleus pulposus cell biology in vivo and in vitro by sponging miR-503

Background

Intervertebral disc degeneration (IDD) is characterized by the loss of nucleus pulposus cells (NPCs) and phenotypic abnormalities. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) are involved in the pathogenesis of IDD. In this study, we aimed to investigate the functional effects of lncRNA MALAT1 on NPCs in IDD and the possible mechanism governing these effects.

Results

We validated the decreased expression of MALAT1 in the IDD tissues, which was associated with decreased Collagen II and Aggrecan expression. In vitro, overexpressed MALAT1 could attenuate the effect of IL-1β on NPC proliferation, apoptosis, and Aggrecan degradation. In vivo, MALAT1 overexpression attenuated the severity of disc degeneration in IDD model rats. Our molecular study further demonstrated that MALAT1 could sponge miR-503, modulate the expression of miR-503, and activate downstream MAPK signaling pathways. The effects of MALAT1 on NPCs were partially reversed/aggregated by miR-503 mimics/inhibitor treatment.

Conclusion

Our data suggested that the MALAT1-miR-503-MAPK pathway plays a critical role in NPCs, which may be a potential strategy for alleviating IDD.

The role of estrogen in intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a main contributor to low back and radicular pain, which imposes heavy economic burdens on society. However, the etiology and mechanism of IVDD are complex and still not completely clear. In particular, the role of estrogen in IVDD has not received much attention in recent research, although estrogen plays a crucial role in the metabolic dysfunction of others musculoskeletal structures, such as bone, muscle, and tendon. In this review, we attempt to describe the role of estrogen in IVDD and to summarize the proposed mechanisms in vivo and in vitro, as well as, to outline several interesting questions in this field.

Effect of Ginsenoside Rg1 on the intervertebral disc degeneration rats and the degenerative pulposus cells and its mechanism

OBJECTIVE

To explore the effect of ginsenoside Rg1 on intervertebral disc degeneration (IVDD) in vivo and in vitro and its mechanism.

METHODS

60 rats were underwent surgery to construct rat models of IVDD and divided in the sham group, model group and gradient G-Rg1 groups (10 mg/kg/d, 20 mg/kg/d and 40 mg/kg/d).The change of histology was observed by HE staining, the water content and the expression of β-catenin in IVD were detected. Rat nucleus pulposus cells(NPCs) were isolated from IVDD rats and divided in D-NPCs group, and gradient G-Rg1 groups(20 μg/ml, 50 μg/ml and 100 μg/ml).The cell proliferation activity, cell apoptosis rate,the expression of proteins related to ECM and Wnt/β-catenin were detected respectively, Finally the agonist of Wnt/β-catenin pathway LiCl was used for reversed experiments.

RESULTS

In vivo, G-Rg1 treatment could improve the structural disorganization, low water content, NPCs number and aggrecan and collagenⅡ expression in IVD and down-regulate the expression of β-catenin. In vitro NPCs, G-Rg1 treatment could improve the low cell proliferation, high apoptosis rate and low expression of aggrecan and collagenⅡ in degenerative NPCs in a dose-dependent manner.G-Rg1 treatment could down-regulate the expression of proteins related to β-catenin signal and LiCl could reverse the increase of cell proliferation and ECM synthesis, decrease of apoptosis of degenerative NPCs induced by G-Rg1.

CONCLUSION

G-Rg1 could promote ECM synthesis of degenerative NPCs and inhibiting its apoptosis, improve the IVDD via inhibiting the Wnt/β-catenin pathway.

Establishment of cervical dynamic and static imbalance models and preliminary study on the mechanism of cervical degeneration in rats

This study aimed to observe dynamically the changes of x-ray, histomorphology appearance and serum inflammatory cytokines of cervical degenerative disease in rat models and to discuss the mechanism of cervical degeneration. Sixty Sprague Dawley rats were randomised into test (n = 45) and control (n = 15) groups, which were randomly subdivided into three groups corresponding to 1, 3 and 6 mo post operation. At the corresponding postoperative stage, cervical x-ray films were acquired, and intervertebral disc space and intervertebral foramen size were measured. Some serum inflammatory cytokines from all rats were quantitatively determined. Then, the morphological change in cervical intervertebral disc specimens stained with hematoxylin and eosin was observed. The results were analysed and compared among groups. Compared to the control group, the cervical x-ray and histomorphology appearance of rats in the test group showed varying degrees of degeneration. Furthermore, the serum IL-1β, TNF-α and IL-10 in the test group increased significantly at the corresponding postoperative stage (P < 0.05, P < 0.01 and P < 0.001, respectively) compared to the control group. This model of cervical disc degeneration can accelerate imaging and histological degeneration, but it may be accompanied by changes in serum inflammatory cytokines levels.

Estrogen Deficiency Exacerbates Intervertebral Disc Degeneration Induced by Spinal Instability in Rats

STUDY DESIGN

An experimental animal study of osteoporosis (OP) and intervertebral disc degeneration (IDD).

OBJECTIVE

The aim of this study was to clarify the effects of estrogen deficiency and supplement on cervical IDD induced by bilateral facetectomy in rats.

SUMMARY OF BACKGROUND DATA

The relationship between IDD and OP is still controversy with the wide prevalence in aged people.

METHODS

Seventy-two Sprague-Dawley female rats were randomly divided into ovariectomy (OVX) group, facet joints resection of C4-6 (FR), FR-OVX group, estrogen replacement therapy (ERT, based on the FR-OVX group) group, and sham group. Specimens of C4-6 segment were harvested at 12 and 24 weeks. The microstructures of C5 vertebrae, vertebral endplate lesions and calcification, and IDD of C5/6 disc were evaluated by micro-computed tomography (micro-CT) and histology. The protein and gene levels of aggrecan, Col2α1, matrix metalloprotease (MMP)-3, and MMP-13 in the C5/6 and C4/5 discs were measured.

RESULTS

Microstructures of C5 vertebral body were weakened significantly after ovariectomy, while restored effectively with estradiol supplementation. The facetectomy led to significant IDD, and the IDD was aggravated when combined with OVX. The IDD of the ERT group was alleviated effectively and similar to that of the FR group in intervertebral disc height, vertebral endplate lesions and calcification, and disc degeneration scores. In addition, the estrogen supplement maintained the extracellular matrix by decreasing MMP-3 and MMP-13, and increasing aggrecan and Col2α1 expression.

CONCLUSION

The present study demonstrated that estrogen deficiency exacerbated IDD induced by spinal instability, while estrogen supplementation alleviated the progression of disc degeneration related to osteoporosis.

LEVEL OF EVIDENCE

N/A.

Radiographic analysis of the correlation between ossification of the nuchal ligament and sagittal alignment and segmental stability of the cervical spine in patients with cervical spondylotic myelopathy

BACKGROUND

Ossification of the nuchal ligament (ONL) caused by chronic injury to the nuchal ligament (NL) is very common in instability-related cervical disorders.

PURPOSE

To determine possible correlations between ONL, sagittal alignment, and segmental stability of the cervical spine.

MATERIAL AND METHODS

Seventy-three patients with cervical spondylotic myelopathy (CSM) and ONL (ONL group) and 118 patients with CSM only (control group) were recruited. Radiographic data included the characteristics of ONL, sagittal alignment and segmental stability, and ossification of the posterior longitudinal ligament (OPLL). We performed comparisons in terms of radiographic parameters between the ONL and control groups. The correlations between ONL size, cervical sagittal alignment, and segmental stability were analyzed. Multivariate logistic regression was used to identify the independent risk factors of the development of ONL.

RESULTS

C2-C7 sagittal vertical axis (SVA), T1 slope (T1S), T1S minus cervical lordosis (T1S-CL) on the lateral plain, angular displacement (AD), and horizontal displacement (HD) on the dynamic radiograph increased significantly in the ONL group compared with the control group. The size of ONL significantly correlated with C2-C7 SVA, T1S, AD, and HD. The incidence of ONL was higher in patients with OPLL and segmental instability. Cervical instability, sagittal malalignment, and OPLL were independent predictors of the development of ONL through multivariate analysis.

CONCLUSION

Patients with ONL are more likely to have abnormal sagittal alignment and instability of the cervical spine. Thus, increased awareness and appreciation of this often-overlooked radiographic finding is warranted during diagnosis and treatment of instability-related cervical pathologies and injuries.

Leptin regulates disc cartilage endplate degeneration and ossification through activation of the MAPK-ERK signalling pathway in vivo and in vitro

Recent findings demonstrate that leptin plays a significant role in chondrocyte and osteoblast differentiation. However, the mechanisms by which leptin acts on cartilage endplate (CEP) cells to give rise to calcification are still unclear. The aim of this study was to evaluate the effects of leptin that induced mineralization of CEP cells in vitro and in vivo. We constructed a rat model of lumbar disc degeneration and determined that leptin was highly expressed in the presence of CEP calcification. Rat CEP cells treated with or without leptin were used for in vitro analysis using RT‐PCR and Western blotting to examine the expression of osteocalcin (OCN) and runt‐related transcription factor 2 (Runx2). Both OCN and Runx2 expression levels were significantly increased in a dose‐ and time‐dependent manner. Leptin activated ERK1/2 and STAT3 phosphorylation in a time‐dependent manner. Inhibition of phosphorylated ERK1/2 using targeted siRNA suppressed leptin‐induced OCN and Runx2 expression and blocked the formation of mineralized nodules in CEP cells. We further demonstrated that exogenous leptin induced matrix mineralization of CEP cells in vivo. We suggest that leptin promotes the osteoblastic differentiation of CEP cells via the MAPK/ERK signal transduction pathway and may be used to investigate the mechanisms of disc degeneration.

Changes and significance of inflammatory cytokines in a rat model of cervical spondylosis

The aim of the present study was to dynamically observe and discuss the significance of inflammatory cytokines in cervical degenerative disease induced by unbalanced dynamic and static forces in rats. A total of 60 Sprague Dawley rats were randomized into test (n=45) and control (n=15) groups, which were randomly subdivided into three groups corresponding to assessment at one, three and six months post-operation. The test group included 10, 15 and 20 rats at the corresponding post-operative stage and the control group had five rats at each time-point. By excising cervicodorsal muscles and ligaments, an unbalanced dynamic and static rat model was established in the test group. At one, three and six-months post-operation, venous serum of test and control group rats was collected and inflammatory cytokines in the serum of all rats were quantitatively determined by ELISA. The results revealed that compared with the control group, the interleukin (IL)-1β, IL-10 and tumor necrosis factor-α levels in the test group were significantly increased at one and three months (P<0.05, <0.01 or <0.001), and that IL-12 was significantly increased at three months (P<0.05). However, transforming growth factor-β1 increased at one month but was significantly decreased at three months (P<0.01). IL-6 did not change significantly throughout the observation period (P>0.05). In conclusion, cervical vertebral stability may be accompanied with changes of inflammatory cytokines.

X-ray dynamic observation of cervical degenerative disease induced by unbalanced dynamic and static forces in rats 1

PURPOSE

To investigate dynamically the X-ray appearance of cervical degenerative disease induced by unbalanced dynamic and static forces in rats.

METHODS

A total of 60 Sprague Dawley rats were randomized into test (n=45) and control (n=15) groups, which were randomly subdivided into the one-, three- and six-month post-operative groups. The test group included 10, 15 and 20 rats at the respective corresponding post-operative stage and the control group included five rats at each time-point. By excising cervicodorsal muscles, interspinous ligaments and supraspinous ligament of rats in the test group, the balance of dynamic and static forces on cervical vertebrae was disrupted to establish a rat model of cervical degeneration. Spinal X-ray images were acquired, and intervertebral disc space and intervertebral foramen size were measured at one, three and six months post-operation. The results were analyzed and compared among groups.

RESULTS

Cervical dynamic and static imbalance accelerated the appearance of cervical degenerative disease on X-ray.

CONCLUSION

Cervical degenerative disease may be induced by unbalanced dynamic and static forces in rats.

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.

A large animal model that recapitulates the spectrum of human intervertebral disc degeneration

OBJECTIVE

The objective of this study was to establish a large animal model that recapitulates the spectrum of intervertebral disc degeneration that occurs in humans and which is suitable for pre-clinical evaluation of a wide range of experimental therapeutics.

DESIGN

Degeneration was induced in the lumbar intervertebral discs of large frame goats by either intradiscal injection of chondroitinase ABC (ChABC) over a range of dosages (0.1U, 1U or 5U) or subtotal nucleotomy. Radiographs were used to assess disc height changes over 12 weeks. Degenerative changes to the discs and endplates were assessed via magnetic resonance imaging (MRI), semi-quantitative histological grading, microcomputed tomography (μCT), and measurement of disc biomechanical properties.

RESULTS

Degenerative changes were observed for all interventions that ranged from mild (0.1U ChABC) to moderate (1U ChABC and nucleotomy) to severe (5U ChABC). All groups showed progressive reductions in disc height over 12 weeks. Histological scores were significantly increased in the 1U and 5U ChABC groups. Reductions in T2 and T1ρ, and increased Pfirrmann grade were observed on MRI. Resorption and remodeling of the cortical boney endplate adjacent to ChABC-injected discs also occurred. Spine segment range of motion (ROM) was greater and compressive modulus was lower in 1U ChABC and nucleotomy discs compared to intact.

CONCLUSIONS

A large animal model of disc degeneration was established that recapitulates the spectrum of structural, compositional and biomechanical features of human disc degeneration. This model may serve as a robust platform for evaluating the efficacy of therapeutics targeted towards varying degrees of disc degeneration.

Radiologic and histological observations in experimental T1-T12 dorsal arthrodesis: A qualitative description of T1-T12 segment and other body parts involved, between prepubertal age and skeletal maturityxs

BACKGROUND

This experimental study provides a qualitative description and the morpho-structural features of the fusions taking place in the thoracic spine between prepubertal age and skeletal maturity. There is a lack of informations regarding the influence of partial or total dorso-thoracic vertebral arthrodesis on the development of the thoracic cage as well as its potential effects on different intra and extra-thoracic organs. This study admits the hypothesis that vertebral arthrodesis may have influence on other body areas and so, it intends to verify the possible secondary involvement of other body parts, such as intervertebral discs, cervical and thoracic spinal ganglia, sternocostal cartilage, ovaries and lungs.

MATERIALS AND METHODS

Fifty-four female New Zealand white rabbits were submitted to dorsal arthrodesis. The radiologic imaging and light microscopy histological pictures were taken and studied in all. Computed tomography (CT) scan measurements were performed in operated and sham operated rabbits at different time. Similarly, histological specimens of intervertebral discs, cervical and thoracic spinal ganglia, sternocostal cartilage, ovaries and lungs were analyzed at different times. The study ended at the age of 17-18 months.

RESULTS

Most rabbits had formed a fusion mass, which was only fibrous at first, then osteofibrous and finally, in the older subjects, structured in lamellar-osteon tissue. Intervertebral foramens were negatively involved in vertebral arthrodesis, as shown by CT scans. Intervertebral discs showed irregular aspects. The increase of atresic follicles and the reduction of primordial follicles in operated rabbits led to the hypothesis of a cause-effect relationship between arthrodesis and modified hormonal status. Dorsal root ganglia showed microscopic alterations in operated rabbits especially.

CONCLUSIONS

The process of fusion mass and bone formation, associated with the arthrodesis, involves at different degrees of the vertebral bodies, discs and intervertebral foramens, ganglia and spinal nerve roots.

Mid-term Outcomes of Anterior Cervical Fusion for Cervical Spondylosis With Sympathetic Symptoms

STUDY DESIGN

Prospective study.

OBJECTIVE

The purpose of this study is to elucidate mid-term outcomes of anterior cervical fusion for cervical spondylosis with sympathetic symptoms (CSSS).

SUMMARY OF BACKGROUND DATE

The terminology, pathogenesis, diagnosis, and treatment of CSSS remain controversial. Surgical treatment of CSSS has been rarely reported. This is the first prospective study to evaluate the mid-term outcome of surgical treatment of CSSS.

METHODS

Thirty-one patients who were diagnosed with CSSS in 2006 were evaluated prospectively. All patients were assigned to undergo anterior cervical fusion with posterior longitudinal ligament (PLL) resection and followed up for ≥5 years. Sympathetic symptoms such as vertigo, headache, and tinnitus, etc. were evaluated using the sympathetic symptom 20-point score. Neurological status was assessed using the Japanese Orthopedic Association (JOA) score. Clinical and radiologic data were prospectively collected before surgery, and at 1 week, 2 months, 6 months, 2 years, and 5 years after surgery. Surgical complications and morbidities of other diseases during the follow-up were also recorded.

RESULTS

The mean 20-point score decreased significantly from 7.3±3.5 before surgery to 2.2±2.7 at the final follow-up (P<0.001), giving a mean recovery rate of 66.1%±50.3%. Good to excellent results were attained in 80.6% of these patients. The sympathetic symptoms were relieved in 23 of the 31 patients in the early postoperative period, and 5 patients in 2 months. No relief of sympathetic symptoms was found in 3 patients. The mean JOA score improved significantly from 12.0±1.9 before surgery to 14.8±1.5 by the end of the follow-up (P<0.001). No late neurological deterioration was found in this group.

CONCLUSIONS

The mid-term outcomes of anterior cervical fusion with PLL resection for CSSS have been satisfactory. Differential diagnosis before surgery is of great importance. PLL may play a role in presenting sympathetic symptoms.

Autophagy in the Degenerating Human Intervertebral Disc: In Vivo Molecular and Morphological Evidence, and Induction of Autophagy in Cultured Annulus Cells Exposed to Proinflammatory Cytokines-Implications for Disc Degeneration

STUDY DESIGN

Autophagy-related gene expression and ultrastructural features of autophagy were studied in human discs.

OBJECTIVE

To obtain molecular/morphological data on autophagy in human disc degeneration and cultured human annulus cells exposed to proinflammatory cytokines.

SUMMARY OF BACKGROUND DATA

Autophagy is an important process by which cytoplasm and organelles are degraded; this adaptive response to sublethal stresses (such as nutrient deprivation present in disc degeneration) supplies needed metabolites. Little is known about autophagic processes during disc degeneration.

METHODS

Human disc specimens were obtained after institutional review board approval. Annulus mRNA was analyzed to determine autophagy-related gene expression levels. Immunolocalization and ultrastructural studies for p62, ATG3, ATG4B, ATG4C, ATG7, L3A, ULK-2, and beclin were conducted. In vitro experiments used IL-1β- or TNF-α-treated human annulus cells to test for autophagy-related gene expression.

RESULTS

More degenerated versus healthier discs showed significantly greater upregulation of well-recognized autophagy-related genes (P ≤ 0.028): beclin 1 (upregulated 1.6-fold); ATG8 (LC3) (upregulated 2.0-fold); ATG12 (upregulated 4.0-fold); presenilin 1 (upregulated 1.6-fold); cathepsin B (upregulated 4.5-fold). p62 was localized, and ultrastructure showed autophagic vacuolization and autophagosomes with complex, redundant whorls of membrane-derived material. In vitro, proinflammatory cytokines significantly upregulated autophagy-related genes (P ≤ 0.04): DRAM1 (6.24-fold); p62 (4.98-fold); PIM-2 oncogene, a positive regulator of autophagy (3-fold); WIPI49 (linked to starvation-induced autophagy) (upregulated 2.3-fold).

CONCLUSION

Data provide initial molecular and morphological evidence for the presence of autophagy in the degenerating human annulus. In vivo gene analyses showed greater autophagy-related gene expression in more degenerated than healthier discs. In vitro data suggested a mechanism implicating a role of TNF-α and IL-1β in disc autophagy. Findings suggest the importance of future work to investigate the relationship of autophagy to apoptosis, cell death, cell senescence, and mitochondrial dysfunction in the aging and degenerating disc.

LEVEL OF EVIDENCE

N/A.

Evidence for an Important Role of Smad-7 in Intervertebral Disc Degeneration

Smad-7 inhibited the transforming growth factor beta (TGF-β)-induced proteoglycan synthesis in chondrocytes and completely antagonized the effect of TGF-β on the proliferation of the cells. The aim of this study was to evaluate the contribution of Smad-7 to the pathophysiology of disc degeneration by determining the expression of Smad-7 in the degenerative intervertebral discs and its effect on the extracellular matrix metabolism of disc cells. Instability of the lumbar spine produced by imbalanced dynamic and static forces was used to induce intervertebral disc degeneration in rats. The expression of Smad-7 was assessed by the immunohistochemical method. Disc cell apoptosis was detected by in situ TUNEL staining. The effect of Smad-7 overexpression on the matrix metabolism of disc cells was analyzed in vitro by real-time polymerase chain reaction (PCR) and Western blotting. Finally, intradiscal injection of the Smad-7 overexpression lentivirus was performed to evaluate the in vivo effect of Smad-7 on disc degeneration. Radiographic and histomorphological examinations showed that lumbar disc degeneration became more and more severe in the rats with induced instability. Immunohistochemical observation demonstrated increasing protein expression of Smad-7 in the degenerative discs. A significantly positive correlation was found between Smad-7 expression and the degree of disc degeneration and between Smad-7 expression and disc cell apoptosis. Overexpression of Smad-7 in disc cells inhibited the expression of TGF-β1, collagen type-I, collagen type-II, and aggrecan and promoted the expression of MMP-13, but did not change the expression of ADAMTS-5. The in vivo findings illustrated that intradiscal injection of lentivirus vector with Smad-7 overexpression accelerated the progress of disc degeneration. In conclusion, Smad-7 was highly expressed in the degenerative discs. Overexpression of Smad-7 weakened the protective role of TGF-β and accelerated the progress of disc degeneration. Interference on Smad-7 might be a potential therapeutic method for the prevention and treatment of degenerative disc diseases.

The correlation between ossification of the nuchal ligament and pathological changes of the cervical spine in patients with cervical spondylosis

STUDY DESIGN

A retrospective clinical data analysis.

OBJECTIVE

This study was conducted to investigate the correlation between ossification of the nuchal ligament (ONL) and pathological changes of the cervical spine in patients with cervical spondylosis.

SUMMARY OF BACKGROUND DATA

ONL can usually be found in cervical spondylosis. Thus, it is important to find the correlation between ONL and pathological changes of the cervical spine in patients with cervical spondylosis.

METHODS

The medical records of 100 patients with cervical spondylosis with the local type of ONL (ONL group) and 50 patients with cervical spondylosis only (control group) were reviewed. Data analysis included patients' sex, age, location of ONL, maximum cord compression level, osteophyte height ratio, and grade of cervical intervertebral disc degeneration. Radiological features were evaluated by lateral plain radiography and magnetic resonance imaging.

RESULTS

In total, 69.0% of subjects in the ONL group had ONL located at the maximum cord compression level; there was no difference based on sex (P = 0.248). The value of the osteophyte height ratio was higher at the ONL level than at its superior and inferior adjacent segments (P < 0.001). The osteophyte height ratio was also significantly different at the C4-C5 (P < 0.001) and C5-C6 (P = 0.008) levels between the ONL group and the control group. There was a significant difference in distribution of intervertebral disc degeneration grading between the ONL level and superior adjacent segments (P = 0.028), as well as inferior adjacent segments (P = 0.049). The distribution of intervertebral disc degeneration grading at the C5-C6 level between patients whose location of ONL and maximum cord compression level were both at C5-C6 and patients whose maximum cord compression level was at C5-C6 in the control group was also significantly different (P = 0.035).

CONCLUSION

The location of ONL commonly corresponds to the most stenotic level of the spinal canal. The location of ONL also correlates with the level of osteophyte formation and intervertebral disc degeneration, indicating that ONL has correspondence to instability-related cervical pathological changes in cervical spondylosis.

Chronic neck pain: making the connection between capsular ligament laxity and cervical instability

The use of conventional modalities for chronic neck pain remains debatable, primarily because most treatments have had limited success. We conducted a review of the literature published up to December 2013 on the diagnostic and treatment modalities of disorders related to chronic neck pain and concluded that, despite providing temporary relief of symptoms, these treatments do not address the specific problems of healing and are not likely to offer long-term cures. The objectives of this narrative review are to provide an overview of chronic neck pain as it relates to cervical instability, to describe the anatomical features of the cervical spine and the impact of capsular ligament laxity, to discuss the disorders causing chronic neck pain and their current treatments, and lastly, to present prolotherapy as a viable treatment option that heals injured ligaments, restores stability to the spine, and resolves chronic neck pain. The capsular ligaments are the main stabilizing structures of the facet joints in the cervical spine and have been implicated as a major source of chronic neck pain. Chronic neck pain often reflects a state of instability in the cervical spine and is a symptom common to a number of conditions described herein, including disc herniation, cervical spondylosis, whiplash injury and whiplash associated disorder, postconcussion syndrome, vertebrobasilar insufficiency, and Barré-Liéou syndrome. When the capsular ligaments are injured, they become elongated and exhibit laxity, which causes excessive movement of the cervical vertebrae. In the upper cervical spine (C0-C2), this can cause a number of other symptoms including, but not limited to, nerve irritation and vertebrobasilar insufficiency with associated vertigo, tinnitus, dizziness, facial pain, arm pain, and migraine headaches. In the lower cervical spine (C3-C7), this can cause muscle spasms, crepitation, and/or paresthesia in addition to chronic neck pain. In either case, the presence of excessive motion between two adjacent cervical vertebrae and these associated symptoms is described as cervical instability. Therefore, we propose that in many cases of chronic neck pain, the cause may be underlying joint instability due to capsular ligament laxity. Currently, curative treatment options for this type of cervical instability are inconclusive and inadequate. Based on clinical studies and experience with patients who have visited our chronic pain clinic with complaints of chronic neck pain, we contend that prolotherapy offers a potentially curative treatment option for chronic neck pain related to capsular ligament laxity and underlying cervical instability.

The effects of osteoporosis and disc degeneration on vertebral cartilage endplate lesions in rats

PURPOSE

Evidence has shown that osteoporosis or intervertebral disc degeneration (IDD) led to cartilage endplate lesions (CEL), but their combined effects on the lesion remain unknown. This study developed an innovative rat model combined ovariectomy (OVX) and cervical muscle section (CMS), and aimed to evaluate the combined effects of osteoporosis and IDD on cartilage endplate lesions of cervical spine.

METHODS

Fifty-two Sprague-Dawley female rats were assigned randomly into four groups as follows: the sham group (n = 10) underwent sham surgery; the OVX group (n = 14) was subjected to bilateral ovariectomy; the CMS group (n = 14) had posterior paraspinal muscles cut from C2 to C7; the CMS-OVX group (n = 14) underwent the OVX and CMS surgeries consecutively. Samples of C6-C7 segments were harvested at 12, 18 and 24 weeks post-surgery. Micro-CT analysis was performed to evaluate the CEL, intervertebral disc height (IDH) and structural indices. Histological analysis with Safranine O/fast green stain and histological score were used to observe the characteristics of the degenerative discs.

RESULTS

Ovariectomy surgery resulted in significant changes of most structural indices of the C6 body, such as decrease of percent bone volume and number of bone trabecula at 12 weeks, and greater changes at 18 and 24 weeks. The CEL following CMS surgery was seen on the ventral, while the CEL in the OVX and sham groups on the peripheral. The CEL was greatest in the CMS-OVX group and significantly greater than that in the CMS and OVX groups at 12 and 18 weeks (P < 0.05). The CMS surgery resulted in significant IDH decrease at 12, 18 and 24 weeks (P < 0.05), while the OVX surgery resulted in mild IDH decrease when compared with the sham group. The IDH in the CMS-OVX group was significantly lower than that in the CMS group at 24 weeks (P < 0.05). Histological evaluation suggested cartilage endplate abrasion at 12 weeks, and in situ calcification at 18 and 24 weeks in the CMS and CMS-OVX groups. Disc degenerative scores were higher following CMS or OVX surgery, and correlated with the CEL and IDH (P < 0.01), respectively.

CONCLUSIONS

The present study suggested that a combination of OVX and CMS led to more lesion of cartilage endplate than any one thereof, as well as more decrease of IDH. The lesion and IDH decrease were associated with the disc degeneration levels. The cartilage endplate was worn out at the early stage and calcified in situ later. The results indicate that osteoporosis may deteriorate the disc degeneration at specific time.

Induction of intervertebral disc cell apoptosis and degeneration by chronic unpredictable stress

OBJECT

The purpose of this study was to evaluate the effects of chronic unpredictable stress on the intervertebral discs of rats.

METHODS

The cellular events involved in injury- and stress-induced disc degeneration were investigated in male Wistar rats. Disc degeneration and apoptosis were evaluated using microscopic (light and electron) and molecular (immunoblotting and immunohistochemistry) methods. Corticosterone levels were used as markers of stress and measured by radioimmunoassay.

RESULTS

The data gathered in this study showed that chronic unpredictable stress can significantly increase corticosterone levels. Furthermore, biochemical markers of apoptosis (that is, increases in the Bax/Bcl2 ratio and TUNEL reactivity [p < 0.05]) were observed in the stressed animals. Electron and light microscopy also showed disc degeneration and apoptotic cells in the experimental groups.

CONCLUSIONS

Taken together, these data demonstrated that chronic stress is most likely to be a risk factor for creating intervertebral disc degeneration and that programmed cell death may be one of the mechanisms of stress-induced disc degeneration.

Histomorphometric and radiographical changes after lumbar implantation of the PEEK nonfusion interspinous device in the BB.4S rat model

STUDY DESIGN

An experimental animal study.

OBJECTIVE

To investigate histomorphometric and radiographical changes in the BB.4S rat model after PEEK (polyetheretherketone) nonfusion interspinous device implantation.

SUMMARY OF BACKGROUND DATA

Clinical effectiveness of the PEEK nonfusion spine implant Wallis (Abbott, Bordeaux, France; now Zimmer, Warsaw, IN) is well documented. However, there is a lack of evidence on the long-term effects of this implant on bone, in particular its influence on structural changes of bone elements of the lumbar spine.

METHODS

Twenty-four male BB.4S rats aged 11 weeks underwent surgery for implantation of a PEEK nonfusion interspinous device or for a sham procedure in 3 groups of 8 animals each: (1) implantation at level L4-L5; (2) implantation at level L5-L6; and (3) sham surgery. Eleven weeks postoperatively osteolyses at the implant-bone interface were measured via radiograph, bone mineral density of vertebral bodies was analyzed using osteodensitometry, and bone mineral content as well as resorption of the spinous processes were examined by histomorphometry. RESULTS.: Resorption of the spinous processes at the site of the interspinous implant was found in all treated segments. There was no significant difference in either bone density of vertebral bodies or histomorphometric structure of the spinous processes between adjacent vertebral bodies, between treated and untreated segments and between groups.

CONCLUSION

These findings indicate that resorption of spinous processes because of a result of implant loosening, inhibit the targeted load redistribution through the PEEK nonfusion interspinous device in the lumbar spinal segment of the rat. This leads to reduced long-term stability of the implant in the animal model. These results suggest that PEEK nonfusion interspinous devices like the Wallis implants may have time-limited effects and should only be used for specified indications.

Increased macroautophagy in the pathological process of intervertebral disc degeneration in rats

OBJECTIVE

Macroautophagy increases with age in rat intervertebral discs; however, the effect of macroautophagy on the process of intervertebral disc degeneration (IVDD) is still unclear. The aim of this study was to examine the presence of autophagosome, as well as the levels of Beclin-1 and LC3 proteins, in vivo. Additionally, in vitro evidence of macroautophagy and GRP78 and GADD153 protein levels were investigated to explore the mechanism of macroautophagy in the process of IVDD.

METHODS

Male Sprague-Dawley rats, aged 2 months, were randomly divided into six groups (three control and three model groups, n = 8 per group). At the 6-, 12-, and 18-week time points, autophagosomes in nucleus pulposus cells were detected with transmission electron microscope (TEM). Expression of Beclin-1 and LC3 protein levels within intervertebral disc was detected using Western blotting analysis. Then, the rat annulus fibrosus cells were isolated and cultured with Earle's balanced salt solution. At 1, 2, and 3 hr of culture, autophagosomes were detected using monodansylcadaverine assay, and LC3, Beclin-1, GRP78, and GADD153 protein levels were detected using Western blotting analysis.

RESULTS

Transmission electron microscopy revealed autophagosomes within nucleus pulposus cells in both the control and model groups. At 6-, 12-, and 18-week posttreatments, the levels of Beclin-1 and the LC3-II/LC3-I protein ratio in the model groups were higher than those in the control groups (p < 0.05). Compared with the control rats, amino acid starvation increased the number of monodansylcadaverine-positive cells and the LC3-II/LC3-I protein ratio in the model rats. Moreover, the in vitro levels of Beclin-1, GRP78, and GADD153 proteins were increased with the prolongation of amino acid starvation (p < 0.05).

CONCLUSIONS

Macroautophagy was present and was associated with increased pathological process of IVDD in rats. Macroautophagy of intervertebral disc cells is possibly secondary to endoplasmic reticulum stress.

Electroacupuncture inhibits apoptosis in annulus fibrosis cells through suppression of the mitochondria-dependent pathway in a rat model of cervical intervertebral disc degradation

The purpose of this study was to investigate whether treatment with electroacupuncture (EA) inhibited mitochondria-dependent apoptosis in annulus fibrosis (AF) cells in a rat model of cervical intervertebral disc degradation induced by unbalanced dynamic and static forces. Forty Sprague-Dawley rats were used in this study, of which 30 underwent surgery to induce cervical intervertebral disc degradation, 10 rats received EA at acupoints Dazhui (DU 14) and Shousanli (LI 10). TUNEL staining was measured to assess apoptosis in AF cells, immunohistochemistry was used to examine Bcl-2 and Bax expression, colorimetric assays were used to determine caspase 9 and caspase 3 activities and RT-PCR and western blotting were used to assess the mRNA and protein expression of Crk and ERK2. Treatment with EA reduced the number of AF-positive cells in TUNEL staining, increased Bcl-2-positive cells and decreased Bax-positive cells in immunohistochemical staining, significantly inhibited the activation of caspases-9 and -3, and enhanced the mRNA and protein expression of Crk and ERK2. Our data show that EA inhibits AF cell apoptosis via the mitochondria-dependent pathway and up-regulates Crk and ERK2 expression. These results suggest that treatment with may be a good alternative therapy for preventing cervical spondylosis.

Study on the effect of Youguiyin () on regulating gene expression profile of the rats with femoral head necrosis induced by steroid

OBJECTIVE

To observe the regulation of Youguiyin (YGY, ) on the gene expression profile of the rat with steroid-induced femoral head necrosis (sFHN), for the sake of investigating its molecular mechanism of sFHN prevention and treatment.

METHODS

All the 30 rats were randomly divided into three groups, the normal control group (A), the model control group (B), and the YGY treated group (C), 10 in each group. After rats in Groups B and C were being made into FHN models with steroid injection, they received a daily intragastric administration of saline and YGY respectively in equal volume for a total of 6 weeks, while to the unmodeled normal rats in Group A, saline was administered instead. The rats were sacrificed at the terminal of administration; their mRNA from femoral head tissue was extracted and prepared to cDNA probe through inverse transcription for detecting gene expression profile by microarray, outcomes of which was passing fluorescence quantitative PCR verification, and the differential expressed genes were analyzed adopting gene ontology (GO) method.

RESULTS

Compared with Group A, the numbers of differential genes found in Groups B and C were 190 and 92, respectively, but the changing trend in the two groups was opposite, mainly manifested as down-regulating in Group B/Group A (GB/GA) and up-regulating in Group C/Group B (GC/GB). The analysis showed that these differential genes were mainly assigned to cell apoptosis, signal transduction, metabolism, cell proliferation and differentiation, cell cycle, blood coagulation, antioxidant activity, etc.

CONCLUSIONS

sFHN was regulated by various genes; the regulation of YGY on expressions of these genes and the intra/extra-cellular signaling processes was possibly the molecular mechanism of YGY for preventing/treating sFHN. This study gave an explanation to the effectiveness of Chinese medicine in preventing/treating FHN from aspects of gene expression and enriched the Chinese medicine theory of "Kidney (Shen) governing bones".

Molecular basis of intervertebral disc degeneration

Intervertebral disc (IVD) degeneration is a disease of the discs connecting adjoining vertebrae in which structural damage leads to degeneration of the disc and surrounding area. Degeneration of the disc is considered to be a normal process of aging, but can accelerate faster than expected or be precipitated by other factors. The scientific community has come a long way in understanding the biological basis and interpreting the lifestyle implications of IVD degeneration. Of all the diseases of the intervertebral disc, degeneration is the most common and has earned much attention due to its diversity in presentation and potential multiorgan involvement. We will provide a brief overview of the anatomic, cellular, and molecular structure of the IVD, and delve into the cellular and molecular pathophysiology surrounding IVD degeneration. We will then highlight some of the newest developments in stem cell, protein, and genetic therapy for IVD degeneration.

Beneficial effects of hyperbaric oxygen on human degenerated intervertebral disk cells via suppression of IL-1β and p38 MAPK signal

Nucleus pulposus cells (NPCs) from degenerating disks produce catabolic and inflammatory factors, including interleukin (IL)-1, nitric oxide (NO), prostaglandin E2 (PGE-2), and matrix metalloproteinaes (MMPs). An imbalance between MMPs and tissue inhibitors of matrix metalloproteinases (TIMPs) has been proposed to exist in the degenerating disk. This study evaluates the effects of hyperbaric oxygen (HBO) on the human degenerated NPCs. NPCs were maintained in alginate bead culture. All hyperoxic cells were exposed to 100% O(2) at 2.5 atmospheres absolute (ATA) in a hyperbaric chamber. p38 MAPK phosphorylation of the NPCs was detected using the phosphor-kinase array kit. RNA was isolated for real-time quantitative polymerase chain reaction (Q-PCR) analysis of aggrecan and type II collagen gene expression. The amounts of IL-1β, NO, PGE-2, MMP-3, and TIMP-1 in the conditioned media were quantified by enzyme-linked immunosorbent assay (ELISA). Our data showed that HBO treatment decreased expression of IL-1β, increased the gene expression of aggrecan and type II collagen, suppressed the phosphorylation of p38 MAPK, decreased NO, PGE-2, and MMP-3, and increased TIMP-1 expression in NPCs as compared with the atmospheric treatment. These results support the hypothesis that IL-1β and the p38 MAPK signal may be responsible for many of the inflammatory and catabolic changes seen in the human disk degeneration, and support our proposal that HBO treatment-induced increase of the anabolic factor (TIMP-1)/catabolic factor (MMP-3) ratio may provide a therapeutic approach to slow the course of intervertebral disk degeneration.

Prostaglandin E2 and prostaglandin F2α differentially modulate matrix metabolism of human nucleus pulposus cells

Prostaglandin (PG) actions on disc metabolism are unclear even though certain PGs are highly expressed by disc cells under inflammatory conditions and nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used to block PG production to treat back pain. Hence this study aimed to (1) quantify gene expression of arachidonic acid cascade components responsible for PG synthesis and (2) examine the effects of key PGs on disc matrix homeostasis. Microarray analysis revealed that inflammatory stress increases expression of synthases and receptors for prostaglandin E2 (PGE(2)) and prostaglandin F2α (PGF(2α)), resulting in elevated PGE(2) and PGF(2α) production in conditioned media of disc cells. PGE(2) diminished disc cell proteoglycan synthesis, in a dose-dependent manner. Semiquantitative RT-PCR revealed differential effects of PGE(2) and PGF(2α) on disc cell expression of key matrix structural genes, aggrecan, versican, collagens type I and II. PGE(2) and PGF(2α) also decreased message for the anabolic factor, IGF-1. PGE(2) decreased mRNA expression for the anti-catabolic factor TIMP-1 while PGF(2α) increased mRNAs for catabolic factors MMP-1 and MMP-3. Thus, PGE(2) and PGF(2α) may have an overall negative impact on disc matrix homeostasis, and the use of NSAIDs may impact disc metabolism as well as treat back pain.

Both endoplasmic reticulum and mitochondria are involved in disc cell apoptosis and intervertebral disc degeneration in rats

Intervertebral disc cell apoptosis occurs through either death receptor or mitochondrial pathway, but whether disc cell apoptosis is also mediated by the endoplasmic reticulum (ER) pathway remains unclear. The objective of this study was to investigate whether ER and mitochondria are co-involved in disc cell apoptosis and intervertebral disc degeneration (IVDD) in rats. Forty-eight rats were used for in vivo experiments. IVDD was characterized by X-ray and histomorphology examination, disc cell apoptosis was detected by TUNEL staining, and the co-involvement of ER and mitochondria in apoptosis was determined by immunohistochemical staining for GRP78, GADD153, caspase-12, and cytochrome C. Additional eight rats were used for annular cell isolation and culture. After sodium nitroprusside treatment, annular cell apoptosis was observed morphologically and quantified by flow cytometry; the expression of biomarkers of ER stress and mitochondrial dysfunction were analyzed by reverse transcriptase PCR (RT-PCR), fluorescence double labeling, and Western blot; and mitochondrial membrane potential was detected by 5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbo cyanine iodide (JC-1) staining. Finally, NS3694 and Z-ATAD-FMK were employed to inhibit the formation of apoptosome complex and the activation of caspase-12, respectively, and apoptotic incidence and caspase-9 activity were assayed. We found that IVDD, induced by unbalanced dynamic and static forces in the rats, was accompanied by increased disc cell apoptosis and enhanced expression of GRP78, GADD153, caspase-12, and cytochrome C. Annular cell apoptosis induced by sodium nitroprusside was confirmed by morphologic observation and flow cytometry. With increased apoptosis, the expression of GRP78, GADD153, and caspase-12 upregulated, mitochondrial membrane potential decreased, and accumulation of cytochrome C in the cytosol manifested. Furthermore, NS3694 and Z-ATAD-FMK dramatically suppress annular cell apoptosis and caspase-9 activity. In conclusion, disc cell apoptosis mediated simultaneously by ER and mitochondria plays a potent role in IVDD.

Muscone protects vertebral end-plate degeneration by antiinflammatory property

Most chronic neck pain is the result of degeneration of the cervical spine. IL-1beta may play an important role in intervertebral disc degeneration. This being the case, inhibiting IL-1beta could provide a therapeutic approach for reducing or preventing disc degeneration. Muscone reportedly relieves pain and suppresses inflammation. Therefore, we asked whether muscone, a potent antiinflammatory agent, could reduce proinflammatory cytokines in vitro (end-plate cartilage cultures) and end-plate degeneration in vivo (a rat model that induces intervertebral disc degeneration). In vitro, muscone reversed IL-1beta-induced upregulation of IL-1beta, tumor necrosis factor alpha, cyclooxygenase 2, inducible nitric oxide synthase, matrix metalloproteinase 13, aggrecanase 2, and nitric oxide and downregulation of Col2alpha1 and aggrecan. Pretreatment with muscone (6.25, 12.5, 25 mumol/L) inhibited the IL-1beta-induced phosphorylation of extracellular signal-regulated kinases 1/2 and c-Jun N-terminal kinase in a dose-dependent manner. In vivo, muscone inhibited the expression of prostaglandin E2, 6-keto-prostaglandin F1alpha, IL-1beta, and tumor necrosis factor alpha and recovered the structural distortion of the degenerative disc. Our findings suggest muscone is a promising agent for treating intervertebral disc degeneration through its antiinflammatory effects.

Assessing the validity of a novel model of vertebral artery type of cervical syndrome induced by injecting sclerosing agent next to transverse process of cervical vertebra

The efficacy of injecting sclerosing agent next to transverse process of cervical vertebra to induce vertebral artery type of cervical syndrome (CSA) was observed. Twenty rabbits were randomly divided into two groups: the model group and the control group. The rabbits in the model group were injected with sclerosing agent next to transverse process of cervical vertebray, on the contrary, the rabbits in the control group were injected with nothing. Transcranial Doppler (TCD) was used to detect the average speed of blood (Vm), pulsatility index (Pi) and the resistant index (Ri) of the vertebral artery, hematoxylin and eosin (HE) staining was used to observe the morphological changes, and immunohistochemistry was used to detect the expression of alpha-smooth muscle actin (alpha-SMA) and matrix metalloproteinase-2(MMP-2). TCD showed increased Pi, Ri and decreased Vm in the model group (P<0.05) compared with the control group. HE staining revealed hyperplasia and hypertrophied smooth muscle cells in the model group (P<0.05). Immunohistochemistry displayed up-regulation of alpha-SMA and MMP-2 in the model group (P<0.05). It was concluded that injecting sclerosing agent next to transverse process of cervical vertebra induces remodeling of vertebral artery in rabbits, suggesting it is a practical method to establish CSA animal model.

Expression of TRAIL and the death receptors DR4 and DR5 correlates with progression of degeneration in human intervertebral disks

Intervertebral disks degenerate far earlier than other musculoskeletal tissues and apoptosis has been suggested to have a vital function in promoting the degeneration process that is strongly associated with back pain. However, the molecular mediators of apoptosis in the intervertebral disk are poorly understood. Fas/FasL, TRAIL/DR4, TRAIL/DR5 and TNF-alpha/TNFR1 are ligand/receptor pairs of the tumor necrosis factor/nerve growth factor family, which are able to induce apoptosis by trimerization of the receptor by its corresponding ligand. We investigated which of these molecules are expressed in intervertebral disks and whether their expression correlates to disk degeneration. Intervertebral disks from 28 donors (age 12-70 years) suffering from scoliosis, vertebrae fracture or disk degeneration were scored histologically for degeneration and analyzed for gene expression of FasL/Fas, TRAIL/DR4, TNF-alpha/TNFR1 and caspase 8. Protein expression of FasL and TRAIL was assessed by immunohistology and apoptotic cell death was quantified by poly(ADP-ribose) polymerase (PARP) p85 staining. Isolated disk cells were analyzed by flow cytometry for Fas, FasL, TRAIL, DR4 and DR5 expression. Gene expression of TRAIL (P=0.002) and caspase 8 (P=0.027) significantly correlated with degeneration. TRAIL expression further correlated with cellularity (P=0.04), muccoid matrix changes (P=0.009) and tears and cleft formation (P=0.019). FasL and TRAIL expression was confirmed by immunohistology and PARP cleavage was significantly associated with degeneration (P=0.027). Flow cytometry on isolated disk cells revealed correlations between DR4 and degeneration (P=0.014), DR4/DR5 double-positive cells and degeneration (P=0.019), as well as DR5 and changes in tissue granularity (P=0.03). This is the first study that shows that intervertebral disk cells express TRAIL, DR4 and DR5, which correlate to the degenerative state of the disk. Therefore, disk cells inherit the molecular machinery to induce and undergo cellular apoptosis, and the frequency of cytokine expression suggests that the TRAIL/DR4/DR5 axis is an important molecular mediator of apoptosis induction in disk tissue.