Possible pathogenesis of painful intervertebral disc degeneration

Degenerative joint disease of the spine

Degenerative changes are the manifestations of metabolic disturbances in the matrix of intervertebral disks and zygapophysial joints. Genetic factors and physical loading contribute, but the strongest correlation is with age. Degenerative changes lack any significant correlation with spinal pain. Therefore, they do not constitute a diagnosis. Internal disk disruption is a distinctive condition that is independent of degeneration and age. Its biophysical and morphologic features correlate with back pain, as do its manifestations on magnetic resonance imaging.

Inflammatory response of intervertebral disc cells is reduced by fibrin sealant scaffold in vitro

Intervertebral disc (IVD) degeneration is a complex process characterized by elevated concentrations of proinflammatory cytokines and proteolytic enzymes. Because of pro-healing constituents, we hypothesized that fibrin sealant (FS) can reduce inflammation and augment soft tissue healing within the damaged or degenerative IVD. To test this, human and porcine nucleus pulposus (NP) and annulus fibrosus (AF) cells were extracted from tissues and encapsulated into alginate beads (NP cells) and type I collagen sponges (AF cells). Half of the alginate and collagen scaffolds were embedded in FS. To provoke inflammatory behaviours, the constructs were cultured with and without continuous IL-1α (10 ng/ml) for 4, 7 and 14 days. ELISA was used to quantify the cellular synthesis (ng/µg DNA) of clinically relevant cytokines, proteolytic enzymes and growth factors. In NP cell constructs with IL-1α, the syntheses of TNFα, IL-1β, IL-6, IL-8 was elevated at all culture durations. In the presence of FS, secretion of several pro-inflammatory cytokines were significantly reduced [IL-6 and IL-8 (porcine); and TNFα, IL-1β, IL-6, IL-8 (human)]. Consistent with these reductions, human NP cultures exposed to FS and FS + IL-1α synthesized significantly reduced amounts of MMP-1 and -3 compared to constructs with IL-1α. For porcine and human AF cells, there were no significant differences in the synthesis of the inflammatory or proteolytic cytokines relative to controls (without IL-1α) at any culture duration. However, the porcine AF cells exposed to FS synthesized elevated amounts of the anti-inflammatory cytokine IL-4. The results suggest that FS may have beneficial effects for patients with degenerated intervertebral discs.

Ex vivo observation of human intervertebral disc tissue and cells isolated from degenerated intervertebral discs

PURPOSE

Disc degeneration, and associated low back pain, are a primary cause of disability. Disc degeneration is characterized by dysfunctional cells and loss of proteoglycans: since intervertebral tissue has a limited capacity to regenerate, this process is at present considered irreversible. Recently, cell therapy has been suggested to provide more successful treatment of IVD degeneration. To understand the potential of cells to restore IVD structure/function, tissue samples from degenerated IVD versus healthy discs have been compared.

METHODS

Discal tissue from 27 patients (40.17 ± 11 years) undergoing surgery for degenerative disc disease (DDD), DDD + herniation and congenital scoliosis, as controls, was investigated. Cells and matrix in the nucleus pulposus (NP) and annulus fibrosus (AF) were characterized by histology. AF- and NP-derived cells were isolated, expanded and characterized for senescence and gene expression. Three-dimensional NP pellets were cultured and stained for glycosaminoglycan formation.

RESULTS

Phenotypical markers of degeneration, such as cell clusters, chondrons, and collagen disorganization were seen in the degenerate samples. In severe degeneration, granulation tissue and peripheral vascularization were observed. No correlation was found between the Pfirrmann clinical score and the extent of degeneration.

CONCLUSION

The tissue disorganization in degenerate discs and the paucity of cells out of cluster/chondron association, make the IVD-derived cells an unreliable option for disc regeneration.

Capability of nondegenerated and degenerated discs in producing inflammatory agents with or without macrophage interaction

STUDY DESIGN

Molecular biological and immunohistological examinations.

OBJECTIVE

To clarify whether nondegenerated and degenerated discs produce inflammatory agents such as prostaglandin (PG)E2, interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)α, which have been reported to play pivotal roles in lumbar disc diseases, in the presence or absence of macrophages.

SUMMARY OF BACKGROUND DATA

A recent study reported discogenic low back pain might be caused by annular disruption followed by vascularized granulation formation extending from the outer layer of the annulus fibrosus into the nucleus pulposus along the torn fissure. Moreover, abundant macrophages have been shown to be present in symptomatic discs but not in normal and aged discs. However, there has been no in vitro report investigating the interaction between macrophages and several degrees of degenerated discs.

METHODS

Degenerated intervertebral discs were obtained from Sprague-Dawley rats with different lengths of rat tail compression (2, 4, and 8 weeks). These degenerated disc and nondegenerated disc tissues were respectively cultured in the presence or absence of macrophages. The culture supernatants were analyzed for PGE2, IL-6, IL-1β, and TNF-α. Immunohistochemical staining for cyclooxygenase-2 and IL-6 was also carried out on 4-week compression discs.

RESULTS

Nondegenerated discs alone, several degrees of degenerated discs alone, and macrophages alone produced small amounts of PGE2 and IL-6. However, they were able to produce significantly higher amounts of PGE2 and IL-6 when cocultured with macrophages. In contrast, we detected small amounts of IL-1β and TNF-α at every stage of degeneration regardless of the presence or absence of macrophages. The immunohistological examination showed anticyclooxygenase-2 and anti-IL-6 reactivities in the chondrocytes embedded in the disc matrix obtained from the degenerated disc.

CONCLUSION

These results suggest PGE2 and IL-6 play a pivotal role in the interaction between degenerated discs and macrophages.

The chemokines CXCL10 and XCL1 recruit human annulus fibrosus cells

STUDY DESIGN

Human annulus fibrosus tissue and cells were analyzed for the presence of chemokine receptors and the migratory effect of selected chemokines.

OBJECTIVE

To investigate spontaneous repair mechanisms and underlying cell recruitment in response to annular tears and degenerative defects.

SUMMARY OF BACKGROUND DATA

Resorption of herniated disc tissue and the attempt to close annulus tears with repair tissue occur spontaneously. Although chemokines are suggested to play a role in resorption of herniated disc tissue, the role of chemokines in annulus fibrosus homeostasis and repair remains unclear.

METHODS

Cells were isolated from annulus fibrosus tissue and expanded in the presence of human serum. Multiwell chemotaxis assays were used to analyze the migratory effect of human serum and 0 to 1000 nM concentrations of the chemokines CXCL7, CXCL10, CXCL12, CCL25, and XCL1 on annulus fibrosus cells (AFCs) (n = 9 per chemokine and dose). Presence of corresponding chemokine receptors in AFCs was determined by real-time polymerase chain reaction analysis and immunohistochemistry.

RESULTS

Serum (0.1%-10%) significantly (P < 0.01) stimulates the migration of AFCs. Compared with untreated cells, the migration of cells was significantly (P < 0.01) enhanced upon stimulation with 100 to 1000 nM CXCL10 and 1000 nM XCL1. Chemokine receptors showed low expression levels in expanded AFCs as assessed by polymerase chain reaction. Immunohistochemical staining of the CXCL10 receptor CXCR3 and the XCL1 receptor XCR1 showed that the presence of the particular receptors in AFCs expanded under conventional cell culture conditions. In native annulus fibrosus tissue, CXCR3 was evident, whereas XCR1 could not be detected.

CONCLUSION

The findings suggest that chemokines, in particular CXCL10, effectively recruit isolated AFCs. This suggests that chemokines are involved in annulus fibrosus homeostasis and potentially in spontaneous annulus repair attempts. This might have important implications for biological annulus-sealing strategies.

Identifying inflammatory targets for biologic therapies for spine pain

The costs associated with treating spine-related conditions are enormous and are trending upward. Current methods employed to treat inflammatory-mediated pain are targeted at alleviating symptoms, rather than correcting the underlying cause of disease. It is clear that a biochemical basis for inflammatory-mediated intervertebral disk, facet joint, and nerve pain exists. Biologic therapies that address the underlying cause of pain could potentially decrease the costs associated with treating spine pathology. MMPs, IL-1, TNF- α, IL-6, NGF, bradykinin, prostaglandins, and nitric oxide are implicated in much of the catabolic effects seen in the pathogenesis of inflammatory-mediated pain and are good targets for inhibition. The anticatabolic and anabolic effects of TIMPs, BMPs, TGF- β, and IGF-1 are targets already shown to favorably impact disk matrix homeostasis. With rapid advances in biomedical technology, these interventions may be available for clinical use in the near future.

Lumbar disc arthroplasty with Maverick disc versus stand-alone interbody fusion: a prospective, randomized, controlled, multicenter investigational device exemption trial

STUDY DESIGN

Randomized, controlled, multicenter, investigational device exemption trial.

OBJECTIVE

To investigate the safety and effectiveness of the first two-piece, metal-on-metal lumbar disc prosthesis for treating patients with single-level degenerative disc disease.

SUMMARY OF BACKGROUND DATA

For patients with degenerative disc disease unresponsive to conservative measures, lumbar disc arthroplasty provides an alternative to fusion designed to relieve persistent discogenic pain and maintain motion.

METHODS

After 2:1 randomization, 577 patients were treated in either the investigational group (405), receiving lumbar disc arthroplasty, or the control group (172), receiving anterior lumbar interbody fusion. Patients were evaluated preoperatively, at surgery/discharge, and at 1.5, 3, 6, 12, and 24 months after surgery. The primary study endpoint was overall success, a composite measure of safety and effectiveness as recommended by the Food and Drug Administration and defined in the protocol.

RESULTS

Both treatment groups demonstrated significant improvements compared with preoperative status. The investigational group had statistically superior outcomes (P < 0.05) at all postoperative evaluations in Oswestry Disability Index, back pain, and Short Form-36 Physical Component Summary scores as well as patient satisfaction. Investigational patients had longer surgical times (P < 0.001) and greater blood loss (P < 0.001) than did control patients; however, hospitalization stays were similar for both groups. Investigational patients had fewer implant or implant/surgical procedure-related adverse events (P < 0.001). Return-to-work intervals were reduced for investigational patients. Disc height and segmental angular motion were maintained throughout the study in the investigational group. In the investigational group, overall success superiority was found when compared to the control group as defined by the Food and Drug Administration Investigational Device Exemption protocol.

CONCLUSION

The investigational group consistently demonstrated statistical superiority versus fusion on key clinical outcomes including improved physical function, reduced pain, and earlier return to work.

Thermosensitive chitosan-gelatin-glycerol phosphate hydrogel as a controlled release system of ferulic acid for nucleus pulposus regeneration

In the degenerative disc, overproduction of reactive oxygen species (ROS) involves in apoptosis and senescence of nucleus pulposus (NP) cells that could accelerate the degenerative process. Ferulic acid (FA) has been reported to have an excellent antioxidant property. In the study, injectable thermosensitive chitosan/gelatin/glycerol phosphate (C/G/GP) hydrogel was applied as a controlled release system for FA delivery. The study was aimed to evaluate possible therapeutic effects of FA-incorporated C/G/GP hydrogel on hydrogen peroxide (H(2)O(2))-induced oxidative stress NP cells. The results showed that the release of FA from C/G/GP hydrogel could decrease the H(2)O(2)-induced oxidative stress. Post-treatment of FA-incorporated C/G/GP hydrogel on H(2)O(2)-induced oxidative stress NP cells showed up-regulation of Aggrecan and type II collagen and down-regulation of MMP-3 in mRNA level. The results of sulfated-glycosaminoglycans (GAGs) to DNA ratio and alcian blue staining revealed that the GAGs production of H(2)O(2)-induced oxidative stress NP cells could reach to normal level. The results of caspase-3 activity and TUNEL staining indicated that FA-incorporated C/G/GP hydrogel decreased the apoptosis of H(2)O(2)-induced oxidative stress NP cells. The results suggested that the C/G/GP hydrogel was very suitable for sustained delivery of FA. The FA-incorporated C/G/GP hydrogel would be used to treat the degenerative disc in the early stage before it developed into the latter irreversible stages.

Engineering of polymer-based grafts with cells derived from human nucleus pulposus tissue of the lumbar spine

Intervertebral disc degeneration is considered a major source of low back pain. We therefore examined an absorbable polyglycolic acid (PGA) biomaterial for its utility to support disc tissue regeneration. Microdiscectomy for lumbar disc herniation was performed in six patients. Intervertebral disc cells were isolated and in vitro cell expansion was accomplished using human serum and FGF2. In a fibrin-hyaluronan solution, disc cells were loaded on PGA scaffolds and cultured for 2 weeks. Formation of disc tissue was documented by histological staining of the extracellular matrix as well as gene expression analysis of typical disc marker genes. The use of human serum and FGF2 ensures efficient isolation and expansion of human disc cells. During this phase, dedifferentiation of the disc cells was observed. Subsequent 3D tissue culture of disc cells in PGA scaffolds, however, is accompanied by the induction of typical disc marker genes, resulting in tissue containing glycosaminoglycans and collagens. Propidium iodide/fluorescein diacetate (PI/FDA) staining documented that 3D assembly of disc cells in PGA scaffolds allows prolonged culture and high viability of disc cells. Disc cells from tissue of the nucleus compartment can be reliably isolated and expanded in vitro with FGF. In combination with a fibrin-hyaluronan solution and loaded on a PGA scaffold, disc cells from expansion culture commence a redifferentiation process. PGA-based scaffolds could be useful as temporal matrices for regenerative disc repair approaches.

Attenuation of inflammatory events in human intervertebral disc cells with a tumor necrosis factor antagonist

STUDY DESIGN

The inflammatory responses of primary human intervertebral disc (IVD) cells to tumor necrosis factor α (TNF-α) and an antagonist were evaluated in vitro.

OBJECTIVE

To investigate an ability for soluble TNF receptor type II (sTNFRII) to antagonize TNF-α-induced inflammatory events in primary human IVD cells in vitro.

SUMMARY OF BACKGROUND DATA

TNF-α is a known mediator of inflammation and pain associated with radiculopathy and IVD degeneration. sTNFRs and their analogues are of interest for the clinical treatment of these IVD pathologies, although information on the effects of sTNFR on human IVD cells remains unknown.

METHODS

IVD cells were isolated from surgical tissues procured from 15 patients and cultured with or without 1.4 nmol/L TNF-α (25 ng/mL). Treatment groups were coincubated with varying doses of sTNFRII (12.5-100 nmol/L). Nitric oxide (NO), prostaglandin E₂ (PGE₂), and interleukin-6 (IL6) levels in media were quantified to characterize the inflammatory phenotype of the IVD cells.

RESULTS

Across all patients, TNF-α induced large, statistically significant increases in NO, PGE₂, and IL6 secretion from IVD cells compared with controls (60-, 112-, and 4-fold increases, respectively; P < 0.0001). Coincubation of TNF-α with nanomolar doses of sTNFRII significantly attenuated the secretion of NO and PGE₂ in a dose-dependent manner, whereas IL6 levels were unchanged. Mean IC₅₀ values for NO and PGE₂ were found to be 35.1 and 20.5 nmol/L, respectively.

CONCLUSION

Nanomolar concentrations of sTNFRII were able to significantly attenuate the effects of TNF-α on primary human IVD cells in vitro. These results suggest this sTNFR to be a potent TNF antagonist with potential to attenuate inflammation in IVD pathology.

Percutaneous diode laser irradiation for lumbar discogenic pain: a clinical study

The present study evaluated the efficiency of laser irradiation for treating discogenic low back pain. Discogenic low back pain is believed to result from the degeneration and disruption of outer fibers of the intervertebral disc annulus, leading to a cycle of persistent inflammation, damage to the disc matrix, and sensitization of developed annular nociceptors. We selected 11 patients as subjects on the basis of clinical findings and the results of provocative disc blockade. The patients underwent percutaneous irradiation of affected lumbar discs with a diode laser. The mean total irradiation energy per disc was 740 ± 2.51 J, with a range of 610 to 960 J. The patients' responses were assessed with the Oswestry Disability Index (ODI) and a visual analogue scale (VAS) to determine the average level of pain. The patients' mean ODI scores at 1 day, 3 months, 6 months, 12 months, 18 months, and 24 months after laser irradiation were 18.63 ± 11.22, 13.6 ± 4.53, 12.5 ± 5.5, 11.8 ± 5.25, 10.5 ± 2.27, and 10.5 ± 2.27, respectively, versus a mean pre-treatment ODI score of 50.27 ± 9.35. Their mean VAS scores at the same post-treatment intervals were 3.09 ± 2.36, 2.4 ± 0.97, 2.7 ± 1.16, 2.1 ± 0.74, 2.1 ± 0.81, and 2.1 ± 0.88, respectively, versus a mean pre-treatment VAS score of 7.64 ± 1.21. The post- versus pre-treatment scores for both the ODI and VAS indicated a statistically significant clinical benefit across the full 24-month follow-up period after laser irradiation. The efficacy of laser irradiation in treating such pain may come from a thermal effect and reductions of intradiscal pressure, of the concentrations of irritant substances, and of the numbers of nociceptors in the affected region.

Healing of a painful intervertebral disc should not be confused with reversing disc degeneration: implications for physical therapies for discogenic back pain

BACKGROUND

Much is known about intervertebral disc degeneration, but little effort has been made to relate this information to the clinical problem of discogenic back pain, and how it might be treated.

METHODS

We re-interpret the scientific literature in order to provide a rationale for physical therapy treatments for discogenic back pain.

INTERPRETATION

Intervertebral discs deteriorate over many years, from the nucleus outwards, to an extent that is influenced by genetic inheritance and metabolite transport. Age-related deterioration can be accelerated by physical disruption, which leads to disc "degeneration" or prolapse. Degeneration most often affects the lower lumbar discs, which are loaded most severely, and it is often painful because nerves in the peripheral anulus or vertebral endplate can be sensitised by inflammatory-like changes arising from contact with blood or displaced nucleus pulposus. Surgically-removed human discs show an active inflammatory process proceeding from the outside-in, and animal studies confirm that effective healing occurs only in the outer anulus and endplate, where cell density and metabolite transport are greatest. Healing of the disc periphery has the potential to relieve discogenic pain, by re-establishing a physical barrier between nucleus pulposus and nerves, and reducing inflammation.

CONCLUSION

Physical therapies should aim to promote healing in the disc periphery, by stimulating cells, boosting metabolite transport, and preventing adhesions and re-injury. Such an approach has the potential to accelerate pain relief in the disc periphery, even if it fails to reverse age-related degenerative changes in the nucleus.

Regeneration potential and mechanism of bone marrow mesenchymal stem cell transplantation for treating intervertebral disc degeneration

Intervertebral disc degeneration is a primary cause of low back pain and has a high societal cost. The pathological mechanism by which the intervertebral disc degenerates is largely unknown. Cell-based therapy especially using bone marrow mesenchymal stem cells as seeds for transplantation, although still in its infancy, is proving to be a promising, realistic approach to intervertebral disc regeneration. This article reviews current advances regarding regeneration potential in both the in vivo and vitro studies of bone marrow mesenchymal stem cell-based therapy and discusses the up-to-date regeneration mechanisms of stem cell transplantation for treating intervertebral disc degeneration.

ISSLS prize winner: a study of effects of in vivo mechanical forces on human lumbar discs with scoliotic disc as a biological model: results from serial postcontrast diffusion studies, histopathology and biochemical analysis of twenty-one human lumbar scoliotic discs

STUDY DESIGN

A comprehensive study of 21 lumbar scoliotic discs by in vivo serial post contrast diffusion magnetic resonance imaging (MRI), histopathological, and biochemical analysis.

OBJECTIVE

To investigate the in vivo effects of compressive and tensile mechanical stress on the lumbar discs with scoliotic disc as the biologic model.

SUMMARY OF BACKGROUND DATA

Most studies implicating mechanical stress in degenerative disc disease (DDD) are on animals, in vitro conditions and cadavers. They are also restricted to histopathological or biochemical evaluation without analyzing the endplate (EP) and nucleus pulposus (NP) separately. The few human studies have not analyzed diffusion changes which is the final pathway for DDD. Adolescent scoliotic disc offer a perfect model to study the effects of mechanical stress.

METHODS

Twenty-one discs from 6 patients with adolescent idiopathic scoliosis undergoing anterior corrective surgery were assessed before surgery by postcontrast MRI to document the EP diffusion patterns. The same discs harvested during surgery were analyzed histologically and biochemically. The results were correlated to clinical and radiologic parameters.

RESULTS

Altered diffusion patterns was seen in all discs with site specific breaks in 2, double peak pattern in 3, high intensity pattern in 14, and frank contrast leak in 2. There was marked decrease in cell density and viability in all discs on both convex and concave sides compared to the control disc (P = 0.001). Neovascularization, calcification, and matrix degeneration were observed to varying extent in different regions of NP and EP. There was a decrease in water content with increasing severity of curves with significant difference between mild and severe curves (NP: P = 0.000, EP: P = 0.002). Lactate was significantly higher in caudal EP (P = 0.035) and discs with coronal migration of more than 15 mm (P = 0.007). Regression analysis showed that truncal decompensation was a main factor for decrease in cell density, matrix degeneration, calcification, and water content.

CONCLUSION

The study documents widespread changes in the EP and NP even in discs with minimal wedging. EP damage and alterations in diffusion were observed earlier than MRI changes and could indicate nutritional factors as the primary mechanism of degeneration induced by mechanical stress. Degeneration was more severe in caudal discs and those with truncal decompensation. Its implications on the timing and choice of surgery in scoliosis are discussed.

Notochordal cells influence gene expression of inflammatory mediators of annulus fibrosus cells in proinflammatory cytokines stimulation

OBJECTIVE

Notochordal cells in the intervertebral disc interact with nucleus pulposus (NP) cells and support the maintenance of disc homeostasis by regulation of matrix production. However, the influence of notochordal cells has not been evaluated in the annulus fibrosus (AF), which is the primary pain generator in the disc. We hypothesized that the notochordal cell has the capacity to modulate inflammatory mediators secreted by AF cells secondary to stimulation.

METHODS

Notochordal and AF cells were isolated from adult New Zealand white rabbits. AF pellets were cultured with notochordal cell clusters or in notochordal cell-conditioned media (NCCM) for 24 or 48 hours with proinflammatory cytokines at varying concentrations. Gene expression in AF pellets were assayed for nitric oxide synthase (iNOS), cyclo-oxygenase (COX)-2, and interleukin (IL)-6 by real time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

AF pellet in NCCM significantly decreased the iNOS and COX-2 messenger ribonucleic acid (mRNA) levels compared to AF pellets alone and AF pellets with notochordal cells (p < 0.05). AF pellet resulted in dose-dependent iNOS and COX-2 expression in response to IL-1beta, stimulation, demonstrating that 1 ng/ml for 24 hours yielded a maximal response. AF pellet in NCCM significantly decreased the expression of iNOS and COX-2 in response to 1ng/ml IL-1beta, stimulation at 24 hours (p < 0.05). There was no difference in IL-6 expression compared to AF pellets alone or AF pellets with notochordal cell clusters.

CONCLUSION

We conclude that soluble factors from notochordal cells mitigate the gene expression of inflammatory mediators in stimulated AF, as expected after annular injury, suggesting that notochordal cells could serve as a novel therapeutic approach in symptomatic disc development.

Use of Temporary Implantable Biomaterials to Reduce Leg Pain and Back Pain in Patients with Sciatica and Lumbar Disc Herniation

The principle etiology of leg pain (sciatica) from lumbar disc herniation is mechanical compression of the nerve root. Sciatica is reduced by decompression of the herniated disc, i.e., removing mechanical compression of the nerve root. Decompression surgery typically reduces sciatica more than lumbar back pain (LBP). Decompression surgery reduces mechanical compression of the nerve root. However, decompression surgery does not directly reduce sensitization of the sensory nerves in the epidural space and disc. In addition, sensory nerves in the annulus fibrosus and epidural space are not protected from topical interaction with pain mediators induced by decompression surgery. The secondary etiology of sciatica from lumbar disc herniation is sensitization of the nerve root. Sensitization of the nerve root results from a) mechanical compression, b) exposure to cellular pain mediators, and/or c) exposure to biochemical pain mediators. Although decompression surgery reduces nerve root compression, sensory nerve sensitization often persists. These observations are consistent with continued exposure of tissue in the epidural space, including the nerve root, to increased cellular and biochemical pain mediators following surgery. A potential contributor to lumbar back pain (LBP) is stimulation of sensory nerves in the annulus fibrosus by a) cellular pain mediators and/or b) biochemical pain mediators that accompany annular tears or disruption. Sensory fibers located in the outer one-third of the annulus fibrosus increase in number and depth as a result of disc herniation. The nucleus pulposus is comprised of material that can produce an autoimmune stimulation of the sensory nerves located in the annulus and epidural space leading to LBP. The sensory nerves of the annulus fibrosus and epidural space may be sensitized by topical exposure to cellular and biochemical pain mediators induced by lumbar surgery. Annulotomy or annular rupture allows the nucleus pulposus topical access to sensory nerve fibers, thereby leading to LBP. Coverage of the annulus and adjacent structures in the epidural space by absorbable viscoelastic gels appears to reduce LBP following surgery by protecting sensory fibers from cellular and biochemical pain mediators.

The immediate reduction in low back pain intensity following lumbar joint mobilization and prone press-ups is associated with increased diffusion of water in the L5-S1 intervertebral disc

STUDY DESIGN

Single-group, prospective, repeated-measures design.

OBJECTIVES

To determine differences in the changes of diffusion of water in the L5-S1 intervertebral disc between subjects with nonspecific low back pain (LBP) who reported an immediate reduction in pain intensity of 2 or greater on an 11-point (0-10) numeric rating scale after a 10-minute session of lumbar joint mobilization, followed by prone press-up exercises, compared to those who did not report an immediate reduction in pain intensity of 2 or greater on the pain scale.

BACKGROUND

Combining lumbar joint mobilization and prone press-up exercises is a common intervention for patients with LBP; however, there is conflicting evidence regarding the effectiveness and efficacy of this approach. Increased knowledge of the physiologic effects of the combined use of these treatments, and the relationship to pain reports, can lead to refinement of their clinical application.

METHODS

Twenty adults, aged 22 to 54, participated in this study. All subjects reported LBP of at least 2 on an 11-point (0-10) verbally administered numeric rating scale at the time of enrollment in the study and were classified as being candidates for the combination of joint mobilization and prone press-ups. Subjects underwent T2- and diffusion-weighted lumbar magnetic resonance imaging scans before and immediately after receiving a 10-minute session of lumbar pressures in a posterior-to-anterior direction and prone press-up exercises. Subjects who reported a decrease in current pain intensity of 2 or greater immediately following treatment were classified as immediate responders, while the remainder were classified as not-immediate responders. The apparent diffusion coefficient, representing the diffusion of water in the nucleus pulposis, was calculated from the midsagittal diffusion-weighted images.

RESULTS

Following treatment, immediate responders (n = 10) had a mean increase in the apparent diffusion coefficient in the middle portion of the L5-S1 intervertebral disc of 4.2% compared to a mean decrease of 1.6% for the not-immediate responders (P<.005).

CONCLUSION

In a group of subjects with LBP, who were classified as being candidates for extension-based treatment, the report of an immediate reduction in pain intensity of 2/10 of greater after a treatment of posterior-to-anterior-directed pressures, followed by prone press-up exercises, was associated with an increase in diffusion of water in the nuclear region of the L5-S1 intervertebral disc. Subjects who did not report a pain reduction of at least 2/10 did not have a change in diffusion. J Orthop Sports Phys Ther 2010;40(5):256-264, Epub 12 March 2010. doi:10.2519/jospt.2010.3284.

A randomized placebo-controlled trial of intradiscal methylene blue injection for the treatment of chronic discogenic low back pain

A preliminary report of clinical study revealed that chronic discogenic low back pain could be treated by intradiscal methylene blue (MB) injection. We investigated the effect of intradiscal MB injection for the treatment of chronic discogenic low back pain in a randomized placebo-controlled trial. We recruited 136 patients who were found potentially eligible after clinical examination and 72 became eligible after discography. All the patients had discogenic low back pain lasting longer than 6 months, with no comorbidity. Thirty-six were allocated to intradiscal MB injection and 36 to placebo treatment. The principal criteria to judge the effectiveness included alleviation of pain, assessed by a 101-point numerical rating scale (NRS-101), and improvement in disability, as assessed with the Oswestry Disability Index (ODI) for functional recovery. At the 24-month follow-up, both the groups differed substantially with respect to the primary outcomes. The patients in MB injection group showed a mean reduction in pain measured by NRS of 52.50, a mean reduction in Oswestry disability scores of 35.58, and satisfaction rates of 91.6%, compared with 0.70%, 1.68%, and 14.3%, respectively, in placebo treatment group (p<0.001, p<0.001, and p<0.001, respectively). No adverse effects or complications were found in the group of patients treated with intradiscal MB injection. The current clinical trial indicates that the injection of methylene blue into the painful disc is a safe, effective and minimally invasive method for the treatment of intractable and incapacitating discogenic low back pain.

p38 MAPK inhibition selectively mitigates inflammatory mediators and VEGF production in AF cells co-cultured with activated macrophage-like THP-1 cells

OBJECTIVES

Recent data have suggested that macrophages are involved in the pathogenesis of discogenic back pain and enhance the secretion of inflammatory mediators in co-cultured annulus fibrosus (AF) cells. The purpose of these studies is to determine the role of p38 mitogen-activated protein kinase (p38 MAPK) signaling in the interactions between macrophage and AF cells.

METHODS

Human AF cells were co-cultured with phorbol myristate acetate-stimulated macrophage-like THP-1 cells with and without p38 MAPK inhibition. Conditioned media from co-cultured cells were assayed for interleukin (IL)-6, IL-8, prostaglandin E2 (PGE2), PGF2alpha, and vascular endothelial growth factor (VEGF). Naïve and macrophage-exposed AF cell responses to 10ng/ml tumor necrosis factor-alpha (TNF-alpha) were compared using the same outcome measures.

RESULTS

IL-6, IL-8, PGE2, PGF2alpha, and VEGF were secreted in greater quantities by cells maintained in co-culture compared to macrophages or AF cells cultured alone. SB202190 blunted IL-6, PGE2, and PGF2alpha production in a dose-dependent manner in co-culture. However, it did not suppress IL-8 and VEGF production. TNF-alpha-stimulated AF cell inflammatory mediators were up-regulated by macrophage exposure. SB202190 successfully suppressed IL-6, IL-8, PGE2, and PGF2alpha secretion in macrophage-exposed AF cells in response to TNF-alpha.

CONCLUSIONS

Annular injury can result in macrophage infiltration, and this can cause enhanced inflammatory mediator and VEGF production by AF cells. The p38 MAPK pathway signals are responsible for much of IL-6 and PG secretion from AF cells with macrophage-like cells, suggesting that blockade of this signal may serve as a therapeutic approach to discogenic pain.

Biomechanical testing of a polymer-based biomaterial for the restoration of spinal stability after nucleotomy

BACKGROUND

Surgery for disc herniations can be complicated by two major problems: painful degeneration of the spinal segment and re-herniation. Therefore, we examined an absorbable poly-glycolic acid (PGA) biomaterial, which was lyophilized with hyaluronic acid (HA), for its utility to (a) re-establish spinal stability and to (b) seal annulus fibrosus defects. The biomechanical properties range of motion (ROM), neutral zone (NZ) and a potential annulus sealing capacity were investigated.

METHODS

Seven bovine, lumbar spinal units were tested in vitro for ROM and NZ in three consecutive stages: (a) intact, (b) following nucleotomy and (c) after insertion of a PGA/HA nucleus-implant. For biomechanical testing, spinal units were mounted on a loading-simulator for spines. In three cycles, axial loading was applied in an excentric mode with 0.5 Nm steps until an applied moment of +/- 7.5 Nm was achieved in flexion/extension. ROM and NZ were assessed. These tests were performed without and with annulus sealing by sewing a PGA/HA annulus-implant into the annulus defect.

RESULTS

Spinal stability was significantly impaired after nucleotomy (p < 0.001). Intradiscal implantation of a PGA-HA nucleus-implant, however, restored spinal stability (p < 0.003). There was no statistical difference between the stability provided by the nucleus-implant and the intact stage regarding flexion/extension movements (p = 0.209). During the testing sequences, herniation of biomaterial through the annulus defect into the spinal canal regularly occurred, resulting in compression of neural elements. Sewing a PGA/HA annulus-implant into the annulus defect, however, effectively prevented herniation.

CONCLUSION

PGA/HA biomaterial seems to be well suited for cell-free and cell-based regenerative treatment strategies in spinal surgery. Its abilities to restore spinal stability and potentially close annulus defects open up new vistas for regenerative approaches to treat intervertebral disc degeneration and for preventing implant herniation.

Diagnosis and surgical treatment of back pain originating from endplate

Twenty-one patients with back pain originating from the endplate injuries were selected to explore the methods of diagnosis and surgical treatment. All patients underwent examinations using radiography, CT, and MR imaging. Pain level of disc was determined through discography in each patient. The principal outcome judgments were pain and disability, and the efficacy of surgical treatment was assessed through the use of the visual analog scale (VAS) for pain and the Oswestry disability index (ODI) for functional recovery. All 21 patients with a diagnosis of back pain originating from endplate injuries according to discography were treated with anterior or posterior fusion surgery. The mean follow-up period was 3 years and 5 months (range, 2-6 years). Of the 21 patients, 20 (20/21) reported a disappearance or marked alleviation of low back pain and experienced a definite improvement in physical function. Statistically significant and clinically meaningful improvements in the VAS and ODI scores were obtained after treatment in the patients with chronic low back pain originating from the endplate injuries (P = 0.0001). The study suggests that discography and fusion surgery may be very effective methods for the diagnosis and treatment, respectively, of chronic back pain originating from the endplate injuries.

Comparison of growth factor and cytokine expression in patients with degenerated disc disease and herniated nucleus pulposus

OBJECTIVES

This study was conducted to investigate the expression of cytokines and growth factors in disc specimens obtained from patients with herniated nucleus pulposus (HNP) and degenerated disc disease (DDD).

DESIGN AND METHODS

MRI and Western blot analyses were performed to evaluate the levels of disc degeneration and the expression levels of cytokines and growth factors.

RESULTS

The levels of TNF-alpha and IL-8 were significantly greater in the DDD group than in the HNP group, but no statistical differences were observed in the expression of IL-1beta, IL-6 and IL-12 between the HNP and DDD groups. In addition, the expression of TGF beta, VEGF and NGF was significantly higher in the DDD group than in the HNP group.

CONCLUSION

The greater levels of cytokine and growth factor expression in the DDD group than in the HNP explain why discogenic patients usually have more severe back pain than patients with herniated discs.

Pathophysiology of degenerative disc disease

The intervertebral disc is characterized by a tension-resisting annulus fibrosus and a compression-resisting nucleus pulposus composed largely of proteoglycan. The most important function of the annulus and nucleus is to provide mechanical stability to the disc. Degenerative disc disease in the lumbar spine is a serious health problem. Although the three joint complex model of the degenerative process is widely accepted, the etiological basis of this degeneration is poorly understood. With the recent progress in molecular biology and modern biological techniques, there has been dramatic improvement in the understanding of aging and degenerative changes of the disc. Knowledge of the pathophysiology of the disc degeneration can help in the appropriate choice of treatment and to develop tissue engineering for biological restoration of degenerated discs.

Uso terapêutico da radiofrequência pulsátil no gânglio dorsal da raiz de L2 na lombalgia discogênica

OBJETIVO: Avaliar a eficácia da radiofrequência pulsátil sobre o gânglio da raiz dorsal de L2 no tratamento dos pacientes com lombalgia discogênica. MÉTODOS: Realizou-se análise retrospectiva de 50 pacientes portadores de lombalgia crônica discogênica atendidos no período de janeiro de 2004 a julho de 2007. O processo diagnóstico foi constituído por exame físico, ressonância magnética e bloqueio diagnóstico do gânglio da raiz dorsal de L2. Todos os pacientes foram submetidos à radiofrequência pulsátil no gânglio da raiz dorsal de L2 e acompanhados por, no mínimo, 12 meses. A intensidade de dor foi medida pela escala visual analógica (EVA) de dor. RESULTADOS: A análise estatística mostrou melhora significativa da intensidade de dor (p<0,001) após 12 meses de seguimento. O uso da radiofrequência pulsátil no gânglio da raiz dorsal de L2 mostrou-se um método alternativo inespecífico eficaz às cirurgias convencionais, apesar do curto seguimento desta série.

Increased cell senescence is associated with decreased cell proliferation in vivo in the degenerating human annulus

BACKGROUND CONTEXT

During disc degeneration, there is a well-recognized loss of cells. This puts the remaining cell population at high risk for any further decrease in cell function or cell numbers. Cell senescence has recently been shown to be present in the aging/degenerating human disc. Senescent cell are viable, metabolically active, persist, and accumulate over time, but cannot divide. Little is known about the relationship between renewal of the disc cell population via cell proliferation and disc cell senescence.

PURPOSE

To determine the percentage of senescent cells and proliferating cells in the human annulus in vivo.

STUDY DESIGN/SETTING

Human annulus specimens were obtained from surgical subjects and control donors in a study approved by the authors' Human Subjects Institutional Review Board.

PATIENT SAMPLE

One Thompson Grade I disc, 4 Grade II discs, 9 Grade III discs, and 12 Grade IV discs were studied.

OUTCOME MEASURES

The percentages of senescent cells and the percentage of proliferating cells.

METHODS

Immunohistochemistry was used to detect senescent cells using an antisenescence-associated beta-galactosidase antibody, and an antiproliferation antibody (Ki67). An average of 410 cells/specimens was counted to determine the percent senescence, and an average of 229 cells was counted to determine the percent proliferation.

RESULTS

Cell proliferation was low in both surgical and control normal donor annulus tissue (4.09%+1.77 (26), mean+SD (n)). There was no significant difference in the percentage of proliferating cells for more degenerate discs versus healthier discs (4.7%+1.6 (21) for Grades III and IV vs. 5.3%+1.9 (5) for Grades I and II). More degenerated Grades III and IV discs contained significantly greater percentages of senescent annulus cells than did the healthier Grades I and II discs (44.4%+20.0 (21) vs. 18.8%+11.0 (5), respectively; p=.011). A significant negative correlation was present between the percentage of senescent cells versus the percentage of proliferating cells, r=-0.013, p=.013. No correlation was present between age and the percentage of senescent cells or age and the percentage of proliferating cells.

CONCLUSIONS

Because senescent cells cannot divide, senescence may reduce the disc's ability to generate new cells to replace cells lost to necrosis or apoptosis. Senescent cells also accumulate in the disc over time, such that their metabolic patterns may contribute to the pathologic changes seen in degenerating discs. Novel data presented here show a significant negative correlation between the percentage of senescent cells and the percentage of proliferating cells during disc degeneration. Molecular work is underway in our lab to help us determine whether senescent cells in the disc secrete factors that can result in decreased proliferation in neighboring cells.

Expression of proteinase-activated receptor-2 in the intervertebral disc

STUDY DESIGN

Immunohistochemical and biochemical analyses of proteinase-activated receptor-2 (PAR-2) in rat and human intervertebral discs (IVDs).

OBJECTIVES

To examine the expression and function of PAR-2 in rat IVD cells, and to determine if PAR-2 is expressed in human IVDs.

SUMMARY OF BACKGROUND DATA

PAR-2 is a G protein-coupled receptor that contributes to the regulation of inflammatory reactions and the pathophysiology of inflammatory diseases, including arthritis. The expression of PAR-2 in the IVD has not been determined.

METHODS

PAR-2 expression by rat IVD cells and tissues was examined using immunohistochemistry and western blot. Rat anulus fibrosus cells in monolayer culture were used to examine the biologic role of PAR-2 in vitro. The effect of PAR-2-activating peptide (PAR-2AP) on the catabolic cascade was assessed by western blot and real-time PCR. The expression of PAR-2 by human IVD tissues at different stages of degeneration was determined by immunohistochemical analyses.

RESULTS

PAR-2 was expressed by rat IVD cells and in both anulus fibrosus and nucleus pulposus tissues, PAR-2 expression was up-regulated by interleukin-1beta (IL-1beta). PAR-2AP significantly increased the release of IL-1beta into the medium. Although PAR-2AP had no direct effect on matrix metalloproteinase-3 (MMP-3) and MMP-13 mRNA levels, treatment with PAR-2AP significantly up-regulated the mRNA levels of a disintegrin and metalloproteinase with thrombospondin motif-4. The simultaneous administration of PAR-2AP and IL-1beta synergistically up-regulated the mRNA levels of a disintegrin and metalloproteinase with thrombospondin motif-4, MMP-3, and MMP-13. The expression of PAR-2 was identified in human IVD tissues. The number of PAR-2-expressing cells was significantly elevated in advanced stages of IVD degeneration compared with those in early stages of degeneration.

CONCLUSION

Our results demonstrate for the first time that IVD cells express PAR-2. The expression of PAR-2 is regulated by IL-1beta stimulation. PAR-2 activation accelerates the expression of matrix-degrading enzymes. PAR-2 may play an important role in the cytokine-mediated catabolic cascade and consequently may be involved in IVD degeneration.

Expression and role of connective tissue growth factor in painful disc fibrosis and degeneration

STUDY DESIGN

We collected the specimens of lumbar intervertebral discs from patients with discogenic low back pain, to study the histopathological features and connective tissue growth factor (CTGF) expressions.

OBJECTIVE

To study the expression and role of CTGF in fibrosis and degeneration of painful disc tissue.

SUMMARY OF BACKGROUND DATA

Previous studies have demonstrated that degenerative disc commonly showed fibrosis in histology. CTGF, a downstream effector mediated by transforming growth factor-beta1 (TGF-beta1), is commonly related to tissue fibrosis. We do not know whether CTGF is expressed in painful disc, and related to painful disc degeneration and fibrosis.

METHODS

This study included 43 lumbar intervertebral disc specimens from 28 patients with discogenic low back pain obtained during posterior lumbar interbody fusion and 16 asymptomatic degenerative discs from patients without low back pain. Further, 8 normal discs were included as controls. Their histopathological features were studied, and the expression of CTGF was assessed using immunohistochemistry.

RESULTS

Histologic examination revealed that the painful discs showed chronic inflammatory reaction with blood vessel infiltration in varying degrees. The anulus fibrosus had lost its normal lamellar architecture, and instead, disorganization, disruption, and crossed fusion were observed. Normal fibroblasts were replaced by chondrocytes in the anulus fibrosus. The nucleus pulposus showed marked fibrosis, blood vessel infiltration, and inflammatory granulation tissue formation. Immunohistochemical staining demonstrated strong CTGF expression in the painful discs, weak expression in the asymptomatic degenerative disc, and no expression in the control discs.

CONCLUSION

The painful degenerative disc is significantly different from the asymptomatic degenerative disc with regard to histopathological findings. The strong CTGF expression in the painful disc may be related to disc fibrosis and degeneration.

Sustained long-term RNA interference in nucleus pulposus cells in vivo mediated by unmodified small interfering RNA

RNA interference (RNAi) technology has recently emerged as an important biological strategy for gene silencing. Previously, the efficacies of RNAi in cultured nucleus pulposus cells in vitro have been reported. However, RNAi in the disc in vivo has never been reported. Therefore, the aims of the present study were to establish a method for RNAi in the disc in vivo and to evaluate the applicability of this technique for endogenous genes in the intervertebral discs using Fas Ligand (FasL) as a representative endogenous gene. To evaluate the efficacy of RNAi in vivo, two reporter luciferase plasmids (Firefly and Renilla) were used. These plasmids and unmodified short interference RNA (siRNA) duplex for targeting Firefly luciferase were co-transfected into coccygeal intervertebral disc of Sprague-Dawley rats in vivo using the ultrasound gene transfer technique. To evaluate the RNAi of the endogenous gene in vivo, siRNAs targeting rat FasL were transfected with the same technique. Non-specific siRNA was used as the negative control. The discs receiving no siRNAs were used as the control. The inhibitory effect of Firefly luciferase against Renilla luciferase was obtained using the results of dual-luciferase assay. Down-regulation of endogenous FasL was calculated by the data from real-time PCR. Our results showed that siRNA for Firefly luciferase can dramatically down-regulate the Firefly luciferase gene expression in vivo compared with Renilla luciferase. The inhibitory effects were maintained for at least 24 weeks and at 24 weeks post transfection, the inhibitory rate was 80% compared with the control group. Furthermore, the siRNA co-transfection group inhibited endogenous FasL expression by 53% compared with the control group. The present study demonstrates long-term down-regulation mediated by unmodified siRNA is possible not only for the exogenous reporter gene, but also for endogenous FasL expression in rat discs in vivo. This application of RNAi might be promising as a local therapy for disc degeneration and associated disorders by down-regulating some of the genes that are harmful for the normal physiology of the disc and may cause disc degeneration.

The change in the diffusion of water in normal and degenerative lumbar intervertebral discs following joint mobilization compared to prone lying

STUDY DESIGN

Prospective, repeated measures obtained under treatment and control conditions.

OBJECTIVES

The purposes of this study were to provide preliminary evidence regarding the immediate change in the diffusion of water in the nuclear region of normal and degenerative lumbar intervertebral discs (IVDs) following a single session of lumbar joint mobilization, and to compare these findings to the immediate change in the diffusion of water following a 10-minute session of prone lying.

BACKGROUND

There is conflicting evidence regarding the effectiveness and efficacy of lumbar joint mobilization. Increased knowledge of the physiologic effects of lumbar joint mobilization can lead to refinement of its clinical application.

METHODS AND MEASURES

A total of 24 people (15 males and 9 females), ranging in age from 22 to 58 years, participated in this study. All subjects had a history of activity-limiting low back pain. Diffusion-weighted magnetic resonance images (DW-MRIs) were obtained immediately before and after a 10-minute session of lumbar joint mobilization. At least 1 month later, a second session was performed in which DW-MRIs were obtained immediately before and after a 10-minute session of prone lying.

RESULTS

Following lumbar joint mobilization, a significant increase (P = .002) in the mean values for diffusion of water was observed within degenerative IVDs at L5-S1 (22.2% increase; effect size, 0.97). Degenerative IVDs at L1-2 to L4-5 and normal IVDs at L1-2 to L5-S1 did not demonstrate a change in diffusion following joint mobilization. Prone lying was not associated with a change in diffusion for normal or degenerative IVDs.

CONCLUSIONS

The stimulus provided by lumbar joint mobilization may influence the diffusion of water in degenerative IVDs at L5-S1; however, these are preliminary findings and the relationship of these findings to pain and function needs further investigation.

Minimally invasive spinal surgery using nucleoplasty: a 1-year follow-up study

BACKGROUND

Nucleoplasty is a minimally invasive percutaneous intradiscal coblation therapy option in patients with chronic discogenic low back pain. The purpose of this prospective study was to assess the effectiveness of nucleoplasty in our patients up to 1 year after treatment.

METHOD

All patients included in this study suffered from established back pain and/or radiating pain in the lower extremities. Age, gender, weight, body mass index (BMI) and smoking status were recorded and the clinical status of the patient documented using a visual analogue pain scale (VAS). Additionally, patients were asked to provide details regarding analgesic consumption, disability and ability to work. Nucleoplasty was carried out under fluoroscopic and CT-guidance. All treated patients were reviewed at 6 and 12 months.

FINDINGS

Between April 2005 and December 2006, 96 patients underwent nucleoplasty in our department. The 69 patients reported here were followed-up to 12 months while data for eight others is available only up to 6 months. Seven patients were lost to follow-up, while eleven were excluded due to a secondary disc sequestration, either at the treated segment or elsewhere. The mean age of the 27 females (39%) and 42 males in this study was 42 years (range 18-74). The mean duration of symptoms was 30.5 months (range 1-120). Forty-two percent of patients were smokers and the mean BMI was 26.3 (17.4-42.4). 73% of treated patients experienced an improvement of more than 50% in their symptoms in the early post-operative VAS score. This was reduced to 61% at 6 months post-operatively and 58% after 1 year. A statistically significant reduction in analgesic consumption, disability and occupational incapacitation resulted from treatment with nucleoplasty.

CONCLUSIONS

Nucleoplasty is an effective therapy for chronic, discogenic back pain which results in significant reductions in levels of disability and incapacity for work as well as decreased analgesic consumption.

The pathophysiology of disc degeneration: a critical review

The pathophysiology of intervertebral disc degeneration has been extensively studied. Various factors have been suggested as influencing its aetiology, including mechanical factors, such as compressive loading, shear stress and vibration, as well as ageing, genetic, systemic and toxic factors, which can lead to degeneration of the disc through biochemical reactions. How are these factors linked? What is their individual importance? There is no clear evidence indicating whether ageing in the presence of repetitive injury or repetitive injury in the absence of ageing plays a greater role in the degenerative process. Mechanical factors can trigger biochemical reactions which, in turn, may promote the normal biological changes of ageing, which can also be accelerated by genetic factors. Degradation of the molecular structure of the disc during ageing renders it more susceptible to superimposed mechanical injuries. This review supports the theory that degeneration of the disc has a complex multifactorial aetiology. Which factors initiate the events in the degenerative cascade is a question that remains unanswered, but most evidence points to an age-related process influenced primarily by mechanical and genetic factors.

SMAD3 functions as a transcriptional repressor of acid-sensing ion channel 3 (ASIC3) in nucleus pulposus cells of the intervertebral disc

The goal of this investigation was to study the regulation of acid-sensing ion channel (ASIC)3 expression by TGFbeta in the nucleus pulposus cells of the intervertebral disc. Analysis of human nucleus pulposus tissue indicated decreased ASIC3 and elevated TGFbeta expression in the degenerate state. In a parallel study, treatment of nucleus pulposus cells with TGFbeta resulted in decreased expression of ASIC3 mRNA and protein. Suppression of ASIC3 promoter activity was evident when the nucleus pulposus cells were treated with TGFbeta or co-transfected with the constitutively active ALK5 or a smad3 construct. On the other hand, co-transfection of dominant negative smad3 or smad7 restored ASIC3 promoter activity. We validated the role of smad3 in controlling ASIC3 expression using cells derived from smad3-null mice. ASIC3 promoter activity in the null cells was 2- to 3-fold higher than the wildtype cells. Moreover, expression of smad3 in null cells decreased ASIC3 promoter activity by almost 50%. Further studies using deletion constructs and trichostatin A treatment showed that the full-length smad3 was necessary, and the suppression involved recruitment of histone deacetylase to the promoter. To determine the mechanism, we evaluated the rat ASIC3 promoter sequence and noted the presence of two smad interacting CAGA box motifs. Gel-shift and supershift analysis indicated that smad3 protein was bound to this motif. Chromatin immunoprecipitation analysis confirmed that smad3 bound both the CAGA elements. Results of these studies clearly show that TGFbeta is highly expressed in the degenerate disc and through smad3 serves as a negative regulator of ASIC3 expression.

Activated macrophage-like THP-1 cells modulate anulus fibrosus cell production of inflammatory mediators in response to cytokines

STUDY DESIGN

Anulus fibrosus (AF) cells obtained from patients undergoing surgery were cocultured with macrophage-like cells and production of inflammatory mediators was analyzed by quantitative assay.

OBJECTIVE

To investigate the role of macrophages in AF cell production of inflammatory mediators by cytokines stimulation.

SUMMARY OF BACKGROUND DATA

Discogenic pain caused by anular disruption is an important cause of low back pain and recent studies show the presence of macrophages in symptomatic discs but not in normal and aging discs. We hypothesize that macrophages play a major role in development of symptomatic disc.

METHODS

Human AF cells were cocultured with phorbol myristate acetate stimulated macrophage-like THP-1 cells. The conditioned medium from cells cultured alone or in coculture was assayed for cytokines by Enzyme-linked immunosorbent assay and nitric oxide (NO) by the Greiss method. Using the same outcome measures, comparisons of cell response to cytokines were made among macrophage-like cells, naïve AF cells, and macrophage exposed AF cells. RESULTS.: Tumor necrosis factor (TNF)-alpha, interleukin (IL)-8, IL-6, and NO (TNF-alpha: 1.45 +/- 0.29 ng/mL, IL-8: 97.02 +/- 7.94 ng/mL, IL-6: 33.40 +/- 3.55 ng/mL, NO: 8.42 +/- 0.78 micromol/L) were secreted in much greater amounts by cells maintained in coculture compared to macrophages (TNF-alpha: 0.78 +/- 0.12 ng/mL, IL-8: 58.04 +/- 4.44 ng/mL, IL-6: 0.14 +/- 0.03 ng/mL, NO: 0.30 +/- 0.08 micromol/L) or AF cells cultured alone. In addition, IL-6 secretion from AF cells in response to TNF-alpha was up-regulated by coculture, however, IL-6 secretion in response to IL-1 beta was downregulated in a dose-dependent manner. Coculture with macrophages also up-regulated AF cell secretion of IL-8 dose-dependently and downregulated NO to TNF-alpha or IL-1beta stimulation.

CONCLUSION

We conclude that exposure to macrophages, as can be expected after anular injury, can result in enhanced response to local inflammation. Although changes were observed in all inflammatory mediators after macrophage exposure, the most significant change was observed in IL-6 and IL-8, implicating these mediators in development of symptomatic disc.

Biological impact of the fibroblast growth factor family on articular cartilage and intervertebral disc homeostasis

Two members of the fibroblast growth factor (FGF) family, basic FGF (bFGF) and FGF-18, have been implicated in the regulation of articular and intervertebral disc (IVD) cartilage homeostasis. Studies on bFGF from a variety of species have yielded contradictory results with regards to its precise role in cartilage matrix synthesis and degradation. In contrast, FGF-18 is a well-known anabolic growth factor involved in chondrogenesis and articular cartilage repair. In this review, we examined the biological actions of bFGF and FGF-18 in articular and IVD cartilage, the specific cell surface receptors bound by each factor, and the unique signaling cascades and molecular pathways utilized to exert their biological effects. Evidence suggests that bFGF selectively activates FGF receptor 1 (FGFR1) to exert degradative effects in both human articular chondrocytes and IVD tissue via upregulation of matrix-degrading enzyme activity, inhibition of matrix production, and increased cell proliferation resulting in clustering of cells seen in arthritic states. FGF-18, on the other hand, most likely exerts anabolic effects in human articular chondrocytes by activating FGFR3, increasing matrix formation and cell differentiation while inhibiting cell proliferation, leading to dispersed cells surrounded by abundant matrix. The results from in vitro and in vivo studies suggest the potential usefulness of bFGF and FGFR1 antagonists, as well as FGF-18 and FGFR3 agonists, as potential therapies to prevent cartilage degeneration and/or promote cartilage regeneration and repair in the future.

Effect of the L2 ramus communicans on the nociceptive pathway in lumbar intervertebral discs in rats

The mechanism underlying discogenic low-back pain is unclear. It is difficult to explain this type of pain by the segmental innervation theory because the groin area is innervated by the genitofemoral or ilioinguinal nerves, which are the terminal branches of the L1 or L2 spinal nerves. Recently, some studies have indicated that sympathetic trunks are closely related to discogenic low-back pain. However, sympathetic trunk resection can severely affect the function of the abdominal organs and lower extremities and may cause retrograde ejaculation in human beings. This study was initiated to evaluate the role of selective transection of the L2 ramus of the nociceptive pathway in the lumbar intervertebral discs in rats, by using the fluorogold (FG) retrograde transport method and immunohistochemistry of substance P (SP). Of the FG-labeled neurons in the L2 and L5 dorsal root ganglia (DRGs), the cross-sectional area of the SP-immunoreactive (ir) neurons ranged from 210 to 1140 microm(2); the mean cross-sectional area was 652+/-320 microm(2). We demonstrated that FG-labeled SP-ir neurons in L2 DRGs decreased when FG was applied to the ventral or dorsal portions of L5-6 discs. The results indicated that the L2 ramus communicans played an important role in the afferent pathway of both the ventral and dorsal portions of the L5-6 disc. Nociceptive information from the L5-6 disc may be transmitted mainly by L2 DRG neurons through the L2 ramus communicans.

Characterization of intervertebral disc aging: longitudinal analysis of a rabbit model by magnetic resonance imaging, histology, and gene expression

STUDY DESIGN

A cohort of young, healthy New Zealand White rabbits was followed longitudinally with serial magnetic resonance imaging (MRI) analysis and terminal analysis of histologic changes and gene expression.

OBJECTIVE

To examine the changes observed during normal aging in the intervertebral disc.

SUMMARY OF BACKGROUND DATA

Although there is a correlation between aging and the onset of intervertebral disc degeneration (IDD), evidence suggests that distinct pathways are involved in these processes. Our group has characterized a reproducible rabbit model of IDD by MRI, radiograph, histology, and mRNA expression. However, no similar analysis has been performed longitudinally for intervertebral disc aging to allow comparison of these 2 important processes.

METHODS

Four skeletally mature female NZW rabbits were housed for 122 weeks, and lumbar spine MRIs were characterized serially. Histologic and quantitative gene expression analysis of the nucleus pulposus of these aging animals was performed, and compared with adult and young rabbits.

RESULTS

Mean MRI index decreased by <25% through 120 weeks. The histologic analysis showed changes in cell composition, with abundant notochordal cells in the young, chondrocyte-like cells and notochordal cells in the adult, and clusters of hypertrophic chondrocytes in the aging discs. The PCR analysis of the nucleus pulposus showed that gene expression of collagen decreased, whereas that for proteoglycans increased with aging. BMP-2, TIMP-1, and SOX-9 expression was significantly lower in the young compared with adult discs and TGF-beta1 demonstrated lower gene expression in young and aging animals.

CONCLUSION

Although dramatic cellular changes were observed, age-related MRI changes occurred in this rabbit model of normal aging at a much slower rate than in a previous injury model of degeneration. In addition, the gene expression analysis of the nucleus pulposus demonstrated remarkable differences between aging and injury induced degeneration. These results suggest that aging and injury contribute uniquely to the process of IDD.

Intradiscal electrothermal therapy (IDET) provides effective symptom relief in patients with discogenic low back pain

STUDY DESIGN

Single-arm, prospective clinical trial.

OBJECTIVE

To evaluate back pain severity, physical function, and quality of life outcomes in highly selected patients with lumbar discogenic pain treated with intradiscal electrothermal therapy (IDET).

SUMMARY OF BACKGROUND DATA

Degeneration and disruption of the intervertebral disc can be the source of severe low back pain and the associated physical dysfunction. IDET is a minimally invasive treatment option in the continuum of care between conservative nonoperative management and spinal surgery.

METHODS

Using magnetic resonance imaging, pressure-controlled discography, and postdiscogram computed tomography findings, 56 patients with lumbar discogenic pain were identified, underwent IDET treatment and followed for 20.5+/-4.4 months, on average. Outcomes included assessments of back pain severity by visual analog scale, sitting, standing, and walking tolerances, and health-related quality of life using the SF-36.

RESULTS

Mean pain severity scores (visual analog scale) improved from 6.1+/-1.8 pretreatment to 2.4+/-2.6 at final follow-up (P=0.0001). Mean tolerance times (minutes) improved from 40.9+/-40.6 to 84.5+/-54.4, 46.8+/-42.9 to 84.4+/-54.2, and 39.2+/-39.6 to 77.9+/-50.8 between baseline and final follow-up for sitting, standing, and walking, respectively (P=0.0001 for all comparisons). Seven of 8 quality of life domains showed significant (P=0.0001 for all comparisons) improvement over baseline. Forty-two patients (75%) were classified as a treatment success by virtue of a >or=2-point improvement in pain severity or a >or=10-point improvement in either the physical functioning or bodily pain domain of the SF-36.

CONCLUSIONS

The findings of this study suggest that durable clinical improvements can be realized after IDET in highly selected patients with mild disc degeneration, confirmatory imaging evidence of annular disruption, and concordant pain provocation by low pressure discography.

Current understanding of lumbar intervertebral disc degeneration: a review with emphasis upon etiology, pathophysiology, and lumbar magnetic resonance imaging findings

Degeneration of the lumbar intervertebral discs (IVDs) is highly prevalent in adults and is nearly universal in the elderly population. Degenerative changes within, and adjacent to, the IVDs are likely to contribute to a variety of pain syndromes; however, the exact association between these findings and symptoms remains speculative. Recent research has provided new information regarding the etiology, pathophysiology, and clinical relevance of degeneration of the IVD. This information will assist clinicians and researchers in understanding the development and clinical course of lumbar disc degeneration, as well as its potential impact upon patients seeking physical therapy care for back pain. The purposes of this clinical commentary are to review the structure and metabolic capacity of the normal and degenerative lumbar IVD, and to discuss factors that influence the onset and progression of disc degeneration. Lumbar magnetic resonance images will be used to illustrate the common findings associated with this condition.

Action of fibroblast growth factor-2 on the intervertebral disc

Introduction

Fibroblast growth factor 2 (FGF2) is a growth factor that is immediately released after cartilage injury and plays a pivotal role in cartilage homeostasis. In human adult articular cartilage, FGF2 mediates anti-anabolic and potentially catabolic effects via the suppression of proteoglycan (PG) production along with the upregulation of matrix-degrading enzyme activity. The aim of the present study was to determine the biological effects of FGF2 in spine disc cells and to elucidate the complex biochemical pathways utilized by FGF2 in bovine intervertebral disc (IVD) cells in an attempt to further understand the pathophysiologic processes involved in disc degeneration.

Methods

We studied the effect of FGF2 on IVD tissue homeostasis by assessing MMP-13 expression (potent matrix-degrading enzyme), PG accumulation, and PG synthesis in the bovine spine IVD, as well as evaluating whether FGF2 counteracts known anabolic factors such as BMP7. To understand the molecular mechanisms by which FGF2 antagonizes BMP7 activity, we also investigated the signaling pathways utilized by FGF2 in bovine disc tissue.

Results

The primary receptor expressed in bovine nucleus pulposus cartilage is FGFR1, and this receptor is upregulated in degenerative human IVD tissue compared with normal IVD tissue. Stimulation of bovine nucleus pulposus cells cultured in monolayer with FGF2 augmented the production of MMP-13 at the transcriptional and translational level in a dose-dependent manner. Stimulation of bovine nucleus pulposus cells cultured in alginate beads for 21 days with FGF2 resulted in a dose-dependent decrease in PG accumulation, due at least in part to the inhibition of PG synthesis. Further studies demonstrate that FGF2 (10 ng/ml) antagonizes BMP7-mediated acceleration of PG production in bovine nucleus pulposus cells via the upregulation of noggin, an inhibitor of the transforming growth factor beta/bone morphogenetic protein signaling pathway. Chemical inhibitor studies showed that FGF2 utilizes the mitogen-activated protein kinase and NF-κB pathways to upregulate noggin, serving as one potential mechanism for its anti-anabolic effects.

Conclusion

FGF2 is anti-anabolic in bovine spine disc cells, revealing the potential of FGF2 antagonists as unique biologic treatments for both prevention and reversal of IVD degeneration.

[Post disc surgery syndrome: indications for surgery and conservative and operative treatment possibilities]

Post disc surgery syndrome is characterised by the presence of persistent disabling pain in the hip, thigh, or lower back. Persistent or recurrent pain may be related to neurologic compression, incomplete discectomy with retained disc fragments, recurrent disc herniation, or altered biomechanics of the operated segments. Early failure is usually due to poor patient selection, incorrect diagnosis, incorrect procedure, or infection. A new onset of pain following a good surgical result may be due to recurrent disc herniation, instability of the operated segment, or disease at a different disc level. It can also be the result of a chronic pain syndrome. Therapy depends on exact diagnostics and can include conservative as well as surgical treatment.

Fas ligand expression on human nucleus pulposus cells decreases with disc degeneration processes

BACKGROUND

The intervertebral disc has been reported to be an immunologically privileged environment, possibly mediated by Fas ligand (FasL) expression. On the other hand, recent studies have shown the infiltration of host immune cells into the degenerated disc, which may indicate the failure of the immune-privilege feature of the disc with degeneration. However, the relationship between FasL expression and disc degeneration is still unclear. Therefore, the purpose of this study was to clarify the relationship between FasL expression and disc degeneration.

METHODS

Ten human degenerated disc specimens were obtained from spondylolisthesis patients and ten nondegenerated discs from idiopathic scoliosis patients during surgical procedures. Immunohistochemical staining was performed to determine the presence of FasL in cross-sections of those discs. Parts of the disc tissues were used to examine FasL expression quantitatively with Western blot analysis. To examine whether the change in FasL expression was influenced by aging, an animal study comparing the discs from young and old rats were performed using magnetic resonance imaging (MRI) and real-time polymerase chain reaction (PCR) assessment.

RESULTS

Nucleus pulposus cells showed strong positive staining for FasL in all specimens examined. Quantitative examination demonstrated a significant decrease in FasL expression in the degenerated group compared with the nondegenerated group (average 67.6%, P<0.05). MRI showed no significant differences in the grade of disc degeneration between young and old rats, and also no significant difference in FasL mRNA in real-time PCR assay.

CONCLUSIONS

The current results indicate that FasL and its potential mechanism of immunological privilege could influence the protection of the intervertebral disc against degeneration.