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In vivo quantification of delayed gadolinium enhancement in the nucleus pulposus of human intervertebral disc.

PURPOSE: To quantify the delayed contrast agent enhancement in the nucleus pulposus of the intervertebral disc by means by T1 relaxation time measurements, and to correlate the enhancement with visual grading of disc degeneration. Diffusion of nutrients through the endplate is a key factor in tissue viability in the intervertebral disc. It can be simulated in vivo using magnetic resonance imaging (MRI) by measuring delayed gadolinium (Gd) enhancement of the disc. MATERIALS AND METHODS: Twenty male volunteers underwent a lumbar spine examination at 1.5T. T2-weighted sagittal images were used to score disc degeneration. T1 relaxation times were measured before and 90 minutes after intravenous administration of Gd-DTPA-BMA by applying a series of sagittal single-slice inversion-recovery fast spin-echo (IR-FSE) scans. RESULTS: A total of 93 discs were analyzed. A statistically significant decrease in the T1 relaxation time of the nucleus pulposus was observed as a result of contrast-agent intake. The percentage change in the T1 relaxation rate for individual discs was up to 126%. A positive trend was observed between the change in the T1 relaxation rate and the grading of disc degeneration. CONCLUSION: Quantification of delayed enhancement of the intervertebral disc may provide a new means of studying alterations in degenerative disc disease (DDD) that explain the variation in diffusion into the intervertebral disc.

Adult↗

[Study of Yiqi Huayu Bushen recipe and its decomposed formulas in regulating gene expressions in degenerated cervical intervertebral discs of rats].

OBJECTIVE: To investigate the gene expression changes in the degenerated cervical intervertebral discs of rats, and to study the function of Yiqi Huayu Bushen Recipe, a compound Chinese herbal medicine, and its discomposed formulas in regulating gene expressions in the degenerated cervical intervertebral discs. METHODS: The rat model with degenerated cervical intervertebral discs caused by imbalance between the dynamic and static forces was established. The mRNA was extracted from the cervical intervertebral discs of rats in the normal control and experiment groups, and the cDNA probes were obtained by inverse transcript. The cDNA probes were hybridized with the gene chips. The gene expression pattern was gained with a laser scanner. Image analysis, standardized ratio value and cluster analysis were used to investigate the differential of gene expressions between the control and experiment groups. RESULTS: Cluster analysis showed that the gene chips of No.1 (Yiqi Huayu group), No.2 (Yiqi Bushen group) and No.3 (Huayu Bushen group) were in one class, while the gene chips of No.4 (untreated group) and No.5 (Yiqi Huayu Bushen group) were in the other. The gene expression of No.4 was different from the others mostly, and the gene expressions of No.2 and No.3 were similar. There were 96 genes expressed differently in three cases and among them 77 genes were already known and the expression of 48 genes were up-regulated (ratio>1.0), and 29 down-regulated (ratio<0.5). There were 25 genes expressed differently between the untreated group and the herb-treated groups. CONCLUSIONS: The gene expressions of the degenerated rat intervertebral discs are changed. Yiqi Huayu Bushen Recipe and its discomposed formulas have the effect of regulating the expressions of related genes, such as PI(3)K, PTK, ERK3, and PH1B1.

Animals↗

Regulation of gene expression in intervertebral disc cells by low and high hydrostatic pressure.

Intervertebral disc structures are exposed to wide ranges of intradiscal hydrostatic pressure during different loading exercises and are at their minimum during lying or relaxed sitting and at maximum during lifting weights with a round back. We hypothesize that these different loading magnitudes influence the intervertebral disc (IVD) by alteration of disc matrix turnover depending on their magnitudes. Therefore the aim of this study was to assess changes in gene expression of human nucleus cells after the application of low hydrostatic pressure (0.25 MPa) and high hydrostatic pressure (2.5 MPa). IVD cells isolated from the nucleus of human (n = 18) and bovine (n = 24 from four animals) disc biopsies were seeded into three-dimensional collagen type-I matrices and exposed to the different loading magnitudes by specially developed pressure chambers. The lower pressure range (0.25 MPa, 30 min, 0.1 Hz) was applied with a recently published device by using an external compression cylinder. For the application of higher loads (2.5 MPa, 30 min, 0.1 Hz) the cell-loaded collagen gels were sealed into sterile bags with culture medium and stimulated in a newly developed water-filled compression cylinder by using a loading frame. These methods allowed the comparison of loading regimes in a wide physiological range under an equal three-dimensional culture conditions. Cells were harvested 24 h after the end of stimulation and changes in the expression of genes known to influence IVD matrix turnover (collagen-I, collagen-II, aggrecan, MMP1, MMP2, MMP3, MMP13) were analyzed by real-time RT-PCR. A Wilcoxon signed-rank test(1) and a Wilcoxon 2-sample test(2) were performed to detect differences between the stimulated and control samples(1) and differences between low and high hydrostatic pressure(2). Multiple testing was considered by adjusting the p value appropriately. Both regimes of hydrostatic pressure influenced gene expression in nucleus cells with opposite tendencies for the matrix forming proteins aggrecan and collagen type-I in response to the two different pressure magnitudes: Low hydrostatic-pressure (0.25 MPa) tended to increase collagen-I and aggrecan expression of human nucleus cells (P < 0.05) but only to a small degree. High hydrostatic pressure (2.5 MPa) tended to decrease gene expression of all anabolic proteins with significant effects on aggrecan expression of nucleus cells (P = 0.004). Low hydrostatic pressure had no influence on the expression of matrix metalloproteinases (MMP1, MMP2, MMP3 and MMP13). In contrast, high hydrostatic pressure tended to increase the expression of MMP1, MMP3 and MMP13 of human nucleus cells with high individual-individual variations. The decreased expression of aggrecan (P = 0.008) and collagen type II (P = 0.023) and the increased MMP3 expression (P = 0.008) in response to high hydrostatic pressure could be confirmed in additional experiments with bovine nucleus cells. These results suggest that hydrostatic pressure as one of the physiological stimuli of the IVD may influence matrix turnover in a magnitude dependent way. Low hydrostatic pressure (0.25 MPa) has quite small influences with a tendency to anabolic effects, whereas high hydrostatic pressure (2.5 MPa) tends to decrease the matrix protein expression with a tendency to increase some matrix-turnover enzymes. Therefore, hydrostatic pressure may regulate disc matrix turnover in a dose-dependent way.

Adolescent↗

Spontaneous lumbar intervertebral disc protrusion in cats: literature review and case presentations.

Reports on intervertebral disc disease in cats are rare in the veterinary literature. It has been postulated that intervertebral disc protrusion is a frequent finding during necropsy in cats, without having any clinical relevance (King and Smith 1958, King & Smith 1960a, King & Smith 1960b). However, a total of six cases with disc protrusions and clinically significant neurological deficits have been reported over the past decade. (Heavner 1971, Seim & Nafe 1981, Gilmore 1983, Littlewood et al 1984, Sparkes & Skerry 1990, Bagley et al 1995). As in dogs, there are also two types of intervertebral disc disease in cats: Hansen's type I (extrusion), and type II (herniation). Cervical spinal cord involvement was more commonly recognised in cats than the lumbar or the thoraco lumbar area. Cats over 15 years were mainly affected (King & Smith 1958, King & Smith 1960a, King & Smith 1960b). We describe two cats with lumbar intervertebral disc protrusions. Emphasis is placed on differential diagnoses, treatment and follow-up.

Animals↗

Effect of chondroitinase ABC on matrix metalloproteinases and inflammatory mediators produced by intervertebral disc of rabbit in vitro.

STUDY DESIGN: Lumbar intervertebral discs in rabbit were cultured in the presence of chondroitinase ABC. The matrix metalloproteinases (MMPs) and inflammatory mediators produced in culture media were then analyzed. OBJECTIVES: To investigate the effect of chondroitinase ABC on MMPs and inflammatory mediators produced by intervertebral disc of rabbit in vitro. SUMMARY OF BACKGROUND DATA: The chemonucleolytic effect of chondroitinase ABC is caused by the decrease in the chondroitin sulfate, hyaluronan, and protein content of the nucleus pulposus in rabbit. The reason for the decreases in protein content remains unclear. METHODS: Anulus fibrosus and nucleus pulposus were cultured for 72 hours with or without chondroitinase ABC stimulated or not stimulated by interleukin-1 after preculture for 4 days. Subsequently, the MMPs (gelatinases MMP-2, MMP-9, and collagenase) and inflammatory mediators (prostaglandin E2 and nitric oxide) produced in the culture media were analyzed. RESULTS: In the anulus fibrosus chondroitinase ABC and interleukin-1 synergistically increased the collagenase activity, which was at a significantly higher level than the increment solely due to interleukin-1. In contrast, chondroitinase ABC counteracted the increase in nitric oxide production by interleukin-1. In the nucleus pulposus the collagenase and nitric oxide productions were not particularly affected by chondroitinase ABC and/or interleukin-1. In zymographic analysis MMP-2 was detected, but MMP-9 was only slightly detected in both tissues. There were no significant differences in both tissues for MMP-2 and prostaglandin E2 following incubation with or without chondroitinase ABC, whether stimulated by interleukin-1 or not. CONCLUSIONS: The collagenase activity in the anulus fibrosus was increased by chondroitinase ABC with interleukin-1. This finding may support the hypothesis that some proteolytic activities are involved in the chemonucleolytic process by chondroitinase ABC treatment.

Animals↗

[An in vitro natural degeneration model of chondrocytes derived from endplate of intervertebral discs of rats].

OBJECTIVE: To set up a natural degeneration model of chondrocytes derived from endplate of intervertebral discs of rats in order to offer an appropriate carrier for the study on mechanism of intervertebral disc degeneration. METHODS: The method of enzyme digestion combined with natural subculture was used to set up the in vitro natural degeneration model of chondrocytes derived from the endplate of intervertebral disc of rats. The morphological appearances and microstructures of the chondrocytes of different generations were observed. The expression of collagen II in chondrocytes was detected by immunocytochemical method. RESULTS: The chondrocytes derived from the endplate of intervertebral disc expressed collagen II. After 13 days of culture, the chondrocytes of generation III showed that the ability of cell division descended, the nucleoli became unclear, the cells deformed obviously, fusiform shape with weak optical activity appeared, and the intercellular space was enlarged. There were vacuoles and lipid droplets in cytoplasm. The synthesis of collagen II, as well as the cell proliferation rate, descended notably. All results showed the natural degeneration process of the chondrocytes. CONCLUSION: The in vitro natural degeneration model of chondrocytes derived from endplate of intervertebral discs of rats was successfully established. This can offer the cytological basis for study on the mechanism of intervertebral disc degeneration.

Animals↗

Histological changes in intervertebral discs after smoking and cessation: experimental study using a rat passive smoking model.

BACKGROUND: Passive smoking has been reported to induce intervertebral disc degeneration in rats, and the objective of the present study was to histologically investigate changes in smoking-induced intervertebral disc degeneration after cessation of smoking. METHODS: Four-week-old rats were subjected to passive smoking for 8 weeks in a smoking box [20 cigarettes a day: one cigarette an hour (inhaled over 3 minutes and followed by ventilation with room air for 5 minutes)] to induce intervertebral disc degeneration. Smoke-free periods of different lengths were then established, and intervertebral discs were histologically analyzed. RESULTS: Immediately after 8 weeks of passive smoking, intervertebral discs exhibited cracks, tears, and misalignment of the annulus fibrosus, and increased fibrous tissue was seen in the nucleus pulposus. In addition, the level of interleukin-1beta in intervertebral discs was higher in the smoking group than in the non-smoking group. After cessation, progression of degeneration ceased, and the matrix of the nucleus pulposus and annulus fibrosus exhibited increased fibrous connective tissue and proteoglycan. However, there were no changes in annulus fibrosus misalignment. Interleukin-1beta levels also remained significantly elevated after 8 weeks of cessation. CONCLUSIONS: While the annulus fibrosus degeneration caused by smoking was partially irreversible after cessation of smoking, the amount of mucin (proteoglycan) in the nucleus pulposus and annulus fibrosus tended to increase after cessation, thus suggesting the possibility that smoking-induced intervertebral disc degeneration can be repaired to some degree by cessation of smoking.

Animals↗

An experimental study of the regeneration of the intervertebral disc with an allograft of cultured annulus fibrosus cells using a tissue-engineering method.

STUDY DESIGN: Cultured annulus fibrosus cells within an atelocollagen honeycomb-shaped scaffold with a membrane seal were allografted into the lacunas of intervertebral discs of which the nucleus pulposus had been vaporized using an indocyanine green dye-enhanced laser. Regeneration of the intervertebral disc was assessed based on the viability and histologic status of the allografted annulus fibrosus cells, as well as the prevention of narrowing disc space. OBJECTIVES: To study the regeneration of intervertebral disc after laser discectomy using tissue-engineering methods. SUMMARY OF BACKGROUND DATA: Intervertebral disc is the most avascular tissue in the human body, and its ability to regenerate is as low as that of articular cartilage. When nucleotomy is carried out, little regeneration of the annulus fibrosus is observed; consequently, intervertebral disc degeneration is inevitable. METHODS: Annulus fibrosus cells isolated from 20 Japanese white rabbits were labeled with a PKH-26 fluorescent dye and seeded within an atelocollagen honeycomb-shaped scaffold with a membrane seal. Annulus fibrosus cells cultured in atelocollagen honeycomb-shaped scaffold with a membrane seal for 1 week were allografted into the lacunas of intervertebral discs of recipient rabbit of which the nucleus pulposus had been vaporized using an ICG dye-enhanced laser. Soft radiograph photographs of the lumbar spine of these anesthetized rabbits were taken, the disc space measured, and the lumbar spine extracted 2, 4, 8, and 12 weeks after the operation. The proliferation of allografted annulus fibrosus cells with 5-bromo-2'-deoxyuridine/PKH-26 fluorescent labels was assessed using consecutive frozen sections, and safranin-O staining carried out for histologic evaluation. RESULTS: The allografted annulus fibrosus cells were viable and showed proliferation activity with a hyaline-like cartilage being produced. The narrowing of the intervertebral disc space of the cell translation group was significantly prevented, as shown, up to 12 postoperative weeks. CONCLUSION: The annulus fibrosus cells cultured in an ACHMS-scaffold were allografted into the lacunae of nucleus pulposus (obtained using laser vaporization), as well as the hole of annulus fibrosus (obtained by laser fiber insertion) of rabbit intervertebral discs. These cells were viable and showed cell proliferation in the disc tissues of recipients.

Animals↗

Articular cartilage and intervertebral disc proteoglycans differ in structure: an electron microscopic study.

Articular cartilage and the intervertebral disc tissues have different material and biological properties and different patterns of aging and degeneration. To determine if the proteoglycans of these tissues differ in structure, we used the electron microscopic monolayer technique to compare baboon articular cartilage proteoglycans with baboon annulus fibrosus, transition zone, and nucleus pulposus proteoglycans. Intervertebral disc and articular cartilage proteoglycans differed significantly. Articular cartilage contained large proteoglycan aggregates formed from hyaluronic acid central filaments, multiple monomers, and large nonaggregated monomers. These molecules were identical to those of nasal cartilage, growth plate cartilage, chondrosarcomas, or menisci. In contrast, the intervertebral disc tissues contained only nonaggregated proteoglycan monomers and clusters of monomers without apparent central filaments. Intervertebral disc nonaggregated monomers were shorter and more variable in length than those from articular cartilage, and nucleus pulposus nonaggregated monomers were even shorter and more variable in length than transition zone and annulus fibrosus monomers. These observations suggest that significant differences in proteoglycan metabolism exist between articular cartilage and intervertebral disc.

Animals↗

Frozen storage affects the compressive creep behavior of the porcine intervertebral disc.

STUDY DESIGN: A biomechanical study of the compressive creep behavior of the porcine intervertebral disc before and after frozen storage. OBJECTIVE: To determine whether frozen storage alters the creep response, hydration, and nuclear swelling pressure of the intact intervertebral disc. SUMMARY OF BACKGROUND DATA: The mechanical response of the disc is dominated by swelling and fluid flow, whose effects are time-dependent. Because fluid content, which may change during storage, plays a significant role in the disc's time-dependent behavior, changes in mechanical response due to freezing may have been missed in previous studies that focused on time-independent behavior only. METHODS: Porcine intervertebral discs were tested in repeated cycles of compressive creep either immediately postmortem or after 3 weeks of frozen storage. Swelling pressure and nuclear hydration were also measured in fresh and frozen discs. A fluid transport model was used to analyze the creep data. RESULTS: The creep behavior of the intact porcine intervertebral disc is dramatically affected by frozen storage. The apparent permeability of the frozen discs was 82% higher than that of the fresh discs, and the swelling pressure of frozen discs was 25% lower in frozen discs (P < 0.01). The behavior of fresh and frozen discs became more dissimilar with repeated cycles of creep. CONCLUSIONS: In vitro tests of frozen porcine intervertebral discs do not represent fresh behavior. Frozen storage appears to permanently alter disc behavior. The precise nature of any freezing-induced damage, and whether frozen storage similarly affects human discs, remains to be seen.

Animals↗

Intervertebral disc disease.

This article describes the functional anatomy of intervertebral discs and their relationship to the vertebrae and spinal cord. The pathologic events and clinical complications of intervertebral disc disease are described. A discussion of proper staging of disc disease and appropriate conservative management of degenerative disc disease is included.

Animals↗

The role of proteoglycans in aging, degeneration and repair of the intervertebral disc.

The ability of the nucleus pulposus of the intervertebral disc to resist compressive loads is due to its high content of the proteoglycan aggrecan. Degeneration of the intervertebral disc is preceded and accompanied by a loss of aggrecan due to proteolysis. Biological repair of intervertebral disc degeneration should strive to restore aggrecan content to its optimal functional level. One approach to such repair is to supplement the degenerate nucleus with cells that are capable of aggrecan synthesis. Such cells can be supported in a biomolecular scaffold, but it is essential that the scaffold is compatible with high aggrecan retention if a functional tissue is to be attained.

Aggrecans↗

Advances in gene therapy for intervertebral disc degeneration.

BACKGROUND CONTEXT: Gene therapy is a growing concept in many fields of medicine, and its potential applications are numerous. With a growing understanding of the molecular and cellular biology of intervertebral disc degeneration, alternatives to current treatment options are under investigation. Gene therapy offers an exciting new direction in the treatment of intervertebral disc degeneration, and potential targets of genetic alteration are being explored. PURPOSE: To describe and update the recent advances in research on gene therapy for the treatment of intervertebral disc degeneration. STUDY DESIGN/SETTING: Review of current research for the application of gene therapy as potential treatment for intervertebral disc degeneration. METHODS: Literature review. RESULTS: There is a growing body of research pertaining to the use of gene therapy as an adjunct or alternative to the current treatment options for intervertebral disc degeneration. In vitro studies have demonstrated that transfer of cDNA encoding growth factors to intervertebral disc cells can favorably modify their metabolic and biological functions. Additionally, initial in vivo studies have demonstrated successful transduction of growth factors to the intervertebral disc with confirmed upregulation of extracellular matrix synthesis. Investigators continue to explore the potential of gene therapy with several factors for the treatment of intervertebral disc degeneration. CONCLUSIONS: The potential of gene therapy to alter the course of intervertebral disc degeneration holds much clinical promise and continues to stimulate further investigations.

Animals↗

Effects of hydrostatic pressure on matrix synthesis and matrix metalloproteinase production in the human lumbar intervertebral disc.

STUDY DESIGN: This study is a unique in vitro study on the effects of hydrostatic pressure on human intervertebral disc metabolism. OBJECTIVE: To investigate the effects of hydrostatic pressure on matrix synthesis and matrix metalloproteinase production in the human lumbar intervertebral disc. SUMMARY OF BACKGROUND DATA: Mechanical stress and hydrostatic pressures influence proteoglycan and protein synthesis rates in bovine articular cartilage and coccygeal discs. However, the mechanism of matrix synthesis regulation of the intervertebral disc under mechanical stress has not been elucidated. METHODS: Twenty-eight human lumbar intervertebral discs obtained from surgery and from cadavers at autopsy were used. Each tissue fraction was charged with medium in a plastic syringe and placed in a water-filled hydrostatic pressure-control vessel. The hydrostatic pressures applied were 1 (control), 3, and 30 atm (atm = atmospheres) for 2 hours. The proteoglycan and protein synthesis rates were determined by radioisotope incorporation. The production of matrix metalloproteinase-3 and tissue inhibitor of metalloproteinases-1 were measured by a one-step enzyme immunoassay method using monoclonal antibodies. RESULTS: Three atm pressure stimulated proteoglycan synthesis rates in the nucleus pulposus and inner anulus (n = 14 in each tissue). Compared with the control group, 30 atm pressure significantly inhibited proteoglycan synthesis in the inner anulus (P = 0.011). In the nucleus pulposus, matrix metalloproteinase-3 production was stimulated at a pressure of 30 atm relative to 3 atm (P = 0.014, n = 16 in each tissue). The highest tissue inhibitor of metalloproteinases-1 production showed highest values at 3 atm pressure in the inner anulus (n = 16 in each tissue). CONCLUSION: The results suggest that hydrostatic pressure influences intervertebral disc cell metabolism. A physiologic level of hydrostatic pressure (3 atm) may act as an anabolic factor for stimulation of proteoglycan synthesis and tissue inhibitor of metalloproteinases-1 production. This may be essential for maintaining the matrix of the disc. If the pressure was 30 atm or more or 1 atm or less, a catabolic effect will be predominant, with reduction of proteoglycan synthesis rate and increase of matrix metalloproteinase-3 production. Abnormal hydrostatic pressure, therefore, may accelerate disc degeneration.

Cadaver↗

The compressive creep properties of normal and degenerated murine intervertebral discs.

Identifying mechanisms by which degeneration alters intervertebral disc material properties and biomechanical behavior is important for clarifying back pain risk factors as well as for evaluating the efficacy of novel interventions. Our goal was to quantify and characterize degeneration-dependent changes in the disc's response to compression using a previously established murine model of disc degeneration. We performed compressive creep tests on normal and degenerated murine intervertebral discs and parameterized the biomechanical response using a previously established fluid-transport model. Using a series of biochemical and histological assays, we sought to determine how biomechanical alterations were attributable to degeneration-related changes in tissue morphology. We observed that with moderate degeneration, discs lost height (mean+/-std. dev. of 0.44+/-0.01 vs. 0.36+/-0.01 mm, p<0.0001), increased in proteoglycan content (31+/-4 vs. 43+/-2 microg/ml of extract, p<0.0002), became less stiff (2.17+/-0.66 vs. 1.56+/-0.44 MPa, p<0.053), and crept more. Model results suggested that the increased creep response was mainly due to a diminished strain-dependent nuclear swelling pressure. We also noted that the model-derived tissue properties varied with the applied load magnitude for both normal and degenerated discs. Overall, our data demonstrate that architectural remodeling stimulated by excessive loading diminishes the disc's ability to resist compression. These results are similar to degeneration-dependent changes reported for human discs.

Animals↗

Inflammatory cells in experimental intervertebral disc injury.

STUDY DESIGN: Inflammatory cells were located by immunocytochemistry in areas of experimental intervertebral disc injury in pigs. OBJECTIVES: To study the occurrence of T lymphocytes and macrophages 1 week, 1 month, and 3 months after partial-thickness transverse scalpel injuries in pig lumbar discs. SUMMARY OF BACKGROUND DATA: Inflammatory cells and mediators recently have been observed in disc herniation tissue that was removed at disc prolapse surgery. The prevalence of inflammatory cell infiltrates in such clinical disc tissue material also has been studied. There are no studies, however, that have analyzed, using immunocytochemical methodology, the occurrence of, types of, and time dependence of inflammatory cells in an experimental disc injury model. The role of inflammation in intervertebral disc injury and repair has not been determined. METHODS: Transverse scalpel injuries 5-mm long and 4-mm deep were cut in the anterolateral anulus of L5-L6 and L4-L5 discs in 16 pigs. The cuts in the center of the anulus did not reach the nucleus pulposus and never produced a disc prolapse. In every pig, two non-adjacent lumbar discs (L1-L2 and L2-L3) were used as controls. Four discs per animal were studied in parallel by two different complementary immunohistochemical staining protocols. T lymphocytes and macrophages were located immunohistochemically using CD3 and CD68 antibodies, respectively. Discs were removed for analysis from four pigs at 1 week, from six pigs at 1 month, and from six pigs at 3 months. Inflammatory cells were categorized by two independent observers as being entirely absent (-), only few scattered cells (+), and at least one larger cellular infiltrate (+2). RESULTS: In none of the discs could extensive inflammatory cell infiltration be observed. T lymphocytes were present in significantly more sections cut from injured discs than in sections cut from control discs. The difference was highly significant particularly at 1 week and 1 month after disc removal. Only the 1-month-after-injury sections from injured discs exhibited significantly more macrophages than those from control discs. CONCLUSIONS: The results suggest the presence of only modest inflammatory cell infiltration in experimental intervertebral disc injury at all follow-up times. The inflammatory response in partial-thickness anterior experimental intervertebral disc injury, in the absence of disc prolapse, seems to be dominated by a T lymphocyte response. The macrophage response is apparently strongest at 1 month after such injury. These findings differ from what has been observed in herniated disc tissue.

Animals↗

Studies of human intervertebral disc cell function in a constrained in vitro tissue culture system.

STUDY DESIGN: This is a laboratory-based study examining a novel in vitro culture system for intervertebral disc tissue. OBJECTIVES: Address the hypothesis that "the novel culture system will preserve intervertebral disc tissue matrix and cell function and prevent cellular apoptosis for periods up to 21 days." SUMMARY OF BACKGROUND DATA: Studies of cell function in human intervertebral disc tissue are scarce. In vivo study of human intervertebral disc cells remains impracticable; in situ molecular biology in histologic sections lacks a dynamic dimension; and as for in vitro studies, cell culture often lacks physiologic relevance and explant cultures are subject to loss of tissue integrity and altered cell behavior. There is a biologic and therapeutic need for a satisfactory explant culture system for studying human intervertebral disc tissue in a controlled environment. METHODS: Samples of human intervertebral disc tissue, obtained at surgery, were examined for a number of tissue and cell parameters immediately after excision (controls) and following culture of tissue samples either in a plastic ring or unconstrained in tissue culture medium for up to 3 weeks. Data were compared between cultured tissue and controls. RESULTS: By comparison with control tissue, unconstrained explants swelled, tissue structure was disturbed, and there were profound changes in cell function. By contrast, tissue cultured in plastic rings maintained tissue structure, and after 3 weeks, the cellular parameters were the same as in controls. CONCLUSIONS: This is the first reported system to preserve cell function of human discal explants for long periods in tissue culture. It will be a useful tool for a wide range of investigations of intervertebral disc biology that have not hitherto been possible.

Adult↗

Immunolocalization of type X collagen in human lumbar intervertebral discs during ageing and degeneration.

Type X collagen has so far not been reported to occur in human intervertebral discs. The objective of this study was therefore to investigate the occurrence of type X collagen in human lumbar intervertebral discs during ageing and degeneration. Ninety intervertebral discs with adjacent endplates were excised in toto from individuals (0-86 years) without known spinal disease and were processed for routine decalcified histology. Appropriate slices of each disc were processed for immunohistochemistry using a type-specific, monoclonal antibody raised against human type X collagen. Each intervertebral disc was examined for macroscopic and histomorphological features of disc degeneration. Immunohistochemically, a positive specific type X staining was observed in the hypertrophic zone of the growth plate and only in the interstitial matrix of juvenile (<2 years) nucleus pulposus. In adult discs, type X collagen could be localized in conjunction with advanced disc degeneration and first occurred in the disc matrix (i.e., pericellular region) of a 47-year-old specimen. Positive type X staining of the disc matrix was more frequently found in senile (>70 years) discs with end stages of disc degeneration. This study provides the first evidence for the occurrence of type X collagen in human lumbar intervertebral discs and it appears that type X collagen is re-expressed in late stages of disc degeneration.

Adolescent↗