Mineral and Bone Consequences of High Dose Denosumab Therapy to Treat an Aneurysmal Bone Cyst, a Child Case Report

Aneurysmal bone cysts (ABCs) are rare benign pseudotumoral bone lesions with potential aggressive behavior due to the extensive destruction of surrounding bone. Traditionally, these tumors were treated with open surgery, but there is more and more a shift to less invasive procedures. In particular, treatment for spinal ABCs is generally unsatisfactory due to the risk of morbidity, neurological impairment and recurrence, and there is a need for innovative therapies. Denosumab has been reported as a useful treatment in giant cell tumors of bone (GCTB), so its efficacy has been tested also in other fibro-osseus lesions affecting children and adolescents, such as spinal aneurysmal bone cysts. The pediatric literature is limited to case reports and small series, all of which highlight the efficacy of this treatment on lesions growth and associated bone pain. Some of these reports have already reported well known side effects associated with denosumab, such as hypocalcemia at the beginning of the treatment, and rebound hypercalcemia at the discontinuation. The latter seems to be more frequent in children and adolescents than in adults, probably due to the higher baseline bone turnover in children. In addition, the use of denosumab in young patients could affect both bone modeling and remodeling, even if the consequences on the growing skeleton have not been reported in detail. Here we describe the case of a spinal ABC diagnosed in an 8-year old young boy which was not accessible to surgery but responded favorably to denosumab. Our aim is to describe the rapid changes in mineral and bone homeostasis in this patient, that required advice from the experts of the European Reference Network (ERN) for rare bone and endocrine diseases.

HTRA1 expression profile and activity on TGF-β signaling in HTRA1 mutation carriers

High temperature requirement A1 (HTRA1) is a serine protease playing a modulatory role in various cell processes, particularly in the regulation of transforming growth factor-β (TGF-β) signaling. A deleterious role in late-onset cerebral small vessel diseases (CSVDs) of heterozygous HTRA1 mutations, otherwise causative in homozygosity of cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy, was recently suggested. However, the pathomechanism of these heterozygous mutations is still undefined. Our aim is to evaluate the expression profile and activity of HTRA1 on TGF-β signaling in fibroblasts from four subjects carrying the HTRA1 heterozygous mutations-p.E42Dfs*173, p.A321T, p.G295R, and p.Q151K. We found a 50% reduction of HTRA1 expression in HTRA1 mutation carriers compared to the control. Moreover, we showed no changes in TGF-β signaling pathway downstream intermediate, Phospho Smad2/3. However, we found overexpression of genes involved in the extracellular matrix formation in two heterozygous HTRA1 carriers. Our results suggest that each heterozygous HTRA1 missense mutation displays a different and peculiar HTRA1 expression pattern and that CSVD phenotype may also result from 50% of HTRA1 expression.

Increased Fibrogenic Gene Expression in Multifidus Muscles of Patients With Chronic Versus Acute Lumbar Spine Pathology

STUDY DESIGN

Prospective observational study-basic science (Level 1).

OBJECTIVE

The aim of this study was to compare expression of functional groups of genes within the atrophic, myogenic, fibrogenic, adipogenic, and inflammatory pathways between paraspinal muscle biopsies from individuals with acute and chronic lumbar spine pathology.

SUMMARY OF BACKGROUND DATA

Low back pain is a complex and multifactorial condition that affects a majority of the general population annually. Changes in muscle tissue composition (i.e., fatty and fibrotic infiltration) are a common feature in individuals with lumbar spine pathology associated with low back pain, which often results in functional loss. Understanding the molecular underpinnings of these degenerative changes in different phases of disease progression may improve disease prevention and treatment specificity.

METHODS

Intraoperative biopsies of the multifidus muscle were obtained from individuals undergoing surgery for acute (<6-month duration) or chronic (>6-month duration) lumbar spine pathology. Expression of 42 genes related to myogenesis, atrophy, adipogenesis, metabolism, inflammation, and fibrosis were measured in 33 samples (eight acute, 25 chronic) using qPCR, and tissue composition of fat, muscle, and fibrosis was quantified using histology.

RESULTS

We found that tissue composition of the biopsies was heterogeneous, resulting in a trend toward lower RNA yields in biopsies with higher proportions of fat (r <-0.39, P < 0.1). There were no significant differences in gene expression patterns for atrophy (P > 0.635), adipogenesis (P > 0.317), myogenesis (P > 0.320), or inflammatory (P > 0.413) genes after adjusting for the proportion of muscle, fat, and connective tissue. However, in the fibrogenesis pathway, we found significant upregulation of CTGF (P = 0.046), and trends for upregulation of COL1A1 (P = 0.061), and downregulation of MMP1 and MMP9 (P = 0.061) in the chronic group.

CONCLUSION

There is increased fibrogenic gene expression in individuals with chronic disease when compared to acute disease, without significant differences in atrophic, myogenic, adipogenic, or inflammatory pathways, suggesting increased efforts should be made to prevent or reverse fibrogenesis to improve patient function in this population.

LEVEL OF EVIDENCE

N/A.

Bone mineral density and bone remodeling markers in chronic low back pain patients with active discopathy: A case-control exploratory study

OBJECTIVE

We aimed to compare bone mineral density (BMD) and bone remodeling markers in chronic low back pain (cLBP) patients with and without active discopathy (Modic 1 changes).

DESIGN

We conducted a single center case-control exploratory study. For 18 months, all patients referred to a tertiary care physical medicine and rehabilitation department in France were consecutively screened. Patients fulfilling the inclusion criteria were prospectively enrolled. Cases were defined as cLBP patients with lumbar active discopathy detected on MRI and controls as cLBP patients without active discopathy. Bone mineral density (BMD) at the spine, femoral neck and total femur was assessed by dual-energy X-ray absorptiometry, and bone remodeling markers were assessed in fasting serum samples. Overall, 37 cLBP patients (13 cases and 24 controls) fulfilled inclusion criteria and were included.

RESULTS

The median age was 42.0 years (Q1-Q3: 36.0-51.0) and mean (SD) LBP duration 72.3 (57.4) months. We found that BMD and levels of bone remodeling markers in cLBP patients did not differ with and without active discopathy.

CONCLUSION

Our results do not support the association between active discopathy and systemic bone fragility.

[Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CARASIL)]

Cerebral small vessel disease (CSVD) is frequently observed among the elderly and is known to cause dementia and gait disturbance associated with white matter lesions, lacunar infarcts, and cerebral hemorrhage. Molecular mechanistic studies promise to provide new insights into the pathogenesis of hereditary CSVD. Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) is one of the hereditary CSVDs caused by a mutation in the high-temperature requirement serine peptidase A1 (HTRA1) gene. The loss of HTRA1 protease activity increases signaling via transforming growth factor (TGF)β, thereby resulting in CARASIL. Although the CARASIL has been characterized by juvenile onset alopecia and spondylosis deformans, these features are not always observed in individuals with an HTRA1 mutation. Moreover, some HTRA1 mutations cause CSVD in heterozygous states. Therefore, the clinical features of CSVD resulting from an HTRA1 mutation extend to patients with CSVD alone or to those with dominantly inherited CSVD.

Characteristic features and progression of abnormalities on MRI for CARASIL

OBJECTIVES

The objective of this study was to clarify the characteristic brain MRI findings for genetically diagnosed CARASIL (cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy).

METHODS

Seven patients with CARASIL carrying HTRA1 mutations (representing 6 Japanese families) were included in this study. Eighteen brain MRIs were reviewed and evaluated with a new rating scale based on scoring for abnormal hyperintense lesions and atrophy.

RESULTS

At the last follow-up MRI, all patients had hyperintense lesions on T2-weighted images of the frontal white matter, anterior temporal lobe, external capsules, and thalami. Patients with longer time from the onset of cognitive impairment had higher MRI severity score. The atrophy advanced, followed by white matter lesion progression. During the early stage, hyperintense lesions were observed in the frontal white matter, external capsule, and pons. During the late stage, the arc-shaped hyperintense lesion from the pons to the middle cerebellar peduncles, which we designated the "arc sign," became evident. The arc sign was a characteristic finding for CARASIL in the advanced stage.

CONCLUSIONS

These characteristic MRI findings for CARASIL are useful for selecting patients for genetic testing. The rating scale correlates well with disease duration and might be useful for assessing disease progression.

Cerebral small vessel disease-related protease HtrA1 processes latent TGF-β binding protein 1 and facilitates TGF-β signaling

High temperature requirement protein A1 (HtrA1) is a primarily secreted serine protease involved in a variety of cellular processes including transforming growth factor β (TGF-β) signaling. Loss of its activity causes cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), an inherited form of cerebral small vessel disease leading to early-onset stroke and premature dementia. Dysregulated TGF-β signaling is considered to promote CARASIL pathogenesis, but the underlying molecular mechanisms are incompletely understood. Here we present evidence from mouse brain tissue and embryonic fibroblasts as well as patient skin fibroblasts for a facilitating role of HtrA1 in TGF-β pathway activation. We identify latent TGF-β binding protein 1 (LTBP-1), an extracellular matrix protein and key regulator of TGF-β bioavailability, as a novel HtrA1 target. Cleavage occurs at physiological protease concentrations, is prevented under HtrA1-deficient conditions as well as by CARASIL mutations and disrupts both LTBP-1 binding to fibronectin and its incorporation into the extracellular matrix. Hence, our data suggest an attenuation of TGF-β signaling caused by a lack of HtrA1-mediated LTBP-1 processing as mechanism underlying CARASIL pathogenesis.

Intervertebral discs from spinal nondeformity and deformity patients have different mechanical and matrix properties

BACKGROUND CONTEXT

It is well-established that disc mechanical properties degrade with degeneration. However, prior studies utilized cadaveric tissues from donors with undefined back pain history. Disc degeneration may present with pain at the affected motion segment, or it may be present in the absence of back pain. The mechanical properties and matrix quantity of discs removed and diagnosed for degeneration with patient chronic pain may be distinct from those with other diagnoses, such as spinal deformity.

PURPOSE

To test the hypothesis that discs from nondeformity segments have inferior mechanical properties than deformity discs owing to differences in matrix quality.

STUDY DESIGN/SETTING

In vitro study comparing the mechanical and matrix properties of discs from surgery patients with spinal nondeformity and deformity.

METHODS

We analyzed nucleus and annulus samples (8-11 specimens per group) from surgical discectomy patients as part of a fusion or disc replacement procedure. Tissues were divided into two cohorts: nondeformity and deformity. Dynamic indentation tests were used to determine energy dissipation, indentation modulus, and viscoelasticity. Tissue hydration at a physiologic pressure was assessed by equilibrium dialysis. Proteoglycan, collagen, and collagen cross-link content were quantified. Matrix structure was assessed by histology.

RESULTS

We observed that energy dissipation was significantly higher in the nondeformity nucleus than in the deformity nucleus. Equilibrium dialysis experiments showed that annulus swelling was significantly lower in the nondeformity group. Consistent with this, we observed that the nondeformity annulus had lower proteoglycan and higher collagen contents.

CONCLUSIONS

Our data suggest that discs from nondeformity discs have subtle differences in mechanical properties compared with deformity discs. These differences were partially explained by matrix biochemical composition for the annulus, but not for the nucleus. The results of this study suggest that compromised matrix quality and diminished mechanical properties are features that potentially accompany discs of patients undergoing segmental fusion or disc replacement for disc degeneration and chronic back pain. These features have previously been implicated in pain via instability or reduced motion segment stiffness.

Variations in gene and protein expression in canine chondrodystrophic nucleus pulposus cells following long-term three-dimensional culture

Intervertebral disc (IVD) degeneration greatly affects quality of life. The nucleus pulposus (NP) of chondrodystrophic dog breeds (CDBs) is similar to the human NP, because the cells disappear with age and are replaced by fibrochondrocyte-like cells. However, because IVD develops as early as within the first year of life, we used canines as a model to investigate in vitro the mechanisms underlying IVD degeneration. Specifically, we evaluated the potential of a three-dimensional (3D) culture of healthy NP as an in vitro model system to investigate the mechanisms of IVD degeneration. Agarose hydrogels were populated with healthy NP cells from beagles after performing magnetic resonance imaging, and mRNA expression profiles and pericellular extracellular matrix (ECM) protein distribution were determined. After 25 days of 3D culture, there was a tendency for redifferentiation into the native NP phenotype, and mRNA levels of Col2A1, COMP, and CK18 were not significantly different from those of freshly isolated cells. Our findings suggest that long-term 3D culture promoted chondrodystrophic NP redifferentiation through reconstruction of the pericellular microenvironment. Further, lipopolysaccharide (LPS) induced expression of TNF-α, MMP3, MMP13, VEGF, and PGES mRNA in the 3D cultures, creating a molecular milieu that mimics that of degenerated NP. These results suggest that this in vitro model represents a reliable and cost-effective tool for evaluating new therapies for disc degeneration.

Tophaceous gout in the cervical spine

A 58-year-old woman with a three-year progressive history of chronic arthritis, had become disabled due to general malaise and fever. Her laboratory data revealed hyperuricemia and elevated levels of C-reactive protein. Neither rheumatoid factor nor anti-citrullinated peptide antibodies were present. We diagnosed her with tophaceous gout with uric crystalline revealed by the arthrocentesis of the elbow. (99m)Tc scintigraphy also disclosed a significant uptake in the cervical spine. The CT of the patient's cervical spine revealed significant bone erosion and destruction. We diagnosed the cervical involvement of gout based on the exclusion of infections and sarcoidosis. Rheumatologists should be aware of this rare association.

Spinal pain and nutrition in adolescents--an exploratory cross-sectional study

BACKGROUND

Spinal pain is an important health issue for adolescents resulting in functional limitations for many and increasing the risk of spinal pain in adulthood. Whilst human and animal studies suggest nutrition could influence spinal pain, this has not been investigated in adolescents. The objective of this exploratory cross sectional study was to evaluate associations between diet and adolescent spinal pain.

METHODS

This study surveyed the spinal pain (neck and back) and nutrition (specific nutrients, broad food groups, diet quality and dietary pattern) of 1424 male and female adolescents at 14 years of age, in Western Australia.

RESULTS

Back or neck pain were experienced by around half of the adolescents, with females more likely to experience spinal pain. Nutrition differed between sexes and deviated from optimal intakes. Vitamin B12, eggs, cereals and meat consumption were related to spinal pain in sex specific multivariate analyses including primary carer education level and adolescent waist girth and smoking.

CONCLUSIONS

The findings of this study suggest that certain aspects of diet may have an association with spinal pain in adolescence.

Disc cell clusters in pathological human intervertebral discs are associated with increased stress protein immunostaining

Intervertebral disc (IVD) cells within the annulus fibrosus (AF) and nucleus pulposus (NP) maintain distinct functional extracellular matrices and operate within a potentially noxious and stressful environment. How disc cells respond to stress and whether stress is responsible for triggering degeneration is unknown. Disc cell proliferation and cluster formation are most marked in degenerate IVDs, possibly indicating attempts at matrix repair. In other tissues, stress proteins increase rapidly after stress protecting cell function and, although implicated in degeneration of articular cartilage, have received little attention in degenerative IVD pathologies. We have compared the distribution of stress protein immunolocalization in pathological and control IVDs. Disc tissues were obtained at surgery from 43 patients with degenerative disc disease (DDD) and herniation, and 12 controls at postmortem. Tissues were immunostained with a polyclonal antibody for heat shock factor 1 (HSF-1) and monoclonal antibodies for the heat shock proteins, Hsp27 and Hsp72, using an indirect immunoperoxidase method. Positively stained cells were expressed as a percentage of the total. Cell cluster formation was also assessed. The proportion of cells in clusters was similar in the AF (both 2%) and NP (8 and 9%) of control and DDD samples, whereas in herniated tissues this was increased (AF 12%, NP 14%). Stress antigen staining tended to be more frequent in clustered rather than in single/doublet cells, and this was significant (P < 0.005) in both the AF and NP of herniated discs. Clustered cells, which are most common in herniated discs, may be mounting a protective response to abnormal environmental factors associated with disc degeneration. A better understanding of the stress response in IVD cells may allow its utilization in disc cell therapies.

A novel, non-functional, COL1A1 polymorphism is not associated with lumbar disk disease in young male Greek subjects unlike that of the Sp1 site

OBJECTIVE

We recently reported the association of the Sp1 site polymorphism of the COL1A1 gene with lumbar disk disease (LDD). In the present study we searched for a different polymorphism of the COL1A1 gene (which is usually not in linkage disequilibrium with the Sp1 site) in subjects with LDD.

DESIGN

Blood was collected from 24 Greek army recruits, aged 29+/-7.6 years, with LDD, and 66 healthy men, aged 26+/-4.38 years, matched for body mass index (BMI) and age, with normal BMD and with no history of trauma or fractures, who served as controls. DNA was extracted and the COL1A1 gene was sequenced. Of the control subjects, 12 were army recruits and 54 were selected from the general population.

RESULTS

The four base-pair insertion polymorphism in the COL1A1 gene analyzed by polymerase chain reaction amplification of DNA produces two different fragments (alleles A1 and A2): 14 patients (58.3%) were homozygous for A2A2, versus 35 controls (53%), while 3 patients (12.5%) were A1A1, and 8 of the control subjects (12%) had this genotype. There were no statistically significant differences in the presence of the two alleles of this polymorphism between patients with LDD and control subjects.

CONCLUSIONS

A four base-pair insertion polymorphism of the COL1A1 gene is not associated with the presence of LDD in young males, unlike the Sp1 site polymorphism of the same gene. These data reinforce the association between LDD and the functional polymorphisms of the Sp1 site by showing that other polymorphic sites of the of the COL1A1 gene in the same population of patients are not linked to the disease.

[Effect of connexin 43 knockout on acupuncture-induced down-regulation of c-fos expression in spinal dorsal horn in visceral pain mice]

OBJECTIVE

To explore the effect of connexin 43 gene knockout on acupuncture analgesia.

METHODS

Seventy-two wide type (WT) and connexin 43 gene knockout mice were separately and randomly divided into: WT control group, WT model group, WT acupuncture group, heterozygous (HT) control group, HT model group and HT acupuncture group, with 12 cases in each. Visceral pain model was established by intraperitoneal administration of acetic acid. "Zhongwan" (CV 12) and bilateral "Zusanli" (ST 36) were punctured with a filiform needle for 30 min and stimulated by manipulating the needle 30 s every 5 min. The expression of c-fos in the spinal dorsal horn was assayed by using RT-PCR and western blot techniques.

RESULTS

There was no significant difference between HT and WT control mice in relative grey value of spinal c-fos mRNA expression (P>0.05), in which few c-fos mRNA and protein expressed. The expression of c-fos mRNA and protein was increased significantly following intraperitoneal acetic acid injection compared with control groups in both HT and WT mice (P<0.01). And no significant difference was found between HT and WT model groups in c-fos mRNA expression (P>0.05). Compared with WT model group, the expression of both c-fos mRNA and c-fos protein in WT acupuncture group was down-regulated significantly (P<0.01). In comparison with HT model group, the expression of both c-fos mRNA and protein in HT acupuncture group was down-regulated but without statistically significant difference (P>0.05). And the expression of c-fos mRNA and protein in HT acupuncture group was significantly higher than that in WT acupuncture group (P<0.05, 0.01).

CONCLUSION

Acupuncture has a marked antinociceptive effect in visceral pain mice, and simultaneously suppresses the expression of c-fos mRNA and protein evoked by noxious stimulation in the spinal dorsal horn. Connexin 43 gene knockout may weaken acupuncture analgesia and reduce EA-induced down-regulation of c-fos expression, suggesting an involvement of connexin 43 in the analgesic effect of acupuncture.

Transplantation of mesenchymal stem cells in a canine disc degeneration model

Transplantation of mesenchymal stem cells (MSCs) is effective in decelerating disc degeneration in small animals; much remains unknown about this new therapy in larger animals or humans. Fas-ligand (FasL), which is only found in tissues with isolated immune privilege, is expressed in IVDs, particularly in the nucleus pulposus (NP). Maintaining the FasL level is important for IVD function. This study evaluated whether MSC transplantation has an effect on the suppression of disc degeneration and preservation of immune privilege in a canine model of disc degeneration. Mature beagles were separated into a normal control group (NC), a MSC group, and the disc degeneration (nucleotomy-only) group. In the MSC group, 4 weeks after nucleotomy, MSCs were transplanted into the degeneration-induced discs. The animals were followed for 12 weeks after the initial operation. Subsequently, radiological, histological, biochemical, immunohistochemical, and RT-PCR analyses were performed. MSC transplantation effectively led to the regeneration of degenerated discs. FACS and RT-PCR analyses of MSCs before transplantation demonstrated that the MSCs expressed FasL at the genetic level, not at the protein level. GFP-positive MSCs detected in the NP region 8 weeks after transplantation expressed FasL protein. The results of this study suggest that MSC transplantation may contribute to the maintenance of IVD immune privilege by the differentiation of transplanted MSCs into cells expressing FasL.

[Study progress of growth differentiation factor 5 or osteogenic protein 1 injection into a degenerated disc]

OBJECTIVE

To review the advance in the experimental studies and evaluate the potential therapeutic application of the growth differentiation factor 5(GDF-5) and osteogenic protein 1 (OP-1) in intervertebral disc degeneration. Methods Relevant literature at home and abroad published in recent years was searched and analyzed comprehensively. Results The growth factor was one of the most potential proteins in curing the intervertebral disc degeneration. In vitro, exogenous GDF-5 or OP-1 increased the deoxyribonucleic acid and proteoglycan contents of both nucleus pulposus and annlus fibrosis cells types significantly. GDF-5 at 200 ng/mL or OP-1 significantly stimulated proteoglycan synthesis and collagen synthesis. In vivo, the injection of GDF-5 (100 microg) or OP-1(100 microg in 10 microL 5% lactose) resulted in a restoration of disc height, improvement of magnetic resonance imaging scores, and histologic grading scores had statistical significance.

CONCLUSION

A single injection of GDF-5 or OP-1 has a reparative capacity on intervertebral discs, presumably based on its effect to stimulate matrix metabolism of intervertebral disc cells and enhance extracellular matrix production. A single injection of exogenous GDF-5 or OP-1 in the degenerated disc shows a good prospect.

Accelerated cellular senescence in degenerate intervertebral discs: a possible role in the pathogenesis of intervertebral disc degeneration

Current evidence implicates intervertebral disc degeneration as a major cause of low back pain, although its pathogenesis is poorly understood. Numerous characteristic features of disc degeneration mimic those seen during ageing but appear to occur at an accelerated rate. We hypothesised that this is due to accelerated cellular senescence, which causes fundamental changes in the ability of disc cells to maintain the intervertebral disc (IVD) matrix, thus leading to IVD degeneration. Cells isolated from non-degenerate and degenerate human tissue were assessed for mean telomere length, senescence-associated β-galactosidase (SA-β-gal), and replicative potential. Expression of P16^INK4A (increased in cellular senescence) was also investigated in IVD tissue by means of immunohistochemistry. RNA from tissue and cultured cells was used for real-time polymerase chain reaction analysis for matrix metalloproteinase-13, ADAMTS 5 (a disintegrin and metalloprotease with thrombospondin motifs 5), and P16^INK4A. Mean telomere length decreased with age in cells from non-degenerate tissue and also decreased with progressive stages of degeneration. In non-degenerate discs, there was an age-related increase in cellular expression of P16^INK4A. Cells from degenerate discs (even from young patients) exhibited increased expression of P16^INK4A, increased SA-β-gal staining, and a decrease in replicative potential. Importantly, there was a positive correlation between P16^INK4A and matrix-degrading enzyme gene expression. Our findings indicate that disc cell senescence occurs in vivo and is accelerated in IVD degeneration. Furthermore, the senescent phenotype is associated with increased catabolism, implicating cellular senescence in the pathogenesis of IVD degeneration.

Human cells derived from degenerate intervertebral discs respond differently to those derived from non-degenerate intervertebral discs following application of dynamic hydrostatic pressure

The intervertebral disc (IVD) is one of the body's most important load-bearing structures with the major mechanical force experienced in the nucleus pulposus (NP) being hydrostatic pressure (HP). Physiological levels of HP have an anabolic effect on IVD matrix metabolism in cells derived from non-degenerate animal and herniated IVD while excessive HP has a catabolic effect. However, no studies have investigated the response of non-degenerate and degenerate human disc cells derived from non-herniated discs to HP. Here we investigate the effect of physiological HP on such cells using a novel loading rig. Human IVD cells (both NP and AF) cultured in alginate were subjected to dynamic HP (0.8-1.7 MPa 0.5 Hz) for 2 h. Cell viability was assessed, RNA extracted and qRT-PCR for 18 s, c-fos, Sox-9, collagen type II, aggrecan and MMP-3 performed. Cell viability was unaffected by the loading regime. In non-degenerate NP cells, HP increased c-fos, aggrecan, Sox-9 and collagen type II (significantly so in the case of c-fos and aggrecan), but not MMP-3 gene expression. In contrast, application of HP to AF or degenerate NP cells had no effect on target gene expression. Our data shows that cells obtained from the healthy NP respond to dynamic HP by up-regulating genes indicative of healthy matrix homeostasis. However, responses differed in degenerate NP cells suggesting that an altered mechanotransduction pathway may be operational.

The aetiology of spinal deformity in Atlantic salmon, Salmo salar L.: influence of different commercial diets on the incidence and severity of the preclinical condition in salmon parr under two contrasting husbandry regimes

A large-scale trial of the effect of different commercial diets on the incidence of preclinical spinal deformation, as assessed by radiography, and the influence of two contrasting rearing systems was carried out. Two sets of three populations of Atlantic salmon, each of 20 000 first feeding fry of identical hatchery origin, created from equal numbers of eggs from 15 different families, were reared under commercial conditions on two different farms. Three commercial (closed formula) extruded fish meal-based diets were used in this study (diets A, B & C). Each diet was fed to one population of 20 000 fish at each site. Fish were fed a percentage of their body weight per day, with feeding rates set at commercial levels, based on water temperature, day length and fish biomass. Additional hand feeding was used to ensure satiation in all tanks. Fish in each tank were bulk-weighed and counted at the beginning and at 2-week intervals throughout the study. The fish were grown for 30 weeks. In addition, phosphorus (P) digestibility was evaluated by in-feed absorption testing in rainbow trout. The morphology of the radiographic lesions conformed to those described previously. Statistical analysis using multivariate regression analysis showed that date of sampling, site and diet were all statistically significant (P < 0.001) on univariable analysis. Farm A had significantly more affected fish than farm B (P < 0.001), which may have been attributable to variation in dissolved oxygen levels. The available dietary P levels were low in each diet. The number of fish affected in the group of fish being fed diet B was significantly lower than in the groups being fed diets A or C (P < 0.001). It appears most likely that the occurrence of preclinical radiographically apparent defects in parr which are believed to lead to the condition known as 'spinal deformity' is predominantly caused by a deficiency of available dietary P in first-feeding fry. The availability of dietary P may also vary considerably between diets formulated using different ingredients. Phytate-P associated with plant ingredients may affect the availability of P as well as other essential dietary nutrients. Additionally, diets for the production of salmonids in fresh water are currently formulated to keep P effluent to a minimum compatible with healthy spinal development. These various factors combine to make it crucial that small Atlantic salmon, especially first-feeding fry, are provided with carefully formulated diets fortified to an adequate level with a high quality source of available P.

F-actin cytoskeletal organization in intervertebral disc health and disease

The cytoskeleton, which in most cell types, including the intervertebral disc described here, comprises microfilaments, microtubules and intermediate filaments, plays important functions in many fundamental cellular events, including cell division, motility, protein trafficking and secretion. The cytoskeleton is also critical for communication; for example, alterations to the architecture of the F-actin (filamentous actin) cytoskeletal networks can affect communication between the cells and the extracellular matrix, potentially compromising tissue homoeostasis. Although there are limited studies to date, this paper aims to review current knowledge on F-actin cytoskeletal element organization in intervertebral disc cells, how F-actin differs with pathology and its implications for mechanotransduction.

Metal ion levels in patients with stainless steel spinal instrumentation

STUDY DESIGN

Case-control study.

OBJECTIVES

To determine whether metal ion concentrations are elevated in patients with spinal instrumentation.

SUMMARY OF BACKGROUND DATA

Studies have shown that serum and urinary levels of component metal ions are abnormally elevated in patients with total joint arthroplasties. Little is known of metal ion release and concentrations in patients with spinal instrumentation.

METHODS

The study group consisted of patients who had undergone spinal instrumentation for various spinal disorders with a variety of stainless steel implants, 5 to 25 years previously. A group of volunteers without metal implants were controls. All subjects were tested for serum nickel, blood chromium, and random urine chromium/creatinine ratio estimation.

RESULTS

The study group consisted of 32 patients with retained implants and 12 patients whose implants had been removed. There were 26 unmatched controls. There was no difference in serum nickel and blood chromium levels between all 3 groups. The mean urinary chromium/creatinine ratio for patients with implants and those with implants removed was significantly greater than controls (P < 0.001). The difference between study subgroups was not significant (P = 0.16). Of several patient and instrumentation variables, only the number of couplings approached significance for correlation with the urine chromium excretion (P = 0.07).

CONCLUSION

Spinal implants do not raise the levels of serum nickel and blood chromium. There is evidence that metal ions are released from spinal implants and excreted in urine. The excretion of chromium in patients with spinal implants was significantly greater than normal controls although lower where the implants have been removed. The findings are consistent with low-grade release of ions from implants with rapid clearance, thus maintaining normal serum levels. Levels of metal ions in the body fluids probably do not reach a level that causes late side-effect; hence, routine removal of the implants cannot be recommended.

Elastin content correlates with human disc degeneration in the anulus fibrosus and nucleus pulposus

STUDY DESIGN

Quantitative study of elastin content in nondegenerate and degenerate human intervertebral discs.

OBJECTIVE

To measure the site-specific changes in elastin content that accompany disc degeneration using a quantitative, dye-binding assay to assess elastin levels.

SUMMARY OF BACKGROUND DATA

Recently, an abundant and organized network of elastic fibers was observed in nondegenerated human disc using immunostaining histochemistry, suggesting a functional role for elastin. While degenerative changes in the disc extracellular matrix composition are well known, changes in elastin content that may accompany degeneration have not been reported.

METHODS

Human discs were assigned a degenerative grade by 3 independent orthopedic surgeons based on gross morphology. Samples were taken from the outer anulus fibrosus (OAF), inner AF (IAF) and nucleus pulposus (NP). Elastin content was measured using a specific, dye-binding assay and normalized to dry weight and collagen content, which was measured via a hydroxyproline assay. Samples were divided into 2 groups: nondegenerate (Grades 1-2.5) and degenerate (Grades 2.6-4.0). A 2-way analysis of variance was used to test for statistical significance where the 2 factors were disc location and degeneration. Correlations of composition with degeneration and age were analyzed.

RESULTS

In nondegenerate tissue, elastin by dry weight was on average 2.0% +/- 0.3%, and there were no differences in elastin content among the locations of OAF, IAF, or NP. With degeneration, there was a significant increase in total disc elastin per dry weight at each location. The degenerate IAF had the largest amount of elastin (9.3% +/- 2.3%), significantly greater than the NP and OAF. Elastin content correlated with degenerative grade and age at each site.

CONCLUSION

Based on the location-dependent degenerative changes, with highest increases in the IAF, elastin may function to restore lamellar structure under radial loads that potentially cause delamination. Future work will focus on distinguishing the changes in elastin orientation with degeneration and understanding the mechanical functional role of elastin in the disc.

Experimental intervertebral disc degeneration induced by chondroitinase ABC in the goat

STUDY DESIGN

In 2 studies, the injection of chondroitinase ABC into intervertebral discs of mature goats was evaluated as an experimental disc degeneration model. The first study analyzed the development of degeneration in time; the second study determined the optimal enzyme concentration.

OBJECTIVES

To develop reproducible, slowly progressive disc degeneration in a large animal model.

SUMMARY OF BACKGROUND DATA

Currently available, small animal models of intervertebral disc degeneration have shortcomings in the comparability to humans in terms of size, geometry, and cell population. Also, the methods to induce degeneration in the current models do not mimic human degeneration, which starts with the loss of proteoglycans. Injecting the enzyme chondroitinase ABC into the nucleus pulposus mimics the loss of proteoglycans.

METHODS

In Study 1, lumbar intervertebral discs of 17 goats were injected with chondroitinase ABC (0.25 U/mL) or phosphate-buffered saline. Degeneration was analyzed with radiograph analysis, MR imaging, and macroscopic and histologic scoring at 5 different time points (4, 8, 12, 18, and 26 weeks). Six control goats were analyzed. The second study used 6 goats in which 4 different concentrations of chondroitinase ABC (0.2-0.35 U/mL) or phosphate-buffered saline were injected. After 12 weeks, similar analyses as in Study 1 were performed.

RESULTS

After 12 weeks, degenerative signs were observed in all parameters in Study 1. The degeneration increased up to 18 weeks and leveled off after 26 weeks. The variability, however, was high. The second study showed a concentration dependent effect of chondroitinase ABC with all analyzed parameters. The injection of 0.25 U/mL chondroitinase ABC resulted in disc degeneration after 12 weeks without signs of severe degeneration.

CONCLUSION

Injection of chondroitinase ABC in the caprine intervertebral disc results in mild, slowly progressive disc degeneration. This effect was optimal at a concentration of 0.25 U/mL. This is a promising model of disc degeneration that deserves further study.

Restoration of disc height loss by recombinant human osteogenic protein-1 injection into intervertebral discs undergoing degeneration induced by an intradiscal injection of chondroitinase ABC

STUDY DESIGN

In vivo study of the effect of an injection of recombinant human osteogenic protein-1 into degenerated discs induced by chondroitinase ABC.

OBJECTIVE

To investigate the efficacy of an injection of recombinant human osteogenic protein-1 to induce the recovery of disc height, and biochemical and histologic repair, in discs degenerated through enzymatic digestion by chondroitinase ABC.

SUMMARY OF THE BACKGROUND DATA

Chondroitinase ABC is currently proposed as a chemonucleolysis agent; however, postchemonucleolysis degeneration is currently unavoidable. Recombinant human OP-1 has been shown to promote extracellular matrix repair in vitro and in vivo.

METHODS

Fifty-four adolescent New Zealand white rabbits were used. Four weeks after an initial injection of chondroitinase ABC (10 mU/disc), 5% lactose (10 microL/disc) or recombinant human osteogenic protein-1 (100 microg in 10 microL lactose/disc) was injected. Disc heights were monitored radiographically at 2-week intervals, and rabbits were killed at 6, 8, 12, and 16 weeks after the initial chondroitinase ABC injections. The intervertebral discs were subjected to histologic and biochemical analyses.

RESULTS

Significant disc space narrowing was observed in both groups 2 weeks after the injection of chondroitinase ABC. In the chondroitinase ABC/lactose group, this narrowing progressed after the vehicle injection and was sustained for up to 16 weeks. In the chondroitinase ABC/recombinant human osteogenic protein-1 group, the disc height index showed a significant increase at 6 weeks (lactose vs. recombinant human osteogenic protein-1; P < 0.01); this recovery was sustained for up to 16 weeks. The proteoglycan content was higher in the chondroitinase ABC/recombinant human osteogenic protein-1 group than in the chondroitinase ABC/lactose group. However, histologic changes, after the recombinant human osteogenic protein-1 injection, were not observed.

CONCLUSIONS

A single injection of recombinant human osteogenic protein-1 into a rabbit disc dramatically reversed the decrease in disc height induced by chondroitinase ABC chemonucleolysis. The recovery was significant and sustained over the next 12 weeks. The therapeutic effects of both chondroitinase ABC chemonucleolysis and recombinant human osteogenic protein-1 injections should be further explored in higher animals before it is applied to humans.

Microarray analysis of laser capture microdissected-anulus cells from the human intervertebral disc

STUDY DESIGN

Five Thompson Grade I/II discs (Group 1), 7 Grade III discs (Group 2), and 3 Grade IV discs (Group IV) were studied here in a project approved by the authors' Human Subjects Institutional Review Board.

OBJECTIVES

Our objective was to use laser capture microdissection (LCM) to harvest cells from the human anulus and to derive gene expression profiles using microarray analysis.

SUMMARY OF BACKGROUND DATA

Appropriate gene expression is essential in the intervertebral disc for maintenance of extracellular matrix (ECM), ECM remodeling, and maintenance of a viable disc cell population. During disc degeneration, cell numbers drop, making gene expression studies challenging.

METHODS

LCM was used to harvest cells from paraffin-embedded sections of human anulus tissue. Gene profiling used Affymetrix GeneChip Human X3P arrays. ANOVA and SAM permutation analysis were applied to dCHIP normalized, filtered, and log-transformed gene expression data ( approximately 33,500 probes), and data analyzed to identify genes that were significantly differentially expressed between the 3 groups.

RESULTS

We identified 47 genes that were significantly differentially expressed between the 3 groups (P < 0.001 and lowest q values). Compared with the healthiest discs (Grade I/II), 13 genes were up-regulated and 19 down-regulated in both the Grade III and the Grade IV discs. Genes with biologic significance regulated during degeneration involved cell senescence, low cell division rates, hypoxia-related genes, heat-shock protein 70 interacting protein, neuropilin 2, and interleukin-23p19 (interleukin-12 family).

CONCLUSIONS

Results expand our understanding of disc aging and degeneration and show that LCM is a valuable technique that can be used to collect mRNA amounts adequate for microarray analysis from the sparse cell population of the human anulus.

Nucleus pulposus cellular longevity by telomerase gene therapy

STUDY DESIGN

Nonviral transfection of nucleus pulposus cells with a telomerase expression construct to assess the effects on cellular lifespan, function, karyotypic stability, and transformation properties.

OBJECTIVES

To investigate whether telomerase gene therapy can extend the cellular lifespan while retaining functionality of nucleus pulposus cells in a safe manner.

SUMMARY OF BACKGROUND DATA

Degeneration of the intervertebral disc is an age-related condition in which cells responsible for the maintenance and health of the disc deteriorate with age. Telomerase can extend the cellular lifespan and function of other musculoskeletal tissues, such as the heart, bones, and connective tissues. Therefore, extension of the cellular lifespan and matrix production of intervertebral disc cells may have the potential to delay the degeneration process.

METHODS

Ovine nucleus pulposus cells were lipofectamine transfected in vitro with a human telomerase reverse transcriptase (hTERT) expression construct. Cellular lifespan and matrix transcript levels were determined by cumulative population doublings and real-time RT-PCR, respectively. G1-cell cycle checkpoint, p53 functionality, growth of transfected cells in anchorage-independent or serum starvation conditions, and karyotypic analysis were performed.

RESULTS

Transfection was achieved successfully with 340% +/- 7% (mean +/- SD) relative telomerase activity in hTERT-transfected cells. hTERT transfection enabled a 50% extension in mean cellular lifespan and prolonged matrix production of collagen 1 and 2 for more than 282 days. Karyotypic instability was detected but G1-cell cycle checkpoint and p53 was functionally comparable to parental cells with no growth in serum starvation or anchorage-independent conditions.

CONCLUSIONS

Telomerase can extend the cellular lifespan of nucleus pulposus cells and prolong the production of extracellular matrix. Safety is still unresolved, as karyotypic instability was detected but no loss of contact inhibition, mitogen dependency, or G1-cell cycle checkpoint control was evident.

Mechanical efficacy of vertebroplasty: influence of cement type, BMD, fracture severity, and disc degeneration

INTRODUCTION

Osteoporotic vertebral fractures can be treated by injecting bone cement into the damaged vertebral body. "Vertebroplasty" is becoming popular but the procedure has yet to be optimised. This study compared the ability of two different types of cement to restore the spine's mechanical properties following fracture, and it examined how the mechanical efficacy of vertebroplasty depends on bone mineral density (BMD), fracture severity, and disc degeneration.

METHODS

A pair of thoracolumbar "motion-segments" (two adjacent vertebrae with intervening soft tissue) was obtained from each of 15 cadavers, aged 51-91 years. Specimens were loaded to induce vertebral fracture; then one of each pair underwent vertebroplasty with polymethylmethacrylate (PMMA) cement, the other with another composite material (Cortoss). Specimens were creep loaded for 2 h to allow consolidation. At each stage of the experiment, motion segment stiffness in bending and compression was measured, and the distribution of compressive loading on the vertebrae was investigated by pulling a miniature pressure transducer through the intervertebral disc. Pressure measurements, repeated in flexed and extended postures, indicated the intradiscal pressure (IDP) and neural arch compressive load-bearing (F(N)). BMD was measured using DXA. Fracture severity was quantified from height loss.

RESULTS

Vertebral fracture reduced motion segment stiffness in bending and compression, by 31% and 43% respectively (p<0.001). IDP fell by 43-62%, depending on posture (p<0.001), whereas F(N) increased from 14% to 37% of the applied load in flexion, and from 39% to 61% in extension (p<0.001). Vertebroplasty partially reversed all these effects, and the restoration of load-sharing was usually sustained after creep-consolidation. No differences were observed between PMMA and Cortoss. Pooled results from 30 specimens showed that low BMD was associated with increased fracture severity (in terms of height loss) and with greater changes in stiffness and load-sharing following fracture. Specimens with low BMD and more severe fractures also showed the greatest mechanical changes following vertebroplasty.

CONCLUSIONS

Low vertebral BMD leads to greater changes in stiffness and spinal load-sharing following fracture. Restoration of mechanical function following vertebroplasty is little influenced by cement type but may be greater in people with low BMD who suffer more severe fractures.

Computation of coupled diffusion of oxygen, glucose and lactic acid in an intervertebral disc

The present numerical study aims to investigate the disc nutrition and factors affecting it by evaluating the concentrations of oxygen, glucose and lactic acid in the disc while accounting for the coupling between these species via the pH level in the tissue and the nonlinear concentration-consumption (for glucose and oxygen) and concentration-production (for lactate) relations. The effects of changes in the endplate exchange area (EA) adjacent to the nucleus or the inner annulus for the transport of nutrients and in the disc geometry as well as tissue diffusivities under static compression loading on species concentrations are also studied. Moreover, alterations in solute diffusion following a central endplate fracture are investigated. An axisymmetric geometry with four distinct regions is considered. Supply sources are assumed at the outer annulus periphery and disc endplates. Coupling between different solutes, pH level, endplate disruptions (calcifications and fractures) and mechanical loads substantially influenced the distribution of nutrients throughout the disc as well as the magnitude and location of critical concentrations; maximum for the lactic acid and minimum for oxygen and glucose. In cases with loss of endplate permeability and/or disruptions therein, as well as changes in geometry and fall in diffusivity associated with fluid expression, the nutrient concentrations could fall to levels inadequate to maintain cellular activity or viability, thus initiating or accelerating disc degeneration.

Stab incision for inducing intervertebral disc degeneration in the rat

STUDY DESIGN

The degenerative response of rat tail and lumbar intervertebral discs to a stab incision was evaluated.

OBJECTIVE

To examine and compare the postinjury degenerative response of lumbar and tail discs.

SUMMARY OF BACKGROUND DATA

Although successful in larger animals, a stab incision for inducing disc degeneration in rats has not been evaluated. Rodents are desirable models for disc repair studies due to their low cost, ease of care, and fast healing times.

METHODS

Lumbar and tail discs were exposed surgically and stabbed with a number 11 blade. Disc architecture, levels of IL-1beta, IL-6, and TNF-alpha, and biomechanical properties were analyzed. A functional disability secondary to multilevel lumbar disc injury was quantified and compared with that of rats undergoing sham surgery.

RESULTS

Histologic evaluation of stabbed tail discs demonstrated a nucleus pulposus size decrease, anular collagen layer disorganization, and cellular metaplasia of anular fibroblasts to chondrocyte-appearing cells. Besides the continued presence of the stab injury tract, few changes were observed in the lumbar disc histology. Cytokine measurements indicated a transient peak in IL-1beta in tail discs 4 days following injury. No significant changes in IL-1beta, IL-6, or TNF-alpha were measured. No significant differences in biomechanical properties were observed between stab injury and sham surgery discs. Yet, despite insignificant differences in histologic, cytochemical, or biomechanical properties in the lumbar discs, the rats with lumbar stab injury had a significant decrease in walking ability 28 days after surgery.

CONCLUSIONS

Tail disc stab injury was successful in creating morphologic signs of degeneration and transient high concentrations of IL-1beta. However, the degenerative response in the lumbar discs was much slower, suggesting that site-specific factors, such as increased stability due to posterior elements and torso musculature, helped facilitate healing. Yet, functional assessment indicated that the rats were partially disabled by multiple lumbar injuries.

Aerobic fitness in women with chronic discogenic nonradicular low back pain

OBJECTIVE

The purpose of this study was to determine if aerobic fitness varies between women with and without chronic discogenic non-radicular low back pain.

DESIGN

Prospective cross-sectional descriptive study.

RESULTS

: Analysis of variance revealed that maximal oxygen consumption was lower (P = 0.05) in women with low back pain compared with the control group. In addition, there was a significant reduction (P = 0.05) in reported exercise training duration and frequency but no change in exercise intensity (P = 0.1) in the study group after the onset of low back pain. The low back pain group had minimal disability (19%) based on the Oswestry Disability Questionnaire.

CONCLUSIONS

Women with chronic discogenic non-radicular low back pain have lower maximal oxygen consumption than age-matched controls. However, this study group continued to exercise safely at the same exercise training intensity as before their low back pain and had minimal disability and above-average aerobic fitness.

Targeted retrograde transfection of adenovirus vector carrying brain-derived neurotrophic factor gene prevents loss of mouse (twy/twy) anterior horn neurons in vivo sustaining mechanical compression

STUDY DESIGN

Immunohistochemical analysis after adenovirus (AdV)-mediated BDNF gene transfer in and around the area of mechanical compression in the cervical spinal cord of the hyperostotic mouse (twy/twy).

OBJECTIVE

To investigate the neuroprotective effect of targeted AdV-BDNF gene transfection in the twy mouse with spontaneous chronic compression of the spinal cord motoneurons.

SUMMARY OF BACKGROUND DATA

Several studies reported the neuroprotective effects of neurotrophins on injured spinal cord. However, no report has described the effect of targeted retrograde neurotrophic gene delivery on motoneuron survival in chronic compression lesions of the cervical spinal cord resembling lesions of myelopathy.

METHODS

LacZ marker gene using adenoviral vector (AdV-LacZ) was used to evaluate retrograde delivery from the sternomastoid muscle in adult twy mice (16-week-old) and (control). Four weeks after the AdV-LacZ or AdV-BDNF injection, the compressed cervical spinal cord was removed en bloc for immunohistologic investigation of b-galactosidase activity and immunoreactivity and immunoblot analyses of BDNF. The number of anterior horn neurons was counted using Nissl, ChAT and AChE staining.

RESULTS

Spinal accessory motoneurons between C1 and C3 segments were successfully transfected by AdV-LacZ in both twy and ICR mice after targeted intramuscular injection. Immunoreactivity to BDNF was significantly stronger in AdV-BDNF-gene transfected twy mice than in AdV-LacZ-gene transfected mice. At the cord level showing the maximum compression in AdV-BDNF-transfected twy mice, the number of anterior horn neurons was sinificantly higher in the topographic neuronal cell counting of Nissl-, ChAT-, and AChE-stained samples than in AdV-LacZ-injected twy mice.

CONCLUSION

Targeted AdV-BDNF-gene delivery significantly increased Nissl-stained anterior horn neurons and enhanced cholinergic enzyme activities in the twy. Our results suggest that targeted retrograde AdV-BDNF-gene in vivo delivery may enhance neuronal survival even under chronic mechanical compression.

[Effects of calcitonin on the pathology of spinal fusion in rabbit models]

OBJECTIVE

To observe the effect of calcitonin on the pathology of fusion in lumbar posterior/facet spinal fusion in rabbit model.

METHODS

Thirty-two male New Zealand white rabbits were used to establish spinal fusion model. Sixteen rabbits received calcitonin at a dose of 1 IU x kg(-1) x d(-1) were classified as calcitonin group, and the remaining 16 rabbits as control group. Rabbits were killed 1, 2, 4, and 8 weeks after operations. Haematoxylin-eosin staining was applied to observe the pathological process of spinal fusion. Expression of bone morphogenetic protein-2 (BMP2) was detected by immunohistochemistry.

RESULTS

Bone resorption and fibrovascular stroma formation were the main histological presentation 1 week after surgery. Two and 4 weeks after surgery, more cartilage formed with varying degrees of mineralization, while less trabeculae could be observed in the phase of active bone formation. No remarked margin was seen between cartilage and bone tissues. Eight weeks after surgery, trabeculae distributed widely. The pathological process of spinal fusion in calcitonin group was faster than in control group. Emery scores showed significant differences at different time points (F = 265.44, P < 0.001). Calcitonin and time had a positively synergistic effect on Emery scores, and calcitonin caused significant difference in terms of Emery scores since the second week (F = 22.43, P < 0.001). Expressions of BMP, were significantly different at different time points (F = 1186.54, P < 0.001). Also, calcitonin and time had a synergistic effect on BMP2 expression (F = 13.14, P < 0. 001).

CONCLUSIONS

Endochondral ossification exists in the spinal fusion process and may be the main way of ossification. Calcitonin may stimulate the expression of BMP2 and thus accelerate the process of spinal fusion.

The expression of anabolic cytokines in intervertebral discs in age-related degeneration

STUDY DESIGN

Quantitative analysis of endogenous messenger ribonucleic acid (mRNA) expression of anabolic cytokines in the anulus fibrosus and nucleus pulposus tissue from the intervertebral discs of young and old rabbits was performed.

OBJECTIVES

To measure the expression of anabolic cytokines bone morphogenetic protein-2 (BMP-2), BMP-7, transforming growth factor-beta (TGF-beta), and insulin-like growth factor-I (IGF-I) in the anulus fibrosus and nucleus pulposus tissue from young and old rabbits to determine if there are differences with age.

SUMMARY OF BACKGROUND DATA

Disc degeneration increases with age and is associated with compromised disc chondrocytic function. Molecules such as BMP-2, BMP-7, TGF-beta, and IGF-I are known to up-regulate disc cell synthesis of key chondrocytic matrix molecules in vitro, and have been proposed as therapeutic agents to prevent disc degeneration. Previous studies have shown that exogenous anabolic cytokines can up-regulate disc-cell function both in vitro and in vivo, however, the endogenous expression of anabolic cytokines in the disc is still unknown.

METHODS

New Zealand white rabbits aged 3 years (old) and 6 months (young) were used. Quantitative real-time polymerase chain reaction was performed to measure the mRNA levels of BMP-2, BMP-7, TGF-beta1, and IGF-I from anulus fibrosus and nucleus pulposus tissue from young and old rabbits. The discs form the young rabbits represent nondegenerated discs, and the discs from the old rabbits represent discs at the onset of degeneration.

RESULTS

In the nucleus pulposus, the mRNA levels, given as a ratio of old to young, were 3.6 for BMP-2 (P = 0.004), 61 for BMP-7 (P = 0.02), 4.0 for TGF-beta1 (P = 0.3), and 0.6 for IGF-I (P = 0.2). In the anulus fibrosus, the mRNA levels, given as a ratio of old to young, were 1.6 for BMP-2 (P = 0.07), 4.6 for BMP-7 (P = 0.004), 2.9 for TGF- beta1 (P = 0.01), and 2.0 for IGF-I (P = 0.1).

CONCLUSION

The disc tissue from the old rabbits as compared to the young rabbits showed, in general, significantly higher mRNA levels of endogenous BMP-2, BMP-7, and TGF-beta in both the anulus fibrosus and nucleus pulposus. The similar patterns of up-regulation in gene expression with age shown by these 3 anabolic cytokines suggest a common pathway in terms of regulation and transcription in the early stage of disc degeneration. The knowledge of the age-related pattern in endogenous gene expression of these anabolic cytokines could provide important information for clinical interventional therapy.

Contrast flow characteristics in the cervical epidural space: an analysis of cervical epidurograms

STUDY DESIGN

A single-center prospective analysis of cervical epidurograms, using a crossover design.

OBJECTIVES

To delineate the extent and pattern of spread of epidural contrast during cervical epidural steroid injections. To determine the volume of solution needed for effective cervical epidural steroid injections. To determine the most appropriate neck flexion angles for cervical epidural steroid injections. To determine the relationships between epidural spread, degree of neck flexion, and volume of solution used during cervical epidural steroid injections.

SUMMARY OF BACKGROUND DATA

The decreased epidural space in the cervical region makes injections here liable to rare, but potentially serious, complications. The lower cervical (C6-C7, C7-T1) levels are thought to be safer because of the increased epidural space here, as compared with higher levels. There is, however, considerable controversy in the scientific literature regarding the levels at which cervical epidural injections should be performed. There is also no consensus regarding the volume of solution needed or the extent of neck flexion required for effective epidural spread. To date, no study has examined these questions.

METHODS

Patients with lower cervical spine pathology who were referred for cervical epidural steroid injections were randomly assigned to have the injections performed at the C6-C7 or C7-T1 midline level. Volume of solutions used and degree of neck flexion were measured. Characteristics of epidural spread were recorded. Patients requiring repeat injections had the injections performed at the adjacent level with identical volume and angle of neck flexion using a goniometer. Contrast flow characteristics were again recorded. Extent of spread was correlated with the level of injection, volume of injectant, and degree of neck flexion.

RESULTS

No major or permanent complications were noted. The contrast was found to spread evenly throughout the entire dorsal cervical epidural space, on a consistent basis, in all cases. At C6-C7, it was found to spread an average of 3.61 +/- 0.84 levels; and at C7-T1, it spread an average of 3.88 +/- 1.01 levels. Using a three-way analysis of variance, the level at which the epidural was performed, the amount of contrast used, and the neck flexion angle did not affect the number of levels spread.

CONCLUSIONS

In cervical epidural steroid injections performed in the midline at C6-C7 and C7-T1, the contrast consistently covers the dorsal cervical epidural space bilaterally, irrespective of the volume used or neck flexion angle used. This suggests that solutions introduced here would cover the dorsal cervical epidural space. This questions the utility of performing potentially more dangerous injections at higher cervical levels or more invasive procedures, such as the use of epidural catheters.

The effect of nucleus pulposus crosslinking and glycosaminoglycan degradation on disc mechanical function

Altered mechanical loading, secondary to biochemical changes in the nucleus pulposus, is a potential mechanism in disc degeneration. An understanding of the role of this altered mechanical loading is only possible by separating the mechanical and biological effects of early nucleus pulposus changes. The objective of this study was to quantify the mechanical effect of decreased glycosaminoglycans (GAG) and increased crosslinking in the nucleus pulposus using in vitro rat lumbar discs. Following initial mechanical testing the discs were injected according to the four treatment groups: PBS control, chondroitinase-ABC (ChABC) for GAG degradation, genipin (Gen) for crosslinking, or a combination of chondroitinase and genipin (ChABC+Gen). After treatment the discs were again mechanically tested, followed by histology or biochemistry. Neutral zone mechanical properties were changed by approximately 20% for PBS, ChABC, and ChABC+Gen treatments (significant only for PBS in a paired comparison). These trends were reversed with genipin crosslinking alone. With ChABC treatment the effective compressive modulus increased and the GAG content decreased; with the combination of ChABC+Gen the mechanics and GAG content were unchanged. Degradation of nucleus pulposus GAG alters disc axial mechanics, potentially contributing to the degenerative cascade. Crosslinking is unlikely to contribute to degeneration, but may be a potential avenue of treatment.

Assessment of human disc degeneration and proteoglycan content using T1rho-weighted magnetic resonance imaging

STUDY DESIGN

T1rho relaxation was quantified and correlated with intervertebral disc degeneration and proteoglycan content in cadaveric human lumbar spine tissue.

OBJECTIVE

To show the use of T1rho-weighted magnetic resonance imaging (MRI) for the assessment of degeneration and proteoglycan content in the human intervertebral disc.

SUMMARY OF BACKGROUND DATA

Loss of proteoglycan in the nucleus pulposus occurs during early degeneration. Conventional MRI techniques cannot detect these early changes in the extracellular matrix content of the disc. T1rho MRI is sensitive to changes in proteoglycan content of articular cartilage and may, therefore, be sensitive to proteoglycan content in the intervertebral disc.

METHODS

Intact human cadaveric lumbar spines were imaged on a clinical MR scanner. Average T1rho in the nucleus pulposus was calculated from quantitative T1rho maps. After MRI, the spines were dissected, and proteoglycan content of the nucleus pulposus was measured. Finally, the stage of degeneration was graded using conventional T2 images.

RESULTS

T1rho decreased linearly with increasing degeneration (r = -0.76, P < 0.01) and age (r = -0.76, P < 0.01). Biochemical analysis revealed a strong linear correlation between T1rho and sulfated-glycosaminoglycan content. T1rho was moderately correlated with water content.

CONCLUSIONS

Results from this study suggest that T1rho may provide a tool for the diagnosis of early degenerative changes in the disc. T1rho-weighted MRI is a noninvasive technique that may provide higher dynamic range than T2 and does not require a high static field or exogenous contrast agents.

Aggrecan Turnover in Human Intervertebral Disc as Determined by the Racemization of Aspartic Acid

We have used the racemization of aspartic acid as a marker for the "molecular age" of aggrecan components of the human intervertebral disc matrix (aggregating and non-aggregating proteoglycans as well as the different buoyant density fractions of aggrecan). By measuring the D/L(Asp) ratio of the various aggrecan species as a function of age and using the values of the racemization constant, k(i), found earlier for aggrecan in articular cartilage, we were able to establish directly the relative residence time of these molecules in human intervertebral disc matrix. For A1 preparations taken from normal tissue, turnover rates of 0.059 +/- 0.01 and 0.063 +/- 0.01/year correspond to half-life values of 12 +/- 2.0 and 11.23 +/- 1.9 years for nucleus pulposus and annulus fibrosus, respectively; the turnover rates of 0.084 +/- 0.022 and 0.092 +/- 0.034/year for degenerate tissue correspond to half-life values of 8.77 +/- 2.2 and 8.41 +/- 2.8 years, suggesting increased rate of removal of small aggrecan fragments. For the large monomer, fraction A1D1, turnover is 0.13 +/- 0.04/year, corresponding to a half-life of 5.56 +/- 1.58 years, similar to 3.4 years in human articular cartilage. For the binding region (A1D6), turnover is 0.033 +/- 0.0012/year, corresponding to a half-life of 21.53 +/- 0.6 years, similar to 23.5 years in articular cartilage. A1 preparations from nucleus pulposus contain a lower proportion of aggregating proteoglycans as compared with annulus fibrosus, suggesting increased proteolytic modification in the nucleus pulposus. D/L(Asp) values in aggregating and non-aggregating proteoglycans of a 24-year-old individual show similar results, suggesting that the non-aggregating molecules are synthesized initially as aggregating proteoglycans, which thereafter undergo cleavage and detachment from hyaluronan.

Expression of receptors for putative anabolic growth factors in human intervertebral disc: implications for repair and regeneration of the disc

Low back pain (LBP) is a common, debilitating and economically important disorder. Current evidence implicates loss of intervertebral disc (IVD) matrix consequent upon 'degeneration' as a major cause of LBP. Degeneration of the IVD involves increases in degradative enzymes and decreases in the extracellular matrix (ECM) component in a process that is controlled by a range of cytokines and growth factors. Studies have suggested using anabolic growth factors to regenerate the normal matrix of the IVD, hence restoring disc height and reversing degenerative disc disease. However, for such therapies to be successful it is vital that the target cells (i.e. the disc cells) express the appropriate receptors. This immunohistochemical study has for the first time investigated the expression and localization of four potentially beneficial growth factor receptors (i.e. TGFbetaRII, BMPRII, FGFR3 and IGFRI) in non-degenerate and degenerate human IVDs. Receptor expression was quantified across regions of the normal and degenerate disc and showed that cells of the nucleus pulposus (NP) and inner annulus fibrosus (IAF) expressed significantly higher levels of the four growth factor receptors investigated. There were no significant differences between the four growth factor expression in non-degenerate and degenerate biopsies. However, expression of TGFbetaRII, FGFR3 and IGFRI, but not BMP RII, were observed in the ingrowing blood vessels that characterize part of the disease aetiology. In conclusion, this study has demonstrated the expression of the four growth factor receptors at similar levels in the chondrocyte-like cells of the NP and IAF in both non-degenerate and degenerate discs, implicating a role in normal disc homeostasis and suggesting that the application of these growth factors to the degenerate human IVD would stimulate matrix production. However, the expression of some of the growth factor receptors on ingrowing blood vessels might be problematic in a therapeutic approach.

Correlation of HR-MAS spectroscopy derived metabolite concentrations with collagen and proteoglycan levels and Thompson grade in the degenerative disc

STUDY DESIGN

A quantitative high-resolution magic angle spinning (HR-MAS) NMR study of human lumbar discs was conducted to determine biomarkers of disc degeneration.

OBJECTIVES

To correlate HR-MAS quantification of compounds relevant to human lumbar disc degeneration to conventional methods of disc grading such as Thompson grading and biochemical analysis.

SUMMARY OF BACKGROUND DATA

It has been shown that there is poor correlation between MRI and CT morphologic findings, spinal biomechanics, and patient symptoms in degenerative disc disease and low back pain. There is a need for an objective, quantitative measurement of biochemical status, morphology, and function.

METHODS

A total of 17 cadaveric human lumbar intervertebral discs were harvested from patients ranging from 20 to 85 years of age. Quantitative HR-MAS data were acquired, and proteoglycan and collagen biochemical analyses were conducted on 3-mm biopsy punches taken from the anulus fibrosus and nucleus pulposus of each sample. HR-MAS data were fitted and analyzed for hydroxyproline (3.42 ppm), glycine (3.56 ppm), and the N-acetyl peak (2.04 ppm) associated with proteoglycans in comparison with an internal standard. These concentrations were then compared directly to biochemical analyses and Thompson grade.

RESULTS

HR-MAS data correlated well with Thompson grade (P < 0.001). An increase was seen in the levels of unbound hydroxyproline and glycine in annular tissue, which is directly associated to collagen breakdown. This trend also correlates with the changes of total collagen measured by a collagen biochemical assay. HR-MAS also detected a decrease in concentration of nucleus pulposus proteoglycans with degeneration. This proteoglycan decrease was verified by a standard proteoglycan biochemical assay.

CONCLUSIONS

Changes in disc chemical composition can be accurately quantified using quantitative HR-MAS NMR spectroscopy ex vivo. This noninvasive method of qualitatively and quantitatively assessing disc degeneration supports the utility of these biomarkers and underlines the need for developing in vivo magnetic resonance spectroscopic imaging (MRSI) for characterizing intervertebral disc degeneration.

Densité minérale et métabolisme osseux des spondylarthropathies

AIMS

To study the prevalence of osteoporosis in a group of patients with spondyloarthropathy and to investigate bone turnover markers and correlation between bone mineral density and the age at the beginning of the disease.

PATIENTS AND METHOD

Patients with spondyloarthropathy as defined by New York and ESSG criteria. Bone mineral density was measured at the lumbar spine and hip with Hologic QDR 1000. Serum levels of osteocalcin, deoxypyridinoline, 25 vitamin D, creatinine and parathyroid hormone were measured.

RESULTS

50 patients were included in the study: 37 men, mean age 40,2+/-13,8 years. Vertebral osteopenia was observed in 34% while femoral osteopenia occurred in 40% of patients. Serum vitamin D was low in 70% of patients without parathyroid hormone or kidney function modification. Markers of bone turn over were increased in 29% of patients. There was no correlation between these biological markers and the bone mineral density. We observed a significative correlation (P=0,02) between the age at the beginning of the disease and the bone mineral density.

CONCLUSION

Osteopenia is present in patients with spondyloarthropathy without any correlation with the bone turnover biological markers. We observed a significative correlation between the age at the beginning of the disease and bone mineral density.

Dysferlinopathy associated with rigid spine syndrome

Dysferlinopathy and rigid spine syndrome occurring in a 50-year-old man is reported. The patient noticed stiffness of knee and ankle joints, which gradually extended to neck, wrist and elbow joints leading to difficulty in anterior flexion. Muscular weakness and wasting of the lower extremities had developed since age 40, accompanied by a limitation of anterior bending of the spine. Elevated serum CK was noticed. Muscle CT revealed atrophy with moderate fatty replacement of muscles in the neck, shoulder and pelvic girdle, and marked replacement in the para-vertebral muscles, posterior compartment of hamstrings and calf muscles. Electromyography showed a typical myogenic pattern, and muscle biopsy disclosed dystrophic changes, compatible with limb-girdle muscular dystrophy 2B. Loss of dysferlin expression was verified by immunohistochemistry, which was confirmed by a mini-multiplex Western blotting system. Gene analyses of the dysferlin gene disclosed compound heterozygotes for frameshift (G3016 + 1A) and a missense mutation (G3370T). This study might propose some clues to resolve the combination of musular dystrophies and rigid spine syndrome.

The promyelotic leukemia zinc finger promotes osteoblastic differentiation of human mesenchymal stem cells as an upstream regulator of CBFA1

Ossification of the posterior longitudinal ligament of the spine (OPLL) is the leading cause of myelopathy in Japan and is diagnosed by ectopic bone formation in the paravertebral ligament. OPLL is a systemic high bone mass disease with a strong genetic background. To detect genes relevant to the pathogenesis of OPLL, we performed a cDNA microarray analysis of systematic gene expression profiles during the osteoblastic differentiation of ligament cells from OPLL patients (OPLL cells), patients with a disorder called ossification of yellow ligament (OYL), and non-OPLL controls together with human mesenchymal stem cells (hMSCs) after stimulating them with osteogenic differentiation medium (OS). Twenty-four genes were up-regulated during osteoblastic differentiation in OPLL cells. Zinc finger protein 145 (promyelotic leukemia zinc finger or PLZF) was one of the highly expressed genes during osteoblastic differentiation in all the cells examined. We investigated the roles of PLZF in the regulation of osteoblastic differentiation of hMSCs and C2C12 cells. Small interfering RNA-mediated gene silencing of PLZF resulted in a reduction in the expression of osteoblast-specific genes such as the alkaline phosphatase, collagen 1A1 (Col1a1), Runx2/core-binding factor 1 (Cbfa1), and osteocalcin genes, even in the presence of OS in hMSCs. The expression of PLZF was unaffected by the addition of bone morphogenetic protein 2 (BMP-2), and the expression of BMP-2 was not affected by PLZF in hMSCs. In C2C12 cells, overexpression of PLZF increased the expression of Cbfa1 and Col1a1; on the other hand, the overexpression of CBFA1 did not affect the expression of Plzf. These findings indicate that PLZF plays important roles in early osteoblastic differentiation as an upstream regulator of CBFA1 and thereby might participate in promoting the ossification of spinal ligament cells in OPLL patients.

Enterogenous cysts of the spinal canal and cerebellopontine angle

Enterogenous cysts are rare, benign lesions involving the spinal canal or the cerebellopontine angle. Typically they present with compression of the spinal cord or cranial nerves. They are usually 1 cm or less in size and are typically lined by columnar mucin-producing epithelium resembling enteric epithelium or columnar ciliated epithelium resembling respiratory epithelium. The case records of the Division of Neuropathology at Indiana University were reviewed for cystic lesions of the spinal canal and cranial cavity for a 26-year period. Seven surgically resected enterogenous cysts were identified. The original slides were studied. Additional sections were stained with mucicarmine, and immunohistochemical stains including thyroid transcription factor 1, epithelial membrane antigen, and cytokeratin 5/6 (CK5/6) were performed. Electron microscopy was performed in 1 case. The cysts ranged in size from 4 to 10 mm. One had stratified cuboidal epithelium, 1 had ciliated columnar and stratified squamous epithelium, 1 had columnar mucinous epithelium, and 4 had ciliated columnar epithelium. Epithelial membrane antigen and CK5/6 positivity were observed in all cases. Strong CK5/6 positivity was seen in the basal cells, with little or no immunoreactivity in the ciliated cells. Mucicarmine positivity was observed in 4 cases, and thyroid transcription factor 1 positivity was observed in 2 cases. Electron microscopy demonstrated well-developed stereocilia, distinct basal cells, and a thin basement membrane. The histopathologic, ultrastructural, and immunologic findings in these lesions are similar to those present in the bronchial epithelium, supporting the hypothesis of endodermal origin for these lesions.

Histological analysis of the ligamentum flavum of patients with dialysis-related spondyloarthropathy

Dialysis-related spondyloarthropathy (DRS) is a severe complication of long-term hemodialysis that ultimately leads to functional disability of the upper and lower extremities. Although the cause of this disease is still unknown, it is thought that amyloid deposits are involved. beta2-Microglobulin (beta2M) is a major component of amyloid fibrils, some of which are modified with the advanced glycation end-product (AGE). To clarify the pathophysiology of DRS we histologically examined the ligamentum flavum of the cervical spine in 15 patients with DRS. The mean duration of hemodialysis was 20 years (12-27 years). In addition to the congo red stain for amyloid, beta2M and AGE were detected by immunohistochemical methods. Macrophages were stained with CD68 antibody. Amyloid deposits were found in tissues, although the extent of the stained area differed among the patients. Part of the amyloid deposit area was positively immunostained for beta2M and AGE. In 10 cases macrophages positive for CD68 infiltrated around the amyloid deposits. Comparing these histological findings with the dialysis duration, more positive staining areas for beta2M and AGE were found in the tissue from patients with long-term dialysis. These findings suggest that both beta2M and AGE play roles in the pathogenesis of DRS.

Changes in nuclear composition following cyclic compression of the intervertebral disc in an in vivo rat-tail model

While in vitro studies have shown that mechanical loading can result in changes in the composition of intervertebral disc matrix, the effects of cyclic loading in vivo have not been considered. The objective of this study was to assess the effect of static and cyclic compression of different frequencies on the nuclear composition of the intervertebral disc. Thirty-six Sprague-Dawley rats were randomly divided into a control group (no pin insertion, no loading), a sham group (pins inserted in sixth and seventh caudal vertebrae, no loading), a static loading group (compression applied via pins) and cyclic loading groups (loading at 0.5, 1.5 or 2.5 Hz). Loading was applied for 1 h each day from the third to 17th day following pin insertion, and the caudal 5-6, 6-7 and 7-8 discs harvested to quantify proteoglycan content, collagen content and chondrocyte density in the nucleus pulposus. Static compression resulted in a significant reduction in total proteoglycan content as compared with the adjacent control disc, but this effect was not seen in any of the cyclic loading groups. However, comparison with the sham group appears to indicate an overall decrease in total proteoglycan content at the targeted and adjacent levels following cyclic loading. The 0.5 Hz loading group showed a significantly greater total proteoglycan content than all other compression groups, and also showed a lower total collagen content than the sham group. Results suggest that frequency dependent changes in composition occur in response to cyclic loading, but are not limited to the directly loaded disc alone. Further studies are required to verify this, but the choice of control appears to need careful consideration in all studies of this nature.

Localization of degradative enzymes and their inhibitors in the degenerate human intervertebral disc

The histological and biochemical changes that occur in the extracellular matrix of the intervertebral disc (IVD) during ageing and degeneration have been investigated extensively. However, the mechanisms behind these changes are not fully understood. A number of studies have suggested the involvement of matrix metalloproteinases (MMPs) and ADAMTS in IVD degeneration, but few have localized the site of production of these enzymes to the cells of the degenerate disc. This study uses immunohistochemical techniques to localize and quantify the production of degrading enzymes (MMPs 1, 3, and 13, and ADAMTS 4) and their inhibitors (TIMPS 1, 2, and 3) within non-degenerate and degenerate discs of varying severity of degeneration. In all discs investigated, the cells that produced the enzymes and their inhibitors were the chondrocyte-like cells of the nucleus pulposus and inner annulus fibrosus (AF), with little immunopositivity in the outer AF. Non-degenerate discs showed low numbers of cells expressing the degradative enzymes MMP 1 and ADAMTS 4, suggesting a role for these enzymes in normal homeostasis. No MMP 3 or MMP 13 immunopositivity was observed in non-degenerate discs. In degenerate discs, the number of cells immunopositive for MMPs 1, 3, 13 and ADAMTS 4 increased with the severity of degeneration. This increase in degrading enzymes was also accompanied by increases in the number of cells immunopositive for TIMPs 1 and 2 but not TIMP 3. This study highlights that although the expression of a number of MMPs increases with degeneration, this is accompanied by an increase in their inhibitors. However, the increase in the number of cells immunoreactive for ADAMTS 4 with increasing degeneration was not paralleled by a rise in its inhibitor TIMP 3. This finding indicates that the aggrecanases, rather then the MMPs, are a possible therapeutic target for the inhibition of disc degeneration.

Establishment of a clonal human mesenchymal cell line that retains multilineage differentiation capacity from a spinal hamartoma

We isolated a single-cell-derived cell line from a spinal hamartoma, a which occurred in a newborn boy and was associated with a rudimentary limb. The maternal cells (HHC-7) differentiated into osteoblasts, chondrocytes, adipocytes, and skeletal muscles when they were cultured in differentiation-inducing media specific to each mesenchymal cell. We isolated a single-cell-derived clonal cell line (Clone K) after transfection with SV40 T antigen. These cells expressed CD73 and CD117, while being negative for expression of CD45. Clone K cells cultured in an osteogenic differentiation medium increased ALP activity and expressed mRNAs for Runx2 and osteocalcin. Treatment with rhBMP-2 induced Clone K cells to differentiate into both osteoblasts and chondrocytes. These cells expressed mRNAs for Sox9 and aggrecan in addition to osteogenic markers. Culture in an adipogenic differentiation medium induced Clone K cells to differentiation into adipocytes, which expressed mRNAs for PPARgamma2 and a2P. Clone K cells cultured in a serum-depleted medium generated desmin-positive cells and expressed MyoD1 mRNA. Clone K cells exhibited numerous alpha-smooth muscle actin-positive cells; however, treatment with rhBMP-2 decreased their number. Clone K cells, transplanted with a carrier containing rhBMP-2 into the muscles of SCID mice, generated ectopic endochondral bone formation. In these tissues, several osteoblasts and chondrocytes expressed SV40 T antigen, indicating their Clone K cell origin. Thus, Clone K cells are useful tools for analyzing the characteristics of human multipotential mesenchymal progenitors.

Dexamethasone induces human spinal ligament derived cells toward osteogenic differentiation

Ossification of spinal ligament is characterized by heterotopic bone formation in the spinal ligaments that are normally composed of fibrous tissues. The pathogenesis of ossification of spinal ligament has been suggested to be associated with osteogenic differentiation of the spinal ligament cells. In order to address this hypothesis, cells derived from human spinal ligament were investigated for their osteogenic potential by the treatment of dexamethasone in vitro. Yellow ligaments were obtained from patients with spinal disorders except ossification of spinal ligament during surgery, and the adhering tissues were removed completely. Most of the ligament cells treated with vehicle exhibited a fibroblast-like spindle shape, while the dexamethasone-treated cells acquired a polygonal morphology. Growth of the ligament cells was suppressed by dexamethasone at a high concentration. Some of the vehicle treated-cells were alkaline phosphatase-positive, and dexamethasone increased the alkaline phosphatase-positive cells and alkaline phosphatase activity in the cells. Northern blot analysis demonstrated that mRNAs expression of pro-alpha1(I) collagen and alkaline phosphatase were promoted by dexamethasone. Analysis by reverse transcription-polymerase chain reaction showed that expression of osteocalcin mRNA was detected in the dexamethasone-treated cells but not in the vehicle-treated cells, and dexamethasone-induced osteocalcin mRNA expression was promoted by 1,25-dihydroxyvitamin D(3). Finally, mineralization of extracellular matrix in the cells was induced by the presence of dexamethasone and 1,25-dihydroxyvitamin D(3). These results suggest for the first time that dexamethasone has a possible involvement in the osteoblastic differentiation of human spinal ligament cells.