Age-dependent microstructural changes of the intervertebral disc: a validation of proteoglycan-sensitive spectral CT

Objective To analyze the two major components of the intervertebral disc (IVD) in an ex vivo phantom, as well as age-related changes in patients. Methods Collagen and chondroitin sulfate were imaged at different concentrations in agar solution. Age-related changes in disc density were retrospectively analyzed in normal-appearing discs in dual-energy computed tomography (DECT) images from a patient cohort with various spinal pathologies (n = 136). All computed tomography (CT) scans were acquired using single-source DECT at 80 and 135 kVp with automatic exposure calculation. In 136 patients, the attenuation of normal-appearing discs on collagen/chondroitin maps (cMaps) correlated with the patients’ age with Pearson’s r using standardized regions of interest in the anterior anulus fibrosus (AAF) and nucleus pulposus (NP). Results DECT collagen mapping revealed concentration-dependent Hounsfield units (HU) of IVD components. For collagen, we found Pearson’s r = 0.9610 (95% CI 0.6789–0.9959), p = 0.0023 at 120 kVe, and r = 0.8824 (95% CI 0.2495–0.9871), p = 0.0199 in cMap. For chondroitin sulfate, Pearson’s r was 0.9583 (95% CI 0.6603–0.9956), p = 0.0026 at 120 kVp, and r = 0.9646 (95% CI 0.7044–0.9963), p = 0.0019 in cMap. Analysis of normal-appearing IVDs revealed an inverse correlation of density with age in the AAF: Pearson’s r = − 0.2294 at 135 kVp (95% CI − 0.4012 to − 0.04203; p=0.0141) and r = − 0.09341 in cMap (95% CI − 0.2777 to 0.09754; p = 0.0003). In the NP, age and density did not correlate significantly at 135 kVp (p = 0.9228) and in cMap (p = 0.3229). Conclusions DECT-based collagen mapping allows microstructural analysis of the two main intervertebral disc components—collagen and chondroitin sulfate. IVD density declines with age, presumably due to a reduction in collagen and chondroitin sulfate content. Age-related alterations of disc microstructure appear most pronounced in the AAF. Key Points • DECT-based collagen mapping allows precise analysis of the two main intervertebral disc components—collagen and chondroitin sulfate. • Intervertebral disc (IVD) density declines with age, presumably due to a reduction in collagen and chondroitin sulfate content. • Age-related alterations of disc microstructure are most pronounced in the anterior anulus fibrosus (AAF).

Degeneration of Lumbar Intervertebral Discs: Characterization of Anulus Fibrosus Tissue and Cells of Different Degeneration Grades

Intervertebral disc (IVD) herniation and degeneration is a major source of back pain. In order to regenerate a herniated and degenerated disc, closure of the anulus fibrosus (AF) is of crucial importance. For molecular characterization of AF, genome-wide Affymetrix HG-U133plus2.0 microarrays of native AF and cultured cells were investigated. To evaluate if cells derived from degenerated AF are able to initiate gene expression of a regenerative pattern of extracellular matrix (ECM) molecules, cultivated cells were stimulated with bone morphogenetic protein 2 (BMP2), transforming growth factor β1 (TGFβ1) or tumor necrosis factor-α (TNFα) for 24 h. Comparative microarray analysis of native AF tissues showed 788 genes with a significantly different gene expression with 213 genes more highly expressed in mild and 575 genes in severe degenerated AF tissue. Mild degenerated native AF tissues showed a higher gene expression of common cartilage ECM genes, whereas severe degenerated AF tissues expressed genes known from degenerative processes, including matrix metalloproteinases (MMP) and bone associated genes. During monolayer cultivation, only 164 differentially expressed genes were found. The cells dedifferentiated and altered their gene expression profile. RTD-PCR analyses of BMP2- and TGFβ1-stimulated cells from mild and severe degenerated AF tissue after 24 h showed an increased expression of cartilage associated genes. TNFα stimulation increased MMP1, 3, and 13 expression. Cells derived from mild and severe degenerated tissues could be stimulated to a comparable extent. These results give hope that regeneration of mildly but also strongly degenerated disc tissue is possible.

Ingrowth of Nociceptive Receptors into Diseased Cervical Intervertebral Disc Is Associated with Discogenic Neck Pain

Objective. To investigate the distribution of nociceptive nerve fibers in the cervical intervertebral discs of patients with chronic neck pain and determine whether these nociceptive nerve fibers are related to discogenic neck pain. Methods. We collected 43 samples of cervical intervertebral discs from 34 patients with severe chronic neck pain (visual analog scale [VAS] ≥ 70 mm), 42 samples from 36 patients who suffered cervical spondylotic radiculopathy or myelopathy without neck pain or with mild neck pain (VAS ≤ 30 mm) and 32 samples from eight donators to investigate their innervation immunohistochemically using an antibody against neuropeptide substance P. Results. The immunohistochemical investigation revealed that substance P–positive nerve fibers were obviously increased in number and deeply ingrown into the inner anulus fibrosus and even into the nucleus pulposus in the degenerative cervical discs of patients with severe neck pain in comparison with the discs of patients with cervical spondylotic radiculopathy or myelopathy and normal control discs (P<0.01). Conclusions. The current study may indicate a key role of nociceptive nerve fibers in the pathogenesis of neck pain of cervical disc origin.

Pro-Inflammatory Stimuli Influence Expression of Intercellular Adhesion Molecule 1 in Human Anulus Fibrosus Cells through FAK/ERK/GSK3 and PKCδ Signaling Pathways

Objective: Intervertebral disc (IVD) degeneration and disc herniation are major causes of lower back pain, which involve the presence of inflammatory mediators and tissue invasion by immune cells. Intercellular adhesion molecule 1 (ICAM1, also termed CD54) is an adhesion molecule that mediates cell-cell interactions, particularly between immune cells and target tissue. The aim of this study was to examine the intracellular signaling pathways involved in inflammatory stimuli-induced ICAM1 expression in human anulus fibrosus (AF) cells. Methods: Quantitative reverse transcription-polymerase chain reaction (qPCR), western blotting, and flow cytometry were performed to dissect the roles of different signaling pathways in inflammatory stimuli-mediated ICAM1 expression. Results: Using qPCR and western blot analyses, a significant increase in ICAM1 expression was observed in AF cells after stimulation of lipopolysaccharide (LPS) plus interferon-gamma (IFNγ) in a time-dependent manner. Flow cytometry revealed ICAM1 upregulation on the surface of AF cells. Importantly, LPS plus IFNγ treatment also significantly promoted Chemokine ligand (CCL)2 expression, but not CCL3. The enhanced ICAM1 expression was abolished after incubation with antibody against CCL2. In AF cells, treatment with LPS plus IFNγ activated the FAK/ERK/GSK3 signaling pathways, promoted a time-dependent increase in PKCδ phosphorylation, and promoted PKCδ translocation to the nucleus. Treatment with the pharmacological PKCδ inhibitor; rottlerin, effectively blocked the enhanced productions of ICAM1 and CCL2. Conclusions: Inflammatory stimuli in AF cells are part of a specific pathophysiology in IVD degeneration and disc herniation that modulates CCL2/ICAM1 activation through the FAK/ERK/GSK3 and PKCδ signaling pathways in AF cells.

Chemokine CCL25 Induces Migration and Extracellular Matrix Production of Anulus Fibrosus-Derived Cells

Intervertebral disc degeneration is a major source of back pain. For intervertebral disc regeneration after herniation a fast closure of anulus fibrosus (AF) defects is crucial. Here, the use of the C-C motif chemokine ligand 25 (CCL)25 in comparison to differentiation factors such as transforming growth factor (TGF)β3, bone morphogenetic protein (BMP)2, BMP7, BMP12, and BMP14 (all in concentrations of 10, 50 and 100 ng/mL) was tested in an in vitro micro mass pellet model with isolated and cultivated human AF-cells (n = 3) to induce and enhance AF-matrix formation. The pellets were differentiated (serum-free) with supplementation of the factors. After 28 days all used factors induced proteoglycan production (safranin O staining) and collagen type I production (immunohistochemical staining) in at least one of the tested concentrations. Histomorphometric scoring revealed that TGFβ3 delivered the strongest induction of proteoglycan production in all three concentrations. Furthermore, it was the only factor able to facilitate collagen type II production, even higher than in native tissue samples. CCL25 was also able to induce proteoglycan and collagen type I production comparable to several BMPs. CCL25 could additionally induce migration of AF-cells in a chemotaxis assay and therefore possibly aid in regeneration processes after disc herniation by recruiting AF-cells.

Herniated Lumbar Disc and Nursing Care

Spinal disc herniation, also known as a slipped disc, is a medical condition affecting the spine in which a tear in the outer, fibrous ring of an intervertebral disc allows the soft, central portion to bulge out beyond the damaged outer rings. Disc herniation is usually due to age-related degeneration of the outer ring, known as the anulus fibrosus, although trauma, lifting injuries, or straining have been implicated as well. Tears are almost always postero-lateral (on the back of the sides) owing to the presence of the posterior longitudinal ligament in the spinal canal. Disc herniations are normally a further development of a previously existing disc protrusion, a condition in which the outermost layers of the anulus fibrosus are still intact, but can bulge when the disc is under pressure. In contrast to a herniation, none of the central portion escapes beyond the outer layers. Most minor herniations heal within several weeks. Anti-inflammatory treatments for pain associated with disc herniation, protrusion, bulge, or disc tear are generally effective. Severe herniations may not heal of their own accord and may require surgery. The condition is widely referred to as a slipped disc, but this term is not medically accurate as the spinal discs are firmly attached between the vertebrae and cannot "slip" out of place. Lumbar disc herniations occur in the lower back, most often between the fourth and fifth lumbar vertebral bodies or between the fifth and the sacrum. Symptoms can affect the lower back, buttocks, thigh, anal/genital region (via the perineal nerve), and may radiate into the foot and/or toe. The sciatic nerve is the most commonly affected nerve, causing symptoms of sciatica. The femoral nerve can also be affected[25]and cause the patient to experience a numb, tingling feeling throughout one or both legs and even feet or even a burning feeling in the hips and legs. A hernia in the lumbar region often compresses the nerve root exiting at the level below the disk. Thus, a herniation of the L4/5 disc will compress the L5 nerve root. With the patient and doctor, plan a pain control regimen. Encourage the patient to express his concerns about the disorder. Urge the patient to perform as much self-care as his immobility and pain allow. Use antiembolism stockings, as prescribed, and encourage the patient to move his legs, as allowed. Assess the patient’s pain status and his response to the pain-control regimen. Perform neurovascular checks of the patient’s legs such as color, motion, temperature, and sensation. Monitor vital signs, and check for bowel sounds and abdominal distention. Teach the patient about treatments, which include bed rest and pelvic traction. Urge the patient to maintain an ideal body weight to prevent lordosis caused by obesity. Discuss all prescribed medications with the patient. If surgery is required, explain all preoperative and postoperative procedures and treatments to the patient and his family.