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PubMed2003

Transplantation of mesenchymal stem cells embedded in Atelocollagen gel to the intervertebral disc: a potential therapeutic model for disc degeneration.

Intervertebral disc degeneration is considered to be one of the major causes of low back pain. Despite this irreversible phenomenon, attempts to decelerate disc degeneration using various techniques have been reported. However, to date there has been no proven technique effective for broad clinical application. Based on previous studies, we hypothesize that maintenance of proteoglycan content in the disc is achieved by avoiding the depletion of nucleus pulposus and preserving the structure of the annulus is a primary factor in decelerating disc degeneration. One novel approach to solve the dilemma of intervertebral disc degeneration is found at the stem cell level. Mesenchymal stem cells (MSCs) are known to possess the ability to differentiate into various kinds of cells from mesenchymal origin. Although the majority of cells that contribute to disc formation are known to obtain chondrocyte-like phenotypes, no reported study has emphasized the correlation with mesenchymal stem cells. To evaluate the possible potential of MSCs in disc cell research and treatment of degenerative disc disease, autologous MSCs embedded in Atelocollagen gel were transplanted into the discs of rabbits which had undergone a procedure proven to induce degeneration. The results suggest that MSC transplantation is effective in decelerating disc degeneration in experimental models and provided new hopes for treatment of degenerative disc disease in humans. Atelocollagen gel served as an important carrier of MSCs in transplantation, permitting proliferation, matrix synthesis and differentiation of MSCs. This study strengthens the viable efficacy of practical application of MSCs in treatment of intervertebral disc disease.

Animals↗
PubMed2006

Human intervertebral disc cells promote nerve growth over substrata of human intervertebral disc aggrecan.

STUDY DESIGN: Coculture assays of the migration and interaction of human intervertebral disc cells and chick sensory nerves on alternate substrata of collagen and aggrecan. OBJECTIVE: To examine the effects of aggrecan on disc cell migration, how disc cells and sensory nerves interact, and whether disc cells affect previously reported inhibitory effects of aggrecan on sensory nerve growth. SUMMARY OF BACKGROUND DATA: Human intervertebral disc aggrecan is inhibitory to sensory nerve growth in vitro, suggesting that a loss of aggrecan from the disc may have a role in the increased innervation seen in disc degeneration. Endothelial cells that appear to co-migrate with nerves into degenerated intervertebral disc express neurotrophic factors, but the effects of disc cells on nerve growth are not known. METHODS: Human disc cells were seeded onto tissue culture plates that had been coated with type I collagen and human intervertebral disc aggrecan. Explants of chick dorsal root ganglions (DRGs) were subsequently added to the plates and sensory neurite outgrowth stimulated by the addition of nerve growth factor. Time-lapse video and fluorescence microscopy were used to examine the migration and interaction of the disc cells and sensory neurites, in the context of the different matrix substrata. The effects of disc cell conditioned medium on nerve growth were also examined. RESULTS: Disc cells spread and migrated on collagen until they encountered the aggrecan substrata, where some cells, but not all, were repelled. In coculture, DRG neurites extended onto the collagen/disc cells until they encountered the aggrecan, where, like the disc cells, many were repelled. However, in the presence of disc cells, some neurites were able to cross onto this normally inhibitory substratum. The number of neurite crossings onto aggrecan correlated significantly with the number of disc cells present on the aggrecan. In control experiments using DRG alone, all extending neurites were repelled at the collagen/aggrecan border. Conditioned medium from disc cell cultures stimulated DRG neurite outgrowth on collagen but did not increase neurite crossing onto aggrecan substrata. CONCLUSIONS: Human disc cells migrate across aggrecan substrata that are repellent to sensory DRG neurites. Disc cells synthesize neurotrophic factors in vitro that promote neurite outgrowth. Furthermore, the presence of disc cells in coculture with DRG partially abrogates the inhibitory effects of aggrecan on nerve growth. These findings have important implications for the regulation of nerve growth into the intervertebral disc, but whether disc cells promote nerve growth in vivo remains to be determined.

Aggrecans↗
PubMed1988

Analysis of rabbit intervertebral disc physiology based on water metabolism. II. Changes in normal intervertebral discs under axial vibratory load.

Metabolic changes induced by axial vibratory load to the spine were investigated based on water metabolism in normal intervertebral discs of rabbits with or without pentobarbital anesthesia. Tritiated water concentration in the intervertebral discs of unanesthetized rabbits was reduced remarkably by axial vibration for 30 minutes using the vibration machine developed for this study. Repeated vibratory load for 18 and 42 hours duration showed the recovery of 3H2O concentration of the intervertebral disc without anesthesia. Computer simulation suggested a reduction of blood flow surrounding the intervertebral disc following the vibration stress. However, no reduction of the 3H2O concentration in the intervertebral disc was noted under anesthesia. Emotional stress cannot be excluded as a factor in water metabolism in the intervertebral disc.

Animals↗
PubMed1999

An allele of COL9A2 associated with intervertebral disc disease.

Intervertebral disc disease is one of the most common musculoskeletal disorders. A number of environmental and anthropometric risk factors may contribute to it, and recent reports have suggested the importance of genetic factors as well. The COL9A2 gene, which codes for one of the polypeptide chains of collagen IX that is expressed in the intervertebral disc, was screened for sequence variations in individuals with intervertebral disc disease. The analysis identified a putative disease-causing sequence variation that converted a codon for glutamine to one for tryptophan in six out of the 157 individuals but in none of 174 controls. The tryptophan allele cosegregated with the disease phenotype in the four families studied, giving a lod score (logarithm of odds ratio) for linkage of 4.5, and subsequent linkage disequilibrium analysis conditional on linkage gave an additional lod score of 7.1.

Adult↗
PubMedDate not supplied

Intraoperative problems associated with intervertebral disc disease.

Intervertebral disc disease in the dog is a common problem in veterinary medicine. The clinician must understand the pathophysiology of disc extrusions so the owner can be informed properly when medical versus surgical treatment is indicated. Intervertebral disc surgery requires the same preoperative considerations as any other surgery would: knowledge of regional anatomy, proper equipment, and good surgical techniques and tissue handling. The spinal cord is an unforgiving structure, forcing the surgeon to understand and to avoid intraoperative complications. Some complications are inevitable. Recognizing these complications early and resolving them quickly will help ease early recovery of neurologic function.

Animals↗
PubMed2006

Biologic modification of animal models of intervertebral disc degeneration.

Intervertebral disc degeneration is a chronic process that can become manifest in clinical disorders such as idiopathic low back pain, sciatica, disc herniation, spinal stenosis, and myelopathy. The limited available treatment options (including discectomy and spinal fusion) for these and other disabling conditions that arise from intervertebral disc degeneration are highly invasive, achieve limited success, and only address acute symptoms while doing nothing to halt the process of degeneration. Although the precise pathophysiology of intervertebral disc degeneration has yet to be clearly delineated, the progressive decline in aggrecan, the primary proteoglycan of the nucleus pulposus, appears to be a final common pathway. Animal models as well as in vitro studies of the process of disc degeneration have yielded many potentially useful targets for the reversal of disc degeneration. One current research trend is the use of established animal models of disc degeneration to study the role of therapeutic modalities in reversing the process of degeneration, often with use of the delivery of genes or gene products that influence the anabolic and catabolic pathways of the disc. This article reviews the ability of gene-product delivery systems and gene therapy to alter biologic processes in animal models of disc degeneration and examines future trends in this field.

Animals↗
PubMed1993

The use of coccygeal discs to study intervertebral disc metabolism.

There have been very few studies on the metabolism of the intervertebral disc. One possible reason is that lumbar discs suitable for in vitro synthesis studies are difficult to obtain. We have examined some properties of coccygeal discs to see if those discs are a suitable alternative. The properties measured appear similar to those of lumbar discs, with collagen content lowest in the nucleus and highest in the outer annulus, while hydration and glycosaminoglycan content were highest in the nucleus and of a similar level to those of canine lumbar discs (approximately 83% water). The discs were under mechanical load in vivo, resulting in an equilibrium swelling pressure of 0.25-0.3 MPa. The 35S-sulphate incorporation rate was 2-5 x 10(-5) mmol/g dry weight per hour in the inner annulus and nucleus, in comparison with 2-3 x 10(-5) mmol/g dry weight per hour in rabbit and canine lumbar discs. Coccygeal discs are a readily obtainable and cheap source of disc material, and they are easy to dissect out. Since the general properties of these discs are similar to those of lumbar discs, we suggest that they are a suitable model for the study of the metabolic and other properties of lumbar discs.

Animals↗
PubMed2000

Human intervertebral disc cells are genetically modifiable by adenovirus-mediated gene transfer: implications for the clinical management of intervertebral disc disorders.

STUDY DESIGN: Human intervertebral disc cells were cultured in monolayer and treated with adenovirus-containing marker genes to determine the susceptibility of the cells to adenovirus-mediated gene transfer. OBJECTIVES: To test the efficacy of the adenovirus-mediated gene transfer technique for transferring exogenous genes to human intervertebral disc cells in vitro. SUMMARY OF BACKGROUND DATA: Upregulated proteoglycan synthesis after direct in vivo adenovirus-mediated transfer of growth factor genes to the rabbit intervertebral disc has previously been reported. Before contemplating extending this approach to the treatment of human disc disease, it is necessary to demonstrate that human intervertebral disc cells are indeed susceptible to adenovirus-mediated gene transduction. METHODS: Human intervertebral disc cells were isolated from disc tissue obtained from 15 patients during surgical disc procedures. The cells were cultured in monolayer and treated with saline containing five different doses of adenovirus carrying the lacZ gene (Ad/CMV-lacZ), saline containing adenovirus carrying the luciferase gene (Ad/CMV-luciferase), or saline alone. Transgene expression was analyzed by 5-bromo-4-chloro-3-indolyl-beta-galactosidase (X-Gal) staining and luciferase assay. RESULTS: Adenovirus efficiently transferred lacZ and luciferase marker genes to cells from degenerated discs as well as to cells from nondegenerated discs. A minimum dose of 150 MOI Ad/CMV-lacZ was found to be sufficient to achieve transduction of approximately 100% of disc cells-regardless of patient age, sex, surgical indication, disc level, and degeneration grade. No statistically significant difference in the luciferase activities could be detected in disc cell cultures from degenerated and nondegenerated discs treated with Ad/CMV-luciferase. CONCLUSIONS: In vitro transducibility of human intervertebral disc cells by adenovirus is relatively insensitive to disc degeneration grade. Because the rate-limiting step for successful gene therapy is the ability to transfer genes efficiently to the target tissue, the achievement of efficient gene transfer to human intervertebral disc cells(using a direct, adenovirus-mediated approach) is an important and necessary step in the development of gene therapy strategies for the management of human intervertebral disc disorders.

Adenoviridae↗
PubMed2006

Histology and pathology of the human intervertebral disc.

The intervertebral disc is a highly organized matrix laid down by relatively few cells in a specific manner. The central gelatinous nucleus pulposus is contained within the more collagenous anulus fibrosus laterally and the cartilage end plates inferiorly and superiorly. The anulus consists of concentric rings or lamellae, with fibers in the outer lamellae continuing into the longitudinal ligaments and vertebral bodies. This arrangement allows the discs to facilitate movement and flexibility within what would be an otherwise rigid spine. At birth, the human disc has some vascular supply within both the cartilage end plates and the anulus fibrosus, but these vessels soon recede, leaving the disc with little direct blood supply in the healthy adult. With increasing age, water is lost from the matrix, and the proteoglycan content also changes and diminishes. The disc-particularly the nucleus-becomes less gelatinous and more fibrous, and cracks and fissures eventually form. More blood vessels begin to grow into the disc from the outer areas of the anulus. There is an increase in cell proliferation and formation of cell clusters as well as an increase in cell death. The cartilage end plate undergoes thinning, altered cell density, formation of fissures, and sclerosis of the subchondral bone. These changes are similar to those seen in degenerative disc disease, causing discussion as to whether aging and degeneration are separate processes or the same process occurring over a different timescale. Additional disorders involving the intervertebral disc can demonstrate other changes in morphology. Discs from patients with spinal deformities such as scoliosis have ectopic calcification in the cartilage end plate and sometimes in the disc itself. Cells in these discs and cells from patients with spondylolisthesis have been found to have very long cell processes. Cells in herniated discs appear to have a higher degree of cellular senescence than cells in nonherniated discs and produce a greater abundance of matrix metalloproteinases. The role that abnormalities play in the etiopathogenesis of different disorders is not always clear. Disorders may be caused by a genetic predisposition or a tissue response to an insult or altered mechanical environment. Whatever the initial cause, a change in the morphology of the tissue is likely to alter the physiologic and mechanical functioning of the tissue.

Adolescent↗
PubMed1995

Development and degeneration of the intervertebral discs.

The intervertebral discs undergo profound changes in structure and composition during development and aging. They also degenerate much earlier than other cartilaginous tissues, and in severe cases may lose function completely. The reasons for this early degeneration are unknown, but external factors, such as mechanical overload on the spine, or smoking, may be involved. However, recent work has revived interest in the importance of genetic and developmental influences on the intervertebral discs.

Aging↗
PubMed1975

Three-dimensional observation of collagen framework of lumbar intervertebral discs.

Lumbar intervertebral discs obtained from rats, dogs and humans were examined by scanning electron microscopy. The nucleus pulposus was constructed of a loose network of fine fibrils and formed lamellated membranes in the peripheral areas. The annulus fibrosus was composed of concentric lamellae of fibrous bundles that ran uniformly in each lamella and crossed over to the bundles of adjoining lamellae. The lamellae were made of fine fibrils measuring 0.1-0.2 mu in diameter, corresponding to matured collagen fibrils. The cartilage plate consisted of a close meshwork of collagen fibrils which interconnected with the annular fibrils. From these results, it was concluded that the intervertebral disc was well developed for shock absorption at the light microscopic and ultrastructural levels. In specimens treated with chymotrypsin, the extra-fibrillar substances were easily digested in the nucleus, as well as in the annulus. The intervertebral disc may thus be easily affected by chemical agents.

Animals↗
PubMed2005

Effects of controlled dynamic disc distraction on degenerated intervertebral discs: an in vivo study on the rabbit lumbar spine model.

STUDY DESIGN: An in vivo study on the rabbit lumbar spine model. OBJECTIVES: Effects of temporary dynamic distraction on intervertebral discs were studied on the lumbar spine rabbit model to characterize the changes associated with disc distraction and to evaluate feasibility of temporary disc distraction to previously compressed discs in order to stimulate disc regeneration. SUMMARY OF BACKGROUND DATA: Studies have shown that accelerated degeneration of the intervertebral disc results from altered mechanical loading conditions. The development of methods for the prevention of disc degeneration and the restoration of disc tissue that has already degenerated are needed. METHODS: New Zealand white rabbits (n = 32) were used for this study. The rabbits were randomly assigned to one of five groups. In 12 animals, the discs were first loaded for 28 days using a custom-made external loading device to stimulate disc degeneration. After 28 days loading time, the discs in six animals were distracted for 7 days and in six animals for 28 days using the same external device, however, modified as dynamic distraction device. In six animals, the discs were distracted for 28 days without previous loading; and in six animals, the discs were loaded for 28 days and afterwards the loading device removed for 28 days for recovery without distraction. Six animals were sham operated. The external device was situated; however, the discs remained undistracted and they also served as controls. After 28 to 56 days loading and distraction time, the animals were killed and the lumbar spine was harvested for examination. Disc height, disc morphology, cell viability, relative neutral zone, and tangent modulus were measured. RESULTS: After 28 days of loading, the discs demonstrated a significant decrease in disc space. Histologically, disorganization of the architecture of the anulus occurred. The number of dead cells increased significantly in the anulus and cartilage endplate. These changes were reversible after 28 days of distraction. The disc thickness increased significantly as compared with the specimens from the 28 days loading group without distraction. Histologically, the discs showed signs of tissue regeneration after 28 days of distraction. The number of dead cells decreased significantly in comparison with the loaded discs without distraction. The flexibility of compressed discs was higher than of compressed/distracted discs. CONCLUSIONS: The results of this study suggest that disc regeneration can be induced by axial dynamic distraction in the rabbit intervertebral disc. The decompressed rabbit intervertebral discs showed signs of tissue recovery on a biologic, cellular, and a biomechanical level after 28 days of distraction.

Animals↗
PubMed1988

Analysis of rabbit intervertebral disc physiology based on water metabolism. I. Factors influencing metabolism of the normal intervertebral discs.

Basic factors influencing the metabolism of intervertebral discs of rabbits were quantitatively analyzed based on the water metabolism. The blood flow surrounding the intervertebral disc was calculated using pharmacokinetic concepts from the data obtained by time-related tritiated water distribution analyses. The blood flow was estimated as 0.056 (mg/min/mg tissue) in the anterior annulus, 0.106 in the posterior annulus, 0.120 in the lateral annulus, and 0.084 in the nucleus pulposus, respectively (Experiment 1). Water content and fixed charge density in the intervertebral disc fractions also were measured (Experiment 2). The cations and uncharged small solutes transported into the disc tissue ranged in descending order from nucleus pulposus, lateral annulus, posterior annulus, to anterior annulus. The authors also calculated theoretically the swelling pressure of the proteoglycan in the intervertebral disc fractions from the results of Experiment 2. It was concluded that swelling pressure was highest in the nucleus pulposus, and lowest in the anterior annulus. The water in the posterior annulus is less exchangeable than in the other disc tissue fractions.

Animals↗