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1.
J Orthop Res ; 24(3): 385-92, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16479572

RESUMEN

The objective of the study was to improve the biological understanding of degenerative disc disease using a rabbit model in which different stages of disc degeneration are induced by variation of the duration of loading with an external compression-device applying 2.4 MPa. Gene expression and protein distribution were analyzed in controls and after 1, 28, and 56 days of hyperphysiologic loading. To evaluate extracellular matrix genes, quantitative real-time reverse-transcriptase polymerase chain reaction was applied for collagen I, collagen II, biglycan, decorin, fibromodulin, fibronectin, aggrecan, and osteonectin. As representatives of catabolic, anticatabolic, and anabolic factors, matrix metalloproteinase-13 (MMP-13), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and bone morphogenetic protein-2 (BMP-2) were chosen. To evaluate protein distribution, immunohistochemistry was performed for collagen I, collagen II, and BMP-2/4. Matrix gene expression was characterized by two major developments: collagen I and II, biglycan, and decorin showed early elevation followed by later downregulation to control levels, whereas fibromodulin, fibronectin, aggrecan, and osteonectin showed continuous upregulation or remained at similar levels. Induction of MMP-13 gene expression was found in degenerated discs. TIMP-1 and BMP-2 were elevated immediately after hyperphysiologic loading and presented highest levels in the 56-day group. Immunohistochemistry showed less collagen II and BMP-2/4 positive cells after compression. In conclusion, elevated matrix gene expression represents an early cellular response to hyperphysiologic loading. As degeneration progresses, some matrix genes increase upregulation, whereas others start downregulation. Continuous upregulation of catabolic, anticatabolic, and anabolic factors indicates their important role in the degeneration process.


Asunto(s)
Proteínas de la Matriz Extracelular/metabolismo , Regulación de la Expresión Génica , Desplazamiento del Disco Intervertebral/metabolismo , Disco Intervertebral/metabolismo , Mecanotransducción Celular/fisiología , Animales , Proteína Morfogenética Ósea 2 , Proteínas Morfogenéticas Óseas/genética , Proteínas Morfogenéticas Óseas/metabolismo , Colágeno/metabolismo , Colagenasas/genética , Colagenasas/metabolismo , Modelos Animales de Enfermedad , Proteínas de la Matriz Extracelular/genética , Femenino , Inmunohistoquímica , Disco Intervertebral/patología , Desplazamiento del Disco Intervertebral/etiología , Desplazamiento del Disco Intervertebral/patología , Metaloproteinasa 13 de la Matriz , ARN Mensajero/análisis , Conejos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estrés Mecánico , Inhibidor Tisular de Metaloproteinasa-1/genética , Inhibidor Tisular de Metaloproteinasa-1/metabolismo , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismo
2.
Spine (Phila Pa 1976) ; 31(15): 1658-65, 2006 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-16816759

RESUMEN

STUDY DESIGN: An animal model of degeneration was used to determine the effects of disc distraction, and was evaluated with magnetic resonance imaging (MRI) as well as gene and protein expression levels. OBJECTIVE: To investigate gene expression and MRI effects of distraction. SUMMARY OF BACKGROUND DATA: Disc degeneration can result from hyper-physiologic loading. Distracted discs with degeneration showed histologic signs of tissue recovery. METHODS: There were 18 rabbits that underwent 28 days of compression (200 N) to induce moderate disc degeneration followed by 28 days of distraction (120 N; attached and loaded distraction device) or sham distraction (attached but unloaded distraction device). Comparison was performed with 56 days of compressed discs without distraction. Quantitative outcome measures were MRI signal intensity and gene expression analysis to determine: messenger ribonucleic acid levels for extracellular matrix genes, including collagen 1, collagen 2, biglycan, decorin, aggrecan, fibromodulin, and osteonectin; and matrix-regulative genes, including matrix metalloproteinase-13, tissue-inhibitor of matrix metalloproteinase-1, and bone morphogenetic protein (BMP)-2. Immunohistology was performed for collagen 2 and BMP-2 to label cells semiquantitatively by staining of the cell-surrounding matrix. RESULTS: A total of 28 days of compression decreased signal intensity. Distraction over the same period reestablished physiologic signal intensity, however, a persistent reduction was found in sham distraction. Distraction resulted in gene expression up-regulation of collagen 1 (5.4-fold), collagen 2 (5.5-fold), biglycan (7.7-fold), and decorin (3.4-fold), while expression of fibromodulin (0.16-fold), tissue-inhibitor of matrix metalloproteinase-1 (0.05-fold), and BMP-2 (0.15-fold) was decreased, as compared with 56 days compression. Distracted discs showed more BMP-2 (19.67 vs. 3.67 in 56 days compression) and collagen 2 (18.67 vs. 11.33 in 56 days compression) positive cells per field. CONCLUSIONS: Distraction results in disc rehydration, stimulated extracellular matrix gene expression, and increased numbers of protein-expressing cells.


Asunto(s)
Perfilación de la Expresión Génica , Desplazamiento del Disco Intervertebral/fisiopatología , Desplazamiento del Disco Intervertebral/cirugía , Procedimientos Ortopédicos/métodos , Regeneración , Animales , Fuerza Compresiva , Descompresión Quirúrgica/instrumentación , Descompresión Quirúrgica/métodos , Modelos Animales de Enfermedad , Fijadores Externos , Proteínas de la Matriz Extracelular/genética , Femenino , Disco Intervertebral/patología , Disco Intervertebral/fisiología , Desplazamiento del Disco Intervertebral/patología , Imagen por Resonancia Magnética , Procedimientos Ortopédicos/instrumentación , Osteogénesis por Distracción , ARN Mensajero/metabolismo , Conejos , Agua/metabolismo , Soporte de Peso
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