| Ossification of thoracic ligamentum flavum (OTLF) is a special kind of ectopic ossification most common in low thorax and thoracic-lumbar areas which can cause spinal cord injury by means of narrowing the spinal canal. Compared with other types of thoracic stenosis, OTLF develops more fast and show a worse prognosis. By far, no medication can stop the development of it's pathological changes. And the surgical treatment can not reach satisfied outcomes. Although many researches have been reported on the etiology of Ossification of ligamentum flavum(OLF), it still remains unclear. There are no efficient preventing ways. The previous studies show that the main reasons for poor post-operation results of OTLF patients include incorrect choice of surgical methods, inappropriate operation techniques, delay of diagnosis and the needs of continued operation in OTLF in spine. So how to find the high risk group of OTLF all in good time and its' preventive treatment is the key to the study of the etiology of OTLF.As we know, bone growth factors play important roles in ectopic ossification. Recent researches indicate that transforming growth factor- β1(TGF- β1) play a key role in the pathogenesis of OLF. The process of OLF shows increase of collagen type Ⅱ. TGF- β1 is a polypeptide with many biologic functions, which promotes the synthesis of extracellular matrix(ECM) and angiogenesis, and inhabits ECM catabolism. BMP, hydrophobic acid protein, is the induction of undifferentiated mesenchymal cell into tissue of cartilage and bone, and the ectopic ossification. However, the expression and the effect of TGF- β1 and BMP in ligamentum flavum in OTLF are not clear. So, in order to investigate theproblems we conduct the following experiments: Firstly, we study the morphological changes of elastic fiber and collagen fiber in ligamentum flavum in OTLF by means of histochemistry. Secondly, we carried out the research on the expression of TGF ￡ 1 and Collagen Type II in OTLF by immunohistochemistry. Thirdly, the RT-PCR was used to observe the BMP-2 mRNA expression in OTLF.As results show, two types of ossification, endochondraJ ossification and the fibrous ossification exist in Ligamentum Flavum in OTLF. The expression of Collagen Type II is positive in part of OTLF. There is trabecula bone deriving from the endochondral ossification, some of which turn into the lamellar bone. There is also the fibrous tissue that directly change into the bone by the fibrous ossification metaplasia mode. The expression of the Collagen Type II is positive partly in OTLF, especially in the cytoplasm of fibro-chond-roid cells and the cartilaginous matrix focally. The expression of TGF0 1 is positive in part of fibroblast of OTLF, mainly distributed in cytoplasm. There were expression of the BMP-2 mRNA in both the normal and OTLF, but the intensity has manifest distinction compared with the normal contruce. The expression of the BMP-2 mRNA in OTLF tissue is rather intense.These experimental results suggest that decrease of elastic fiber and increase of collagen fiber are the main reason of the degeneration of the ligament flavum. The ossification modes of the ligament flavam include the endochondral ossification as well as the fibrous ossification metaplasia. The high expression of TGF- & 1 > Collagen Type II and BMP-mRNA in OTLF may play a crucial role in the pathogenesis and development of OTLF. Endougenous BMP-2 may participated in the priming of OTLF and could keep the activity form of the ossification. TGF P 1 may play roles in later ossification process in OTLF. the... |
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