Development and progression of immobilization-induced skin fibrosis through overexpression of transforming growth factor-ß1 and hypoxic conditions in a rat knee joint contracture model

ABSTRACTPurpose: The purpose of this study was to investigate the pathology and mechanism of immobilization-induced skin fibrosis in a rat joint contracture model. Methods: Rats were randomly divided into control and immobilization groups. In the immobilization groups, knee joints of the rats were immobilized for 1, 2, and 4 weeks. After each immobilization, skin was dissected. To assess fibrosis in the skin, the thickness and area of adipocytes and connective tissue fibers were measured. Myofibroblasts were analyzed by immunohistochemistry by using anti-α-SMA as a marker. Gene expression levels of type I and III collagen, TGF-s1, and HIF-1α were measured by using RT-PCR. Results: One week after immobilization, there was a marked increase in the area of connective tissue fibers in the immobilization group. Type I and type III collagen were significantly increased with prolonged immobilization. Higher numbers of α-SMA-positive cells were noted in the immobilized group at 2 and 4 weeks after immobilization....