Excessive skeletal muscle fibrosis and its correlation of tumor growth factor-.BETA. in rats with traumatic osteomyelitis

Objective To examine excessive fibrosis of the skeletal muscle in rats with traumatic osteomyelitis and its correlation with tumor growth factor-β (TGF-β). Methods Eighty male Wistar rats were randomized into osteomyelitis group (n=40) and control group (n=40), according to the random number table. Rats in osteomyelitis group were subjected to soft tissue injury, intramedullary Kirschner wire fixation and bacterial infection with 102 CFU/ml Staphylococcus aureus. In control group, aseptic normal saline was used instead of bacteria solution. At postoperative 3, 7, 14 and 28 d, muscular tissues surrounding the injury site were harvested to detect histopathologic changes and expression of TGF-β by HE staining and immunohistochemistry. Results HE staining showed more severe pathological changes in osteomyelitis group than in control group, such as inflammation, necrosis and fibroplasia. Positive immunohistochemical staining was detected, but a strong positive staining was recognized within both myocyte and matrix in osteomyelitis group versus only myocyte in control group. At postoperative 3 d, expression of TGF-β was similar between osteomyelitis group (19.4±2.7) and control group (18.6±2.8) (P>0.05) .At postoperative 7, 14 and 28 d, expressions of TGF-β in osteomyelitis group were 25.3±1.9, 28.5±2.7 and 36.0±1.8 respectively, higher than 21.7±2.5, 25.6±1.8 and 34.2±1.6 in control group (P<0.05). After operation, expressions of TGF-βin both groups showed gradual increase and peaked at 28 d. Conclusion Traumatic osteomyelitis can increase skeletal muscle fibrosis and the process is related to the increased expression of TGF-β. Key words: Osteomyelitis; Transforming growth factor beta; Fibrosis