| Objective : To investigate the effect of local injection of Staphylococcal Enterotoxin C on the healing of fresh fractures in rats.Methods:In this experiment,60 healthy 6-month-old SD female rats were randomly divided into three groups: group A,B,and C(20 in each group): control group(group A),and saline injection group(group B)and staphylococcal enterotoxin C injection fracture group(group C).After adaptive feeding of rats in each group for 1 week,a fresh fracture model was established by surgery.After modeling,rats in group C were injected with 0.1 ml of staphylococcal enterotoxin C at the fractured end every week from the first week after operation.Group B was injected with the same amount of normal saline at the fractured end at the same time.Group A was not treated.And at the 3rd and 6th weeks after the modeling,X-ray filming,gross specimens and pathological examination of the femoral femur of the rats were taken to observe the changes of bone histology and Density(Bone mineral density,BMD),bone mineral content(BMC)of the rats in each group,and the level of BALP,BMP-2,OCN,TGF-β 1.Results:1.According to the X-ray examination results,at 3 and 6 weeks,all the three groups of rats had different texture of callus formation at the femoral fractures,and the local bone density became higher and higher.At the same time,among the three groups,the bone callus at the fracture of group C is larger than that of the other two groups,and the crawling range is wider.The connectivity of the fracture is better than that of the other two groups;2.By inspection of the general specimens,the rats of group C at3 and 6 weeks,a certain size of callus was formed at the fracture of the femur,a strength of the connection formed at the far and near ends of the fracture,and the size of the callus formed by the femur of the rats in groups A and B at the same time and the strength of the connection at the fracture end less than or weaker than those in group C;3.Pathology shows that at the third week,rats in group C had fewer inflammatory cells than groups A and B.There are more chondrocytes in group C than group A and group B,and more osteoclasts can be seen in group C,indicating that the fracture site of group C has already been in the period of bone callus remodeling At both third week and at the sixth week,the fracture sites of group A and B rats have formation of denser,better connected trabecular bone tissue,with a small amount of inflammatory cells infiltrating and more proliferating cartilage around cells and few primitive bone cells,while the trabecular bone formed at the fracture site of rats in group C has higher in density,better connectivity,less infiltration of inflammatory cells,more chondrocytes proliferation,almost no original bone cell;4.At third week,the average BMD of rats in each group has notshown a significant difference yet;at sixth week,The average BMD in group C is sinigicantly higher than Groups A and B.Within group comparison,there is no significant difference of the BMD in groups A or B,while the BMD within group C has a significant difference,indicating that staphylococcin can significantly increase the amout of BMD at the fracture;5.The level of BALP and BMP-2 at third week in group A were significantly lower than that at the sixth week and also significantly lower than other groups at the same period;thelevel of BALP and BMP-2 at sixthweekin group C was significantly lower than at third week,and also significantly lower than other groups at the same period.6.The serum levels of OCN and TGF-β1 of rats in all three groups at different periods did not show significant statistical difference between groups or within each group.Conclusion: By comparing X-ray examinationresults,gross specimens,pathological results,and local BMD,BMC,and BALP,BMP-2,OCN and TGF-β1levels in the blood of the three groups of rats,we can find that staphylococcal enterotoxin C can significantly increase the bone density of the femoral fracture,and make the femoral fracture healing progress faster in rats than other groups of rats.The early use of local injection of staphylococcal enterotoxin C at the fracture end is beneficial to fracture healing. |
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