Preliminary Investigate The Appropriate Concentration Gradient Of NGF To Promote Fracture Healing

Objective:To study the effect of local application of different concentrations of NGF on fracture healing, and further search for the appropriate concentration gradient of NGF on fracture healing.Methods:seventy-five adult male S-D rats(weighing 220±2.5g)were made tibia fractur model under the right tibia nodules 1 cm and randomly divided into five groups(groups A,B, C,D and E,n=15).Fracture was treated with different concentration NGF (0.00648×10-2,0.0324×10-2,0.162×10-2和0.81×10-2μg/g) in groups A,B,C and D,and the same amount of normal saline in groups E,respectively. After 2 weeks,4 weeks and 6 weeks,the specimens were selected 5 rats from each group to do the biochemical and histological analysis。Before the rat was killed,the arteriovenous blood was taken from their eye-ball to test the ALP activity.Results:After 2,4 and 6 weeks, the gross observation showed that the size and hardness of bone tissue,and callus tissue growth increased in groups A,B,C and D order,and those in group D were higher than in group A,B,C and E; the X-ray films showed that the calcified area increased in groups A,B,C and D order, and the calcified area in group D was higher than those in group A,B,C and E; the histological observation showed that the trabecular quality and maturity in group D was better than group A,B,C and E. The 4 and 6 weeks'gray degree varadiographs in callus tissue and calcium content of callus tissue, the 2 and 4 weeks'net weigh of callus tissue and the 2 weeks'ALP contents of serum in group D were higher than groups A,B,C and E.There were significant differences(P<0.05) in gray degree values of the radiographs and calcium content of callus tissue at 4 and 6 weeks, in net weigh of callus at 2 and 4 weeks and in ALP contents of serum at 2 weeks between group D and groups A,B,C and E. At 2 and 4 weeks,the trabecula surface index of osteoblast (IBO),the average trabecular volume(TV) and the mean trabecular width(TW) decreased as time went on; at the same time point the group A, B, C and D in turn increased, and were higher than the group E. The group D were the highest at each time point.there were significant differences (P<0.05) in IBO,TV and TW between group D and groups A,B,C and E at 2 and 4 weeks.Conclusion:The local application of nerve growth factor (NGF) can promote fracture healing. The high concentration gradient of NGF (0.81×10-2μg/ g) had a significant role on fracture healing. So it is the appropriate concentration gradient in this experiment.