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Objective To study GM / BG sustained release drug delivery system in vivo role of its anti-inflammatory and repair of bone defects role for future prevention and treatment of clinically infected bone defects and provide experimental evidence. Method (1) GM / BG Preparation: The Kawanabe prepared by the method such as GM / BG delivery system. (2) GM / BG vitro drug release experiment: Take four GM / BG, were placed in a small vial, adding PBS solution 3ml, after the incubator at 37 ℃ every two days to replace all the PBS solution. By HPLC measuring the concentration of the eluting solution of gentamicin and depicting GM / BG for release curve. Peppas equation on drug release through curve fitting to discuss GM / BG drug release mechanism. (3) GM / BG Antibacterial experiment: Take two Petri dishes were inoculated with S. aureus, each dish implanted two GM / BG and a BG, then put it in the incubator, 35 ℃ for 24h. Measuring GM / BG and BG bacteriostatic ring, remove the sample is placed in a new medium inoculated with S. aureus cultured. Measured once every three days later bacteriostatic ring and replace the culture medium, this process is repeated until no longer appears bacteriostatic ring so far. Based on the measurement results do bacteriostatic ring size with time curve. (4) GM / BG vivo drug release experiment: Take 6 New Zealand white rabbits, male or female, weighing 2-2.5kg. Making the right proximal radius 10mm rabbit bone defect model, GM / BG implanted into the bone defect site, respectively, and 25 days after surgery 1,3,5,7,10,15,20 rabbit blood drawn to measure blood concentration, while away from the bone at 0.5cm cut soft tissue within the measured area of ??soft tissue graft concentration of the drug. According to the experimental results for the in vivo drug release profile. (5) GM / BG treat bone defects in rabbits infected with experiment: Take 24 New Zealand white rabbits, male or female, weighing 2-2.5kg, were randomly divided into experimental group and control group 12. First made rabbit tibia bone defect infection model, the right of each rabbit medial tibia caused 3 * 5 * 10mm ~ 3 rectangular bone window in the experimental group implanted bone window GM / BG, the control group implanted bone window into BG, bone window was added in each standard Staphylococcus aureus. Rabbits were observed after the general situation; at 4w and 8w X-ray examination, osteomyelitis were observed formation and repair of bone defects; 4w and 8w in each group were sacrificed rabbits, remove the right tibia, gross observation, disease Physical examination and bacterial culture examination. Results (1) GM / BG drug delivery system in vitro release of long-term capacity up to 23 days, and drug concentrations were greater than the minimum inhibitory concentration of gentamicin 2ug/ml. Peppas equation based curve fitting of drug release, indicating that GM / BG drug release followed Fickian diffusion law. (2) GM / BG in vitro inhibition experiments, up to 26 days has antibacterial ring. (3) GM / BG release in vivo experiments, the local tissue drug concentration in the first 20 days, the concentration was 6.53 ± 1.42ug/ml, greater than the minimum inhibitory concentration of gentamycin 2ug/ml, but the blood drug concentration in section 3 day undetectable. (4) GM / BG in the treatment of bone defects in rabbits infected with the experiment, the control group, two rabbits died postoperatively due to severe infection, the experimental group had no one case rabbit died. General observation, postoperative 4w and 8 w drawn, the control group was pus and bone parts inflammatory granulation tissue wrapped bioactive glass is not fused with the surrounding bone tissue, but being immersed in pus; experimental group was implanted bioactive glass gradually degraded, and better integration with the surrounding bone. X-ray examination, after 4w, the control group had periosteal reaction, bone hyperplasia, bone destruction, soft tissue mass and sequestrum, etc.; experimental group bioactive glass density fades gradually absorbed, and bone tissue gradually fused together, blurred; postoperative 8w, the control group showed bone destruction, soft tissue mass, sequestrum, bioactive glass density fades, but together with the surrounding bone tissue fusion; experimental group bioactive glass density further fades absorbed, and bone fusion, boundaries disappear. Pathology, postoperative 4w, the experimental group see a small amount of inflammatory cells, fibrous tissue ingrowth bioactive glass; see infiltration of inflammatory cells in control group and abscess formation, bioactive glass was purulent tissue surrounding the bioactive glass No cells and fibrous tissue ingrowth. Postoperative 8w, experimental group showed bioactive glass absorption, immature callus formation in the control group still visible sequestrum, bioactive glass is wrapped in inflammatory tissue. Bacterial culture test, the experimental results by the chi-square test, the experimental group and the control group in 4w, 8w bacterial culture in the soft tissue and bone marrow cavity positive rate of bacterial culture positive rate on both statistical difference. Cultured bacteria by Gram-positive cocci, and the dish with hemolysis, in line with the characteristics of Staphylococcus aureus, that it is the implantation of S. aureus strains. Conclusions (1) GM / BG has good in vitro sustained release, and there is good antibacterial properties. (2) GM / BG release in vivo with good effect, high local drug concentration, systemic drug concentration is low, topical safer and more effective. (3) GM / BG delivery system with anti-infection and repair of bone defects role for the prevention and treatment of clinically infected bone defects and provide experimental evidence.
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