Introduction. Major trauma during military conflicts involve heavily contaminated open fractures. Staphylococcus aureus (S. aureus) commonly causes infection within a protective biofilm. Lactoferrin (Lf), a natural milk glycoprotein, chelates iron and releases bacteria from biofilms, complimenting antibiotics. This research developed a periprosthetic biofilm infection model in rodents to test an Lf based lavage/sustained local release formulation embedded in Stimulin beads. Method. Surgery was performed on adult rats and received systemic Flucloxacillin (Flu). The craniomedial tibia was exposed, drilled, then inoculated with S. aureus biofilm. A metal pin was placed within the medullary cavity and treatments conducted. Lf in lavage solutions: The defect was subject to 2× 50 mL lavage with 4 treatment groups (saline only, Lf only, Bactisure with Lf, Bactisure with saline). Lf embedded in Stimulin beads: 4 bead types were introduced (Stimulin only, Lf only, Flu only, Lf with Flu). At day 7, rats are processed for bioluminescent and X-ray imaging, and tibial explants/pins collected for bacterial enumeration (CFU). Results. Rats without treatments established a mean infection of 2×106 CFU/tibia. 4 treatment groups with a day 0, one-off lavage demonstrated >95% reduction in bacterial load 7 days post-op, with a reduction in CFU from 1×106/tibia down to 1×104/tibia. There was no statistically significant difference between each group (p = 0.55 with one way ANOVA). The stimulin bead experiments are ongoing and complete results will be obtained in the end of July. Conclusions. This research demonstrated a clinically relevant animal model of implanted metalware that establishes infection. No additional benefit was observed with a one-off, adjuvant Lf lavage during the initial decontamination of the surgical wound, compared with saline alone, and in combination with the antiseptic Bactisure. This animal model provides the foundation for
Chondrosarcoma responds poorly to adjuvant therapy and therefore, new targeted therapy is required. Animal models have been utilised to test therapeutic candidates, however clinically relevant, orthotopic models are lacking. The aim of this study was to develop such a model. In vitro: two human chondrosarcoma cell lines, JJ012 and FS090, were compared with respect to proliferation, colony formation, invasion, MMP-2 and MMP-9 secretion, osteoclastogenesis, endothelial tube stimulation, and expression of the angiogenic factor VEGF, and the anti-angiogenic factor RECK on western blotting. In vivo: 20,000 cells (JJ012 or FS090) were injected either into the intramedullary canal of the mouse tibia (n=5 for each cell line), or into the tibial periosteum (n=5 for each cell line). Animals were measured, and x-rayed weekly. Once euthanised, tibias and lungs were preserved, embedded and sectioned to determine the presence of tumour and lung metastases. In vitro: compared with FS090, JJ012 demonstrated significantly higher proliferative capacity at both day two and day four (p=0.017, and p=0.01). JJ012 had a significantly greater ability to invade Matrigel with an average number of 812.5 invading cells, versus 140.8 FS090 cells (p=0.0005). JJ012 readily formed colonies in collagen I, while FS090 formed none. JJ012 conditioned medium stimulated endothelial tube formation and osteoclastogenesis with a greater potency than FS090 conditioned medium. In vivo: tumours formed in the intratibial and periosteal groups injected with JJ012, whilst no mice injected with FS090 cells developed discernable tumours on physical inspection, caliper measurement or histological section. Periosteal tumours grew to three times the non-injected limb size by seven weeks, whereas intratibial injected limbs required 10 weeks to achieve the same extent of tumour growth. All JJ012 periosteal tumours resulted in lung micrometastases, while only 2/4 JJ012 intratibial tumours demonstrated metastases. Lung metastases stained positive with Von Kossa and alizarin red stains, indicating a tendency for calcification, which is similar to metastases in the human disease. Sectioned tumour tissue demonstrated features of grade II-III chondrosarcoma. Similarities with the human disease were also noted on the X-ray, including endosteal scalloping, and cortical thickening. Both intratibial and periosteal JJ012 models replicate the site, morphology, and many behavioural characteristics of human chondrosarcoma. Local tumour invasion of bone and spontaneous lung metastasis offer valuable assessment tools to test the potential of novel agents for
