A Study For Immunological Evaluation On The Inflammation Induced By Biomaterials

Objective: Biomaterials are playing important roles in the aspect of substituting for tissue or organ, which could also enhance its function, and the biocompatibility is the key factor for the biomaterials' study. With the application of the biomaterials, its evaluation level is increased from "acceptable" to "safe to use", so a great deal of study is being concentrated in how to set up a set of high efficiency, sensitive, exact and secure evaluation system. The researchers gradually know that the reciprocity between immune system and biomaterials is important, and the inflammation is also an emphasis, which can reflect the reaction of the body and biomaterials. But at present, the immunological standards and guides have not been publicized. So, in this study we selected the cytokines, chemokines, circulating immune complex and hemolysin as the object, and study immunological evaluation on the inflammation induced by biomaterials at the molecular level.Materials and methods: The positive control material, Polyvinyl chloride (PVC), which contained 8 % organic tin and the test materials, including American NPG alloy, β-Tricalcium Phosphate (8-TCP), Calcium Phosphate Cement (CPC), Poly-Lactic-co-Glycolic acid (PLGA) and Polytetrafluoroethylene (PTFE) were implanted into each group at the dorsal region. Meanwhile, all the materials' extracts were made, that contacted the rat peritoneal macrophages and the human umbilical vein endothelial cells ECV-304, and then performs the experiment listed below:(1) The rat serum was gotten after the materials implanted within 7d, 14d, 21d, 30d and serum before the implantation was applied as the self-control, then Sandwich ELISA was used to determinate the TNF-a and IL-1β both in the serum and macrophages. RT-PCR was used to compare the expression of TNF-a and IL-1β at the mRNA level.(2) MCP-1 of the ECV-304, which contacted with materials, was also determinated by RT-PCR.(3) PEG sedimentation and calculating HC50 were used to determinate the circulating immune complex and hemolysin of the rat serum which were gotten atdifferent time.Result:(1) At the protein and mRNA level, cytokines expression of the PTFE group contacted with macrophages were high (p<0.001); PLGA and NPG group have a moderate expression (p<0.01), B-TCP and CPC group have almost no expression of cytokines at the protein level, but compared with negative control, cytokines expression of both 8-TCP and CPC group has distinct difference at mRNA level. The results in vivo indicate that cytokines expression of different groups reach the peak value at the 14d after implantation, compared with self-control, the difference is also obvious (p<0.001); and at this time compared with blank-control, NPG group has a high cytokines expression (p<0.001), PTFE and PLGA group have a moderate expression (p<0.01), but the influence on cytokines of 8-TCP and CPC is the least (p<0.05).(2) When both cytokines and biomaterials induced the endothelial cells, PTFE, PLGA and NPG group have a high MCP-1 expression (p<0.001), 8-TCP and CPC group have also distinct difference compared with negative control (p<0.01).(3) The CIC and hemolysin of NPG group reach the peak value at the 7d after implantation, they have distinct difference compared with control (p<0.01), but CIC t and hemolysin of the other groups reach the peak value at the 14d after implantation, PTFE influence CIC and hemolysin furthest (p<0.001), PLGA influence that secondly (p<0.01); but the variety of CIC and hemolysin induced by 8-TCP and CPC is the least (p<0.05).Conclusion:(1) The expression of TNF-a, IL-18, MCP-1, and variety of the circulating immune complex and hemolysin all play significant roles in immune reaction induced by biomaterials; furthermore they have a close relationship with biocompatibility of biomaterials.(2) Not only the protein and molecular level, but also in vivo and in vitro, all the methods which test TNF-a or IL-18 have the relativity. Furthermore, a good correlationship was found between the expression of TNF-a and IL-18.(3) The biomateri...