Development Of Hdpe Control Material For Muscle Implantation Test

To use the proper reference material in the biological evaluation of biomaterial hassome advantages. The use of reference material (RM) as experimental controls helps instandardization of these methods and making the results traceable.Another use of RM isround robin tests employed for inter laboratory comparisons between differentlaboratories. They are also used to identify technical errors during biomaterials research.Many efforts have been intiated aroud the globe to develop RM for a series of biologicaltests since1977and some achievements were made.But unfortunately, this field in ourcountry is almost vacant.Implantation tests shall be used to assess the local pathological effects on livingtissue, at both the gross level and microscopic level, of a sample of a material or finalproduct that is surgically implanted or placed in an implant site or tissue appropriate tothe intended application. It is important to use proper RM in implantation test. Since theRM recommended by the ISO10993-12is expensive and not easy to get, it is urgent todevelop our own RM.Negative rererence material for muscle implantation was developed in this project.High density polyethylene granules were used as the raw material for preparingimplantation reference material. Implants of a width of diameter1mm with a length ofapproximately10mm were made by the injection moulding way from them. Thereference material should have rounded edges and the ends finished to a full radius.Ethylene oxide sterilization and packing were carried out after that procedure. Then thesize, struxture, surface feature, the content of heavy metals and the residue of Ethyleneoxide were tested and the result showed that the reference material meet the requirementof the implantation test. We also carried out the homogenicity test and stability test.Neither of the tests could screened out this reference materialThe MTT assay was used to evaluate the cytotoxicity of the HDPE referencematerial.The result of the test showed that the cytotoxicity response of the HDPEreference material was ranked1.The implants were inserted in the paravertebral musclesof the rabbits. Four reference materials (HDPE reference material from Japan) and four samples (HDPE reference material made by our research team) were implanted in the leftand right paravertebral muscles respectively. Five animals were used for eachimplantation period. The animals were sacrificed at week1,2，4,12,26,52aftersurgery.Then evaluate the histological responses according to the Semi-quantitativescoring system of ISO10993-6:2007. The results show that there was no significantdifference between the control group and the sample group in histological responses afterimplantation. Besides, the analysis of the retrieval of the reference material afterimplantation revealed that the structure and the surface feature of it has no obviouschanges in the implantation period.To sum up, the reference material made by us was homogeneous, stable, nontoxicand showed similar response to the RM from Japan. So it is possible to develop it asnegative reference material for muscle implantation.It is possible to develop it as implantation reference material since it provednegative results stably.