Immunohistochemical detection of cytokine expression in tissue-implant response associated with TCP bioceramic implants loaded with steroid hormones.

Recent studies in our laboratory have demonstrated the need for an experiment comparing cytokine expression in fibrous tissue capsules surrounding tricalcium phosphate (TCP) bioceramics loaded with androstenedione, dihydrotestosterone, and testosterone to that of a control to further elucidate the mechanisms involved in the tissue-implant response. The effect of steroid hormones on inflammatory cells has been widely reported in the scientific literature. The purpose of this research is to contribute to the development of a long-term ceramic drug delivery system with human and veterinary applications. This study contributes information on the presence of cytokines in fibrous tissue capsules surrounding hormone loaded TCP bioceramic implants at 90 days post-implantation. Sixteen animals in four experimental groups were implanted with one TCP bioceramic each. Group I animals were implanted with a sham TCP ceramic not containing a steroid hormone (control group). Group II animals received the testosterone loaded TCP ceramic. Group III animals were implanted with the dihydrotestosterone loaded ceramic. Group IV animals received the androstenedione ceramic. At 90 days post-implantation, the animals were euthanized. The implants and fibrous tissue capsules surrounding them were then extracted. The fibrous tissue capsules were evaluated microscopically following routine H&E staining and IHC staining of antibodies to IL-1 beta, Il-2, IL-6, TNF infinity, and cell specific markers for CD-4 and CD14 positive cells. The results of this study indicate that these hormones, particularly androstenedione, limit the expression of cytokines and greatly affect the cellular composition of the tissue-implant response.