[Comparative evaluation of TNF-alpha induction in vitro and in local tissue reaction after implantation of HAP/TCP and HAP].

The aim of this work was the evaluation of biocompatibility and bioactivity of HAP/TCP as compared to HAP. This evaluation was carried out by the in vitro assessment of the induction of TNF-alpha in the rat blood after the contact with the tested HAP. The anther target was to investigate of local muscle tissue reaction of rats bones reaction of rabbits, after the implantation of tested materials. The level of TNF-alpha was estimated by biological method in the supernatants of rat blood cell cultures stimulated in vitro by tested materials. The implantation assessment was carried out on 25 rats and 15 rabbits. The muscle tissue reaction was evaluated after 2, 4, 8, 12, and 24 weeks, while the reaction of bones after 4, 12, and 26 weeks since the implantation. The level of TNF-alpha in the blood after stimulation in vitro with HAP/TCP was on the same level as control group. The implantation of HAP the level of TNF-alpha was twice as high as compared to HAP/TCP and control groups. These differences were of statically importance. The muscle tissue reaction after implantation of HAP/TCP was characterized by moderate inflammation during the early period which lead to the formation of two layer connective tissue capsule. In the capsule wall there were great cells of foreign body type and macrophages. In the cytoplasm of some the cells particles of HAP were noted, what could be regarded as the proof of its resorption. In the bone tissue surrounded HAP/TCP implants the stronger osteoconductive proprieties were observed as compared to the tissue around HAP.