The role of antioxidants-filled HAL delivery system on the fibrous tissue formation using adult rats as a model

Fibrous tissue formation is often used as a screening method to determine biocompatibility of orthopaedic and dental implanted material. In this investigation, porous implants of hydroxyapatitelysine (HAL) delivery devices filled with Vitamin E were implanted intraperitoneally (IP) using adult male rats as a model. The fibrous tissue surrounding the implant was studied histochemically to determine the resorbability rate of the devices. Fibrous capsular tissues were carefully dissected away from the capsule noting the tissue closest to the implanted material. Evaluation of the sections (5 μm, H&E) collected from various areas of the implants (n=5 per group) revealed that: (1) all Vitamin E-HAL capsules were encapsulated with fibrous tissue within seven days post-implantation and the thickness of the fibrous tissue was found to be directly proportional to duration of implantation, (2) the thickness of fibrous tissues collected from IP site were significantly higher (22%±3.4 SD) than those collected from SC site of implantation in another study, (3) vascularity, macrophages, fibroblasts, and plasma cells at the Vitamin E-HAL implant-interface were evident after the first week, and the persistence of these cell types and progressive angiogenesis in subsequent weeks was apparent. The formation of distinct cell layers was remarkable in the ninth week phase, (4) SEM and radiographs analysis of retrieved devices showed a significant (P<0.05) increase in the number of macropores (14 to 46 μm²) in HAL devices implanted SC than the number of macropores in HAL devices implanted IF. These observations confirm our previous finding using different biochemical material (TCPL). In conclusion, the results of this study demonstrate that the site of surgical implantation is an instrumental key in designing HAL delivery system