Auricular reconstruction using tissue-engineered alloplastic implants for improved clinical outcomes

Background: Alloplastic implants have been used clinically to treat congenital abnormalities and traumatic injuries. However, these implants are often associated with complications, including inflammation, infection, erosion, and dislodgment. To minimize these complications, the authors have developed a system in which tissue-engineered cartilage serves as a shell that entirely covers the implant. This system is designed to improve the structural and functional stability between the implant and recipient tissue. Methods: Chondrocytes isolated from rabbit ear cartilage were expanded in vitro. The cells were mixed with fibrin hydrogel for spray-coating a human ear-shaped implant. The surface of the implant was modified using an oxidizing solution to provide hydrophilic characteristic; thus, the cell-fibrin suspension readily adhered onto the surface of the implants. The engineered cartilage-covered implants were implanted into the dorsal subcutaneous space of athymic mice. Histologic and gross examinations of the implants were performed at 2, 4, 8, and 12 weeks after implantation. Results: None of the engineered cartilage-covered implants showed evidence of skin necrosis, implant exposure, or extrusion (n = 10). However, the control implants developed extensive necrosis following implantation (n = 10). In the experimental group, histologic evaluations showed the formation of neocartilage covering the implants. The presence of sulfated glycosaminoglycans was evident in the engineered cartilage tissue. Conclusions: These results demonstrate that engineered cartilage tissues can be used as a biological cover for an alloplastic implant. This system may improve the structural and functional interactions between the implant and the recipient's tissues and thus enhance the outcome of total auricular reconstruction.