Human conchal cartilage and temporal fascia: an evidence-based roadmap from rhinoplasty to an in vivo study and beyond.

Conchal cartilage or cartilage/ temporal fascia composite grafting (DC-F) used for rhinoplasty is applied by plastic surgeons for reconstructive purposes. Previous studies on experimental models such as mice or rabbits have elucidated on the late events following grafting, with tissue specimens being harvested two months after implantation. Early microscopic and molecular events following DC-F grafting are completely unknown. We designed a chick embryo chorioallantoic membrane model for human grafts study, regarding the dynamic observation of graft survival and its mutual interrelation with the chick embryo chorioallantoic membrane microenvironment. The DC-F graft preserved its cartilage component in a normal state compared to cartilage graft-only because of protective factors provided by temporal fascia. Its strong adherence to the cartilage, lack of angiogenic factors and high content of collagen IV-derived fragments with anti-angiogenic effects make the temporal fascia a good protective tissue to prevent implanted cartilage degeneration. The cartilage graft produced high inflammation, stromal fibrosis and activated angiogenic cascade through VEGF-mediated pathways followed by cartilage degeneration. Also, high content of podoplanin from conchal cartilage chondrocytes exerted a major role in inflammation accompanying cartilage graft. The presently employed experimental model allowed us to characterize the early histological and molecular events triggered by temporal fascia, cartilage or composite graft DC-F implanted on chick embryo chorioallantoic membrane. Our microscopic and molecular observations may help explain some post-surgical complications generated after using cartilage alone as biomaterial for nasal augmentation, supporting the use of DC-F composite graft, with the aim to reduce unwanted post-surgical events.