A Biodesigned Nanocomposite Biomaterial for Auricular Cartilage Reconstruction

Current biomaterials for auricular replacement are associated with high rates of infection and extrusion. The development of new auricular biomaterials that mimic the mechanical properties of native tissue and promote desirable cellular interactions may prevent implant failure. A porous 3D nanocomposite scaffold (NS) based on POSS-PCU (polyhedral oligomeric silsesquioxane nanocage into polycarbonate based urea-urethane) is developed with an elastic modulus similar to native ear. In vitro biological interactions on this NS reveal greater protein adsorption, increased fibroblast adhesion, proliferation, and collagen production compared with Medpor (the current synthetic auricular implant). In vivo, the POSS-PCU with larger pores (NS2; 150-250 m) have greater tissue ingrowth (approximate to 5.8x and approximate to 1.4 x increase) than the POSS-PCU with smaller pores (NS1; 100-50 m) and when compared to Medpor (>100 m). The NS2 with the larger pores demonstrates a reduced fibrotic encapsulation compared with NS1 and Medpor (approximate to 4.1x and approximate to 1.6x, respectively; P < 0.05). Porosity also influences the amount of neovascularization within the implants, with no blood vessel observed in NS1 (12 weeks postimplantation). The lack of chronic inflammatory response for all materials may indicate that the elastic modulus and pore size of the implant scaffold could be important design considerations for influencing fibrotic responses to auricular and other soft tissue implants.