Modular assembly of human auricular chondrocyte-derived microtissues for ear cartilage tissue engineering

Existing grafts for reconstructing deformed human auricles, primarily autologous rib cartilage graft and synthetic Medpor implant, have significant drawbacks. Tissue engineering approaches offer hope in developing better human ear grafts but existing attempts exhibit limitations including heterogeneous cell densities and stiff material properties. Here, we report a fully biologically grown ear graft with customizable complex geometry and native ear cartilage-mimicking auricular cartilage quality, compositional and mechanical properties. Specifically, the cell aggregate and low collagen concentration groups are found optimal for auricular phenotype maintenance, maturation of tissue composition and mechanical properties, in both in vitro 3D microtissue culture model and in vivo subcutaneous implantation nude mouse model. Moreover, a modular fabrication approach, which utilizes human auricular chondrocyte-derived microtissues to assemble into an ear-shaped tissue graft in one-piece with native tissue-mimicking matrix composition, is developed. STATEMENT OF SIGNIFICANCE: Auricular reconstruction remains challenging because current clinical options, including autologous rib cartilage grafts and synthetic implants, are associated with donor-site morbidity, limited tissue mimicry, and long-term complications. This study presents a fully biological strategy for engineering human auricular cartilage using auricular chondrocyte-derived microtissues. Upon subcutaneous implantation in nude mice, the engineered tissues further mature developed native tissue-like characteristics. Most importantly, the modular assembly approach enabled generation of anatomically relevant one-piece ear-shaped constructs, offering a clinically translatable strategy for auricular reconstruction.