Enhanced Auricular Cartilage Regeneration via 3D-Printed Hydrogel With miR-92a-3p-Enriched Platelet-Rich Plasma-Derived Extracellular Vesicles.

Auricular cartilage reconstruction in microtia remains a formidable challenge in regenerative medicine. Although cartilage tissue engineering holds substantial promise, achieving reliable and efficient chondrogenesis remains a pressing challenge owing to the intrinsically quiescent phenotype of chondrocytes. We present engineered platelet-derived extracellular vesicles (PEVs) that enhance auricular chondrocyte chondrogenesis in a 3D-printed hydrogel, enabling safe and efficient ear regeneration. Initially, we demonstrated PEVs activated auricular chondrocytes, and sequencing identified miR-92a-3p as the key effector. Then we employed 3D bioprinting to fabricate a biomimetic ElaMA/GelMA double-network hydrogel auricular scaffold incorporating PEVs that were engineered to carry miRNA-92a-3p (miR@PEVs). In vivo, miR@PEV-laden scaffolds exhibited the most robust chondrogenesis compared with PEVs and control groups; after one month of subcutaneous implantation, their Young's modulus approached that of native human auricular cartilage. The scaffolds also preserved satisfactory auricular morphology and displayed excellent biocompatibility. In vitro, miR@PEVs enhanced chondrocyte proliferation and migration, chiefly through miR-92a-3p-mediated suppression of SMAD7 and subsequent activation of TGFβ/Smad signaling. Moreover, miR@PEVs promoted macrophage polarization toward the M2 phenotype, creating an immunological milieu conducive to cartilage formation. Altogether, integrating miR-92a-3p-enriched miR@PEVs into the 3D-printed ElaMA/GelMA scaffold overcomes the key hurdles of auricular reconstruction and represents a promising strategy for total ear reconstruction.