3D printing of an E7 peptide-functionalized biomimetic cartilage composite scaffold for auricular reconstruction

Auricular cartilage reconstruction for microtia remains limited by insufficient shape maintenance, restricted cell migration, and inconsistent quality of the regenerated cartilage-like matrix. To improve the regenerative performance of tissue-engineered auricular cartilage, this study developed an E7 peptide-functionalized biomimetic composite scaffold. Through dual-nozzle 3D printing, a mechanically reinforced polycaprolactone (PCL) scaffold was spatially integrated with an E7 peptide-functionalized gelatin methacryloyl (GelMA)/carboxylated nanocellulose (CNC) composite hydrogel to provide support for complex shapes, a hydrated matrix microenvironment, and local bioactive cues. In vitro results showed that 0.10 mg mL^-1 E7 peptide effectively promoted chondrocyte migration while maintaining good cytocompatibility, adhesion, and spreading. Based on this, further incorporation of perichondrial stem/progenitor cells (PSPCs) into a chondrocyte co-culture system enhanced overall cell migration, spatial proximity, and cellular interactions. In vivo, a rabbit dorsal subcutaneous implantation model was applied for the PGCE + CC + PC system. Results indicated that this system induced more sustained and homogeneous cartilage-like tissue formation than the scaffold-only and chondrocyte-only groups, as evidenced by enhanced SOX9 and COL2 expression, as well as increased proteoglycan and acidic glycosaminoglycan depositions. Transcriptomic analysis further proved that this system enhanced molecular programs related to cell adhesion, intercellular junctions, mechanotransduction, and cartilage matrix synthesis, while reducing inflammatory and matrix degradation-related responses. RT-qPCR confirmed increased relative mRNA expression levels of SOX9, COL2A1, ACAN, and ELN in this group. This study demonstrates that the E7 peptide-functionalized composite scaffold combined with co-culture of chondrocytes and PSPCs provides a promising biomimetic construction strategy for auricular cartilage regeneration.