3D printing of a beehive-inspired tissue-engineered auricular cartilage scaffold for reconstruction of autologous microtia

Tissue-engineered auricular cartilage (TEAC) represents a promising solution for microtia reconstruction. However, current approaches often fail to address the long-term stability and regeneration of the elastic cartilage, which is essential for maintaining the structural integrity and functional properties of the reconstructed tissue over time. In this study, a bionic TEAC scaffold fabricated by 3D bioprinting of thermoplastic polyurethane (TPU) scaffold loaded with GelMA cryogel microspheres and perichondrial stem/progenitor cells (PSPCs) was proposed for microtia reconstruction. The microcarriers (GelMA CM-30) were inspired by the beehive and prepared using a combination of emulsion and cryogel techniques. This design enhanced the interconnection pores that biomimic the lacunar structure of native auricular cartilage. In vitro study indicated that the temporal 3D culture of PSPCs on GelMA CM-30 uniquely promoted chondrogenic differentiation and extracellular matrix (ECM) remodeling, which promoted regeneration of elastic cartilage in response to mechanical restraint of the pores. Transcriptome analyses further revealed a remarkable upregulation of relevant genes related to collagen synthesis and elastic cartilage ECM and a downregulation of genes related to matrix metalloproteinases (MMPs). In vivo results indicated that the TPU@CM-30@PSPCs scaffold exhibited favorable cytocompatibility and promoted the formation of elastic neocartilage from PSPCs. This strategy combining scaffold reinforcement with potent tissue-specific stem cells and mechanical cues shows good potential for the development of clinically applicable TEACs for microtia reconstruction.