GelMA Hydrogel/Alginate-Based Scaffolds: 3D Bioprinting for Cartilage Tissue Engineering

The perichondrium-a natural fibrous membrane encasing cartilage-plays a pivotal role in nutrient delivery and matrix regulation; however, it is often overlooked in engineered constructs. This study aimed to fabricate a perichondrium-mimicking three-dimensional (3D) bioprinted auricular cartilage construct utilizing a hybrid bioink and to assess the effects of adipose-derived stem cell (ADSC) outer layers on cartilage matrix formation, vascularization, and construct stability.

Chondrocyte spheroids and ADSCs were isolated from New Zealand white rabbits and embedded in bioinks composed of either alginate alone or alginate/GelMA composites. A dual-mode printing strategy facilitated the fabrication of constructs with 3 and 10 layers. ADSCs were printed as outer "perichondrium-mimicking" layers in designated groups (G2, G4, and G6). Constructs were implanted subcutaneously in nude mice for 6 weeks. Histological analyses, immunohistochemical assessments (CD31), and image-based quantitative analyses were conducted.

The inclusion of ADSC layers significantly enhanced cartilage matrix synthesis and decreased calcification, particularly in constructs containing GelMA. Group G4 exhibited the highest levels of glycosaminoglycan and collagen content, as well as the lowest calcium deposition. Ten-layer constructs (G6) preserved structural integrity and supported neovascularization; however, the final cartilage thickness did not proportionally scale with the initial print height.

The incorporation of ADSC-laden perichondrium-mimicking layers in conjunction with a hybrid alginate/GelMA bioink synergistically enhances cartilage formation, matrix quality, and vascular integration in large constructs. This biomimetic approach is a promising platform for developing clinically relevant cartilage grafts for auricular reconstruction and other cartilage repair applications.