3D-bioprinted dual-crosslinked oxidized gellan gum-decellularized human amniotic membrane hydrogels reinforced with aminolyzed electrospun nanofibers for cartilage regeneration

Articular cartilage has limited self-healing capacity, driving the need for biomaterial scaffolds that replicate its hierarchical architecture and mechanical resilience. In this study, we present a dual-crosslinked hydrogel system for 3D bioprinting, composed of gellan gum (GG), oxidized GG (OGG), decellularized human amniotic membrane (dHAM), and aminolyzed polycaprolactone nanofibers (A-PCL NFs). Schiff base linkages between OGG aldehydes and amine groups in dHAM/A-PCL NFs, combined with Ca²⁺-mediated ionic gelation, provided a reinforced hydrogel network with tunable physicochemical properties. The resulting scaffolds exhibited high structural fidelity, a compressive modulus of 232.6 kPa, controlled swelling, and sustained degradation (30 % mass loss over 21 days). The integration of A-PCL NFs significantly enhanced mechanical performance and stabilized the hydrogel matrix, while dHAM supplied native extracellular matrix (ECM) cues. Rat bone marrow-derived mesenchymal stem cells (rBMSCs) encapsulated in the bioink showed >85 % viability after 7 days and underwent robust chondrogenic differentiation, as confirmed by histology and increased glycosaminoglycan deposition. This biomimetic design-combining dynamic crosslinking, ECM-derived bioactivity, and NF reinforcement-demonstrates how structural and biochemical synergies can be harnessed to advance functional cartilage scaffolds. The platform shows strong potential for translational application in articular cartilage repair and may be extended to other load-bearing tissues requiring both mechanical integrity and biological functionality.