Gellan Gum-based Hydrogels for Osteochondral Repair

Gellan gum (GG) is a naturally derived polysaccharide that has gained increasing attention as a versatile biomaterial for tissue engineering and regenerative medicine. Due to its intrinsic properties, including biocompatibility, biodegradability, injectability, and structural similarity to components of the extracellular matrix, GG can be processed into hydrogel systems capable of supporting cell encapsulation, proliferation, and tissue regeneration. These characteristics, combined with its ability to undergo ionic or chemical crosslinking and to be easily functionalized, have positioned GG as a promising platform for a wide range of tissue engineering applications. In cartilage tissue engineering, GG-based hydrogels have demonstrated the capacity to maintain chondrocyte viability, promote stem cell chondrogenic differentiation and support the deposition of cartilage-like extracellular matrix. In parallel, GG has also been explored for bone regeneration, where its combination with inorganic phases such as hydroxyapatite, calcium phosphates or bioactive glass can enhance mechanical properties and provide osteoinductive cues. These composite systems aim to mimic the organic-inorganic structure of native bone tissue while promoting mineralization and osteogenic activity. More recently, advances in biomaterial design and biofabrication technologies have enabled the development of GG-based multiphasic systems targeting osteochondral tissue regeneration. Approaches including bilayer and gradient scaffolds, spatially controlled mineralization and extrusion-based 3D bioprinting have been investigated to better replicate the structural, mechanical and biological complexity of the osteochondral unit. Furthermore, the incorporation of bioactive molecules, extracellular matrix components and therapeutic cells has allowed GG-based hydrogels to actively modulate cellular behaviour and enhance tissue formation. Herein, the physicochemical properties of GG and the main strategies used to tailor its functionality for regenerative applications are overviewed. Particular emphasis is placed on recent developments in GG-based scaffolds for cartilage and bone regeneration, as well as emerging approaches for the design of integrated osteochondral constructs. Together, these advances highlight the growing potential of GG as a flexible and powerful platform for the development of next-generation biomaterials for joint repair.