Redefining gingival substitutes: Enhanced mechanics and bioactivity in SVV-functionalised bioprinted CollMA/HAMA hydrogels

Bioactive hydrogels with tuneable mechanical properties were engineered to support endothelial cell-driven pre-vascular network formation, a critical step toward ensuring adequate oxygen and nutrient diffusion in engineered tissues. These hydrogels were subsequently adapted for 3D bioprinting and functionalised with pro-angiogenic peptides (SVV and QK) to promote the formation of interconnected vascular networks maintained over a 14-day in vitro pre-incubation period, a prerequisite for subsequent host anastomosis. Several composite HAMA/CollMA bioinks were developed, including 0.1% CollMA/1% HAMA (formulation 1), 0.1% CollMA/2.5% HAMA (formulation 2), 0.5% CollMA/1% HAMA (formulation 3), and 0.5% CollMA/2.5% HAMA (formulation 4). Among the tested formulations, 0.5% CollMA/2.5% HAMA generated hydrogels exhibiting physiologically relevant low-kPa viscoelastic properties, controlled swelling behaviour, and long-term mechanical stability. To further enhance biological performance, the hydrogels were functionalised with bioactive peptides (RGD, SVV and QK), either individually or in combination (SV + QK). Peptide functionalisation enhanced cell adhesion and metabolic activity compared with non-functionalized hydrogels, while supporting the formation of prevascular networks. Notably, grafting the SVV peptide alone resulted in higher cell viability and metabolic activity. Combined with matrix-bound SVV peptide and hGF/HUVEC co-culture, the system supported stable and organised vascular-like network formation over 14 days in vitro. Overall, this work introduces a 3D-bioprintable bioink that integrates tuneable mechanical properties, controlled bioactivity, and ease of use. These features position this system as a promising and cost-effective platform for clinically relevant applications, particularly for the fabrication of large vascularized gingival connective tissue substitutes.