Physicochemical properties of gelatin/hyaluronic acid printed hydrogel and incorporated with thymoquinone: In Vitro evaluation of biocompatibility for wound healing

Wound healing is a multifaceted biological process that necessitates the development of advanced materials that can effectively support tissue regeneration and repair. The fabrication of bioengineered wound dressings has evolved significantly, with three-dimensional (3D) bioprinting emerging as a promising method to produce personalized, structurally stable hydrogels. In this study, we leveraged extrusion-based 3D bioprinting technology to develop gelatin-hyaluronic acid (GEL-HA) hydrogels, incorporating thymoquinone (TQ), a bioactive compound known for its regenerative properties. The use of 3D printing allowed for precise control over the scaffold’s architecture, optimizing its compressive strength and resilience while creating a bioactive, biocompatible platform for wound healing applications. This enabling precise control over their architecture and mechanical properties to enhance wound healing where it offers promising potential as biocompatible scaffolds for wound healing applications due to their favorable physicochemical properties and ability to promote cell proliferation and migration. GEL-HA hydrogels were fabricated with varying hyaluronic acid (HA) concentrations (0.1-1.0 wt%), and the effects on the gelation process and physical characteristics were evaluated.  Results showed that the ideal gelation temperature for the GEL-HA hydrogel was 22°C, with the inclusion of HA reducing polymerization time. The printed hydrogels exhibited high water retention (>1000%) and satisfactory mechanical properties, with a degree of crosslinking of up to 40.21%. Furthermore, the hydrogels demonstrated a low biodegradation rate (less than 0.300 mg/h) and favorable water vapor transmission rates (WVTR) in a range of 2000-3000 gm-2day-1, which are crucial for maintaining a moist environment in wound healing. The incorporation of TQ further enhanced the biocompatibility and cellular proliferation of human dermal fibroblasts (HDFs). Cell viability assays indicated that TQ promoted HDF growth at concentrations of 0.005–0.1 μg/mL without toxicity. Moreover, the wound scratch assay demonstrated that TQ facilitated cell migration, with the optimum concentration of 0.1 μg/mL showing the most significant effect. The GEL-HA-TQ hydrogel also supported HDF attachment and proliferation, as confirmed by live and dead cell staining, also with Ki-67, and collagen type-I immunocytochemistry. These findings suggest that GEL-HA hydrogels, combined with TQ, provide a promising and biocompatible platform for wound healing. It effectively promotes cell viability, migration, and extracellular matrix synthesis, which could be beneficial in regenerative medicine and tissue engineering applications.