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Objectives and questions: Chronic and non-healing wounds persist due to impaired cell migration and extracellular matrix remodeling and increased infection risk. In vitro wound models that reproduce defined defect geometry and cellular repair dynamics are needed to evaluate biomaterial-based wound strategies. This study developed a 3D bioprinted hydrogel wound model to quantify fibroblast viability and defect closure under controlled conditions.

Material and methods: Bioinks were screened by mechanical characterisation, printability metrics (filament width, pore size, fidelity), and disintegration testing. The final formulation was gelatin/alginate (30%/7% w/v) with 5 mM CaCl₂, post-crosslinked in 100 mM CaCl₂ for 7 min. Cylindrical constructs containing a conical defect were printed to mimic acute wound morphology. Rat dermal fibroblasts were isolated, expanded, and encapsulated (baseline cell density per construct). Viability and metabolic activity were assessed by Live/Dead staining, Cell Counting Kit-8 (CCK-8), and MTT over the incubation period. Three groups (equal initial construct cell density) were prepared: (i) fibroblast-laden constructs (control), (ii) fibroblast-laden constructs with cell-free hydrogel injected into the defect, and (iii) fibroblast-laden constructs with hydrogel containing a lower fibroblast density (1 × 10⁶ cells/mL) injected into the defect.

Results: Optimisation selected the Gel/Alg (30%/7% w/v) bioink and CaCl₂ crosslinking protocol as the best-performing combination for print fidelity and mechanical stability. Live/Dead staining showed high immediate post-print viability and increasing viable cell numbers over time. CCK-8 and MTT confirmed sustained fibroblast metabolic activity and proliferation in the final formulation, remaining above a 70% viability threshold.

Discussion and conclusions: A reproducible 3D bioprinted hydrogel wound construct with a defined conical defect supported fibroblast viability and metabolic activity under the selected printing and crosslinking conditions. The platform enables controlled testing of fibroblast-mediated defect closure and hydrogel-based interventions; future examinations will quantify infiltration and closure histologically.