Chronic wounds (CW) are one of the leading causes of illness worldwide, impacting around 40 million people globally. Several advanced therapies have been developed over the years, although often being ineffective due to the lack of patient-specificity and reliable testing conditions. Consequently, there is a growing demand for developing skin tissue models which can adequately mimic the complexity of CW environment and work as reliable tools for testing/validating wound dressings. In this context, this thesis aims at designing a 3D in vitro ulcer model by integrating extrusion-based bioprinting and murine fibroblasts (NIH-3T3). To this purpose, methacryloyl gelatine (GelMA) was first synthetized by reacting gelatine with methacrylic anhydride to expose acrylate groups along the polymer chains, thus obtaining a thermo- and photo-sensitive polymer.