15502-m-pleumeekers

Cartilage plays an important role in the form and function of the face as it provides flexibility and mechanical support to soft tissues. Once damaged, cartilage defects or deficits can lead to functional problems and major aesthetic impairment. Unfortunately, cartilage has a very limited capacity for self-regeneration. Currently, these defects are reconstructed with autologous cartilage grafts or artificial implants. Although autologous cartilage grafting has been used successfully, the procedure requires a high degree of surgical expertise, is associated with limited availability of autologous cartilage and can cause severe donor site morbidity. Besides, the alternative use of artificial implants is questioned in the head and neck area, since implants in this area are prone to induce a foreign body reaction and frequently lead to extrusion. [276] Cartilage tissue engineering offers a promising solution for restoring missing or destructed cartilage and has the potential to overcome limitations of current treatments, re-establishing unique biological and functional properties of the tissue. The successful translation of tissue-engineering strategies to clinical application is however limited and mainly focusses on articular and tracheal cartilage tissue engineering. This thesis focusses on the generation of a tissue-engineered cartilaginous framework for the reconstruction of cartilage defects in the face and evaluates the suitability of cells or combination of cells on natural scaffolds . Therefore, the following research questions have been answered: Q1 What are the biomechanical and biochemical characteristics of native facial cartilages (i.e. ear and nasal cartilages)? Q2 Which cells or combination of cells are most suitable for cell-based cartilage repair in the head and neck area? Q3 Which natural scaffolds (i.e. alginate, bacterial nanocellulose, decellularized extracellular matrix (ECM)) are a suitable candidate for future cell-based cartilage repair in the head and neck area? Cartilage characteristics Q1 What are the biomechanical and biochemical characteristics of native facial cartilages (i.e. ear and nasal cartilages)? Replacing damaged or missing cartilage requires an accurately sculpted cartilaginous framework that provides sufficient strength and stiffness to substitute for the biomechanical properties of the damaged cartilage in order to resist tissue deformation. Moreover, a cartilage framework that is too stiff may give an unnatural contour and may cause shearing forces of the overlying tissue, resulting in graft failure. Currently, costal cartilage is widely used as graft material for the replacement of facial cartilages. However, its biomechanical properties are evidently different from that of ear and nasal cartilages. [362] Ideally, tissue- engineered cartilage should overcome this biomechanical mismatch and possess similar biomechanical properties to native tissue. To date, most research on biomechanical characterization of native cartilages has been performed on articular cartilage (reviewed by Little et al . [158]) and only few studies have characterized the biomechanical properties of human facial cartilages, such as ear [23, 24, 363] and nasal cartilages [25-30]. However, these 177 DISCUSSION AND FUTURE PERSPECTIVES 9