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studies were relatively small and frequently used tensile behaviour to reflect biomaterial properties, which requires large sample dimensions and complicates the translation towards biomechanical properties of tissue-engineered cartilage constructs. Chapters two and three present the equilibrium behaviour (Eeq) of stress-relaxation indentation to study biomechanical behaviour of native facial cartilages (i.e. ear, nasoseptal and alar cartilages) to obtain a benchmark against which to evaluate tissue-engineering strategies. In general, indentation Eeq of human adult facial cartilages ranged from approximately 1-15 MPa. (Table 1) Cartilage subtype Biomechanical property Value Ear cartilage Equilibrium modulus 4.5 ± 1.7 MPa Anti-tragus Equilibrium modulus 7.2 ± 4.7 MPa Tragus Equilibrium modulus 5.4 ± 2.4 MPa Concha Equilibrium modulus 4.5 ± 2.2 MPa Anti-helix Equilibrium modulus 3.6 ± 2.1 MPa Scapha Equilibrium modulus 3.1 ± 1.0 MPa Helix Equilibrium modulus 2.2 ± 1.2 MPa Nasal cartilage Equilibrium modulus Septum Equilibrium modulus 15.7 ± 7.4 MPa Ala nasi Equilibrium modulus 1.3 ± 0.5 MPa Costal cartilage Equilibrium modulus 20.0 ± 14.7 MPa [364] Articular cartilage Equilibrium modulus 3.5 ± 1.1 MPa [156] Table 1. Native human cartilages. The indentation equilibrium modulus, Eeq, used in our studies compares well with that of costal and articular cartilage using the same test setup. Ear and alar cartilage had significantly lower equilibrium moduli compared to septal cartilage, and regional variations were observed. (Table 1) Griffin et al. have recently measured regional biomechanical behaviour of facial cartilages using compressive Young’s modulus on human ear and nasal cartilages [28, 363], indicating similar results. Although cartilage biomechanical behaviour is difficult to directly compare in various experimental setups, they similarly state that ear and alar cartilage have lower moduli compared to septal cartilage, with helical cartilage being the softest region of the ear. [28, 363] To be able to understand biomechanical behaviour of facial cartilages, one should realise that cartilage biomechanics are determined by ECM composition and architecture. In hyaline cartilage (i.e. nasoseptal cartilage), biomechanical behaviour is mainly the consequence of the swelling of negatively charged aggregated proteoglycans trapped into a collagen fiber network. [202] The biomechanical properties of ear and alar cartilage are also influenced by the presence of an elastin fiber 178 CHAPTER 9