[Truncated abstract] Articular cartilage has no vascular, neural, or lymphatic supply, and hence no intrinsic capacity to self-repair following injury. These physiological limitations, combined with the inability of local chondrocytes to contribute to the repair process, translate to poor structural and functional outcomes in these troublesome defects, and osteoarthritic deterioration with time. Subsequently, many surgical therapies have been trialed to stimulate cartilage repair, but none have produced reliable outcomes. Hence, cartilage repair research has been broadened, with many investigators now focused on cell-based treatment. Smith began a revolution of autologous cell research when in 1965 she isolated chondrocytes from articular cartilage and transplanted them into fresh cartilage nodules (Smith, 1965). Since, new technologies and improved techniques have seen autologous chondrocyte implantation (ACI) widely accepted for use in clinical orthopaedics (Bentley et al., 2003; Brittberg et al., 1994; Grande et al., 1989; Peterson et al., 2002). At present, matrix-induced autologous chondrocyte implantation (MACI) is the most surgically simple form of ACI, boasting clinical outcomes comparable to any technique on the market, and far less complications compared to the first generation of ACI - periosteal ACI (Bartlett et al., 2005; Behrens et al., 2006; Gigante et al., 2006; Henderson et al., 2004; Marlovits et al., 2005; Minas, 2001; Willers et al., 2007; Zheng et al., 2007). But whilst MACI has been adopted by the orthopaedic surgeon for articular cartilage repair, many of the molecular, histological, and clinical factors governing patient outcomes are still largely understudied. Firstly we assessed the bioactivity of fibrin sealant (FS - Tisseel®), a critical component of MACI, on the migration and proliferation of human articular chondrocytes in vitro. We also looked to elucidate the associated molecular mechanisms of thrombin, a key active ingredient in FS, by examining the expression and activation of proteaseactivated receptors (PARs), established thrombin receptors. All four PAR isoforms were detected in human chondrocytes, with PAR-1 being the major isoform expressed. '...' This thesis has demonstrated biological, histological, and clinical features of the MACI technique. Our in vitro has supported the use of fibrin sealant and collagen membrane as the major material components of MACI, illustrating improved chondrocyte proliferation, migration, and chondrogenic differentiation. We have evidenced that MACI stimulates successful production of hyaline-like cartilage by 6 months, while also showing that revised and clinically failed repair tissues are predominantly hyaline-like and fibrocartilage with inferior composition. Clinically, we have documented significant improvements in patient repair structure, function, symptoms, quality of life, and satisfaction, whilst concurrently confirming sentiment within the literature regarding the importance of exercise/ rehabilitation for maximising MACI outcome. In summary, the findings presented in this thesis suggest that MACI is a biologically sound and clinically efficacious cell-based treatment option for repairing articular cartilage defects.