Summary: In spite of progress in understanding the pathophysiology of OA, there remain no definitive non-surgical treatment options. Further, tissue engineering strategies designed to produce cartilage-mimetic materials have seen only limited success; a significant impediment is the inability to fully assess the molecular structure of developing tissue such that optimal constructs for implantation can be identified. Recently, we demonstrated that the technique of non-destructive near infrared spectroscopy (NIRS) analysis can be utilized to assess the primary molecular components of native and engineered cartilage. NIRS data correlates strongly to water and matrix content (collagen and proteoglycan) in these tissues, and to mechanical properties. Having validated the NIR technology for cartilage assessment, we propose to extend our studies to address an important emerging area of musculoskeletal tissue engineering, identification of individual constructs suitable for clinical implantation. These studies are based on the principle that increases in construct maturation prior to implantation can be utilized to predict in vivo success. We hypothesize that maturation of the cartilaginous matrix can be monitored by NIRS, and that the spectral data can be used as a predictor of clinical success. We will address this in a series of in vitro and in vivo studies that evaluate construct development using NIRS analysis. A cell-seeded hyaluronic acid (HA) scaffold, previously shown to be effective at promoting matrix production and the development of functional material properties, will serve as the model system for implantation into a porcine model of cartilage repair. The proposed NIRS technology would establish a novel, non-destructive modality for pre-implantation evaluation of developing engineered tissues for clinical implantation. There are currently no minimally-invasive methods available for the clinical assessment of cartilage repair tissue maturation based on molecular signatures. The development of clinically-relevant optical methods to evaluate full-depth composition of tissues in a large animal model will provide a strong underpinning for translation of this technique into the clinical setting. Such analyses would also represent a fundamentally new and powerful approach for evaluating and guiding cartilage therapeutics. The possibility of one non-destructive modality that can be used in vitro during laboratory experiments of developing tissues to assess composition and identify constructs for implantation, as well as after the constructs are implanted clinically, would indeed be a powerful technique that could play a central role in the regenerative medicine field.