Advanced Tissue Engineered Models of Human Cartilage for Studying Joint Disease

PROJECT SUMMARY / ABSTRACT Disease and trauma of articular cartilage are highly debilitating to the quality of life, as damaged cartilage has a very limited ability for self-repair. The management of articular cartilage defects continues to be a prevalent and challenging problem with limited treatment options, in part due to the lack of high-fidelity models that would advance our understanding of disease/injury progression and enable testing of novel therapeutics. Rodents are commonly used to study joint disease and development, yet they fail to recapitulate key aspects of human cartilage anatomy and biology, in particular the intricate zonal organization of human cartilage. While engineered in vitro models can be biologically faithful, they generally lack the complexity offered by in vivo models, including the interactions with other tissues. To address this gap, I propose to engineer zonally organized human cartilage in vitro by applying the appropriate spatiotemporal gradients of TGF-β signaling (Aim 1), while concurrently including living subchondral bone for enhanced osteochondral interactions (Aim 2). I seek to demonstrate the utility of this human cartilage model for studying joint disease using a monogenic connective tissue disorder, Marfan syndrome (MFS), in which fibrillin defects affect TGF-β bioavailability and musculoskeletal development (Aim 3). I hypothesize that the precise regulation of TGF-β signaling and the inclusion of a subchondral bone substrate will generate native-like human articular cartilage with zonal organization and cartilage-bone interactions, which can be used to model diseases such as MFS. Optogenetics presents a strategy by which we can control TGF-β signaling by light with unprecedented precision. At the osteochondral junction, biochemical and biomechanical interactions mediate cartilage health and disease, yet most established cartilage models fail to incorporate bone due to the complexity of supporting both tissue types. Our lab has designed perfusion bioreactors which can provide separate physical and chemical cues to each tissue type to overcome this challenge. Using MFS patient-derived hiPSCs, the advanced engineered cartilage model will be used to recapitulate functional and structural features of disease, benchmarked to clinical data and compared to data from existing in vitro models of chondrogenic micromass cultures. The proposed work will establish a novel method for cartilage tissue engineering and provide an advanced human tissue model for studying joint diseases.