Stem Cell-laden Hyaluronic Acid Gels for Cartilage Repair: In Vivo Translation

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DESCRIPTION (provided by applicant): Intrinsic repair of articular cartilage damage is unsatisfactory, largely due to its avascular nature and demanding physical environment. Various reconstructive techniques have not yet succeeded in restoring the complex mechanical properties of articular cartilage. Tissue engineering approaches have been pursued in the laboratory setting with results on the order of the native tissue. However, in vitro and in vivo daa suggest that increased tissue maturity may limit the ability to integrate with cartilage explants. Thus, these data indicate that "static" measures of construct maturity upon implantation (e.g. compressive modulus) may not be the best indicators of in vivo success. Alternatively, time-dependent increases in these properties in vitro (i.e. positive maturation rates) may provide a better indicator of success in vivo. Thus, the overall goal of this application is to take a "trajectory-based" approach to cartilage tissue engineering to determine the importance of in vitro culture parameters on the performance of tissue engineered constructs in vivo. To accomplish this objective, the PI will train under a unique team of mentors and will utilize a successful tissue engineering approach using a novel hydrogel combined with adult mesenchymal stem cells (MSCs). Once optimized, this approach will be implemented in a large animal model. Using this model system, we will 1) optimize in vitro formation and maturation of constructs made from porcine MSC- seeded HA hydrogels to establish baseline maturation trajectories, 2) compare mechanisms to accelerate construct maturation in vitro (increase trajectories), and 3) evaluate the role of maturation trajectories on construct properties and integration to the surrounding cartilage using both in vitro and in vivo models. Analysis will include cellular, histological, biochemical, and biomechanical measures of construct maturation. Successful completion of this project will represent a marked advance in the restoration of cartilage after injury, and will provide a novel treatment strategy for a debilitating condition affecting millions of people. This represents a shift in the paradigm away from the gold standard benchmark of cartilage TE constructs (i.e. properties similar to native tissue). Instead, we focus on "priming" the constructs, and then allowing them to appropriately remodel and integrate in vivo to restore normal function. Moreover, the unique experience gained will greatly benefit the PI's burgeoning career in orthopaedic research with a strong focus on translational models for tissue engineering.