Successful repair of knee cartilage relies on an ideal integration of surgical technique and supportive scaffolds promoting cartilage formation. Existing commercial scaffolds are often associated with poor implant integration, sub-optimal cellular environment, and open surgery, which can lead to long recovery time, graft failure, reoperation and high costs. FiberGel is a phase-transformable scaffold made of inter- crosslinkable, protein-based microfibers, which are paste-like, mixable with cells, and able to solidify into a porous scaffold with optimal, tissue-specific porosity. FiberGel is injectable and supports minimally invasive procedures, while the paste-like fibers can fill a random defect with arbitrary geometry before forming a scaffold, facilitating the integration of implant to host cartilage. These features can potentially save patients and insurance providers significant costs per procedure. Supported by the Coulter-Drexel Translational Research Partnership, experimental results to date have demonstrated the advantage of FiberGel used in vitro and in explant models.  Next steps in the development plan are to test the efficacy of FiberGel using horse models. In this proposed project, the animal model will increase the duration of in vivo testing in a statistically relevant number of subjects.