PROJECT SUMMARY Post-traumatic osteoarthritis (PTOA) is an insidious consequence of joint injury, ~50% of patients with knee- injuries exhibit PTOA within 10-years of injury. Presently, no cure for PTOA exists, but the acute nature of the precipitating injuries provides for a unique approach to PTOA treatment: targeted prophylactic pharmaceutical intervention to mitigate/prevent the initiation of disease post-injury. Many pre-clinical investigations for targeted treatment have been conducted. However, due to incredibly rapid intra-articular (i.a.) drug clearance, disease- modifying drug efficiency is highly limited, requiring repeated high-dose administration of free drug for efficacy. Give the inefficiencies of i.a. administration of free drug, delivery approaches that extend drug-residence time by targeting the tissues of the injured joint could represent a cost-effective method of increasing therapeutic efficacy. We propose a novel and versatile platform for the thermally responsive, localized delivery of candidate PTOA drugs to injured joints to limit initiation/progression of PTOA. Our approach relies on our pioneering development of elastin-collagen-peptide conjugates that uniquely form cargo-laden nanovesicles that facilitate long-term passive release at body temperature and accelerated-/burst-delivery at mildly hypothermic temperatures. In addition, the collagen-like peptides comprising the vesicle’s outer ‘shell’ can target denatured collagens, allowing accumulation in tissues with elevated collagen damage/remodeling. In this proposal, we will evaluate the loading of candidate PTOA disease-modifying drugs (with a focus on dexamethasone (Dex)) in refined elastin-collagen nano-vesicles (ECnV) and monitor their stability, as well as passive and hypothermally-triggered drug release. Studies on naïve and ‘injured/activated’ chondrocytes, synovial fibroblasts, and monocyte/macrophages, and articular cartilage and synovial tissue explants, will confirm the cyto-/biocompatibility and quantify the suppression of ‘injury’ markers by Dex-loaded ECnVs. We will conduct in vivo experiments using a non-invasive repeated joint loading (overuse) model of PTOA to demonstrate the selective retention of ECnVs within injured joints after intra-articular (i.a.) injection. Multi-scale in vivo, in situ, and histological/immunohistochemical analyses will be employed to evaluate the pharmacokinetics of passively and hypothermally-triggered cargo release, tissue localization/biodistribution, and the local and systemic biocompatibility/safety of ECnVs delivered to both healthy and early-PTOA joints. Finally, we will characterize the ability of ECnV-based delivery of Dex to improve disease-modifying physiology and PTOA outcomes prophylactically in the aforementioned non-invasive, joint injury model, with standard i.a. liposomal and free-Dex treatments serving as comparators. Although the proposed work focuses on increasing PTOA therapy effectiveness, it will also lay a foundation for the use of collagen-targeting ECnV drug carriers across a broad range of diseases and pathologies characterized by aberrant collagen remodeling.

PROJECT NARRATIVE Post-traumatic osteoarthritis is a crippling disease that can rapidly affect over half of patients suffering acute joint injuries, such as ACL ruptures and meniscal tears, as well as patients with overuse injuries. Presently, there are no clinical treatments that can prevent the initiation and progression of PTOA after joint injury, and the translation of therapeutic candidates with PTOA-disease modifying potential has been hindered by poor targeting to and rapid clearance of therapeutics from the joint. In this program, we will demonstrate the feasibility of novel collagen-targeting, thermoresponsive approaches for localizing candidate drugs to the injured joint and extending their ability to prevent/mitigate PTOA, thereby improving treatment efficacy and reducing costs.