Matrix-reinforcing and cell-instructive smart hydrogel for cartilage preservation

软骨损伤在现役和退伍军人中极为常见，包括外伤和磨损

Cartilage damage is extremely common in the active-duty and Veteran populations, both by trauma and wear- and-tear. These initial injuries compromise the biophysical and biochemical environment around cells, characterized by softening of the surrounding microenvironment and production of pro-inflammatory cytokines. The softer cellular microenvironment leads to volumetric and morphological changes of the cartilage cells, or chondrocytes, and the pro-inflammatory signaling leads to the continued degradation of the surrounding matrix. Combined, these early degenerative changes lead to aberrant cell behavior and a vicious deteriorative process, leading to progressive cartilage wear with time and culminating in osteoarthritis (OA). OA is a significant burden on the Veteran population, causing pain, discomfort, and reduced quality of life. Halting the degenerative process early in its progression, by specifically rehabilitating the cell and its surrounding environment, represents an impactful and innovative approach to preventing or delaying the onset of OA. Thus, the overarching goal of this proposal is to utilize a novel hyaluronic acid (HA) hydrogel system to both fortify damaged cartilage tissue and provide persistent presentation of inflammation-inhibiting peptides, all with the goal of preventing the progression of OA. This goal will be tested with the following specific aims: Aim 1: Determine the restorative effect of PCM fortification on chondrocyte cytoskeletal organization and mechano-transduction. First, a library of HA formulations and applications will be developed and tested on damaged cartilage tissue to achieve 3-4 levels of PCM fortification. Then, in a cartilage explant culture model, the impact of fortification on chondrocyte volume regulation, morphology, cytoskeletal composition and organization, and mechano-transductive properties will be determined and compared to healthy cells. Aim 2: Establish whether the combination of PCM fortification and persistent inflammatory inhibition prevents catabolism and restores chondrocyte homeostasis. HA will be conjugated with cell-instructive peptides that mimic an active sequence of IL-1 receptor antagonist (inhibits inflammation). In cartilage explants, the relative effects of fortification and inflammatory-inhibiting peptide, and their combination, will be tested on inflammatory cytokine release, matrix breakdown and loss, and matrix synthesis. Specifically, focus will be maintained on restoring the balance of matrix synthesis and deposition (anabolism) with degradation (catabolism). Aim 3: Evaluate the in vivo therapeutic effect of combined reinforcement and anti-inflammatory peptide presentation on cartilage deterioration. In a Yucatan minipig model, partial-thickness defects will be treated with fortification or a combination of fortification and anti-inflammatory peptide. Functional multi-scale biomechanical testing and matrix retention and quality will be assessed at 1- and 3-months post-treatment, to characterize whether early markers of cartilage deterioration were prevented or reduced. This research will enhance knowledge and understanding of the early degenerative changes to chondrocytes and their surrounding matrix, and directly develops a novel therapeutic strategy to mechanically stabilize cartilage and deliver cell-instructive cues to prevent, or even reverse, aberrant chondrocyte behavior. Furthermore, the multi-scale, multi-modal nature of the proposed work uses these cell-level outcomes to drive tissue-scale function and rehabilitation. Such a therapy would be monumental in the cartilage injury and osteoarthritis treatment in the Veteran population, improving activity levels and quality of life, and delaying or preventing the need for total joint replacement. Finally, the proposed CDA-2 research combined with the proposed mentoring and training plan, will allow Dr. Patel to acquire a plethora of new skills and knowledge, and position him well for a transition to a successful VA-based, independent research career.