Injectable Matrix Metalloproteinase-Responsive Nanoparticle Hydrogel Scaffold for Sustained Local Drug Delivery in Fibrous Dysplasia

Receptor activator of nuclear factor kappa-B ligand (RANKL) inhibition has shown significant therapeutic benefit in fibrous dysplasia. However, sustained RANKL inhibition is required to maintain its therapeutic effect. Moreover, disease rebound following discontinuation of denosumab, a human monoclonal RANKL antibody, poses a major clinical challenge to fibrous dysplasia treatment, thereby highlighting the need for strategies that preserve lesion-level efficacy while limiting systemic exposure. Matrix Metalloproteinases (MMPs), which are essential for osteoclast function and bone remodeling, have emerged as a key pathogenic pathway in fibrous dysplasia. Lesion profiling revealed elevated expression of MMP-9, -13, and -14 in osteoclast-rich fibrous dysplasia lesions, with dynamic regulation in response to pharmacologic RANKL inhibition and withdrawal. We hypothesized that Matrix Metalloproteinases may serve as lesion-associated biological cues for localized drug delivery in fibrous dysplasia. We developed an injectable, sustained, and matrix metalloproteinase-responsive local drug delivery system by integrating triglycerol monostearate nanoparticles within a dynamically crosslinked hyaluronic acid-based hydrogel scaffold (HPD/TGMS). To validate this strategy, the small-molecule RANKL inhibitor AS2676293 was loaded into triglycerol monostearate to generate HPD/TGMS@A. Matrix metalloproteinase-mediated cleavage of the ester linkage in triglycerol monostearate enabled protease-responsive drug release, further regulated by hydrogel-constrained perilesional retention. HPD/TGMS@A demonstrated favorable injectability, self-healing behavior, cytocompatibility, and matrix metalloproteinase-dependent anti-osteoclastic activity in vitro. HPD/TGMS@A significantly attenuated fibrous dysplasia lesion progression and improved bone microarchitecture in a GNASR201C knock-in fibrous dysplasia mouse model through perilesional injection. Altogether, these findings establish HPD/TGMS as a localized, lesion-responsive drug delivery strategy in fibrous dysplasia.