Sustained Delivery of RhoA activator for Treatment of Intervertebral Disc Degeneration

Discogenic back pain, is a leading cause of disability, and involves degenerative changes of the intervertebral disc (IVD). Since only a small subset of patients responds favorably to conventional treatments which address the symptoms but not the disease, there is a need for new therapies to treat disc degeneration (DD). The avascular nature and the dense matrix of the IVD makes it challenging for systemically administered drugs to reach their target cells inside the nucleus pulposus (NP). While local intra-discal injection of therapeutic drugs directly into the NP is a clinically relevant delivery approach, it suffers from low persistence and rapid diffusion from the injection site resulting in short lived benefits, off target effects and potentially, systemic toxicity. In the current proposal, we will develop a charge based (Avidin) nanocarrier system to deliver a months long dose of a large molecular weight drug (CN03) intradiscally to the rat IVD in vivo from a single administration, reducing the often-observed low penetration or short-lived benefits of disease modifying drugs in the IVD. CN03 is a RhoA GTPase activator. We recently discovered are mediated by Rho GTPase regulation of actomyosin contractility. Our study demonstrates that RhoA can regulate the master pro-inflammatory transcription factor NF-ĸB, its downstream signaling including degradative effects at the matrix level, making Rho GTPase mediated actomyosin contractility a novel therapeutic target to prevent pro-inflammatory cytokine induced degradation of the IVD ECM. The goal of this MPI proposal is to test the efficacy of CN03 as a novel therapeutic drug in a preclinical model of IVD degeneration and to design a sustained delivery system for controlled local administration of CN03. In Aim 1, we will quantify actomyosin contractility and biological efficacy of CN03 in a rat IVD puncture injury model. In Aim 2, we will synthesize and characterize an intra-NP drug depot for sustained release of CN03 in rat IVD over a period of 1 month. In Aim 3, we will assess the therapeutic efficacy of CN03 conjugated to Avidin-Dextran in an in vivo rat IVD puncture injury model. Successful completion of these high risk/high reward studies will demonstrate that actoymyosin contractility is an appropriate disease modifying drug target for DD, that Avidin cationic nanostructures can deliver a sustained cargo of a large molecular weight protein up to 1 month in the IVD, and that optimized delivery of CN03 conjugated Avidin-Dextran improves disc functional repair in vivo. These therapeutic strategies are highly translational, and future studies will therefore evaluate these strategies in a large animal model of DD and in treating symptomatic back pain.