Catheter-injectable, engineered biomaterial for sustained Neuregulin-1 delivery to the myocardium - Myocardial infarction (MI) is a leading cause of death in the United States, affecting over 800,000 people annually. Numerous strategies have been developed to treat MI, but effective delivery of protein therapeutics to the heart remains a formidable challenge. Systemic, intravenous (IV) delivery results in low tissue specificity and rapid loss of bioactivity, necessitating high dosing, repeated administration, and/or long treatment periods. On the other hand, direct injection of therapeutics into the myocardium commonly results in rapid clearance due to the heart’s contractility. To address this critical need for a technology that provides (i) sustained bioactivity and (ii) tissue-localization of protein therapies, we propose a new type of injectable, biodegradable hydrogel. This novel biomaterial has a unique molecular structure, with hyaluronic acid (HA) biopolymers bridging between self- assembled lipids to form a liposome network crosslinked hydrogel (HA-LINC). The reversibility of lipid self- assembly into multilamellar liposomes allows the covalently crosslinked gel to be easily injectable and self- healing, while also providing a means for sustained delivery of bioactive protein. As a proof-of-concept test case, we will develop the HA-LINC hydrogel to deliver neuregulin-1β (NRG1), a promising recombinant protein therapy that currently requires 10-hour intravenous delivery for clinical efficacy. In Aim 1, we will evaluate the hypothesis that our unique strategy of crosslinking a hydrogel through lipid self-assembly will result in the formulation of stiff yet injectable hydrogels, resulting in tissue-localization of protein therapies. We will synthesize a library of HA- LINC hydrogels by tuning liposome functionalization, HA functionalization, and HA concentration. Viscoelastic mechanics, in vitro catheter injectability, and in vivo cardiac retention in a rat MI model will be quantitatively evaluated. In parallel, in Aim 2, we will evaluate the hypothesis that chemically stabilized, multilamellar liposomes can achieve sustained bioactivity of encapsulated protein drugs by preventing protein degradation and providing controlled release. Liposomes with varying degree of internal stabilization will be quantified for size, shape, and cargo release rate. Bioactivity of released NRG1 will be quantified using human cardiomyocytes and cardiac fibroblasts. In vivo NRG1 will be quantitatively evaluated using a 2-compartment pharmacokinetic model. In Aim 3, the biopolymer network chemistry with the best tissue-localization (Aim 1) and the engineered liposomes with the optimal NRG1 sustained bioactivity (Aim 2) will be evaluated in vivo for therapeutic functionality. Following induction of MI through ligation of the left anterior descending (LAD) artery, animals will be randomly assigned into one of 5 treatment groups: sham, HA-LINC hydrogel with NRG1 encapsulated into stabilized liposomes, HA-LINC hydrogel only, free NRG1 in HA-LINC hydrogel, and NRG1 encapsulated into stabilized liposomes without gel. We will evaluate treatment effects on cardiac function, immune response, tissue remodeling, gel retention, cardiomyocyte survival, angiogenesis, and expression of proinflammatory and reparative factors.
