Liposome-crosslinked hyaluronic acid hydrogels with localized protein delivery for myocardial infarction therapy

Myocardial infarction (MI) is a leading cause of death in the United States, affecting over 800,000 people
annually. Numerous protein therapies have been developed to treat MI, but effective delivery of therapeutics to
the heart remains a formidable challenge. Systemic, intravenous (IV) delivery of therapeutics results in low tissue
specificity and rapid loss of function, necessitating high dosing, repeated administration, and/or long treatment
periods. Direct injection of therapeutics into the myocardium commonly results in rapid clearance due to the
heart’s contractility. To be successful as therapies for MI, protein drugs need new delivery methods that allow
localized delivery in a sustained, controlled manner with minimal cargo loss. Here, I propose the development of
injectable liposome nanoparticle crosslinked (LINC) hydrogels designed for sustained protein therapeutic
delivery in the myocardium. These hydrogels are formed by crosslinking hyaluronic acid (HA) with functionalized
liposomes, forming HA-LINC hydrogels, through strong yet reversible dynamic covalent chemistry (DCC) bonds.
The Heilshorn Group has shown that HA-based hydrogels crosslinked through DCCs are injectable, retained in
the myocardium, and cyto-compatible. To evaluate their performance in a preclinical setting, I will use HA-LINC
hydrogels to deliver the promising MI protein therapy neuregulin-1β (NRG1) in a rat model of MI. In Aim 1, I will
synthesize a library of distinct HA-LINC hydrogels by tuning liposome functionalization, HA functionalization, and
HA concentration. The resulting gels will be analyzed for viscoelasticity, in vitro hand injectability using a syringe
pump, and toxicity when cultured with primary cardiomyocytes. In Aim 2, I will systematically tune the degree of
liposome internal stabilization and evaluate the effects on liposome structure, hydrogel viscoelasticity, and cargo
release rates. To determine the bioactivity of released NRG1, it will be delivered from HA-LINC hydrogels to
primary cardiomyocytes. Cardiomyocytes will be examined for viability, proliferation, and morphology in a
hypoxia challenge representing MI. Additionally, I will evaluate the ability of released NRG1 to rescue the
phenotype of hydrogen peroxide-treated cardiac fibroblasts. In Aim 3, the HA-LINC formulation with the highest
stiffness and lowest required injection force (Aim 1) and most sustained NRG1 release profile (Aim 2) will be
evaluated in vivo. Following induction of MI through ligation of the left anterior descending (LAD) artery, HA-
LINC hydrogels encapsulating NRG1 will be injected. NRG1 plasma concentration over time will be used to
create a pharmacokinetic model of release. I will evaluate effects on cardiac function, tissue remodeling, gel
retention, cardiomyocyte survival, and angiogenesis. The proposed HA-LINC hydrogels will provide localized,
long-lasting, controllable protein delivery to treat MI. This work will be completed in the Heilshorn lab at Stanford
University in collaboration with Profs. Wu and Appel, experts in cardiology and pharmacokinetics. I will be directly
mentored by Prof. Heilshorn and my collaborators, take courses on drug delivery, cardiac regenerative medicine,
and bioethics, and continue mentoring undergraduates in the lab.

Grant Number: 5F31HL175888-02
NIH Institute/Center: NIH
Principal Investigator: Neil Baugh