Bioinspired Oligo-Urethane Nanoparticles for Delivering Exogenous C-Type Natriuretic Peptide: Synthetic Biomaterial Nanocarrier Complexes and Their Interactions with Cardiac Myofibroblasts

In a healthy heart, cells naturally secrete C-type natriuretic peptide (CNP), a cytokine that protects against myofibroblast differentiation of cardiac fibroblasts and extracellular matrix deposition leading to fibrosis. CNP availability during myocardial remodeling is important to prevent cardiac fibrosis, but CNP is limited after an injury because of the loss of cardiomyocytes and the activation of cardiac fibroblasts to myofibroblasts. We hypothesized that the sustained release of exogenous CNP from oligo-urethane nanoparticles (NPs) would reduce differentiation of human cardiac fibroblasts toward a myofibrogenic phenotype. Our work used a modified form of a degradable polar hydrophobic ionic (D-PHI) oligo-urethane, which has shown the ability to self-assemble into NPs for the delivery of peptide and oligonucleotide biomolecules. The CNP-loaded NPs (NP_CNP) were characterized for a diameter of 129 ± 1.4 nm and a ζ potential of -46 ± 7.8 mV. Treatment of cardiac fibroblasts with NP_CNP increased cyclic guanosine-monophosphate (cGMP) synthesis, confirming that exogenous CNP delivered via oligo-urethane NPs is bioactive and can induce downstream signaling that has been implicated in antagonizing transforming growth factor-β1 (TGF-β1)-induced myofibrogenic differentiation. It is also shown that treatment with NP_CNP attenuated contraction of collagen gels by cardiac myofibroblasts stimulated with TGF-β1. Coating with heparin on the NP_CNP (HEP-NP_CNP) exemplified an approach to extend the release of CNP from the NPs. Both HEP-NP_CNP and NP_CNP show minimal cell toxicity, studied up to 0.25 × 10¹⁰ NPs/mL in culture media. These findings support further investigation of CNP delivery via NPs as a future therapy for suppressing cardiac fibrosis.