Enzyme-Responsive Nanoparticles for the Targeted Delivery of an MMP Inhibitor to the Heart post Myocardial Infarction

In this paper, we describe block copolymer amphiphiles consisting of a hydrophilic matrix metalloproteinase (MMP) peptide substrate, and a hydrophobic small molecule MMP inhibitor PD166793 for the treatment of acute myocardial infarction. These resulting drug loaded peptide-polymer amphiphiles (PPAs) assemble in aqueous solution to yield drug loaded micellar nanoparticles. Following minimally invasive intravenous injection, these nanoparticles preferentially exit the vasculature and are physically trapped at the infarcted region of the heart due to MMP-induced peptide cleavage and aggregation. This MMP directed active assembly prevents the material from leaking out into the blood stream, enabling long-term retention. Further, we show that the conjugated MMP inhibitor (PD166793) is inactivated in the core of the micelles and can be released upon the action of proteases and esterases, leading to MMP inhibition. This work establishes a promising targeted nanoparticle platform for delivering small molecule therapeutics to the heart.