Cobweb-Inspired Microenvironment-Targeting Nanosystem with Sequential Multiple-Stage Stimulus-Response Capacity for Ischaemic Tissue Repair

Myocardial ischaemia is pathologically complicated; various changes in intracellular and extracellular microenvironments make it essential to develop a smart drug system with multiple stimulus responses to adapt to the complex process. Inspired by the cobweb, this study designs a microreticular nanosystem that adheres to tissue and is sequentially responsive to multiple stimuli in the ischaemic microenvironment. The nanosystem is fabricated from hyaluronic acid (HA), ROS-responsive B-PDEA, and hypoxia-sensitive VEGF-expressing plasmids (EPODNA) through electrostatic interactions. After intramyocardial injection, the tissue-adhesive property of the nanosystem will significantly decrease its acute loss from the injection site. Extracellularly, the microreticular nanosystem first responds to activated hyaluronidase (hyal), releasing HA for microenvironment regulation and B-PDEA/DNA nanoparticles (NP) with high transfection efficiency for cardiac cells. Intracellularly, ROS sequentially induced B-PDEA/DNA NP dissociation, consuming some ROS to attenuate oxidative stress and releasing DNA to promote its expression. Meanwhile, local hypoxia significantly activates VEGF expression in plasmids for myocardial revascularization and repair. The function of the microreticular nanosystem is systematically evaluated in vitro. In a rat model of myocardial infarction, treatment with the microreticular nanosystem significantly promotes functional and structural improvements. Collectively, the study provides a promising smart nanosystem to promote tissue repair after complex damage.