Hydrogel-mediated delivery of microRNA-92a inhibitor polyplex nanoparticles induces localized angiogenesis

Abstract

Localized stimulation of angiogenesis is an attractive strategy to improve the repair of ischemic or injured tissues. Several microRNAs (miRNAs) such as miRNA-92a (miR-92a) have been reported to negatively regulate angiogenesis in ischemic disease. To exploit the clinical potential of miR-92a inhibitors, safe and efficient delivery needs to be established. Here, we used deoxycholic acid-modified polyethylenimine polymeric conjugates (PEI-DA) to deliver a locked nucleic acid (LNA)-based miR-92a inhibitor (LNA-92a) in vitro and in vivo. The positively charged PEI-DA conjugates condense the negatively charged inhibitors into nano-sized polyplexes (135 ± 7.2 nm) with a positive net charge (34.2 ± 10.6 mV). Similar to the 25 kDa-branched PEI (bPEI₂₅) and Lipofectamine RNAiMAX, human umbilical vein endothelial cells (HUVECs) significantly internalized PEI-DA/LNA-92a polyplexes without any obvious cytotoxicity. Down-regulation of miR-92a following the polyplex-mediated delivery of LNA-92a led to a substantial increase in the integrin subunit alpha 5 (ITGA5), the sirtuin-1 (SIRT1) and Krüppel-like factors (KLF) KLF2/4 expression, formation of capillary-like structures by HUVECs, and migration rate of HUVECs in vitro. Furthermore, PEI-DA/LNA-92a resulted in significantly enhanced capillary density in a chicken chorioallantoic membrane (CAM) model. Localized angiogenesis was substantially induced in the subcutaneous tissues of mice by sustained release of PEI-DA/LNA-92a polyplexes from an in situ forming, biodegradable hydrogel based on clickable poly(ethylene glycol) (PEG) macromers. Our results indicate that PEI-DA conjugates efficiently deliver LNA-92a to improve angiogenesis. Localized delivery of RNA interference (RNAi)-based therapeutics via hydrogel-laden PEI-DA polyplex nanoparticles appears to be a safe and effective approach for different therapeutic targets.

Keywords: Angiogenesis; In situ forming hydrogel; MicroRNA-92a inhibitor; Polyethylenimine; Sustained release.