Design, Synthesis and Characterization of Novel Polymeric Nanocarriers for Oligonucleotides Delivery

RNAi therapeutics carried a great promise to the world of personalized medicine: the ability to target “undruggable” oncogenic pathways. These sequences of oligonucleotides can downregulate gene’s expression via full or partial complementation to mRNA and subsequent degradation or translation-arrest. Nevertheless, their efficient tumor targeting via systemic administration had not been resolved yet. Unfortunately, current delivery approaches suffer from pharmacokinetic limitations that raise the need for proper characterization and the substantial investigation of the relationship between structure, physico-chemical properties and activity as a fundamental tool in the quest for the ideal RNAi delivery vehicle. To address this, we have designed, synthesized and characterized a delivery vehicle based on the biodegradable poly-α-glutamic acid (PGA) polymer. Amine modifications on the pending carboxylic groups enable electrostatic-based complexation with the negatively charged RNAi. In addition, amine modifications facilitate cellular internalization via attraction to the negatively charged components of membranes that further lead to endocytosis-based uptake. We have tuned our polyplexes to form a nano-sized supramolecular structure that allows selective and passive (extravasation-dependent) accumulation in tumors due to the enhanced permeability and retention (EPR) effect, the leakiness and damaged lymphatic drainage of endothelium in tumors. In vitro analyses demonstrated that our polyplexes internalized into cultured cells and induce there gene silencing. Finally, our polyplexes were evaluated to be safe, biocompatible and effective gene regulators as demonstrated on various in vivo tumor models. So far, our study laid the foundation for the development of an efficient and safe delivery vehicle for oligonucleotides, to serve as personalized, systemically-administered, anti-cancer treatment.