Peptide-based nanoparticle for ex vivo and in vivo drug delivery

One of the major challenges for new therapeutics molecules to enter the clinic remains improving their bioavailability and cellular uptake. Therefore, delivery has become a key stone in therapeutic development and several technologies have been designed to improve cellular uptake of therapeutic molecules, including cell-penetrating peptides (CPPs) or protein transduction domain (PTD). PTDs or CPPs were discovered twenty years ago, based on the potency of several proteins to enter cells and nowadays, numerous peptide carriers have been described and successfully applied for ex vivo and in vivo delivery of varying therapeutic molecules. Two CPP-strategies have been reported; the first one requires chemical linkage between the drug and the carrier for cellular drug internalization and the second is based on the formation of stable complexes with drugs depending on their chemical nature. Peptide-Based-Nanoparticle Devices (PBND), correspond to short amphipathic peptides able to form stable nanoparticles with proteins and/or nucleic acids. Three PBND-families, PEP, MPG and CADY have been described, these carriers mainly enter cells independently of the endosomal pathway and efficiently deliver cargoes in a large variety of challenging cell lines as well as in animal models. This review will focus on the structure/function relationship of the PBND: CADY, PEP and MPG, in the general context of drug delivery. It will also highlight the requirement of primary or secondary amphipathic carriers for in vitro and in vivo delivery of therapeutic molecules and provide an update of their pre-clinical evaluation.