Chapter 17 - Cell-penetrating peptide polymer nanomicelle-based cytosol-sensitive nucleotide delivery systems

Abstract

Transactivator of transcription (Tat)-like cell-penetrating peptides (CPPs) involved in the uptake of large molecules such as proteins, nucleotides, and nanoparticles are expected to be safe nonviral carriers for gene therapy. Several kinds of cytosol-sensitive polymers complexed to genes, including disulphide-crosslinked low-molecular-weight polyethyleneimines, poly(amido amine)s, and polypeptides, have been investigated. We focused on the Tat peptide and an artificial CPP, CH2R4H2C (C, cysteine [Cys]; H, histidine [His]; R, arginine [Arg]). This CPP has two Cys residues for physically trapping genes in micelles by disulphide linkage, which is conjugated with stearic acid to enhance transfection efficiency by local administration or with methoxy-poly(ethylene glycol)-block-poly(ɛ-caprolactone) for systemic administration. Nucleotides are rigidly shielded on the surface of nanomicelles, protected against nucleases in the blood, and persistently released into the reductive environment of the cytoplasm (glutathione, 0.5–10mM). In this chapter, we describe the use of these cytosol-sensitive functional CPP nanomicelles in gene transfection into cells.