Rational design of novel cell-penetrating peptides

Sammanfattning: Although cell-penetrating peptides (CPPs) have been an active field of research for over 20 years there are still properties such as efficiency and stability that must be improved for CPPs to reach their full potential as delivery vectors.In this thesis two peptides were designed for non-covalent oligonucleotide delivery, in an attempt to overcome two major issues hampering wider use of CPPs, namely low stability and endosomal entrapment.In Paper I we designed a new peptide named PepFect14, which has unnatural amino-acid ornithine as the source of positive charge, to address the stability issue. PepFect14 was shown to deliver SCOs in a highly efficient manner into different cell-lines. Furthermore, formulation of non-covalent PepFect14:SCO complexes into solid form, suitable for storage and transportation, was developed. The formulated complexes were stable for weeks and retained high activity.In Paper II we modified PepFect14 with endosomolytic groups to facilitate endosomal escape, the resulting peptide was named PepFect15. Delivery of SCO and miRNA was efficiently mediated by PepFect15 into HeLa cells and endosomolytic property was validated. Additionally, uptake of Pepfect15:SCO complexes was shown to be mediated by scavenger receptor class A.