Beyond Transduction: Biological Effects of Cell Penetrating Peptides

One of the bottlenecks to bringing new therapies to the clinic has been a lack of vectors for delivering novel therapeutics in a targeted manner. Cell penetrating peptides (CPPs) have received a lot of attention and have been the subject of numerous developments since their identification nearly 3 decades ago. Known for their transduction abilities, they have generally been considered inert vectors. In this review we present a schema for their classification, highlight what is known about their mechanism of transduction, and outline the existing literature, as well as our own experience, vis a vis the intrinsic anti-inflammatory properties that certain CPPs exhibit. Given the inflammatory responses associated with viral vectors, CPPs represent a viable alternative to these vectors; further, the anti-inflammatory properties of CPPs, mostly through inhibition of the NF-κB pathway, are encouraging. Much work in relevant animal models, toxicity studies in large animal models, and ultimately human trials are needed before their potential is fully realized.