Plasma membrane damage limits cytoplasmic delivery by conventional cell penetrating peptides

TL;DR

This study shows that using cell penetrating peptides to deliver large molecules into cells is limited by membrane damage and toxicity, making it hard to achieve efficient and safe delivery.

Contribution

The study reveals that plasma membrane damage is an inherent part of CPP uptake, limiting delivery efficiency and linking it to cell toxicity.

Findings

Delivery efficiency of CPPs correlates with plasma membrane damage and cell toxicity.

Smaller peptides are delivered more efficiently than large molecule cargo.

Conventional CPPs have low delivery yields due to toxicity constraints.

Abstract

Intracellular delivery of large molecule cargo via cell penetrating peptides (CPPs) is an inefficient process and despite intense efforts in past decades, improvements in efficiency have been marginal. Utilizing a standardized and comparative analysis of the delivery efficiency of previously described cationic, anionic, and amphiphilic CPPs, we demonstrate that the delivery ceiling is accompanied by irreparable plasma membrane damage that is part of the uptake mechanism. As a consequence, intracellular delivery correlates with cell toxicity and is more efficient for smaller peptides than for large molecule cargo. The delivery of pharmaceutically relevant cargo quantities with acceptable toxicity thus seems hard to achieve with the CPPs tested in our study. Our results suggest that any engineered intracellular delivery system based on conventional cationic or amphiphilic CPPs, or the design principles underlying them, needs to accept low delivery yields due to toxicity limiting efficient cytoplasmic uptake. Novel peptide designs based on detailed study of uptake mechanisms are required to overcome these limitations.

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