Redesigning of Cell-Penetrating Peptides to Improve Their Efficacy as a Drug Delivery System

Abstract

Cell-penetrating peptides (CPP) are promising tools for the transport of a broad range of compounds into cells. Since the discovery of the first members of this peptide family, many other peptides have been identified; nowadays, dozens of these peptides are known. These peptides sometimes have very different chemical–physical properties, but they have similar drawbacks; e.g., non-specific internalization, fast elimination from the body, intracellular/vesicular entrapment. Although our knowledge regarding the mechanism and structure–activity relationship of internalization is growing, the prediction and design of the cell-penetrating properties are challenging. In this review, we focus on the different modifications of well-known CPPs to avoid their drawbacks, as well as how these modifications may increase their internalization and/or change the mechanism of penetration.

The influence of degree of labelling upon cellular internalisation of antibody-cell penetrating peptide conjugates

“…cyclic- and multimeric-TAT, 12,13,18 r9, 19 CPP12 (ref. 20)) may yield even greater enhancements in internalisation and pharmacological properties, 21 and the optimisation of this next-generation of antibody–CPP conjugates would benefit from a similar investigation to that described herein. With the principal aim of developing a facile, modular strategy capable of enhancing the therapeutic index of antibody-based drugs, future work will examine the applicability of these findings to other clinically relevant antibodies and ADCs, and systematically assess the impact of DOL TAT upon key factors, including cellular internalisation mechanisms, immunoreactivity, pharmacokinetics, and biodistribution in preclinical models.…”

Towards rational computational peptide design

“…In both scenarios a functional motif will allow these peptides to target and inhibit or enhance interactions and pathways. Peptides have some intrinsic limitations like fast degradation and difficulty crossing barriers that might make them precursors of other molecules such as modified peptides (Szabó et al, 2022), mini-proteins (Cao et al, 2022) and small molecule peptidomimetics (Rubin et al, 2018;Perez, 2021). However, predicting the initial structure and identifying high affinity binders will be critical to develop these peptide derivatives.…”

Approaches for evaluation of novel CPP-based cargo delivery systems

“…By including modifications, such as replacing or adding new amino acid residues to the sequence, or adding cancertargeting elements (Feni et al, 2019;Säälik et al, 2019), new CPPs with increased efficacy at specific conditions (Reissmann and Filatova, 2021;Szabó et al, 2022) can be generated. The CPP family includes peptides from ranging degrees of structural complexity and high chemical versatility.…”

“…To experimentally evaluate the internalization and trafficking of the CPP-cargo, there are some common methods that are used and varied. Often flow cytometry and microscopy based approaches are applied (Szabó et al, 2022;Zorko and Langel, 2022) accompanied with fluorescence detection. For example, the assessment of the CPP backbone rigidity effect (Nagel et al, 2017), or a standardized evaluation of 474 sequence motifs by Remaker et al (Ramaker et al, 2018).…”