Cyclic Cell-Penetrating Peptides for Endosomal Escape
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Solution Overview
Problem
Existing cell-penetrating peptides (CPPs) face challenges in traversing the plasma membrane, particularly for delivering biologics like peptides, proteins, and nucleic acids, due to the barrier posed by endosomal membranes, hindering cytoplasmic delivery.
Innovation Solution
Development of cyclic peptides comprising 6 to 20 amino acids, with at least three arginine residues and three hydrophobic side chains from aryl or heteroaryl groups, optionally substituted, to enhance membrane penetration and endosomal escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear cell-penetrating peptides are used to deliver biologics across the plasma membrane, then cell entry can be achieved via endocytosis, but the endosomal membrane barrier prevents effective cytoplasmic delivery
Solution Approach 1:
The peptide is divided into functionally distinct segments: arginine-rich regions for endosomal membrane interaction and hydrophobic aromatic regions for membrane insertion and escape. This segmentation allows each region to perform its specialized function, with arginines facilitating endocytosis and aromatic residues enabling endosomal escape, thereby resolving the contradiction between achieving cell entry and overcoming the endosomal barrier.
Solution Approach 2:
The peptide combines chemically distinct amino acid types (basic arginines and hydrophobic aromatic residues) into a single composite structure. This composite design integrates the cell-entry capabilities of arginine-rich sequences with the membrane-disrupting properties of hydrophobic aromatic regions, enabling both endocytosis and endosomal escape in one molecule, thus improving cytoplasmic delivery without requiring complex multi-component systems.
2Reliability
If cyclic peptide structure is adopted with specific amino acid composition, then endosomal escape efficiency is improved by 400%, but peptide synthesis complexity increases
Solution Approach 1:
The cyclic peptide is designed with segmented functional regions: arginine residues positioned for endosomal membrane interaction and hydrophobic aromatic residues positioned for membrane insertion. This deliberate segmentation within the cyclic structure optimizes endosomal escape while maintaining a relatively simple 6-20 amino acid sequence that can be synthesized using standard peptide synthesis methods, thus balancing manufacturing ease with high escape efficiency.
Solution Approach 2:
The invention optimizes specific parameters of the peptide including the number of arginine residues (at least three), the number of hydrophobic aromatic residues (at least three), the total length (6-20 amino acids), and the cyclic conformation. These parameter optimizations achieve 400% improved endosomal escape efficiency while keeping the peptide length and composition within ranges that are amenable to standard synthesis protocols, thereby maintaining ease of manufacture.
3Reliability
If peptides contain multiple arginine residues and hydrophobic aromatic side chains, then membrane penetration and endosomal escape are enhanced, but peptide stability and selectivity challenges arise
Solution Approach 1:
The peptide employs a composite amino acid composition combining basic arginines and hydrophobic aromatic residues in a cyclic structure. This composite design creates a stable configuration where arginines provide electrostatic interactions with anionic endosomal membranes while hydrophobic aromatic residues provide membrane insertion capability through hydrophobic effects and pi-stacking, enhancing overall membrane penetration stability.
Solution Approach 2:
The cyclic peptide segments functional roles between different amino acid types: arginines handle electrostatic membrane binding and the hydrophobic aromatic residues handle membrane insertion. This functional segmentation within the stable cyclic framework allows each component to contribute to membrane penetration while the cyclic structure itself provides structural stability, resolving the contradiction between enhanced penetration and structural stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cyclic peptides demonstrate improved cytosolic delivery efficiency, enhancing delivery by 110% to 400% compared to existing CPPs, and improved endosomal escape efficiency, up to 400%, facilitating effective intracellular delivery of therapeutic and detectable moieties.
Implementation Method 1
CPPs that enter cells via endocytosis must exit from endocytic vesicles in order to reach the cytosol
Implementation Method 2
at least three of the amino acids are arginine
Implementation Method 3
at least three of the amino acids have a hydrophobic side chain selected from an aryl or heteroaryl
Data Source
AI summary
Provided herein are novel cyclic cell penetrating peptides comprising at least two arginines and at least three hydrophobic amino acids. The disclosure also provides methods of using the cyclic cell penetrating peptides to transport cargo into cells and to treat diseases.