Unmet Need
There are significant roadblocks to the routine delivery of macromolecules such as proteins, peptides, imaging agents, polysaccharides and more to the cytosol of mammalian cells. While most macromolecules are easily directed to existing cellular uptake mechanisms, they are often trapped in endosomal pathways leading to lysosomal degradation or recycling without significant entry into the cytosol. Cationic lipids and peptides have been used to successfully deliver nucleic acids to cells; however, these reagents are ineffective at delivering other macromolecules. Extensive research over the past two decades has identified over 1000 cell-penetrating peptides (CPPs) capable of delivering small molecules (mostly fluorescein and biotin) but have not been robustly shown to deliver larger macromolecules. CPPs that are known to deliver macromolecules need to be covalently tethered to their cargo requiring unique chemistry and limiting generalization. The only tool used in basic science research that can reliably deliver any desired macromolecule (other than oligonucleotides) to most cells is electroporation. However, electroporation requires a specialized apparatus and can perturb cells significantly. Delivery through the endocytic pathway, which lacks these impediments, will open new avenues to study complex biochemical processes in cells.
Technology Overview
Johns Hopkins researchers and colleagues at Tulane University have identified cell-penetrating peptides capable of delivering macromolecules while avoiding endosomal degradation and recycling pathways. These peptides are pH sensitive and open up macromolecular sized pores upon endosomal uptake and acidification in a pH and concentration dependent manner. They are inactive at physiological pH and are therefore harmless to the cellular plasma membrane but allow co-encapsulated macromolecules to enter into the cytosol. Importantly, these CPPs are cargo agnostic and enable cellular delivery of any number of macromolecules. Beyond a useful biological research tool, CPPs have the potential to serve as a therapeutic agent delivery platform due to their pH dependent permeabilization mechanism.
Publications
Kim, Sarah Y. et al. “Design of pH Triggered, Macromolecular Pore Forming Peptides for Endosomal Escape.” Biophysical Journal, Volume 110, Issue 3, 415a
U.S. Patent 11,149,068
