IMX Seminar Series - Stimuli-Responsive Coacervates as Universal Carriers for Intracellular Delivery of Macromolecular Therapeutics

Macromolecular therapeutics (peptides, proteins, mRNAs, plasmid DNAs, etc…) hold vast therapeutic potential across human disease states by providing opportunities to address targets that have proven refractory to traditional approaches. However, a critical impediment for the successful application of these modalities is their inability to cross cellular membranes, preventing access to intracellular targets. Current approaches to solve this key issue are based on nanoscale carriers to deliver the payloads, which however have several drawbacks including a tendency to get entrapped in endosomal compartments, poor biodistribution, and in some cases dose-limiting toxicity. Bypassing endosomal entrapment for direct cytosolic payload delivery is an attractive alternative approach but current methods suffer from their own pitfalls. For example, the carriers are typically limited to delivery of a particular therapeutic modality or to relatively low molecular weight (MW) cargos. Furthermore, many approaches involve laborious synthetic procedures and/or encapsulation processes using organic solvents that can decrease bioactivity of the therapeutic cargo.
In this talk, I will present a unifying delivery strategy of macromolecular therapeutics recently developed by our team that is cargo-agnostic, does not cross the cell membrane through classic endocytosis, and non-cytotoxic. This new method exploits Liquid-Liquid Phase Separation (LLPS) of engineered peptides self-assembling into therapeutic-carrying coacervate microdroplets that are capable to release their cargo in the cytosol. These peptide microdroplet carriers benefit from several unique advantages that set them apart from other approaches:

(1) A remarkable wide range of therapeutics can be quickly recruited in the droplets, from short therapeutic anti-cancer stapled peptides to very large enzymes (430 kDa) to mRNAs;
(2) The recruitment process is rapid and carried out under aqueous environments, thus preserving bioactivity of the therapeutics. Furthermore, the recruitment efficiency is above 90% in all tested macromolecular therapeutics tested so far;
(3) The coacervates readily cross the cellular membrane, bypassing classical endocytosis pathways to enter in the cytosol;
(4) The side-chains of the peptides are conjugated with a redox-responsive moiety, which triggers disassembly of the droplets in the reducing environment of the cell, leading to efficient payload release;
(5) Finally, we have demonstrated that the bioactivity of the released therapeutics is retained in the cell and that mRNAs exhibit high transfection efficiency.

Together, this platform thus represents a general and robust strategy for the intracellular delivery of a range of macromolecular modalities with promising potential for the treatment of a spectrum of human diseases such as cancers, metabolic diseases, or genetic disorders. Furthermore, these peptide coacervates could also be used as novel carriers for next-generation mRNA-based therapeutics.
References

1.    Sun, Y., Lim, Z. W., Guo, Q., Yu, J. & Miserez, A. Liquid–Liquid Phase Separation of Proteins and Peptides Derived from Biological Materials: Discovery, Protein Engineering, and Emerging Applications. MRS Bull 45, 1039–1047 (2020). 

2.    Sun, Y., Lau SY. Lim, ZW., Chang, SC., Ghadessy, F., Partridge, A. & Miserez, A. Phase-Separating Peptides for Direct Cytosolic Delivery and Redox-Activated Release of Macromolecular Therapeutics. Nature Chemistry, in press, (2022).
       https://www.nature.com/articles/s41557-021-00854-4
Bio: Ali Miserez is a Full Professor of Biomimetic and Bioinspired Materials at Nanyang Technological University (Singapore), which he joined in 2009, with joint appointments in the School of Materials Science and Engineering and the School of Biological Sciences. He obtained his PhD (2003) from EPFL (Switzerland) in the field of composite and mechanics of materials. From 2004 to 2009, he was a post-doctoral fellow at UC Santa Barbara, working in the lab of Herbert Waite where he expanded his research towards biomimetic engineering and biochemistry of extra-cellular tissues. Miserez’s research aims at revealing the molecular, physico-chemical, and structural principles from unique biological materials, and at translating their molecular design into novel biomimetic materials, including for healthcare applications. At NTU, he is currently the founding Director of the “Center for Sustainable Materials”.

His interdisciplinary research has been published in over 100 articles in a wide range of journals across the Physical and Life Sciences, including in Science, Nature Materials, Nature Biotechnology, Nature Chemical Biology, Nature Chemistry,Biomacromolecules, ACS Nano, Acta Biomaterialia, Advanced Materials, J. Biological Chemistry, Polymer Chemistry, etc. He has delivered numerous invited talks, including at Gordon Research Conferences in the field of bioinspired materials and biomineralization.