1. Academic Validation
  2. Optimization of the activity and biodegradability of ionizable lipids for mRNA delivery via directed chemical evolution

Optimization of the activity and biodegradability of ionizable lipids for mRNA delivery via directed chemical evolution

  • Nat Biomed Eng. 2024 Nov;8(11):1412-1424. doi: 10.1038/s41551-024-01267-7.
Xuexiang Han 1 2 Mohamad-Gabriel Alameh 3 4 Ying Xu 3 Rohan Palanki 1 Rakan El-Mayta 3 Garima Dwivedi 3 Kelsey L Swingle 1 Junchao Xu 1 Ningqiang Gong 1 Lulu Xue 1 Qiangqiang Shi 1 Il-Chul Yoon 1 Claude C Warzecha 5 James M Wilson 5 Drew Weissman 3 4 Michael J Mitchell 6 7 8 9 10 11
Affiliations

Affiliations

  • 1 Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA.
  • 2 Key Laboratory of RNA Innovation, Science and Engineering, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
  • 3 Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
  • 4 Penn Institute for RNA Innovation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
  • 5 Gene Therapy Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
  • 6 Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA. mjmitch@seas.upenn.edu.
  • 7 Penn Institute for RNA Innovation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. mjmitch@seas.upenn.edu.
  • 8 Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. mjmitch@seas.upenn.edu.
  • 9 Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. mjmitch@seas.upenn.edu.
  • 10 Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. mjmitch@seas.upenn.edu.
  • 11 Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. mjmitch@seas.upenn.edu.
Abstract

Ionizable lipids largely determine the biocompatibility of lipid nanoparticles (LNPs) and the efficacy for mRNA delivery. Rational design and combinatorial synthesis have led to the development of potent and biodegradable ionizable lipids, yet methodologies for the stepwise optimization of ionizable lipid structure are lacking. Here we show that iterative chemical derivatization and combinatorial chemistry, and in particular the amine-aldehyde-alkyne coupling reaction, can be leveraged to iteratively accelerate the structural optimization of propargylamine-based ionizable lipids (named A3-lipids) to improve their delivery activity and biodegradability. Through five cycles of such directed chemical evolution, we identified dozens of biodegradable and asymmetric A3-lipids with delivery activity comparable to or better than a benchmark ionizable lipid. We then derived structure-activity relationships for the headgroup, ester linkage and tail. Compared with standard ionizable lipids, the lead A3-lipid improved the hepatic delivery of an mRNA-based genome editor and the intramuscular delivery of an mRNA vaccine against SARS-CoV-2. Structural criteria for ionizable lipids discovered via directed chemical evolution may accelerate the development of LNPs for mRNA delivery.

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