Related Experiment Video
Updated: Mar 14, 2026
Using Lipid Nanoparticles for the Delivery of Chemically Modified mRNA into Mammalian Cells
Published on: June 10, 2022
Efficacy and immunogenicity of unmodified and pseudouridine-modified mRNA delivered systemically with lipid
Kevin J Kauffman1, Faryal F Mir2, Siddharth Jhunjhunwala2
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Abstract:
mRNA has broad potential for treating diseases requiring protein expression. However, mRNA can also induce an immune response with associated toxicity. Replacement of uridine bases with pseudouridine has been postulated to modulate both mRNA immunogenicity and potency. Here, we explore the immune response and activity of lipid nanoparticle-formulated unmodified and pseudouridine-modified mRNAs administered systemically in vivo. Pseudouridine modification to mRNA had no significant effect on lipid nanoparticle physical properties, protein expression in vivo, or mRNA immunogenicity compared to unmodified mRNA when delivered systemically with liver-targeting lipid nanoparticles, but reduced in vitro transfection levels. Indicators of a transient, extracellular innate immune response to mRNA were observed, including neutrophilia, myeloid cell activation, and up-regulation of four serum cytokines. This study provides insight into the immune responses to mRNA lipid nanoparticles, and suggests that pseudouridine modifications may be unnecessary for therapeutic application of mRNA in the liver.
Insights
Pseudouridine modification did not alter messenger RNA (mRNA) immunogenicity or protein expression in vivo. This suggests pseudouridine may be unnecessary for liver-targeted mRNA therapeutics.
Area of Science:
- Biotechnology
- Immunology
- Molecular Biology
Background:
- Messenger RNA (mRNA) holds promise for treating diseases by enabling protein expression.
- However, mRNA can trigger immune responses and toxicity.
- Pseudouridine modification is explored to potentially reduce mRNA immunogenicity and enhance potency.
Purpose of the Study:
- To investigate the immune response and activity of unmodified and pseudouridine-modified mRNA.
- To evaluate systemic delivery of lipid nanoparticle-formulated mRNA in vivo.
- To assess the impact of pseudouridine modification on mRNA properties and immune reactions.
Main Methods:
- Systemic administration of lipid nanoparticle-formulated unmodified and pseudouridine-modified mRNAs in vivo.
- Analysis of lipid nanoparticle physical properties.
- Evaluation of protein expression, immunogenicity, and innate immune response indicators (neutrophilia, myeloid cell activation, serum cytokines).
- In vitro transfection level assessment.
Main Results:
- Pseudouridine modification had no significant effect on lipid nanoparticle physical properties, in vivo protein expression, or mRNA immunogenicity.
- A transient, extracellular innate immune response was observed, including neutrophilia, myeloid cell activation, and increased serum cytokines.
- In vitro transfection levels were reduced by pseudouridine modification.
Conclusions:
- Pseudouridine modification did not significantly impact the in vivo immune response or therapeutic potential of liver-targeted mRNA lipid nanoparticles.
- A transient innate immune response to mRNA lipid nanoparticles was detected.
- Pseudouridine modifications may not be essential for therapeutic mRNA applications targeting the liver.
