Modified self-amplifying RNA mediates robust and prolonged gene expression in the mammalian brain

Area of Science:

• Neuroscience
• Biotechnology
• Molecular Biology

Background:

• Self-amplifying RNA (saRNA) modifications, like 5-hydroxymethylcytidine (hm5C), reduce immune responses and extend protein production.
• Lipid nanoparticles (LNPs) are effective delivery vehicles for nucleic acids, including saRNA, for therapeutic applications.

Purpose of the Study:

• To evaluate the protein expression and cell tropism of modified saRNA-LNPs in the mammalian brain.
• To compare the efficacy of hm5C saRNA-LNPs with N1mΨ mRNA for gene expression in neural cells.

Main Methods:

• Modified saRNA encoding fluorescent proteins encapsulated in ALC-0315 LNPs were injected into the mammalian brain.
• Protein expression levels and cell type targeting (tropism) were analyzed over time.
• Comparison of hm5C saRNA-LNPs with N1mΨ mRNA was performed.

Main Results:

• saRNA-LNPs demonstrated robust and sustained protein expression in brain cells for over five weeks.
• Detectable neuronal expression persisted up to three months post-injection.
• hm5C saRNA showed superior performance compared to N1mΨ mRNA.
• saRNA-LNPs transfected astrocytes and neurons at the injection site and exhibited retrograde labeling of neurons.

Conclusions:

• Modified saRNA-LNPs are a potent nonviral gene transduction method for brain cells.
• This technology enables long-lasting gene expression in the central nervous system.
• saRNA-LNPs show promise for neurological gene therapy and research applications.