Bottlebrush-architectured poly(ethylene glycol) as an efficient vector for RNA interference in vivo

Area of Science:

• Biotechnology
• Polymer Chemistry
• RNA Therapeutics

Background:

• Nonhepatic delivery of small interfering RNAs (siRNAs) is a significant hurdle in developing RNA interference (RNAi) therapeutics.
• Conventional vectors often face challenges related to toxicity, immunogenicity, and inefficient delivery.
• Poly(ethylene glycol) (PEG), while biologically inert and safe, has limitations as a direct vector for nucleic acids.

Purpose of the Study:

• To engineer a novel noncationic vector for enhanced siRNA delivery beyond the liver.
• To transform linear PEG into a bottlebrush architecture for improved siRNA conjugation and stability.
• To evaluate the in vivo pharmacokinetics, biodistribution, and therapeutic efficacy of the novel siRNA conjugates.

Main Methods:

• Conjugation of siRNA to a bottlebrush polymer architecture based on poly(ethylene glycol) (PEG).
• Characterization of the resulting PEG-siRNA conjugates for nuclease stability and cellular uptake.
• Pharmacokinetic studies in vivo to assess blood elimination half-life and area under the curve (AUC).
• Biodistribution analysis to determine tumor uptake and liver capture.

Main Results:

• The bottlebrush PEG-siRNA conjugates demonstrated significantly increased nuclease stability and cellular uptake compared to unmodified siRNA.
• Pharmacokinetic profiling revealed a ~25-fold increase in blood elimination half-life and a ~19-fold increase in AUC.
• Enhanced tumor uptake and reduced liver accumulation were observed, indicating improved biodistribution.
• Efficient in vivo gene knockdown was achieved without apparent toxic or immunogenic responses.

Conclusions:

• The bottlebrush polymer architecture effectively transforms biologically inert PEG into a functional vector for siRNA delivery.
• This noncationic, PEG-based system offers a promising strategy for nonhepatic delivery of siRNA therapeutics.
• The technology exhibits potential for broad impact in the field of RNA interference-based medicines due to its simplicity, safety profile, and efficacy.