Hyperbranched polymeric "star vectors" for effective DNA or siRNA delivery

Area of Science:

• Biomaterials Science
• Gene Therapy
• Polymer Chemistry

Background:

• Gene therapy for inherited disorders faces challenges with current viral and nonviral delivery systems, particularly in achieving efficient in vivo transfection.
• Viral vectors pose risks of negative outcomes, driving interest in nonviral alternatives like cationic polymers.
• Cationic polymers form nanoparticles (polyplexes) with DNA but struggle with in vivo transfection efficiency.

Purpose of the Study:

• To develop novel hyperbranched star vectors (SVs) for enhanced DNA and siRNA delivery.
• To investigate strategies for improving gene transfection efficiency using SVs.
• To evaluate the efficacy of modified SVs for targeted gene delivery and in vivo gene silencing.

Main Methods:

• Molecular design of SVs using living radical polymerization, controlling chain length and branch composition.
• Preparation of cationic poly(N,N-dimethylaminopropyl acrylamide) (PDMAPAAm)-based SVs with varying branching numbers.
• Modification of SVs with ligands (e.g., RGD peptide) for targeted delivery and block copolymerization with nonionic monomers.
• Evaluation of gene expression activity, colloidal stability, and in vivo gene silencing efficacy.

Main Results:

• Gene expression activity increased with SV branching degree, molecular weight, and narrower polydispersity index (PDI).
• RGD-modified SVs enabled gene transfer into endothelial cells, which are typically resistant to transfection.
• Block copolymerized SVs (BSVs) exhibited excellent colloidal stability and efficient in vitro/in vivo gene delivery and siRNA-mediated gene silencing.
• A novel thermoresponsive transfection method using SVs improved gene delivery effectiveness.

Conclusions:

• Hyperbranched star vectors offer a promising nonviral strategy for enhancing gene and siRNA delivery.
• Molecular design, including branching, molecular weight, and PDI, significantly impacts transfection efficiency.
• BSVs demonstrate superior performance for stable gene delivery and effective in vivo gene silencing.
• Novel transfection methods utilizing SVs can overcome limitations of conventional approaches.