Nontoxic, Biodegradable Hyperbranched Poly(β-amino ester)s for Efficient siRNA Delivery and Gene Silencing

Area of Science:

• Biomaterials Science
• Gene Therapy
• Nanotechnology

Background:

• RNA interference (RNAi) offers therapeutic potential but faces delivery challenges.
• Non-viral vectors like poly(β-amino esters) (pBAEs) are promising but often require high doses, raising toxicity concerns.
• Optimizing pBAE structure is crucial for efficient and safe siRNA delivery.

Purpose of the Study:

• To design and optimize hyperbranched pBAEs for efficient siRNA condensation and gene silencing.
• To evaluate the performance of these novel pBAEs compared to commercial transfection agents.
• To assess the potential of these pBAEs for delivering siRNA to difficult-to-transfect primary cells.

Main Methods:

• Synthesis and characterization of a series of hyperbranched pBAEs with varying monomer combinations and branching densities.
• In vitro evaluation of siRNA condensation, cytotoxicity, cellular uptake, and gene silencing efficiency in HeLa cells and primary neural cells.
• Comparison of the lead pBAE candidate (h(A2B3)-1) with Lipofectamine 2000.
• Incorporation of bioreducible disulfide bonds into the polymer backbone to enhance cytocompatibility.

Main Results:

• A hyperbranched pBAE, h(A2B3)-1, demonstrated superior siRNA condensation and gene silencing at significantly lower polymer/siRNA ratios and siRNA doses.
• h(A2B3)-1 exhibited lower cytotoxicity and higher transfection efficiency than Lipofectamine 2000 in HeLa cells.
• Effective gene silencing was achieved in hard-to-transfect primary cortical neurons (34.8% knockdown) and oligodendrocyte progenitor cells (53.4% knockdown).
• Incorporation of disulfide bonds further improved cytocompatibility without compromising transfection efficiency.

Conclusions:

• Hyperbranched pBAEs, particularly h(A2B3)-1, represent a highly effective non-viral vector for siRNA delivery.
• These novel polymers offer a promising solution for safe and efficient RNAi-mediated gene silencing, with potential for clinical translation.
• The study provides valuable insights for developing next-generation non-viral gene delivery systems.