Thermo-sensitive nanoparticles for triggered release of siRNA

Area of Science:

• Biomaterials Science
• Nanotechnology
• Cancer Gene Therapy

Background:

• Efficient delivery of small interfering RNA (siRNA) is critical for cancer gene therapy.
• Thermo-sensitive polymers offer potential for controlled drug release applications.
• Existing siRNA delivery systems face challenges in targeted and triggered release.

Purpose of the Study:

• To develop novel thermo-sensitive nanoparticles (DENPs) for cold-shock triggered siRNA release.
• To evaluate the efficacy and safety of DENPs for cancer gene therapy.
• To investigate the in vivo biodistribution of DENPs.

Main Methods:

• Synthesis of a thermo-sensitive copolymer: poly(ethylene glycol) methyl ether acrylate-b-poly(N-isopropylacrylamide) (mPEG-b-PNIPAM).
• Construction of DENPs using mPEG-b-PNIPAM and a cationic lipid (DC-Chol) via double emulsion-solvent evaporation.
• Characterization of DENPs using transmission electron microscopy and dynamic light scattering.
• Assessment of siRNA encapsulation efficiency and release kinetics under cold-shock conditions.
• In vitro gene silencing efficacy in HeLa-Luc cells and cell viability assays (MTT).
• In vivo biodistribution studies.

Main Results:

• DENPs demonstrated high siRNA encapsulation efficiency (96.8%), significantly reduced without DC-Chol (23.2%).
• Cold shock treatment induced a thermo-sensitive release of siRNA, with approximately 2.2-fold higher cumulative release after 7 days.
• DENPs/siRNA showed potent in vitro gene silencing in HeLa-Luc cells, enhanced by cold shock.
• Cell viability remained above 80% with DENPs/siRNA up to 200 nM, indicating low toxicity.
• In vivo studies showed preferential accumulation of siRNA in the kidney.

Conclusions:

• DENPs represent a novel, cold-shock responsive nanocarrier for efficient siRNA delivery.
• The cold-shock triggered release mechanism offers a new strategy for nanocarrier design.
• This approach holds promise for advancing cancer gene therapy and the delivery of hydrophilic macromolecules.