Polyplex micelle installing intracellular self-processing functionalities without free catiomers for safe and...

Area of Science:

• Biomaterials Science
• Gene Therapy
• Nanomedicine

Background:

• Gene delivery systems require both high efficiency and safety for clinical translation.
• Previous work established a poly(ethylene glycol) (PEG)-based block catiomer (PEG-PAsp(DET)-cholesteryl) for gene delivery.
• Toxicity and limited transfection efficiency were identified as key challenges for this system.

Purpose of the Study:

• To optimize the safety profile of the PEG-PAsp(DET)-cholesteryl gene delivery system by controlling polymer-plasmid DNA (pDNA) interactions.
• To enhance the transfection efficiency of the optimized system through strategic functionalization.
• To evaluate the therapeutic potential of the enhanced system in a pancreatic tumor model.

Main Methods:

• Quantification of free polymer to determine toxicity origins.
• Preparation of polyplex micelles under optimal conditions to exclude free polymers.
• Functionalization with cyclic (Arg-Gly-Asp) (cRGD) peptide for cellular targeting.
• Utilizing the pH-dependent properties of PAsp(DET) for endosomal escape.
• In vivo evaluation in a pancreatic tumor model using confocal microscopy and gene therapy.

Main Results:

• Toxicity was primarily attributed to unbound polymer, with polyplex micelles showing negligible toxicity.
• Optimal conditions were identified to create safe polyplex micelles with maximal polymer binding and no free polymers.
• Functionalization with cRGD peptide and PAsp(DET) significantly improved cellular uptake and endosomal escape, leading to enhanced transfection.
• The cRGD ligand facilitated vascular targeting of pancreatic tumors, confirmed by in situ imaging.
• Systemic gene delivery of an anti-angiogenic gene resulted in significant therapeutic efficacy against pancreatic tumors.

Conclusions:

• The optimized PEG-PAsp(DET)-cholesteryl formulation offers a safe and effective platform for systemic gene delivery.
• Strategic functionalization overcomes limitations of transfection efficiency and enables targeted therapy.
• This approach holds promise for treating intractable diseases like pancreatic cancer by overcoming physiological barriers.