Decationized polyplexes as stable and safe carrier systems for improved biodistribution in systemic gene therapy

Area of Science:

• Biomaterials Science
• Nanotechnology
• Gene Therapy

Background:

• Polycation-based gene delivery vectors exhibit high in vitro transfection but suffer from significant toxicity and poor in vivo performance, limiting clinical applications.
• Conventional polycation systems face challenges due to their inherent cationic nature, leading to undesirable side effects and reduced efficacy in systemic delivery.

Purpose of the Study:

• To evaluate the applicability of decationized polyplexes, based on neutral polymers, for systemic administration.
• To compare the stability, safety, biodistribution, and in vivo gene expression of decationized polyplexes against their cationic counterparts.

Main Methods:

• Decationized polyplexes were prepared via a three-step process: condensation, disulfide crosslinking, and decationization, forming a pHPMA core with entrapped pDNA and a PEG shell.
• Stability in plasma was assessed using fluorescence single particle tracking (fSPT). Cytocompatibility was evaluated with MTT assays on HUVEC cells, and safety was tested in zebrafish assays.
• Biodistribution and tumor accumulation in tumor-bearing mice were monitored using noninvasive optical imaging of NIR dye-labeled polyplexes. In vivo transgene expression was confirmed by histology.

Main Results:

• Decationized polyplexes exhibited stable size distribution in plasma for 48 hours, unlike cationic polyplexes.
• Neutral polymers showed excellent cytocompatibility, and decationized polyplexes displayed low teratogenicity and mortality in zebrafish assays.
• Systemic administration in mice revealed increased circulation time and higher tumor accumulation of decationized polyplexes, leading to reporter transgene expression in tumors.

Conclusions:

• Decationized polyplexes represent a promising platform for developing safer polymeric gene delivery vectors.
• These neutral vectors demonstrate superior stability, reduced toxicity, and improved biodistribution for effective systemic administration.
• The enhanced properties of decationized polyplexes pave the way for their potential clinical application in gene therapy.