Enhancing gene transfection of poly(β-amino ester)s through modulation of amphiphilicity and chain sequence

Poly(β-amino ester)s (PAEs) have emerged as a type of highly safe and efficient non-viral DNA delivery vectors. However, the influence of amphiphilicity and chain sequence on DNA transfection efficiency and safety profile remain largely unexplored. In this study, four PAEs with distinct amphiphilicity and chain sequences were synthesized. Results show that both amphiphilicity and chain sequence significantly affect the DNA binding and condensation ability of PAEs, as well as size, zeta potential and cellular uptake of PAE/DNA polyplexes. PAEs with different amphiphilicity and chain sequence exhibit cell type-dependent transfection capabilities: in human bladder transitional cell carcinoma (UM-UC-3), hydrophilic PAE (P-Philic) and amphiphilic PAE random copolymer (R-Amphilic) exhibit relatively higher gene transfection efficiency, while in human bladder epithelial immortalized cells (SV-HUC-1), hydrophobic PAE (P-Phobic), R-Amphilic, and amphiphilic PAE block copolymer (B-Amphilic) demonstrate higher transfection capability. Regardless of cell types, amphiphilic PAE block copolymer (B-Amphilic) always exhibits much lower gene transfection efficiency. In addition, in human colon cancer cells (HCT-116), P-Philic and R-Amphilic achieved superior gene transfection efficiency at high and low polymer/DNA weight ratios, respectively. Importantly, R-Amphilic can effectively deliver the gene encoding tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to human chondrosarcoma cells SW1353 to induce their apoptosis, highlighting its potential application in cancer gene therapy. This study not only establishes a new paradigm for enhancing the gene transfection efficiency of PAEs by modulating their amphiphilicity and chain sequence but also identifies R-Amphilic as a potential candidate for the effective delivery of TRAIL gene in cancer gene therapy.

Cyclization-enhanced poly(β-amino ester)s vectors for efficient CRISPR gene editing therapy

Among non-viral gene delivery vectors, poly(β-amino ester)s (PAEs) are one of the most versatile candidates because of their wide monomer availability, high polymer flexibility, and superior gene transfection performance both in vitro and in vivo. Over two decades, PAEs have evolved from linear to highly branched structures, significantly enhancing gene delivery efficacy. Building on the proven efficient sets of monomers in highly branched PAEs (HPAEs), this work introduced a new class of cyclic PAEs (CPAEs) constructed via an A2 + B4 + C2 cyclization synthesis strategy and identified their markedly improved gene transfection capabilities in gene delivery applications. Two sets of cyclic PAEs (CPAEs) with rings of different sizes and topologies were obtained. Their chemical structures were confirmed via two-dimensional nuclear magnetic resonance and the photoluminescence phenomena, and their DNA delivery behaviours were investigated and compared with the HPAE counterparts. In vitro assessments demonstrated that the CPAEs with a macrocyclic architecture (MCPAEs), significantly enhanced DNA intracellular uptake and facilitated efficient gene expression while maintaining perfect biocompatibility. The top-performance MCPAEs have been further employed to deliver a plasmid coding dual single guide RNA-guided CRISPR-Cas9 machinery to delete COL7A1 exon 80 containing the c.6527dupC mutation. In recessive dystrophic epidermolysis bullosa (RDEB) patient-derived epidermal keratinocytes, MCPAEs facilitated the CRISPR plasmid delivery and achieved efficient targeted gene editing in multiple colonies.

Potent gene delivery from fluorinated poly(β-amino ester) in adhesive and suspension difficult-to-transfect cells for apoptosis and ferroptosis

Tremendous efforts have been made to improve polymeric property in gene delivery performances, especially when obstacle of transferring gene construct into difficult-to-transfect cells occurs. Innovations in the area of fluorination and fluorinated compounds with biomedical potential in medicinal chemistry are believed to assist in the development of new therapeutics. Fluorine modified polymers have shown to navigate the gene transfection cellular barriers and promoted the transfection outcomes. Gene transfer into some liver cancer cells and human leukemia cells has always been a challenge. Here, by facile incorporation of a fluorine containing amine monomer, 1H,1H-undecafluorohexylamine, fluorinated poly(β-amino ester) (FPAE) was synthesized to significantly improve the transfection performance, achieving high transfection efficiency of 87% and 55% in two representative difficult-to-transfect cells, HepG2 and Molt-4, which were cultured in adhesive and suspension condition, respectively. However, the potency of Lipofectamine 3000 was very limited. More importantly, functional studies revealed that FPAE can dramatically outperform Lipofectamine 3000 in delivering Bcl-xL and PKCβII to either provide the protection against apoptosis or promote the ferroptosis in HepG2 cells. This work facilitates gene therapies by overcoming biological barriers for targeting difficult-to-transfect cells and disease models when medically necessary.

Synthesis and characterization of low molecular weight polyethyleneimine-terminated Poly(β-amino ester) for highly efficient gene delivery of minicircle DNA

Gene therapy has held great promise for treating specific acquired and inherited diseases. However, the lack of safe and efficient gene delivery systems remains as the major challenge. Poly(β-amino ester)s (PBAEs) have attracted much attention due to their outstanding properties in biosafety, DNA delivery efficiency and convenience in synthesis. In this paper, we reported the further enhancement of the PBAE functions by increasing its positive charge through conjugating with low molecular weight polyethylenimine (LPEI). The resulted LPEI-PBAE polymer was able to condense minicircle DNA (mcDNA) forming nanoparticles with a diameter of 50-200nm. Furthermore, as compared to parental PBAE and a commercial transfection reagent very common in laboratory application, the LPEI-PBAE demonstrated significantly higher transfection efficiency with little cytotoxicity. These results suggested LPEI-PBAEs are worthy of further optimization for gene therapy applications.

Oligopeptide-terminated poly(β-amino ester)s for highly efficient gene delivery and intracellular localization

The main limitation of gene therapy towards clinics is the lack of robust, safe and efficient gene delivery vectors. This paper describes new polycations for gene delivery based on poly(β-amino ester)s (pBAE) containing terminal oligopeptides. The authors developed oligopeptide-modified pBAE-pDNA nanoparticles that achieve better cellular viability and higher transfection efficacy than other end-modified pBAE and commercial transfection agents. Gene expression in highly permissive cell lines was remarkably high, but transfection efficiency in less-permissive cell lines was highly dependent on oligopeptide composition and nanoparticle formulation. Moreover, the use of selected oligopeptides in the pBAE formulation led to preferential intracellular localization of the particles. Particle analysis of highly efficient pBAE formulations revealed different particle sizes and charge features, which indicates chemical pseudotyping of the particle surface, related to the oligopeptide chemical nature. In conclusion, chemical modification at the termini of pBAE with amine-rich oligopeptides is a powerful strategy for developing delivery systems for future gene therapy applications.