Enhanced gene transfection performance and biocompatibility of polyethylenimine through pseudopolyrotaxane formation with α-cyclodextrin.

Polyethylenimine (PEI), a commercially available gene transfection reagent, is a promising nonviral vector due to its inherent ability to efficiently condense genetic materials and its successful transfection performance in vitro. However, its low transfection efficiency in vivo, along with its high cytotoxicity, limit any further applications in gene therapy. To enhance the gene transfection performance and reduce the cytotoxicity of linear polyethylenimine, pseudopolyrotaxane PEI25k/CD and the polyrotaxanes PEI25k/CD-PA and PEI25k/CD-PB were prepared and their transfection efficiencies were then evaluated. The pseudopolyrotaxane PEI25k/CD exhibited better transfection efficiency and lower cytotoxicity than the transfection reagent linear PEI25k, even in the presence of serum. It also showed a remarkably higher cell viability, similar DNA protecting capability, and better DNA decondensation and release ability, and could be useful for the development of novel and safe nonviral gene delivery vectors for gene therapy.

Design and application of cationic amphiphilic ß-cyclodextrin derivatives as gene delivery vectors.

The nano self-assembly profiles of amphiphilic gene delivery vectors could improve the density of local cationic head groups to promote their DNA condensation capability and enhance the interaction between cell membrane and hydrophobic tails, thus increasing cellular uptake and gene transfection. In this paper, two series of cationic amphiphilic ß-cyclodextrin (ß-CD) derivatives were designed and synthesized by using 6-mono-OTs-ß-CD (1) as the precursor to construct amphiphilic gene vectors with different building blocks in a selective and controlled manner. The effect of different type and degree of cationic head groups on transfection and the endocytic mechanism of ß-CD derivatives/DNA nanocomplexes were also investigated. The results demonstrated that the designed ß-cyclodextrin derivatives were able to compact DNA to form stable nanocomplexes and exhibited low cytotoxicity. Among them, PEI-1 with PEI head group showed enhanced transfection activity, significantly higher than commercially available agent PEI25000 especially in the presence of serum, showing potential application prospects in clinical trials. Moreover, the endocytic uptake mechanism involved in the gene transfection of PEI-1 was mainly through caveolae-mediated endocytosis, which could avoid the lysosomal degradation of loaded gene, and had great importance for improving gene transfection activity.

Construction of α-Cyclodextrin-Based Stimuli-Responsive Gene Delivery Nanovectors: In Vitro, Ex Vivo, and In Vivo Investigations.

Stimuli-responsive materials are promising paradigm applied to construct diagnostic and therapeutic intracellular controlled release vectors, while highlighting many challenges and opportunities. In this paper, six α-cyclodextrin-based supramolecular nanovectors were constructed and the efficacy of amine groups, stimuli-responsive profiles and endocytic mechanisms were investigated. The results indicated that the designed supermolecules can compact DNA to form stable complexes and display low cytotoxicity. Among them, PRPEI-2 with suitable PEI amine group exhibited enhanced transfecting performance, high dilution stability, nice serum compatibility, and good acid-responsive profiles to enable endosome escape, significantly higher than commercially available transfecting agent PEI25000, the most effective vector studied to date. The endocytic uptake mechanisms involved in the transfection was mainly through clathrin-mediated pathway, which is closely associated with and can be improved by endosome escape. Moreover, PRPEI-2/DNA polyplex can be effectively expressed in vivo even after 48 h via only single tail-vein injection, and the gene expression and main tissue distribution appeared in the testis, liver, brain and spleen. These excellent characteristics demonstrated that the supramolecular PRPEI-2 represents an excellent prospect as stimuli-responsive nanovectors for gene diagnosis and therapy.