Polyethylenimine-based nanovector grafted with mannitol moieties to achieve effective gene delivery and transfection.

Polyethylenimine (PEI), a kind of cationic non-viral gene delivery vector, is capable of stable and efficient transgene expression for gene delivery. However, low transfection efficiency in vivo along with high toxicity limited the further application of gene therapy in the clinic. To enhance gene transfection performance and reduce cytotoxicity of polyethylenimine, branched polyethylenimine-derived cationic polymers BPEI25 k-man-S/L/M/H with different grafting degree with mannitol moieties were prepared and the transfection efficiency was evaluated. Among them, BPEI25 k-man-L showed the best transfection efficiency, lower toxicity, and significantly enhanced long-term systemic transgene expression for 96 h in vivo even at a single-dose administration. The results of cellular uptake mechanism and western-blot experiments revealed that the mannitol modification of BPEI25 k induced and up-regulated the phosphorylation of caveolin-1 and thus enhanced the caveolae-mediated cellular uptake. This class of gene delivery system highlights a paradigmatic approach for the development of novel and safe non-viral vectors for gene therapy.

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.

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.

[Clinical observation of dry eye in patients before and after cataract surgery].

OBJECTIVE: To investigate dry eye in patients before and after cataract surgery. METHODS: 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ25) and Ocular Surface Disease Index (OSDI) were used for the study in 37 patients (50 eyes) 3 days before cataract surgery and repeated after surgery 1 week, 1 month and 3 months. Slit lamp microscope examination, cornea and conjunctiva fluorescein staining, tear break-up time (BUT), Schirmer test I (STI), impression cytology (IC) were carried out at the same time. RESULTS: After cataract surgery, the incidence of dry eye increased dramatically. Tear river was narrowed, BUT and STI were decreased and shorted in patients after cataract surgery. IC examination showed there was serious squamous metaplasia in epithelial layer of conjunctiva. NEI-VFQ25 was increased from 27.66 +/- 22.08 (before cataract surgery) to 74.69 +/- 11.67 (3 months after cataract surgery). All items of OSDI were remarkable increased, ocular surface abnormal was increased from 2.60 +/- 2.91 (before cataract surgery) to 12.66 +/- 11.40 (3 months after cataract surgery) and environmental trigger was increased from 3.57 +/- 2.67 (before cataract surgery) to 11.40 +/- 10.24 (3 months after cataract surgery). CONCLUSION: Dry eye can be induced or deteriorated after cataract surgery, if it can not be treated on time.