Nanoparticle-mediated delivery of siRNA into zebrafish heart: a cell-level investigation on the biodistribution and gene silencing effects.

Nanomaterials hold promise for the delivery of nucleic acids to facilitate gene therapy in cardiac diseases. However, as much of the in vivo study of nanomaterials was conducted via the "trial and error" method, the understanding of the nanomaterial-mediated delivery in cardiac tissue was limited to the gross efficiency in manipulating the gene expression while little was known about the delivery process and mechanism in particular at the cell level. In this study, small interfering RNA (siRNA) nanoparticles formulated with a polyamidoamine (PAMAM) nanomaterial were applied to the injured heart of zebrafish. The distribution of nanoparticles in cardiomyocytes, endothelial cells, macrophages and leukocytes was quantitatively analyzed with precision at the cell level by using transgenic models. Based on the distribution characteristics, gene silencing effects in a specific group of cells were analyzed to illustrate how siRNA nanoparticles could get potent gene silencing in different cells in vivo. The results elucidated the heterogeneous distribution of siRNA nanoparticles and how nanoparticles could be efficient despite the significant difference in cellular uptake efficiency in different cells. It demonstrated a paradigm and the need to decouple cellular processes to understand nanoparticle-mediated delivery in complex tissue and the investigation/methodology may lead to important information to guide the design of advanced targeted drug-delivery systems in heart.

Engineering Escherichia coli to bind to cyanobacteria.

We engineered Escherichia coli cells to bind to cyanobacteria by heterologously producing and displaying lectins of the target cyanobacteria on their surface. To prove the efficacy of our approach, we tested this design on Microcystis aeruginosa with microvirin (Mvn), the lectin endogenously produced by this cyanobacterium. The coding sequence of Mvn was C-terminally fused to the ice nucleation protein NC (INPNC) gene and expressed in E. coli. Results showed that E. coli cells expressing the INPNC::Mvn fusion protein were able to bind to M. aeruginosa and the average number of E. coli cells bound to each cyanobacterial cell was enhanced 8-fold. Finally, a computational model was developed to simulate the binding reaction and help reconstruct the binding parameters. To our best knowledge, this is the first report on the binding of two organisms in liquid culture mediated by the surface display of lectins and it may serve as a novel approach to mediate microbial adhesion.

A Neutralized Noncharged Polyethylenimine-Based System for Efficient Delivery of siRNA into Heart without Toxicity.

Cationic polymers constitute an important class of materials in development of delivery vehicles for nucleic acid-based therapeutics. Among them, polyethylenimine (PEI) has been a classical cationic carrier intensively studied for therapeutic delivery of DNA, RNA, and short RNA molecules to treat diseases. However, the development of PEI for in vivo applications has been hampered by the inherent problems associated with the material, particularly its cytotoxicity and the instability of the nucleic acid complexation systems formed via electrostatic interactions. Here, we demonstrate a strategy to modify PEI polymers via hydrazidation to create neutralized, stable, and multifunctional system for delivering siRNA molecules. Through substitution of the primary amino groups of PEI with neutral hydrazide groups, cross-linked nanoparticles with surface decorated with a model targeting ligands were generated. The neutral cross-linked siRNA nanoparticles not only showed favorable biocompatibility and cell internalization efficiency in vitro but also allowed for significant tissue uptake and gene silencing efficiency in zebrafish heart in vivo. Our study suggests transformation of conventional branched PEI into a neutral polymer that can lead to a new category of nonviral carriers, and the resulting functional delivery systems may be further explored for development of siRNA therapeutics for treating cardiovascular disease/injury.

Farmers' attitudes toward mandatory water-saving policies: A case study in two basins in northwest China.

China began to implement stringent water-saving policies in 2012. Mandatory water-saving measures implemented in arid inland river basins include the measures of allocating surface water among upper, middle and lower beaches, restricting household agricultural water use, closing wells, reducing farmland and increasing water prices. These measures have negative influences on the agricultural production of farmers. This study aimed to reveal the demographic and psychological correlates of farmers' attitudes toward these policies. The participants included 672 farmers in the Heihe River Basin and the Shule River Basin in northwest China. Structural equation analyses showed that farmers' awareness of the beneficial consequences of restricting household agricultural water and their perception of policy enforcement had significant relationships with their attitudes toward water-saving policies, whereas the effects of the New Ecological Paradigm and collectivism on farmers' attitudes were mediated through their awareness of beneficial consequences and their perception of policy enforcement. Multivariable regression analyses revealed that as a whole, there were no significant correlations between demographic variables and farmers' attitudes. Policy implications include propagandizing these policies among local farmers, strengthening open and fair policy enforcement, and cautiously using water prices as an instrument to control irrigation water.