Hydrophobization of cationic polymers, as an efficient strategy, had been widely developed in the structure of cationic polymer micelles to improve the delivery efficiency of nucleic acids. However, the distribution of hydrophobic segments in the polymer chains is rarely considered. Here, we have elaborated three types of hydrophobized polyethylene glycol (PEG)-blocked cationic polymers with different distributions of the hydrophobic segments in the polymer chains PEG–PAM–PDP (E–A–D), PEG–PDP–PAM (E–D–A), and PEG–P(AM/DP) (E–(A/D)), which were synthesized by reversible addition–fragmentation chain transfer polymerization of methoxy PEG, cationic monomer aminoethyl methacrylate, and pH-sensitive hydrophobic monomer 2-diisopropylaminoethyl methacrylate, respectively. In aqueous solution, all of the three copolymers, E–A–D, E–D–A, and E–(A/D), were able to spontaneously form nanosized micelles (100–150 nm) (ME–A–D, ME–D–A, and ME–(A/D)) and well-incorporated small interfering RNA (siRNA) into complex micelles (CMs). The effect of distributions of the hydrophobic segments on siRNA delivery had been evaluated in vitro and in vivo. Compared with ME–D–A and ME–(A/D), ME–A–D showed the best siRNA binding capacity to form stable ME–A–D/siRNA CMs less than 100 nm, mediated the best gene-silencing efficiency and inhibition effect of tumor cell growth in vitro, and showed better liver gene-silencing effect in vivo. In the case of ME–(A/D) with a random distribution of cationic and hydrophobic segments, a gene-silencing efficiency higher than Lipo2000 but lesser than ME–A–D and ME–D–A was obtained. As the mole ratio of positive and negative charges increased, ME–D–A/siRNA and ME–A–D/siRNA showed similar performances in size, zeta potential, cell uptake, and gene silencing, but ME–(A/D)/siRNA showed reversed performances. In addition, ME–A–D as the best siRNA carrier was evaluated in the tumor tissue in the xenograft murine model and showed good anticancer capacity. Obviously, the distribution of the hydrophobic segments in the amphiphilic cationic polymer chains should be seriously considered in the design of siRNA vectors.Keywords: amphiphilic cationic polymers; delivery efficiency; distribution of the hydrophobic segments; gene silence; siRNA delivery;

•Hydrodynamics strategy of Dean vortex was utilized to isolate the cells from electrode enhance the cell viability.•An optimized flow rate for cell electroporation was obtained.•The device realized successful electroporation on several cell types with high viability and high transfection rate.•The high-throughput reaching 2.2 ml/min and continuous electroporation were achieved.In this paper, by utilizing a curved channel, where the Dean flow is generated, the cell viability in the microfluidic electroporation chip has been significantly increased. The Dean vortex plays two major roles. Firstly, in the middle region of the curved channel, the cell solution is enveloped by the protective buffer, which keeps cells away from the metal electrodes throughout the electroporation process. Therefore, distasteful effects due to water electrolysis, such as air bubbles, Joule heating and pH changing, are mitigated or avoided. Secondly, in the ending region of the curved channel, the Dean vortex will recombine the split protective flow and neutralize positive and negative ions. Consequently, several hard-to-transfect cell types were successfully transferred with this device. Compared to conventional microfluidic electroporation devices, our electroporation chip can achieve flow-through electroporation with high viability and high transfection rate, while providing a continuous electroporation environment to address large doses of biological transfection requirement.

The drug development of siRNA has been seriously hindered by the lack of an effective, safe and clinically applicable delivery system. The cyclic NGR motif and its isomerization product isoDGR recruit CD13 and integrin as their specific receptors, both of which are overexpressed by tumor and neovascular cells. In this study, a bi-functional peptide, named NGR-10R, was designed and tested for siRNA delivery in vitro and in vivo. Through the formation of peptide/siRNA nanoparticles, RNase resistance was greatly enhanced for the siRNAs. Both FACS and confocal assays revealed that the peptide/siRNA complexes were effectively internalized by MDA-MB-231 cells. Gene silencing assays indicated that anti-Lamin A/C siRNA delivered by NGR-10R robustly repressed gene expression in MDA-MB-231 and HUVEC (a CD13+/αvβ3+ cell). Importantly, the siRNAs were efficiently delivered into tumor tissues and localized around the nuclei, as revealed by in vivo imaging and cryosection examination. In summary, NGR-10R not only efficiently delivered siRNAs into MDA-MB-231 cells in vitro but also delivered siRNAs into tumor cells in vivo, taking advantage of its specific binding to CD13 (neovascular) or αvβ3 (MDA-MB-231). Therefore, the NGR-10R peptide provides a promising siRNA delivery reagent that could be used for drug development, particularly for anti-tumor therapeutics.

Novel, non-invasive biomarkers to diagnose breast cancer with high sensitivity and specificity are greatly desired. Circulating microRNAs (miRNAs) show potential for breast cancer detection, but the existing results appear to be mixed. Using microscale serum, we established a novel serum-direct multiplex detection assay based on RT-PCR (SdM-RT-PCR). Ninety-three miRNAs dysregulated or with functions in breast cancer were selected as candidates, and additional 3 miRNAs were chosen as endogenous controls. We first conducted miRNA profiling of these 96 miRNAs by SdM-RT-PCR using the sera of 25 breast cancer patients at diagnosis prior to treatment and 20 age-matched healthy controls. miRNAs showing significantly different expression levels between patients and controls were further analyzed using a logistic regression model. A miRNA signature was validated in an independent set of 128 serum samples composed of 76 breast cancer patients and 52 healthy controls. In the discovery stage, we identified 23 miRNAs as significantly dysregulated in breast cancer patients compared with healthy controls. Of these, 10 miRNAs were previously identified as dysregulated in breast cancer; 14 miRNAs remained significant after P-values were adjusted by both correction methods. Principal component analysis and hierarchical clustering of these miRNAs separated patients from controls. Furthermore, the 3-miRNA signature (miR-199a, miR-29c, and miR-424) with the highest diagnostic accuracy for distinguishing breast cancer patients from controls by ROC curve analysis (AUC = 0.888) was successfully confirmed in the validation set (AUC = 0.901). Our data demonstrate that the SdM-RT-PCR assay is an effective breast cancer profiling method that utilizes very small volumes and is compatible with Biobank. Furthermore, the identified 3-miRNA signature is a promising circulating biomarker for breast cancer diagnosis.

Microfluidics based continuous cell electroporation is an appealing approach for high-throughput cell transfection, but cell viability of existing methods is usually compromised by adverse electrical or hydrodynamic effects. Here we present the validation of a flow-through cell electroporation microchip, in which dielectrophoretic force was employed to sort viable cells. By integrating parallel electroporation electrodes and dielectrophoresis sorting electrodes together in a simple straight microfluidic channel, sufficient electrical pulses were applied for efficient electroporation, and a proper sinusoidal electrical field was subsequently utilized to exclude damaged cells by dielectrophoresis. Thus, the difficulties for seeking the fine balance between electrotransfection efficiency and cell viability were steered clear. After careful investigation and optimization of the DEP behaviors of electroporated cells, efficient electrotransfection of plasmid DNA was demonstrated in vulnerable neuron cells and several hard-to-transfect primary cell types with excellent cell viability. This microchip constitutes a novel way of continuous cell transfection to significantly improve the cell viability of existing methodologies.

The therapeutic application of small interfering RNA (siRNA) requires safe nanocarriers for specific and efficient delivery in vivo. Herein, PEGylated cationic cerasomes (PCCs) were fabricated by doping a cationic lipid with a hydroxyl group into nanohybrid cerasomes. Multiple properties of PCCs provide a solution to many of the limitations associated with current platforms for the delivery of siRNA. The polyorganosiloxane surface imparts PCCs with higher morphological stability than conventional liposomes. The PEGylation of the cationic cerasome could protect the cerasome nanoparticles from agglomeration and macrophage capture, reduce protein absorption, and consequently prolong the blood circulating time and enhance the siRNA delivery efficiency. In addition, incorporation of the lipid containing a hydroxyl group further facilitates endosome release. Moreover, PCCs were further used to transport siRNA into the cytosol primarily via endocytosis. When applied to systemic administration, PCCs have demonstrated effective delivery into the liver and preferential uptake by hepatocytes in mice, thereby leading to high siRNA gene-silencing activity. All these results show potential therapeutic applications of PCCs-mediated delivery of siRNA for liver diseases.

We have developed a rapid method to optimize the electric parameters of cell electroporation. In our design, a pair of ring-dot formatted electrodes was used to generate a radial distribution of electric field from the center to the periphery. Varied electric field intensity was acquired in different annulus when an electric pulse was applied. Cells were cultured on the microchips for adherent cell electroporation and in situ observation. The electroporation parameters of electric field intensity were explored and evaluated in terms of cell viability and transfection efficiency. The optimization was performed in consideration of both cell viability, which was investigated to decrease as electric field increases, and the transfection rate, which normally increases at stronger electric field. The electroporation characteristics HEK-293A and Hela cells were investigated, and the optimum parameters were obtained. Verified by a commercial electroporation system as well as self-made microchips endowed the optimization with wider meaning. At last, as applications, we acquired the optimal electroporation pulse intensity of Neuro-2A cells and a type of primary cell (human umbilical vein endothelial cell, HUVEC) by one time electroporation using the proposed method.

By introducing a hydrodynamic mechanism into a microfluidics-based electroporation system, we developed a novel laminar flow electroporation system with high performance. The laminar buffer flow implemented in the system separated the cell suspension flow from the electrodes, thereby excluding many unfavorable effects due to electrode reaction during electroporation, such as hydrolysis, bubble formation, pH change, and heating. Compared to conventional microfluidic electroporation systems, these improvements significantly enhanced transfection efficiency and cell viability. Furthermore, successful electrotransfection of plasmid DNA and, more importantly, synthetic siRNA, was demonstrated in several hard-to-transfect cell types using this system.

Oncogenic c-Myc has been described to modulate the expression of a subset of microRNAs (miRNAs), which include miR-22; however, the mechanism through which a miRNA controls c-Myc activity remains unclear. Here we report a novel anti-c-Myc function mediated by miR-22. Ectopically expressed miR-22 inhibited cell proliferation and anchorage-independent growth of human cancer cell lines. Microarray screening and western analyses revealed that miR-22 repressed the c-Myc-binding protein MYCBP, a positive regulator of c-Myc. Consistent with this, reporter assays showed that miR-22-mediated MYCBP gene suppression largely depends on the conserved miR-22 target site within the MYCBP 3′-untranslational region (3′UTR), implying that MYCBP mRNA is a direct miR-22 target. Depletion of MYCBP using small interfering RNA (siRNA) recapitulated the miR-22-induced anti-growth effect on tumor cells, whereas ectopically expressed MYCBP rescued cells from the growth suppression mediated by miR-22. Moreover, repression of MYCBP by miR-22 downregulated a panel of E-box-containing c-Myc target genes. Our results suggest that miR-22 acts as a tumor suppressor through direct repression of MYCBP expression and subsequent reduction of oncogenic c-Myc activities. As c-Myc inhibits the expression of miR-22, we propose a novel positive feedback loop formed by oncogenic c-Myc to accelerate cell proliferation by suppressing miR-22, a potent inhibitor of MYCBP.

To modulate gene expression in research studies or in potential clinical therapies, transfection of exogenous nucleic acids including plasmid DNA and small interference RNA (siRNA) are generally performed. However, the cellular processing and the fate of these nucleic acids remain elusive. By investigating the cellular behavior of transfected nucleic acids using confocal imaging, here we show that when siRNA was co-transfected into cultured cells with other nucleic acids, including single-stranded RNA oligonucleotides, single and double-stranded DNA oligonucleotides, as well as long double-stranded plasmid DNA, they all aggregate in the same cytoplasmic granules. Interestingly, the amount of siRNA aggregating in granules was found not to correlate with the gene silencing activity, suggesting that assembly of cytoplasmic granules triggered by siRNA transfection may be separable from the siRNA silencing event. Our results argue against the claim that the siRNA-aggregating granules are the functional site of RNA interference (RNAi). Taken together, our studies suggest that, independent of their types or forms, extraneously transfected nucleic acids are processed through a common cytoplasmic pathway and trigger the formation of a new type of cytoplasmic granules “transfection granules”.

siRNA technology has not only greatly facilitated functional characterization of new genes, but also presented tremendous potential for becoming the next generation of blockbuster drugs. The technology has penetrated life science research in an extremely fast speed, thus providing a huge knowledge base for siRNA drug development. Significant technical progresses have been achieved over the past ten years towards the research and development of siRNA therapeutics, and several compounds have been put into clinical trials. This review would provide a summary of such progresses.

•Translocation of MALAT-1 from the nucleus to the cytoplasm during G2/M cell cycle phase.•Down-regulation of MALAT-1 expression compromises the cytoplasmic translocation of hnRNP C and leads to cell cycle arrest.•MALAT-1 interacts with hnRNP C to function in cell cycle regulation.As a conserved non-coding RNA gene, transcripts of MALAT-1 localize predominately in the nucleus. However in G2/M cell cycle phase, MALAT-1 transcripts were surprisingly found to translocate from the nucleus into the cytoplasm. Investigation also found that in this process MALAT-1 interacts with an abundant nuclear factor, hnRNP C protein. Using a loss-of-function assay, we found that down-regulation of MALAT-1 expression compromised the cytoplasmic translocation of hnRNP C in the G2/M phase and resulted in G2/M arrest. In addition to characterize the physiological interaction between MALAT-1 and hnRNP C, our study also highlights the role of MALAT-1 in cell cycle regulation.