Carbon nanodot-based self-delivering microRNA sensor to visualize microRNA124a expression during neurogenesis.

MicroRNAs (miRNAs, miRs) are recognized as regulators of gene expression related to cellular development and diseases. In this study, we developed a carbon nanodot (C-dot)-based miR124a molecular beacon (miR124a CMB). The C-dots were purified from candle soot (cC-dots) by thermal oxidation. The double-stranded DNA oligonucleotide containing a miR124a binding site and black hole quencher 1 (miR124a sensing oligo) was further conjugated with the cC-dots to form the miR124a CMB. P19 cells were incubated with the miR124a CMB to sense miR124a expression during neurogenesis. The physical properties of the cC-dots showed multi-color light emission with various excitation wavelengths, a broad size distribution ranging from 2 to 4 nm, a graphitic carbon core (sp2), an abundance of carboxyl groups on the surface, no evidence of cellular toxicity and a high level of self-promoted uptake into cells. The miR124a CMB showed great fluorescence quenching in the absence of miR124a. The miR124a CMB internalized into P19 cells successfully visualized a gradual increase in miR124a expression during neuronal differentiation by providing signal-on imaging activity acquired by the following mechanism: the miR124a, which was highly expressed during neurogenesis, was bound to the miR124a binding site, resulting in the detachment of the quencher from the miR124a CMB and producing fluorescence recovery. The miR124a CMB demonstrated great specificity for sensing miR124a biogenesis with the advantages of self-passivated carboxyl groups, no toxicity, and self-illumination and highly self-promoted cellular uptake which will make the sensing of other various miRNAs related to diseases easy, convenient and accurate.

Effect of Glycosaminoglycans on In vitro Fertilizing Ability and In vitro Developmental Potential of Bovine Embryos.

The glycosaminoglycans (GAGs) present in the female reproductive tract promote sperm capacitation. When bovine sperm were exposed to 10 µg/ml of one of four GAGs (Chondroitin sulfate, CS; Dermatan sulfate, DS; Hyaluronic acid, HA; Heparin, HP) for 5 h, the total motility (TM), straight-line velocity (VSL), and curvilinear velocity (VCL) were higher in the HP- or HA-treated sperm, relative to control and CS- or DS-treated sperm. HP and HA treatments increased the levels of capacitated and acrosome-reacted sperm over time, compared to other treatment groups (p<0.05). In addition, sperm exposed to HP or HA for 1 h before IVF exhibited significantly improved fertilizing ability, as assessed by 2 pronucleus (PN) formation and cleavage rates at d 2. Exposure to these GAGs also enhanced in vitro embryo development rates and embryo quality, and increased the ICM and total blastocyst cell numbers at d 8 after IVF (p<0.05). A real-time PCR analysis showed that the expression levels of pluripotency (Oct 4), cell growth (Glut 5), and anti-apoptosis (Bax inhibitor) genes were significantly higher in embryos derived from HA- or HP-treated sperm than in control or other treatment groups, while pro-apoptotic gene expression (caspase-3) was significantly lower in all GAG treatment groups (p<0.05). These results demonstrated that exposure of bovine sperm to HP or HA positively correlates with in vitro fertilizing ability, in vitro embryo developmental potential, and embryonic gene expression.

Establishment of bovine embryonic stem cell lines using a minimized feeder cell drop.

Bovine embryonic stem cells (ESCs) are a powerful tool for agricultural and biomedical applications. The purpose of this study was to introduce a new method for generating bovine ESCs. Mechanically isolated bovine inner cell masses (ICMs) from in vitro-produced blastocysts were cultured individually on a 10-µL mouse embryonic fibroblast (MEF) feeder cell drop covered with oil. From 126 blastocysts classified by their developmental stage and ICM size, 21 primary bovine ESC-like colonies were formed (16.7%) and established six JNU (Jeju National University)-ibES cell lines (28.6%, 6/21; hatched blastocyst×4, hatching blastocyst×1, and expanded blastocyst×1). These cells exhibited typical ESC morphology, and pluripotency markers were detected through immunocytochemistry, RT-PCR, and real-time RT-PCR, including Oct4, stage-specific embryonic antigen-1 (SSEA-1), Nanog, Tumor rejection antigen-1-81, Rex1, and alkaline phosphatase. Through RT-PCR analysis of spontaneous differentiation, gene expression of all three embryonic germ layers was detected: ectodermal (Pax6 and DBH), mesodermal (CMP and Enolase), and endodermal [alpha fetoprotein (α-FP) and albumin]. In addition, JNU-ibES cell lines were directed differentiated into neuronal (Map2 and Tuj1) and glial (GFAP) cells. Bovine ESC lines had a normal karyotype, with a chromosome count of 58+XY (JNU-ibES-05). This is the first trial investigating a minimized microdrop culture method for the generation of bovine ESCs. These results demonstrated that the minimized MEF feeder cell drop can support the establishment of bovine ESC lines.

Efficient generation of virus-free iPS cells using liposomal magnetofection.

The generation of induced pluripotent stem (iPS) cells is a powerful tool in regenerative medicine, and advances in nanotechnology clearly have great potential to enhance stem cell research. Here, we introduce a liposomal magnetofection (LMF) method for iPS cell generation. Efficient conditions for generating virus-free iPS cells from mouse embryonic fibroblast (MEF) cells were determined through the use of different concentrations of CombiMag nanoparticle-DNA(pCX-OKS-2A and pCX-cMyc)-lipoplexes and either one or two cycles of the LMF procedure. The cells were prepared in a short reprogramming time period (≤ 8 days, 0.032-0.040%). Among the seven LMF-iPS cell lines examined, two were confirmed to be integration-free, and an integration-free LMF-iPS cell line was produced under the least toxic conditions (single LMF cycle with a half-dose of plasmid). This cell line also displayed in vitro/in vivo pluripotency, including teratoma formation and chimeric mouse production. In addition, the safety of CombiMag-DNA lipoplexes for the transfection of MEF cells was confirmed through lactate dehydrogenase activity assay and transmission electron microscopy. These results demonstrated that the LMF method is simple, effective, and safe. LMF may represent a superior technique for the generation of virus-free or integration-free iPS cell lines that could lead to enhanced stem cell therapy in the future.

Improved cloning efficiency and developmental potential in bovine somatic cell nuclear transfer with the oosight imaging system.

In somatic cell nuclear transfer (SCNT) procedures, exquisite enucleation of the recipient oocyte is critical to cloning efficiency. The purpose of this study was to compare the effects of two enucleation systems, Hoechst staining and UV irradiation (hereafter, irradiation group) and Oosight imaging (hereafter, Oosight group), on the in vitro production of bovine SCNT embryos. In the Oosight group, the apoptotic index (2.8 ± 0.5 vs. 7.3 ± 1.2) was lower, and the fusion rate (75.6% vs. 62.9%), cleavage rate (78.0% vs. 63.7%), blastocyst rate (40.2% vs. 29.2%), and total cell number (128.3±4.8 vs. 112.2 ± 7.6) were higher than those in the irradiation group (all p<0.05). The overall efficiency after SCNT was twice as high in the Oosight group as that in the irradiation group (p<0.05). The relative mRNA expression levels of Oct4, Nanog, Interferon-tau, and Dnmt3A were higher and those of Caspase-3 and Hsp70 were lower in the Oosight group compared with the irradiation group (p<0.05). This is the first report to show the positive effect of the Oosight imaging system on molecular gene expression in the SCNT embryo. The Oosight imaging system may become the preferred choice for enucleation because it is less detrimental to the developmental potential of bovine SCNT embryos.