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Reprogramming mediated with proteins provides a novel, simpler, and safer strategy for generating induced pluripotent stem cells (iPSCs); in order to efficiently produce the recombination proteins and optimize the gene delivery system, different agents were screened to efficiently transfect plasmid DNA (pDNA) encoding "Yamanaka factor" (Oct 4, Sox 2, Klf 4, or c-Myc) into human embryonic kidney (HEK)-293T cells. The results indicated that 10 μg/mL Poly-MAG (polyethyleneimine (PEI)-MIONP) combined with exogenous magnetic field, 5 μg/mL Lipofectamine® 2000, and 40 μg/mL PEI were, respectively, more suitable to deliver the pDNA encoding Oct 4 into HEK-293T cells in the same transfection reagent groups, but the cell survival rate in 10 μg/mL Poly-MAG treatment group was significantly higher than that in the latter two groups (P < 0.01). "Yamanaka factor" recombination proteins could be extracted and purified from enhanced green fluorescent protein positive (EGFP+) HEK-293T cells. These recombination proteins could be delivered into fibroblasts of miniature pig via the actions of poly-arginine 9R, Poly-MAG, and exogenous magnetic field, producing iPSC-like cells. Furthermore, these iPSC-like cells with MIONPs would be enriched under the action of magnetic force. Therefore, the synergistic action of Poly-MAG and exogenous magnetic field could not only mediate the gene delivery of "Yamanaka factor", but also enhance the transmembrane of functional recombination proteins and enrichment of generated iPSC-like cells, which laid a solid foundation for future safer iPSC-based targeted therapies. [ABSTRACT FROM AUTHOR]

In order to improve the gene-delivering efficiency of polyethylenimine-modified superparamagnetic iron oxide nanoparticle (PEI-SPION) and elucidate the related mechanisms, the binding ratio and protection actions of PEI-SPION to plasmid DNA (pDNA), the physical characteristics of PEI-SPION/pDNA complex, and effects of exogenous factors (including magnetic field, inhibitors, and activator) on gene transfection in human embryonic kidney 293T cells (HEK-293T cells) were explored here. The results showed that the diameter of PEI-SPION was about 45 nm. When PEI-SPION and pDNA encoding Oct 4 (pDNA-Oct 4) were mixed at the mass ratio of 1: 1, the hydrodynamic diameter (299.10 ± 5.01 nm) of conjugate complex was significantly smaller than that of complex at the mass ratio of 1: 2 (469.23 ± 28.86 nm; P < 0.05) or 1: 4 (593.67 ± 20.81 nm; P < 0.01); but its zeta potential was significantly higher than that of these latter two treatment groups, respectively (23.57 ± 0.84 mV vs 18.07 ± 1.03 mV, 14.7 ± 0.44 mV; P < 0.01); if the proportion of PEI-SPION to pDNA-Oct 4 was further adjusted to 1: 8 or 1: 16, the zeta potential of conjugate became negative. DNA binding test also indicated that the combining ability of PEI-SPION to pDNA-Oct 4 was close to saturation state when the mass ratio was 1: 4. The PEI-SPION-mediated transfection efficiency would be significantly enhanced under the auxiliary action of external magnetic field (280 mTesla) for 20 min (P < 0.01). No significantly difference in transfection efficiency was observed among chlorpromazine (CPZ) treatment groups and control group (P > 0.05), and similar results were found for treatments of nystatin. Compared with control group, 2-deoxy-D-glucose (2-DG) and amiloride could significantly decrease the transfection efficiency (P < 0.01), and only 0.3 ± 0.58% cells were successfully transfected with pDNA-Oct 4 in 10 mM 2-DG treatment group. One hundred nanomolar phorbol-12-myristate-13-acetate (PMA) could enhance the cell transfection of pDNA-Oct 4, and the transfection efficiency was increased up to 83.44 ± 2.16%. Therefore, PEI-SPION could efficiently concentrate pDNA-Oct 4 and protect them from the digestion of DNase I. The uptake of PEI-SPION/pDNA-Oct 4 by HEK-293T cell was an energy-consuming process, and the main pathway for this process was macropinocytosis. One hundred nanomolar PMA and external magnetic field could improve the PEI-SPION-mediated gene transfection. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of the behavior of three one-story, two-bay unbonded partially prestressed concrete (UPPC) frames, of which two frames are self-control energy dissipation UPPC frames. This study aims to use the self-control energy dissipation UPPC frame as a new frame, and its seismic performance is evaluated compared to that of existing UPPC frames. The new frame utilizes energy dissipation components to provide energy dissipation capabilities, which allow the frame to form a beam-hinge mechanism under earthquake actions. The influence of the prestress release percentage on the seismic performance of the UPPC frame is experimentally examined. The test results show that the new UPPC frame displays better ductility and energy dissipation capabilities as the prestress release percentage increases, but the lateral resistance is slightly weaker than that of a common UPPC frame. Overall, the new frame displays better seismic performance than the conventional UPPC frame and can be reused after retrofitting. [ABSTRACT FROM AUTHOR]