Objective To investigate the ability of gene-loaded lipopolysaccharide-amine nanopolymersomes (LNPs) in inducing osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by in vitro gene transfection, where LNPs were used as a non-viral cationic carrier, and their properties were optimized during synthesis. Methods LNPs were synthesized by a graft-copolymerization method, and the effects of different pH environments during synthesis on physicochemical properties of LNPs and LNPs/plasmid of bone morphogenetic protein 2-green fluorescent protein (pBMP-2-GFP) complexes were explored. Then, optimized LNPs with maximum transfection efficiency and safe cytotoxicity in rat BMSCs were identified by cytotoxicity and transfection experiments in vitro. Thereafter, the optimized LNPs were used to mediate pBMP-2-GFP to transfect rat BMSCs, and the influences of LNPs/pBMP-2-GFP on osteogenic differentiation of BMSCs were evaluated by monitoring the cell morphology, concentration of BMP-2 protein, activity of alkaline phosphatase (ALP), and the formation of calcium nodules. Results The nitrogen content, particle size, and zeta potential of LNPs synthesized at pH 8.5 were lower than those of the other pH groups, with the lowest cytotoxicity (96.5%±1.4%) and the highest transfection efficiency (98.8%±0.1%). After transfection treatment, within the first 4 days, BMSCs treated by LNPs/pBMP-2-GFP expressed BMP-2 protein significantly higher than that treated by Lipofectamine2000 (Lipo)/pBMP-2-GFP, polyethylenimine 25K/pBMP-2-GFP, and the blank (non-treated). At 14 days after transfection, ALP activity in BMSCs treated by LNPs/pBMP-2-GFP was higher than that treated by Lipo/pBMP-2-GFP and the blank, comparable to that induced by osteogenic medium; with alizarin red staining, visible calcium nodules were found in BMSCs treated by LNPs/pBMP-2-GFP or osteogenic medium, but absent in BMSCs treated by Lipo/pBMP-2-GFP or the blank with apoptosis. At 21 days after transfection, transparent massive nodules were discovered in BMSCs treated by LNPs/pBMP-2-GFP, and BMSCs exhibited the morphologic features of osteoblasts. Conclusion LNPs synthesized at pH 8.5 has optimal transfection efficiency and cytotoxicity, they can efficiently mediate pBMP-2-GFP to transfect BMSCs, and successfully induce their directional osteogenic differentiation, whose inducing effect is comparable to the osteogenic medium. The results suggest that gene transfection mediated by LNPs may be a convenient and effective strategy in inducing directional differentiation of stem cells.
Objective To systematically evaluate the clinical value of remote ischemic preconditioning (RIPC) in elective percutaneous coronary intervention (EPCI). Methods We electronically searched databases including PubMed, EMbase, The Cochrane Library (Issue 6, 2015), WanFang Data, CBM and CNKI from inception to June 2016, to collect randomized controlled trials (RCTs) about RIPC in EPCI. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.3 software. Results Nine RCTs involving 1 099 patients were included. The results of meta-analysis showed that: There were no significant difference in the level of troponin I and T between the RIPC group and the control group (SMD=–0.24, 95%CI –0.63 to 0.16,P=0.24). Sensitive analysis showed that with 3×5–min remote preconditioning protocol, there was still no significant difference in the level of troponin I and T between the two groups (SMD=–0.16, 95%CI –0.36 to 0.04,P=0.12). Another, RIPC could significantly reduce the incidence of peri–procedural myocardial infarctions (RD=–0.14, 95%CI –0.20 to –0.08,P<0.000 01) and the risk of ST-segment deviation in the elective PCI procedure (RD=–0.17, 95%CI –0.26 to –0.07,P=0.000 6), but there was no significant difference in postoperative eGFR between both groups (SMD=–0.03, 95%CI –0.18 to 0.12,P=0.71). Conclusion RIPC can significant reduce the incidence of peri-procedural myocardial infarctions, and the risk of ST-segment deviation in the elective PCI procedure. Due to limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusion.