BACKGROUND:Cationic liposome-mediated celltransfection is reliable and repeatable. However the transfection efficiency is often low.
OBJECTIVE:To study the optimized methods for gene transfection mediated by liposome into N2a cells (mouse neuroblastma cells).
METHODS:Using traditional adherent method and improved suspension method, 500 ng recombinant plasmid pcDNA3-GFP carrying green fluorescence protein was transfected into N2a cells in 24-wel culture plate, which was mediated by 1.5μL Lipofectamine?LTX Reagent. The expression of green fluorescent protein was observed by inverted fluorescence microscope, and the transfection efficiencies at different transfection ways were calculated. By using improved suspension transfection method, 500 ng plasmid DNA was transfected with different doses of Lipofectamine?LTX Reagent (1.0, 1.5, 2.0, 2.5μL). The optimal ratio of liposome and DNA was explored.
RESULTS AND CONCLUSION:The transfection efficiency of suspension transfection method was significantly higher than that of the tranditional adherent method (P<0.01) when using 1.5μL liposome/500 ng DNA. The transfection efficiency of the 1.0, 1.5, 2.0, 2.5μL Lipofectamine?LTX on 500 ng plasmid DNA was respectively (76.60±3.85)%, (80.00±4.17)%, (88.00±5.89)%, (54.96±4.23)%. It showed the 500 ng DNA and 2.0μL liposome achieve the highest transfection efficiency.

AIM: To investigate the process of human bone marrow stromal cells (hBMSCs) differentiation into neural-like cells and to determine the role of 26S proteasome in neuronal differentiation. METHODS: Purified hBMSCs were treated with β-mercaptoethanol (β-ME) for 1 day and retinoic acid (RA) for 3 days, followed by growth factor (10 μg/L bFGF or 20 μg/L NGF) for another 3 days. Immunofluorescence was performed to detect the expression of nestin (a neural precursor cells marker), Tuj1 (a premature neuronal marker), and neurofilament (NF, a mature neuronal marker) at all stages of induced differentiation. Immunostaining and RT-PCR were used to analyze the expression of 26S proteasome during neuronal differentiation of hBMSCs. To further confirm the role of 26S proteasome in hBMSCs differentiation, cells were treated with β-ME/RA and then followed by protesome inhibitor MG132 and growth factor. Immunostaining was performed to detect NF-positive cells. RESULTS: Quantification results showed that the untreated cells were almost never positive for nestin, Tuj1 and NF. After treated with β-ME/RA, the numbers of nestin-positive cells (34.41%±1.27%) and Tuj1-positive cells (27.79%±1.27%) were increased. Notably, the numbers of NF-positive cells were significantly increased to 56.72%±2.4% after induction with β-ME/RA/GF. Immunofluorescence analysis showed that undifferentiated hBMSCs cells were weakly stained by antibody against 26S proteasome, but the numbers of cells with high-intensity of 26S proteasome were increased after treated with β-ME/RA. The RT-PCR result of 26S proteasome further confirmed that the mRNA level of the cells differentiated by β-ME/RA (1.33), as well as by β-ME/RA/GF (1.77), was significantly increased compared to the undifferentiated cells. Moreover, hBMSCs incubated with protesome inhibitor MG132 significantly decreased the numbers of NF-positive cells (37.59%±1.52%). CONCLUSION: After induction with β-ME/RA/GF, hBMSCs can be differentiated into neural-like cells, which is concomitant with the increase in 26S proteasome expression. Inhibitor of 26S protesome prevents hBMSCs differentiation, suggesting that 26S proteasome may be involved in the differentiation of hBMSCs into neural-like cells.

Objective To explore the status and influencing factors of surgical site infection (SSI)following lapa-roscopic surgery in patients in department of general surgery,so as to take effective measures to reduce SSI. Methods Active monitoring method was used to survey SSI among 401 patients undergoing laparoscopic surgery from January 1 ,2013 to December 31 ,2013,univariate analysis and multivariate analysis on risk factors for SSI were conducted.Results Of 401 investigated patients,12 (2.99%)developed SSI.Univariate analysis showed that risk factors for SSI in patients with laparoscopic surgery were elderly patients,emergency operation,infected wound,gastrointestinal tract operation,and grade Ⅳof ASA score (all P <0.05 ).Multivariate logistic regression analysis revealed that elderly patients (OR,5.02[95%CI ,1 .38 -30.25]),emergency operation (OR,4.37 [95%CI ,1 .96-28.55]),infected wound (OR,7.27[95%CI ,2.54-25.05]),and gastrointestinal tract operation (OR, 8.13 [95%CI ,1 .38 - 18.33 ])were high risk factors for SSI following laparoscopic surgery (all P < 0.05 ). Conclusion Thereare multiple factors influencing SSI after laparoscopic surgery,diversified prevention and control measures can effectively reduce the incidence of postoperative SSI.

BACKGROUND:It is not fuly understood that whetherp53 inhibitor can directly intervene in the viability of bone marrow mesenchymal stem cels and the possible mechanism. OBJECTIVE:To investigate the effect of p53 inhibitor, PFT-α, on the aging process of bone marrow mesenchymal stem cels in late-phase amplification and to discover the key target to delay the replicative senescence of human bone marrow mesenchymal stem cels. METHODS:The expression levels ofp53,p21, andp15 mRNA in human bone marrow mesenchymal stem cels in both early and late-phase amplification were detected by quantitative PCR assay. Then, human bone marrow mesenchymal stem cels in late-phase amplification were respectively treated with 20 μmol/L PFT-α or an equivalent amount of dimethyl sulfoxide for 2 weeks. The positive rate of aging cels was determined by SA-β-Gal staining. The apoptosis was detected by TUNEL staining. Human bone marrow mesenchymal stem cels were treated with 300 μmol/L H2O2 for 30 minutes, and then celular anti-oxidative stress capacity was detected by cel counting kit-8 assay. RESULTS AND CONCLUSION:The quantitative PCR assay showed that the mRNA expression level ofp15, p21 andp53 in human bone marrow mesenchymal stem cels in late-phase amplification was significantly increased (1.45±0.23), (1.51±0.14) and (1.78±0.14) times as much as that in early phase amplification (P < 0.05). The positive rate of aging cels in PFT-α group was significantly lower than that in the dimethyl sulfoxide group[(41±5)%vs. (63±7)%,P < 0.05)]. However, there was no significant difference in apoptosis rate between PFT-α group and dimethyl sulfoxide group. After treatment with H2O2, the absorbance value in the PFT-α group was(1.27±0.13) times as much as that in the dimethyl sulfoxide group (P < 0.001). The above results demonstrate that the activation ofp53 signaling pathway may be an important factor of causing aging of human bone marrow mesenchymal stem cels. Application ofp53 inhibitor PFT-αcan enhance the anti-oxidative stress capacity of human bone marrow mesenchymal stem cels in late phrase amplification.