The Methodology Study Of Ultrasound And Microbubble Contrast Agent Induced Gene Delivery

Objective Liposomal nano bubbles (NB) have a potential use in ultrasoundmolecular imaging and targeting therapy. Here, a kind of NB was made andinvestigated to observe its basic physical properties and ultrasound contrast enhancedeffect, and compared with a commercial-lipid microbubbles, SonoVue, in vitro and invivo.Methods The liposome was made with the method of reverse phase evaporation,and then the liposome was sonicated to prepare NB. After the physical properties ofNB such as its morphous, average particle size, surface potential and concentrationwere observed and calculated,200μL of saline and two contrast agents (NB andSonoVue) were injected into degassed PBS (10ml) respectively to observe theirenhancing effects. For in vivo study, a healthy rabbit heart and liver were imaged before and after intravenous injection of2.0ml/kg of saline and two contrast agents insuccession to compare their dynamic enhancing effects in the grey scale imagingsubjectively.Results The self-made nano-liposomal bubbles distributed uniformly and its sizeranged from133.1~199.5nm with a mean diameter of (171.6±30.82) nm. Its surfacepotential and concentration were–(1.92±0.65) mV and (3.8~5.6)×108/mlindividually. These basic characteristics were not observed changing dramaticallyafter placement one week to one month under room temperature. The nano-liposomalbubble and SonoVue all displayed significantly enhancing effect comparing withsaline no matter in vitro or in vivo.Conclusion The self-made nano-liposomal bubbles are stable and distributeuniformly, which display the same contrast enhancing effect as the commercialultrasound contrast agent, SonoVue, in vitro and in vivo. The self-made NB wouldhave a more potential use in ultrasound molecular imaging and gene or drug delivery. Objective To investigate whether ultrasound and PEI can enhance plasmid DNAtransfection in HepG2cell synergistically or not.Methods Two kinds of PEI, which one used specifically in gene delivery （sPEI）and the other used just as general industrial materials （iPEI）, were used. Thetoxicity of PEI was determined by trypan blue dye exclusion. The PEIs wereincubated with the plasmid DNA to prepare cationic compounds (PEI/DNA), whichwere added into HepG2cell with or without ultrasound irradiation. After24hours, thetransfection efficiency was assessed by fluorescence microscope and FACS.Ultrasound parameters:1MHz,1W/cm2,20s,20%duty cycle.Results Ultrasound could induce gene delivery in HepG2cell. PEI displayed hightoxic to cell and the concentration of0.001%was used in gene delivery, whichinduced about70%cell survival rate. The two PEI compounds significantly enhancedthe plasmid DNA gene delivery in HepG2cell (P＜0.01) and the transfection rates ofthe iPEI and sPEI were15.42±4.71%and12.27±3.58%respectively. Even though thedifference of the two PEI was not significant (P＞0.05), their transfection rates werehigher than that of the ultrasound group (P＜0.01). On the other hand, PEI withultrasonic irradiation group showed a lower transfection rate compared with the PEIgroups (P＜0.01).Conclusions PEI and ultrasound irradiation all can promote plasmid DNAtransfection in vitro respectively but they do not show synergistically.