超声靶向微泡破裂联合PEI增强小鼠EGFP基因心肌转染

目的探讨超声靶向微泡破裂(UTMD)联合聚乙烯亚胺(PEI)增强BALB/c小鼠心肌绿色荧光蛋白基因(EG-FP)转染的可行性和应用价值。方法实验分为7组:PBS组、裸质粒组、质粒 超声辐照组(P US)、质粒 SonoVue 超声辐照组(P UTMD)、质粒 PEI组(P PEI)、质粒 PEI 超声辐照组(P PEI US)、质粒 PEI SonoVue 超声辐照组(P PEI UTMD)。由BALB/c小鼠尾静脉注入EGFP质粒和SonoVue微泡或PEI的复合物,处理4d后检测心肌基因表达效率及HE染色,并对超声辐照后的质粒完整性进行分析。结果电泳显示超声辐照不会损坏DNA或PEI/DNA复合物。非超声辐照时,EGFP只在心内膜下层表达;而超声辐照时,表达最强的位置为靠近探头的左室前壁;超声联合PEI时,EGFP的分布差异不明显。P PEI UTMD组的转染率最高,荧光强度最强。结论UTMD联合PEI可高效、靶向地将质粒DNA输送至心肌,这种非侵入性的技术在心脏基因治疗上很有前景,有望应用于迅速发展的心脏病基因疗法。     

超声靶向微泡破裂联合聚乙烯亚胺介导大鼠心肌母细胞Bax基因沉默

目的 探讨超声靶向微泡破裂(ultrasound-targeted microbubble destruction,UTMD)联合聚乙烯亚胺(polyethyleneimine,PEI)的方法转染大鼠心肌母细胞(H9c2细胞)以达到沉默Bax基因的效果.方法 构建靶向Bax基因的shRNA表达质粒,将其与微泡及PEI共同处理后加入H9e2细胞并予以超声辐照,实验分组为:①单纯质粒组;②Lipofectamine2000+质粒组;③UTMD+质粒组;④PEI+ UTMD+质粒组;⑤PEI+ SonoVue+质粒组(无超声辐照).采用荧光显微镜和FCM法评估基因转染效率,应用RT-PCR检测Bax mRNA水平的变化,Western Blot检测蛋白表达情况.结果 超声辐照对所构建的BaxshRNA表达质粒无破坏.H9c2细胞采用UTMD+ PEI处理后,转染率显著高于其他各组(P＜0.05).PT-PCR及Western Blot检测结果显示,PEI+UTMD+质粒组Bax mRNA及Bax蛋白表达抑制率分别为(71.41±4.91)％及(64.09±2.38)％,显著高于其余各组(P＜0.05).结论 超声靶向微泡破裂联合聚乙烯亚胺的方法能有效地沉默H9c2细胞Bax基因的表达.     

载自杀基因的靶向微泡联合超声辐照抑制视网膜母细胞瘤的实验研究

目的探讨载自杀基因的靶向微泡联合超声辐照对视网膜母细胞瘤(RB)的抑制作用。方法制备携带单纯疱疹病毒Ⅰ型胸苷激酶(HSV1-tk)质粒和血管内皮细胞生长因子受体2抗体的靶向微泡,分为空白对照组、细胞+质粒组、细胞+质粒+Sono Vue组、细胞+靶向微泡组、细胞+质粒+超声辐照组、细胞+质粒+Sono Vue+超声辐照组及细胞+靶向微泡+超声辐照组进行实验。荧光显微镜观察各组基因转染情况,流式细胞仪检测转染率,加入丙氧鸟苷(GCV)后检测细胞的抑制率。结果细胞+靶向微泡+超声辐照组的转染率为(24.78±1.04)%,高于细胞+质粒+Sono Vue+超声辐照组(14.31±0.69)%,差异有统计学意义(P0.05)。随着GCV浓度的增加和培养时间的延长,各组抑制率逐渐升高。当GCV浓度为100 mg/L,培养96 h后,细胞+靶向微泡+超声辐照组对RB细胞的抑制率达(92.91±1.71)%。结论加入GCV后,携带HSV1-tk基因的靶向微泡联合超声能有效地抑制RB细胞。     

超声联合聚乙烯亚胺增强MCF-7癌细胞基因表达的转染参数优化

目的 探讨超声辐照并超声造影剂联合聚乙烯亚胺(PEI)增强MCF-7乳腺癌细胞质粒DNA转染的最优条件及协同作用.方法 制备PEI/荧光素酶质粒(pCMV-luciferase-GL3)复合物,用于MCF-7癌细胞基因转染,超声辐照前添加超声造影剂SonoVue.通过荧光素酶活性和细胞存活率的测定,对超声辐照参数进行优化,对质粒浓度、孵育时间、血清、溶媒类型、培养基体积等因素进行分析.结果 细胞活力和荧光素酶活性均受超声强度、辐照时间和占空比的影响,适当条件的超声辐照可促进PEI/DNA复合物渗透入胞内,从而提高质粒DNA的转染率.最优超声辐照条件为1 w/cm2,10%占空比,辐照3 min.超声辐照并超声造影剂联合PEI的转染效率显著高于单纯超声辐照和PEI转染(P<0.01).在超声辐照前将细胞与PEI/DNA复合物共孵育2h时,荧光素酶活性显著增强(P<0.01).此外,血清、培养基体积和溶媒类型也对转染效率有影响.结论 优化的超声和转染参数能显著提高MCF-7癌细胞的基因表达效率.超声辐照并超声造影剂联合PEI对DNA转染效率有协同作用,是一种增强质粒DNA基因表达简单而有应用前景的方法.     

超声辐照联合PEI增强体外基因转染的实验研究

目的 探讨超声辐照联合聚乙烯亚胺(PEI)增强子宫内膜癌细胞(Ishikawa)荧光素酶质粒(pCMV-LUC)基因表达的可行性.方法 以不同氮/磷酸盐比(N/P比)将2种不同分子量PEI与质粒DNA共孵育,制备阳离子复合物(PEI/DNA).利用凝胶阻滞实验测定PEI与DNA形成复合物时所需的比例,运用MTT法比较不同浓度PEI的细胞毒性.通过检测荧光素酶活性和细胞活力,评价不同分子量PEI对基因转染的影响及超声辐照的增强作用.结果 当N/P比达到3或更高时,PEI可有效地缩合质粒DNA.细胞毒性与PEI浓度相关.超声辐照均能提高裸质粒和复合物的荧光素酶活性(P<0.05),但前者的增加幅度显著小于后者(P<0.05),25 kDa显著优于750 kDa(P<0.01).适当的转染条件对细胞活力无明显影响.结论 超声辐照联合25 kDaPEI可明显提高基因转染效率,可为基因治疗提供一种高效的新方法.     

超声微泡靶向破坏转染shRNA沉默Survivin表达诱导裸鼠宫颈癌移植瘤凋亡的研究

目的 通过超声微泡靶向破坏(UTMD)对靶向存活素的短发夹状重组质粒(Survivin-shRNA)进行转染,探讨其凋亡诱导效应、增殖抑制作用及其安全性.方法 将荷人宫颈癌(Hela)裸鼠随机分为三组:质粒+超声辐照(P+US)组,注入质粒溶液后予以超声辐照;质粒+微泡+超声辐照(P+UTMD)组,注入质粒/微泡复合物后辐照;对照组,不予任何处理.对组织样本行组织学检查,采用免疫组化SABC法检测移植瘤增殖细胞核抗原(PCNA)、Survivin、Bcl-2、Bax、Caspase-3、Ki-67、核干细胞因子(NS)、p53蛋白在各组肿瘤标本中的表达.结果 P+UTMD组的PCNA、Ki-67、Bcl-2、Survivin及NS蛋白表达下降,而Bax、Caspase-3、p53蛋白表达明显增加,与对照组及P+US组比较差异均有统计学意义(P＜0.05).结论 UTMD联合Survivin-shRNA能有效沉默Survivin基因表达,具有抑制增殖和促分化的作用,并诱发细胞凋亡,无明显副作用,为癌症基因疗法提供一种高效、无创、有前景的新方法.     

脂质体微泡对超声介导基因转染的增效作用研究

目的 探讨超声介导基因转染时,脂质体微泡(LM)对体内、外红色荧光蛋白基因(RFP)转染的增效作用及其安全性.方法将RFP和LM加入培养的Hela细胞后行超声辐照(US),对微泡浓度、超声强度、辐照时间进行优化研究,运用荧光显微镜、流式细胞术评估基因转染率,并对细胞损伤进行分析.在裸鼠移植瘤的体内实验中,将LM和RFP质粒(P)经尾静脉注入后予以超声辐照(P+LM+US),以单纯质粒注射(P)、P+US、P+LM作为对照,行冰冻切片,组织学检查,RFP表达检测.结果培养的Hela细胞经LM和超声辐照联合处理后,RFP基因转染率显著增加,差异有统计学意义(P＜0.01),在超声强度为1.0 W/cm2、微泡浓度为6%、辐照3 min的条件下最显著,且未发现显著的细胞损伤.P+LM+US组的裸鼠移植瘤内RFP表达显著高于P组、P+US组或P+LM组,差异均有统计学意义(P＜0.01),且未观察到明显的组织损伤.结论 LM对超声介导基因转染的体内、外转染效率有显著的增效作用,而无明显的细胞或组织损伤,为临床基因治疗提供一种新颖、高效、安全的非病毒基因转染方法.     

超声微泡靶向增强RNA干扰质粒转染对移植瘤微血管形成和细胞凋亡的影响

目的 通过超声微泡靶向破坏的方法,选择Survivin作为靶点对短发夹状RNA干扰质粒(pSIREN/S3)进行转染,探讨其对裸鼠移植瘤微血管形成和细胞凋亡的影响.方法 将荷瘤裸鼠分为对照组、超声辐照诱导质粒组及超声微泡靶向破坏诱导质粒组,对组织样本行组织学检查,测定微血管密度(MVD),以末端脱氧核苷酸转移酶标记法(TUNEL)定量检测分析荷瘤裸鼠模型肿瘤组织的凋亡指数(AI).结果 超声微泡靶向破坏诱导质粒组的MVD明显减少,AI明显升高,与对照组及超声辐照诱导质粒组比较,差异均有统计学意义(P＜0.05).结论 超声微泡靶向破坏联合pSIREN/S3质粒敲除Survivin,能使肿瘤组织中血管生成减少,明显诱导细胞凋亡,为恶性肿瘤基因治疗领域的一个新方法.     

超声靶向微泡破坏联合聚乙烯亚胺增强小鼠肌肉基因转染的实验研究

目的 探讨超声(US)靶向微泡(MB)破坏(UTMD)联合聚乙烯亚胺(PEI)对小鼠肌肉基因转染的增强效果.方法 30只Balb/c小鼠随机分为6组,每组5只.绿色荧光蛋白(GFP)质粒DNA (20μg)按下列分组与SonoVue微泡和(或)PEI混合,注入小鼠后肢胫前肌内,然后予以治疗性超声辐照(声强2 W/cm2,占空比50％,超声辐照声强与占空比在实验前予以优化).A组:PBS组(空白对照组);B组:质粒+ US;C组:质粒+MB+ US;D组:质粒+PEI组;E组:质粒+PEI+ US组;F组:质粒+PEI+ MB+US组.10d后处死小鼠,立即取小鼠双后肢胫前肌冰冻切片,荧光显微镜计数GFP阳性肌纤维数.组织同时送检石腊切片,HE染色光镜观察有无炎性损伤及坏死.结果 A组肌肉组织内未见明显绿色荧光;B组可见绿色荧光表达肌纤维,计数为(14±3)个;C组GFP阳性纤维个数(58±6)个,D组(96±7)个,E组(119±11)个,F组(158±18)个.F组的GFP阳性纤维数最多,与其他各组比较差异均有统计学意义 (P＜0.05).各组石腊切片未显示明显的炎症反应和坏死.结论 UTMD联合PEI可显著提高小鼠肌肉组织的基因转染效率.     

超声介导微泡破裂增强体外基因转染的方法学研究

目的 对超声促进基因转染的方法进行系统的优化研究,初步确定超声介导微泡破裂(UMMD)增强体外基因转染的最优参数.方法 选用 Ishikawa、Hela 和 MCF-7 3种细胞系为研究对象,用1 MHz超声仪.超声强度为1.0W/cm2,系统研究不同参数下的细胞活力及两种DNA质粒[红色荧光蛋白质粒(DsRed)和荧光索酶质粒(pCMV-LUC)的基因转染情况,优化UMMD的转染条件(质粒浓度、占空比及辐照时间),分析SonoVue微泡对基因转染的增强作用.结果 基因转染率随着质粒浓度的增加而增高,当质粒浓度达到30 μg/孔时转染率最高,两种DNA质粒的最佳转染浓度相同.与10%占空比的超声辐照相比,20%占空比的转染率显著提高(P＜0.01).辐照3 min时基因表达率最高,但存活率无明显下降(89.03±2.01)%,为最佳辐照时间.无超声辐照时,单独应用质粒或微泡十质粒的样本几乎不表达红色荧光蛋白.与单纯超声辐照相比,超声辐照联合SonoVue微泡可显著提高基因转染效率(P＜0.01).结论 UMMD的转染参数影响转染效率和细胞活力,优化的参数有利于促进基因转染.     

Ultrasound targeted microbubble destruction increases capillary permeability in hepatomas

Ultrasound-targeted microbubble destruction (UTMD) has evolved as a promising tool for organ-specific gene and drug delivery. Taking advantage of high local concentrations of therapeutic substances and transiently increased capillary permeability, UTMD could be used for the treatment of ultrasound accessible tumors. The aim of this study was to evaluate if UTMD can locally increase capillary permeability in a hepatoma model of the rat. Furthermore, we evaluated whether UTMD can transfect DNA into such tumors. Subcutaneous Morris hepatomas were induced in both hind limbs of ACI rats by cell injection. A total of 18 rats were divided into three groups. Only one tumor per rat was treated by ultrasound. The first group received injection of Evans blue, followed by UTMD. The second group received a phosphate-buffered saline solution infusion and ultrasound to the target tumor after Evans blue injection. The third group received UTMD first, followed by Evans blue injection. Tumors and control organs were harvested, and Evans blue extravasation was quantified. Another 12 rats received DNA-loaded microbubbles by UTMD to one tumor, encoding for luciferase. Evans blue injection followed by UTMD showed about fivefold higher Evans blue amount in the target tumors compared with the control tumors. In contrast, no significant difference in Evans blue content was detected between target and control tumors when ultrasound was applied without microbubbles or when UTMD was performed before Evans blue injection. Plasmid transfection was not successful. In conclusion, ultrasound targeted microbubble destruction is able to transiently increase capillary permeability in hepatomas. Using naked DNA, this technique does not seem to be feasible for noninvasive transfection of hepatomas.     

Microbubble ultrasound improves the efficiency of gene transduction in skeletal muscle in vivo with reduced tissue damage

Intramuscular injection of naked plasmid DNA is a safe approach to the systemic delivery of therapeutic gene products, but with limited efficiency. We have investigated the use of microbubble ultrasound to augment naked plasmid DNA delivery by direct injection into mouse skeletal muscle in vivo, in both young (4 weeks) and older (6 months) mice. We observed that the albumin-coated microbubble, Optison (licensed for echocardiography in patients), significantly improves the transfection efficiency even in the absence of ultrasound. The increase in transgene expression is age related as Optison improves transgene expression less efficiently in older mice than in younger mice. More importantly, Optison markedly reduces muscle damage associated with naked plasmid DNA and the presence of cationic polymer PEI 25000. Ultrasound at moderate power (3 W/cm2 1 MHz, 60 s exposure, duty cycle 20%), combined with Optison, increases transfection efficiency in older, but not in young, mice. The safe clinical use of microbubbles and therapeutic ultrasound and, particularly, the protective effect of the microbubbles against tissue damage provide a highly promising approach for gene delivery in muscle in vivo.     

Gene therapy of carcinoma using ultrasound-targeted microbubble destruction

When microbubble contrast agents are loaded with genes and systemically injected, ultrasound-targeted microbubble destruction (UTMD) facilitates focused delivery of genes to target tissues. A mouse model of squamous cell carcinoma was used to test the hypothesis that UTMD would specifically transduce tumor tissue and slow tumor growth when treated with herpes simplex virus thymidine kinase (TK) and ganciclovir. UTMD-mediated delivery of reporter genes resulted in tumor expression of luciferase and green fluorescent protein (GFP) in perivascular areas and individual tumor cells that exceeded expression in control tumors (p = 0.02). The doubling time of TK-treated tumors was longer than GFP-treated tumors (p = 0.02), and TK-treated tumors displayed increased apoptosis (p = 0.04) and more areas of cellular drop-out (p = 0.03). These data indicate that UTMD gene therapy can transduce solid tumors and mediate a therapeutic effect. UTMD is a promising nonviral method for targeting gene therapy that may be useful in a spectrum of tumors. (E-mail: villanuevafs@upmc.edu)     

声学造影剂联合野生型P53质粒治疗大鼠肝癌的实验研究

目的　探讨超声破坏造影剂微气泡介导裸质粒DNA治疗大鼠肝癌的有效性。方法　将 2 4只肝癌模型Wistar大鼠分成 4组。第 1组 ,瘤体内直接注入造影剂和野生型P5 3质粒的混合物 ,立刻用超声照射 ;第2组 ,注射混合物后不用超声照射 ;第 3组 ,注入裸质粒后用超声照射瘤体 ;第 4组 ,仅注入裸质粒而不行超声照射。 2d后 ,用半定量逆转录 -聚合酶链式反应法检测野生型P5 3mRNA在肝癌组织中的表达。结果　第 1组的P5 3mRNA表达明显增强 ,高于其他 3组 (P <0 .0 0 1) ,是第 4组的 6.88倍。第 3组高于未行超声照射组 (P<0 .0 5 ) ,是第 4组的 2 .16倍。第 2组与第 4组在基因表达上的差异无显著性意义 (P >0 .0 5 )。结论　瘤体内直接注射造影剂和野生型P5 3质粒混合物后行超声照射 ,可明显增加裸质粒DNA的转录 ,是一种高效、安全的基因治疗方法。     

Augmentation of cardiac protein delivery using ultrasound targeted microbubble destruction

Gas-filled microbubbles have become an important tool as ultrasonic contrast agents. We have previously shown that ultrasound-targeted microbubble destruction (UTMD) can direct plasmids to the heart. The aim of this study was to evaluate UTMD for protein delivery. Six different groups of rats received 1 microg of luciferase protein with varying protocols: (1) luciferase-loaded microbubbles and ultrasound; (2) luciferase only; (3) luciferase and ultrasound; (4) luciferase-loaded microbubbles; (5) unloaded microbubbles incubated with luciferase and ultrasound; (6) unloaded microbubbles with ultrasound followed by luciferase. Relative luminescence units per mg protein per s were determined in hearts and control organs. The rats that received ultrasound and luciferase-loaded bubbles showed a six-fold higher cardiac luciferase uptake compared with control groups that did not include bubbles. None of the other groups significantly augmented cardiac luciferase activity. We conclude that ultrasound-targeted microbubble destruction can substantially and noninvasively augment organ-specific delivery of proteins.     

Spatial Distribution of Ultrasound Targeted Microbubble Destruction Increases Cardiac Transgene Expression But Not Capillary Permeability

Ultrasound targeted microbubble destruction (UTMD) has evolved as a promising tool for organ specific gene and drug delivery. Using DNA-loaded microbubbles, cardiac transfection has been shown to be feasible. However, two-dimensional properties of the ultrasound beam limit cardiac transgene expression to the focal zone, thus, reducing its potential therapeutic effect. The aim of this study was to test if spatial distribution of ultrasound targeted microbubble destruction in the heart could lead to augmented transgene expression or increased capillary permeability. Lipid microbubbles containing plasmids with a luciferase transgene were used to target rat hearts. The diagnostic ultrasound probe was fixed in a mid-short axis view with a gel stand-off between the chest and probe. Ultrasound (1.3 MHz) with a mechanical index of 1.6 was intermittently applied to rats during microbubble infusion. Rats were randomized to either stay in that position or move horizontally in a cranio-caudal direction (3 mm sweep) relative to the ultrasound probe during UTMD. After 4 days, organs were harvested and analyzed for reporter gene expression. Another group of rats received Evans Blue, followed by UTMD with unloaded microbubbles. Again, rats were randomized into a static or moving group. Hearts were harvested to evaluate extravasation of Evans Blue. Moving rats in a cranio-caudal direction significantly increased transgene expression by 19-fold in the anterior heart, by sixfold in the posterior heart and by 32-fold in the apex. Interestingly, Evans Blue extravasation was not augmented in the moving group. Spatial distribution of UTMD may increase transgene expression due to sonication of larger areas in the heart. In contrast, capillary permeability does not increase, indicating less capillary damage. (E-mail: raffi.bekeredjian@med.uni-heidelberg.de)