中国科技论文统计源期刊 中文核心期刊
美国《化学文摘》《国际药学文摘》
《乌利希期刊指南》
WHO《西太平洋地区医学索引》来源期刊
日本科学技术振兴机构数据库（JST）
第七届湖北十大名刊提名奖
美国《化学文摘》《国际药学文摘》
《乌利希期刊指南》
WHO《西太平洋地区医学索引》来源期刊
日本科学技术振兴机构数据库（JST）
第七届湖北十大名刊提名奖
在癌症基因治疗领域,鉴于siRNA序列的简单和有效性,其递送载体的设计吸引了人们越来越多的关注。由于siRNA可被RNA酶快速降解和肾脏滤过,因此需要一个递送载体用于将其有效地运输到靶细胞。到目前为止,已研发出多种阳离子脂质、聚合物或无机纳米颗粒等递送制剂,用于将其递送至实体肿瘤。该文对siRNA递送载体的设计策略包括提高载体稳定性、触发响应释放、靶向识别以及内涵体逃逸能力等设计策略进行了总结和分析,并对未来的设计要求进行了展望。
目前研究中的siRNA可用于多种实体瘤的治疗,包括肝癌、胰腺癌、肺癌、前列腺癌、乳腺癌和卵巢癌等。其中,靶向血管内皮生长和Polo样激酶1基因的用于肝癌治疗的两个基于脂质载体siRNA药物ALN-VSP02和TKM-080301已经完成Ⅰ期临床试验。另外,用于治疗胰腺癌的基于聚合物载体的siRNA植入剂siG12D LODER已进入Ⅱ期临床试验。而用于治疗肺癌、前列腺癌、乳腺癌和卵巢癌的siRNA递送制剂仍处于早期动物实验阶段。
siRNA发挥作用之前需要通过层层关卡,目前已经研发了多种递送载体用于将治疗性siRNA全身递送到实体瘤中[6],以保护脆弱的siRNA免受酶降解,避免被肾脏快速过滤以及吞噬细胞的截留,并进一步从血液外渗到肿瘤组织。siRNA一旦到达肿瘤组织,它们需要:①被癌细胞内化;②从内涵体逃逸到细胞质中;③最终释放siRNA以形成RISC。这就对siRNA递送载体提出了许多要求,笔者对目前siRNA递送策略进行梳理和分析,为相关设计提供参考。
体内注射siRNA载体系统后,必须保持其在血液循环系统中的稳定性,以防止被核酸酶RNase降解,以及网状内皮系统清除。因此用于递送siRNA的载体系统应具有以下特征:①在血液循环中保持稳定;②选择性地从稳定结构中向细胞质中释放siRNA;③具有靶向识别能力;④具有内涵体逃逸功能。
1.1.1 静电相互作用稳定的载体系统 阳离子脂质可与带负电的siRNA 通过静电相互作用较容易的形成纳米粒,阳离子聚合物材料包括树枝状或线性的聚乙烯亚胺(polyethyleneimine,PEI)、聚赖氨酸(poly-L-lysine,PLL)、基于环糊精的多聚阳离子材料等均可通过静电作用与siRNA自组装形成纳米粒,从而保护siRNA不被核酸酶降解。通过提高递送载体与siRNA的静电相互作用可提高递送载体的稳定性。例如提高PEI中仲胺和叔胺基团的质子化能够增强其表面电荷浓度,PEI与siRNA的结合就会越紧密,使递送载体系统更难解离。除提高PEI表面正电荷浓度外,也可用PLL-聚乙二醇(PEG)共聚物来延长siRNA体内的循环时间。相比于低分子量的PLL(分子量7 000),高分子量的PLL(分子量28 000)更能增加siRNA在血液中的循环时间。聚乙二醇将亲水性的长链PEG部分引入阳离子聚合物PEI中,可提高PEI-siRNA复合物的稳定性,同时降低PEI的毒性。
1.1.2 疏水相互作用稳定的载体系统 通过提高疏水相互作用可提高递送载体的稳定性,例如烷基链、胆固醇的引入可以通过疏水相互作用促进载体分子结构与siRNA进行自发组装,使递送载体更难解离。与未修饰的阳离子组分比较,疏水化的阳离子组分和siRNA之间缔合数的增加提高了载体在含血清培养基中的稳定性[9]。疏水性的递送载体能够提高siRNA装载有效性,从而更有效地被细胞摄取,增强癌细胞中内源基因的沉默效率。
然而,在血清培养基中高稳定性不一定能保证其血液系统中的稳定性。有报道将PEG聚阳离子疏水化后,装载siRNA,尾静脉注射后,血液循环时间只增加10 min[10]。所得的递送载体在肿瘤皮下模型中表现出较差的肿瘤生长抑制效果,这表明将简单的疏水部分引入阳离子组分不足以增加载体在血液系统中的稳定性。将亲水性siRNA与阳离子疏水核心有效隔离可提高载体系统稳定性,因为疏水性组分可更紧密地包装在载体颗粒的核心中,没有亲水性siRNA和聚阳离子的干扰。与没有疏水部分分隔的对照载体比较,该载体在血液系统中呈现出更好的稳定性。
内化的递送载体需要将siRNA释放到细胞质中,以便于与RISC蛋白结合。siRNA的触发响应释放可以通过设计响应细胞内外3种不同的生物信号(氧化还原电位、pH和ATP浓度)以释放包封的siRNA。其设计策略可分为两类:一类是通过化合键将siRNA共价连接到递送载体中。另一类是将组建载体系统的构建单元分子设计成具有信号响应性。两种策略都可触发siRNA在靶细胞中的快速释放。
1.2.1 氧化还原电位响应递送载体 肿瘤细胞内内源性还原物质谷胱甘肽(glutathione,GSH)的浓度为0.5~10 mmol·L-1,但在血浆中降低至10~30 μmol·L-1 [11]。这种差别使得含二硫键载体分子在细胞质中快速断裂,而在血液循环期间降解缓慢。CAVALIERI 等[12]将聚赖氨酸通过二硫键与PEG相连接,而后通过介孔硅模板法制备了包载siRNA的具有中空结构的纳米囊。前列腺癌细胞实验表明,siRNA快速释放至细胞质中,并导致59%靶基因沉默。有文献报道,将PEG-聚阳离子侧链中的伯胺基团用2-亚氨基四氢噻吩修饰,以引入游离硫醇基团和胺基团[13]。所得二硫化物交联的递送载体具有直径为40~50 mm的硫醇盐内核结构,并且呈电中性,ζ电位为0.1 mV。与裸siRNA和非交联载体对照(两种载体系统半衰期均为3~4 min)比较,该载体将血液循环半衰期延长至10 min。采用荧光染料标记法研究了siRNA的体内分布,结果表明,注射裸siRNA和非交联载体24 h后,在肾中蓄积相同量的siRNA,而注射交联载体在肾中仅观察到前者一半量的siRNA。相反,与两种对照组比较,二硫化物交联载体在肿瘤中递送的siRNA是裸siRNA和非交联载体的2倍。硫醇交联载体策略存在一个固有的问题就是当载体核心或中间层引入大量的巯基时,分子内形成二硫键的概率往往高于分子间二硫键的形成,因而二硫键交联纳米粒存在氧化还原响应不稳定的缺点。
1.2.2 酸性pH响应递送载体 细胞晚期内涵体中的pH值偏酸性(pH值4.5~6),而细胞外pH为中性,这种pH变化经常被用于药物递送载体的设计,以触发药物的释放,包括小分子抗癌药物和生物大分子。已经应用的各种酸不稳定键包括缩醛、缩酮[14]、腙[15]、β-硫代丙酸酯和柠康酰胺[16,17]等。例如,将氨基缩酮连接于聚阳离子骨架中,所得缩酮化聚阳离子纳米粒可有效装载siRNA[18]。在细胞质中,缩酮化的载体可快速分解并释放出siRNA,而未修饰的对照组载体在培养的细胞中孵育4 h后,才检测到有siRNA释放。这种缩酮化的递送载体显示出选择性释放siRNA的优点。
另有研究报道将胆固醇通过乙缩醛与PEG化聚乙烯醇相连接[19],将该酸敏性聚合物进一步与siRNA和阳离子环糊精组装,得到直径为120~170 nm的纳米颗粒。胆固醇基团可通过疏水作用进一步压缩siRNA进入纳米颗粒。胆固醇部分的缩醛连接可在晚期内涵体中降解,促进纳米颗粒的解聚和siRNA的释放。实验结果证明其pH敏感性,pH值7.4条件下,该纳米颗粒的粒径保持不变长达24 h,但在pH值5.5条件下,纳米颗粒开始解聚,多分散性增加。
值得注意的是,为了增强响应释放的效果,很多载体多设计为具有pH和还原环境双重敏感性。HAN等[20]以穿膜肽修饰的介孔硅纳米粒为核心,首先吸附一层荷负电的聚盐酸丙烯胺-甲基顺丁烯二酸酐,随后静电吸附荷正电的半乳糖修饰的三甲基壳聚糖-半胱氨酸,以包封siRNA。以此类推,通过不断的正、负吸附循环,构建了一种层层自组装体系。在pH值7.4血液循环和pH值6.5肿瘤组织微环境条件下,该载体系统很好保护siRNA,体现出良好的稳定性;进入pH值5.0的内涵体后,触发了聚盐酸丙烯胺-甲基顺丁烯二酸酐的电荷反转,导致层层自组装体系解聚,释放至细胞质中;细胞质中高浓度的GSH又破坏了三甲基壳聚糖-半胱氨酸层的二硫键,加速了siRNA的释放,从而产生了很高的基因沉默效果。CHEN等[21]通过酸敏感键将聚酯H40与分子内部含有二硫键的聚苄基天冬氨酸-聚乙二醇-马来酰亚胺阳离子聚合物共价耦联在一起,也设计一种pH及还原环境双敏感的单分子自组装纳米载体,在pH值5.3和10 mmol·L-1GSH条件下,siRNA快速释放,并在三阴乳腺癌肿瘤细胞中显示出良好的基因沉默效果。
1.2.3 ATP浓度响应递送载体 ATP是最丰富的核糖核苷酸,其在细胞外的浓度约为0.4 mmol·L-1,而在细胞内的浓度高达3 mmol·L-1 [22],可作为细胞特异性释放siRNA的响应信号。与上述环境响应递送载体类似,递送载体可以设计成通过利用苯基硼酸(phenylboronic acid,PBA)化学将siRNA释放到富含ATP的细胞质中。PBA可以与siRNA和ATP核糖环上的1,2-顺-二醇形成共价酯键[23]。例如,有报道将3-氟-4-羧基苯基硼酸共价连接在PEG-聚阳离子聚合物侧链的伯氨基,随后将其作为分子间交联剂与siRNA交联,形成纳米递送载体[24]。这种递送载体表现出较好的稳定性,原因在于非离子化FPBA产生的疏水相互作用以及siRNA磷酸基团和聚阳离子中的残留氨基之间形成的离子对。因此,与在一端或两端含有脱氧核糖封端的siRNA的对照比较,含有核糖封端的siRNA的递送载体表现出对抗聚阴离子交换与硫酸葡聚糖的更好的稳定性。更重要的是,该载体系统体现出良好的ATP响应性,在大于1 mmol·L-1的ATP浓度范围内迅速解离,将siRNA释放出来。但与氧化还原响应的递送载体比较,ATP响应性递送载体存在一个问题,即二硫键交联递送载体形成过程中巯基并不影响聚阳离子载体和siRNA之间的静电相互作用,而ATP响应性递送载体形成过程中相对疏水和大体积的PBA基团可能会显著抑制二醇基和PBA的交联。
肿瘤细胞往往会过表达某些特异性受体,递送载体可以通过配体-受体相互作用实现靶向功能。靶向设计时,通常将细胞特异性配体安装在递送载体的表面,或者将配体包埋于载体系统中,当载体系统随血液运送至肿瘤组织附近,通过酸敏或特异性酶的作用将其暴露出来,以促进其靶向摄取能力。
配体密度、连接链的长度以及密度等都会对配体介导的靶向能力产生影响。通常较高密度的配体可保证其与受体有更高机会的结合。例如,siRNA与三价
配体修饰时,通常是利用PEG分子做桥连将配体连接于纳米粒表面,PEG分子具有柔性,其长度与密度亦影响配体结合能力。最佳PEG长度取决于递送载体本身的属性。例如,有文献报道,相比PEG6000、PEG10000或PEG20000,采用PEG2000或PEG3000修饰的抗体靶向纳米粒表现出更好的树突细胞靶向性[27];而另有文献报道,相比PEG2000,采用PEG350连接的肽配体靶向脂质体更显著地增强了肿瘤细胞摄取效果[28]。提示在配体修饰时,应进行比较,以选择出最佳的PEG长度。纳米粒表面的PEG修饰密度也会对主动靶向摄取能力有影响。HAK等[29]的研究表明,采用5%PEG2000修饰密度制备的精氨酸-甘氨酸-天冬氨酸三肽(arginyl-glycyl-aspartic acid,cRGD)靶向纳米粒在体外癌细胞和动物实验中均表现出最高的摄取量,而用10%~50%PEG2000密度修饰的cRGD靶向纳米粒的靶向活性却较弱。
siRNA递送载体必须具有内涵体逃逸功能,以增加其基因沉默效率。PEI是一种具有代表性的siRNA递送阳离子聚合物,通过质子海绵作用引发内涵体逃逸[30]。PEI在内涵体酸性条件下大量捕获质子,引起氯离子内流,导致内涵体渗透性肿胀,最后破裂从而将内吞的siRNA释放到细胞质中[31]。PEI的一个显著缺点是随着分子量增加,细胞毒性迅速增加。然而,低分子量PEI在生理环境下对核酸的离子配对位点较少,不能维持稳定的载体结构,从而导致转染效率下降。因此,低分子量PEI(800)通过可生物降解的连接链彼此共价结合,以使其具有较高分子量(10 000~20 000),从而在提高转染效率的同时,降低其细胞毒性[32]。
阳离子聚合物中的其他化学结构也促进pH介导的膜破裂。例如,聚合物聚二甲氨基甲基丙烯酸酯-丙基丙烯酸-甲基丙烯酸丁酯(poly dimethylaminoe-thylmethacrylate-co-propyl acrylic acid-co-butyl metha-crylate,p DMAEMA-co-PAA-co-BMA)由阳性DMA-EMA、阴性PAA和疏水BMA组成,生理pH条件下呈现两亲性[33]。在内涵体pH条件下,PAA的羧酸酯基团由亲水性转变为疏水性,并且DMAEMA电正性增强。这导致聚合物由聚两性电解质转变为疏水性聚阳离子,从而破坏内涵体膜。
到目前为止,已有数种siRNA递送载体进入癌症治疗临床试验,如基于脂质载体SNALP、ALN-VSP02和基于环糊精包合的聚合物纳米粒CALAA-01等[39]。CALAA-01是第一个在人体上做了I期临床试验的癌症治疗siRNA药物,但最近其试验已经终止。原因可能是由于其血液循环时间较短(半衰期<30 min),在小鼠体内静脉给药后60 min时后,约60%的纳米颗粒被肾脏滤过清除[40]。基于脂质的血液循环时间相对较长(半衰期>2 h),但其粒径>50 nm,不能有效渗透至肿瘤组织中[41]。
临床测试的递送载体各有各的缺陷,临床试验结果和新的生物学证据为更为理想的递送载体的设计提出了更多要求:①载体应显示出长的血液循环性质(半衰期≥2 h)。循环时间越长,载体扩散并蓄积到肿瘤组织中的可能性越大。②载体粒径应当<30 nm,以增强其在肿瘤中的扩散能力。研究表明,递送载体进入肿瘤内是一种自由扩散过程,粒径越小渗透能力越强。③递送载体的制备工艺应简单易行,具有良好制备重现性。到目前为止,虽然尚不清楚是递送载体的哪个功能更为关键,但在载体设计时,上述要求最好能够同时满足。
基于siRNA递送的癌症治疗的成功与肿瘤生物学和siRNA递送载体的构建密切相关,肿瘤细胞的超强适应性极大地阻碍了siRNA癌症治疗的临床应用。未来应进一步寻找新的靶向RNA基因,并构建更优的递送载体,以促进癌细胞凋亡,同时降低对正常细胞的毒副作用。
The authors have declared that no competing interests exist.
| [1] |
Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.
[本文引用:0]
|
| [2] |
RNA interference has become an indispensable tool for loss-of-function studies across eukaryotes. By enabling stable and reversible gene silencing, shRNAs provide a means to study long-term phenotypes, perform pool-based forward genetic screens and examine the consequences of temporary target inhibition in vivo. However, efficient implementation in vertebrate systems has been hindered by technical difficulties affecting potency and specificity. Focusing on these issues, we analyse current strategies to obtain maximal knockdown with minimal off-target effects.
[本文引用:0]
|
| [3] |
RNA interference (RNAi) therapy is a rapidly emerging platform for personalized treatment. Recent advances in small interfering RNA delivery and target selection provide unprecedented opportunities for clinical . Here, we discuss these advances and present strategies for making RNAi-based therapy a viable part of management.
[本文引用:0]
|
| [4] |
|
| [5] |
Abstract RNA interference (RNAi) is a potent and specific mechanism for regulating gene expression. Harnessing RNAi to silence genes involved in disease holds promise for the development of a new class of therapeutics. Delivery is key to realizing the potential of RNAi, and lipid nanoparticles (LNP) have proved effective in delivery of siRNAs to the liver and to tumors in animals. To examine the activity and safety of LNP-formulated siRNAs in humans, we initiated a trial of ALN-VSP, an LNP formulation of siRNAs targeting VEGF and kinesin spindle protein (KSP), in patients with cancer. Here, we show detection of drug in tumor biopsies, siRNA-mediated mRNA cleavage in the liver, pharmacodynamics suggestive of target downregulation, and antitumor activity, including complete regression of liver metastases in endometrial cancer. In addition, we show that biweekly intravenous administration of ALN-VSP was safe and well tolerated. These data provide proof-of-concept for RNAi therapeutics in humans and form the basis for further development in cancer. SIGNIFICANCE: The fi ndings in this report show safety, pharmacokinetics, RNAi mechanism of action, and clinical activity with a novel fi rst-in-class LNP-formulated RNAi therapeutic in patients with cancer. The ability to harness RNAi to facilitate specifi c multitargeting, as well as increase the number of druggable targets, has important implications for future drug development in oncology. 2012 AACR.
[本文引用:0]
|
| [6] |
Abstract RNA interference (RNAi) has broad potential as a therapeutic to reversibly silence any gene. To achieve the clinical potential of RNAi, delivery materials are required to transport short interfering RNA (siRNA) to the site of action in the cells of target tissues. This Review provides an introduction to the biological challenges that siRNA delivery materials aim to overcome, as well as a discussion of the way that the most effective and clinically advanced classes of siRNA delivery systems, including lipid nanoparticles and siRNA conjugates, are designed to surmount these challenges. The systems that we discuss are diverse in their approaches to the delivery problem, and provide valuable insight to guide the design of future siRNA delivery materials.
[本文引用:1]
|
| [7] |
siRNA therapeutics have promise for the treatment of a wide range of genetic disorders. Motivated by lipoproteins, we report lipopeptide nanoparticles as potent and selective siRNA carriers with a wide therapeutic index. Lead material cKK-E12 showed potent silencing effects in mice (ED50 0.002 mg/kg), rats (ED50 < 0.01 mg/kg), and nonhuman primates (over 95% silencing at 0.3 mg/kg). Apolipoprotein E plays a significant role in the potency of cKK-E12 both in vitro and in vivo. cKK-E12 was highly selective toward liver parenchymal cell in vivo, with orders of magnitude lower doses needed to silence in hepatocytes compared with endothelial cells and immune cells in different organs. Toxicity studies showed that cKK-E12 was well tolerated in rats at a dose of 1 mg/kg (over 100-fold higher than the ED50). To our knowledge, this is the most efficacious and selective nonviral siRNA delivery system for gene silencing in hepatocytes reported to date.
[本文引用:1]
|
| [8] |
Artificial oligo(ethylene amino) acids, together with selected natural amino acids and fatty acid modifications, have been used for the solid-phase-assisted synthesis of polymers with precise sequence, topology, and modifications (see picture). First proof-of-concept studies demonstrate the high potential of such polymers in pDNA and siRNA delivery. K=lysine, A=alanine.
[本文引用:1]
|
| [9] |
Abstract Applications of siRNA for cancer therapy have been spotlighted in recent years, but the rational design of efficient siRNA delivery carriers is still controversial, especially because of possible toxicity of the carrier components. Previously, a cationic polyaspartamide derivative, poly{N-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (PAsp(DET)), was reported to exert high transfection efficacy for plasmid DNA with negligible cytotoxicity. However, its direct application for siRNA delivery was fairly limited due to the unstable polymer/siRNA complex formation. In this study, to overcome such instability, stearic acid as a hydrophobic moiety was conjugated to the side chain of PAsp(DET) with various substitution degrees. The stearoyl introduction contributed not only to siRNA complex formation with higher association numbers but also to complex stabilization. The obtained stearoyl PAsp(DET)/siRNA complex significantly accomplished more efficient endogenous gene (BCL-2 and VEGF) knockdown in vitro against the human pancreatic adenocarcinoma (Panc-1) cells than did the unmodified PAsp(DET) complex and commercially available reagents, probably due to the facilitated cellular internalization. This finding suggests that the hydrophobic PAsp(DET)-mediated siRNA delivery is a promising platform for in vivo siRNA delivery. Copyright (c) 2010 Elsevier B.V. All rights reserved.
[本文引用:1]
|
| [10] |
For systemic small interfering RNA (siRNA) delivery to tumor mass, a multifunctional polyion complex micelle was constructed with a block copolymer bearing a targeting ligand and a micelle-stabilizing moiety as well as an endosome-disrupting cationic unit. The block copolymer was comprised of poly(ethylene glycol) (PEG) and a polyaspartamide derivative with flanking cationic tetraethylenepentamine (TEP) moiety (PAsp(TEP)), in which the distal ends of PEG and PAsp(TEP) were further installed with cyclic RGD (cRGD) peptide ligand and cholesteryl (Chol) moiety, respectively. The resulting polymer was confirmed to form siRNA-loaded micelle with a diameter of sub 50/nm and a narrow size distribution. In the stability assays with fluorescently labeled siRNA, the terminal Chol moiety significantly suppressed both the rapid dissociation of the micelles in the serum-containing medium and their rapid elimination from the bloodstream, presumably due to its hydrophobic interactions in the micellar core. Moreover, the targeting cRGD ligand, associated with the stabilizing moiety, significantly enhanced the accumulation of siRNA-loaded micelle in a subcutaneous lung (A549) tumor, compared to a non-targeted control, after systemic administration. Ultimately, significant tumor growth inhibition was achieved by systemic administration of the targeted/stabilized micelle incorporating polo-like kinase 1 (Plk1) siRNA with negligible liver toxicity, consistent with the significant sequence-specific gene silencing of Plk1 in the tumor tissue. These results demonstrated the therapeutic potential of cRGD-PEG-PAsp(TEP)-Chol/siRNA micelle for systemic siRNA delivery toward cancer therapy.
[本文引用:1]
|
| [11] |
|
| [12] |
We report the engineering of intracellular redox-responsive nanoporous poly(ethylene glycol)-poly(l-lysine) particles (NPEG-PLLs). The obtained particles exhibit no toxicity while maintaining the capability to deliver a small interfering RNA sequence (siRNA) targeting the anti-apoptotic factor, survivin, in prostate cancer cells. The redox-mediated cleavage of the disulfide bonds stabilizing the NPEG-PLL-siRNA complex results in the release of bioactive siRNA into the cytosol of prostate cancer PC-3 cells, which, in turn, leads to the effective silencing (59 - 8%) of the target gene. These findings, obtained under optimal conditions, indicate that NPEG-PLLs may protect the therapeutic nucleic acid in the extracellular and intracellular environments, thus preventing the occurrence of competitive interactions with serum and cytosolic proteins as well as degradation by RNase. The intracellular trafficking and final fate of the NPEG-PLLs were investigated by a combination of deconvolution microscopy, fluorescence lifetime imaging microscopy, and super-resolution structured illumination microscopy. A significant impairment of cell survival was observed in cells concomitantly exposed to paclitaxel and siRNA-loaded NPEG-PLLs. Overall, our findings indicate that NPEG-PLLs represent a highly loaded depot for the delivery of therapeutic nucleic acids to cancer cells.
[本文引用:1]
|
| [13] |
Small interfering ribonucleic acid (siRNA) cancer therapies administered by intravenous injection require a delivery system for transport from the bloodstream into the cytoplasm of diseased cells to perform the function of gene silencing. Here we describe nanosized polymeric micelles that deliver siRNA to solid tumors and elicit a therapeutic effect. Stable multifunctional micelle structures on the order of 45 nm in size formed by spontaneous self-assembly of block copolymers with siRNA. Block copolymers used for micelle formation were designed and synthesized to contain three main features: a siRNA binding segment containing thiols, a hydrophilic nonbinding segment, and a cell-surface binding peptide. Specifically, poly(ethylene glycol)-block-poly(L-lysine) (PEG-b-PLL) comprising lysine amines modified with 2-iminothiolane (2IT) and the cyclo-Arg-Gly-Asp (cRGD) peptide on the PEG terminus was used. Modification of PEG-b-PLL with 2IT led to improved control of micelle formation and also increased stability in the blood compartment, while installation of the cRGD peptide improved biological activity. Incorporation of siRNA into stable micelle structures containing the cRGD peptide resulted in increased gene silencing ability, improved cell uptake, and broader subcellular distribution in vitro and also improved accumulation in both the tumor mass and tumor-associated blood vessels following intravenous injection into mice. Furthermore, stable and targeted micelles inhibited the growth of subcutaneous HeLa tumor models and demonstrated gene silencing in the tumor mass following treatment with antiangiogenic siRNAs. This new micellar nanomedicine could potentially expand the utility of siRNA-based therapies for cancer treatments that require intravenous injection.
[本文引用:1]
|
| [14] |
The effect of structural variations in acetal- and ketal-based linkers upon their degradation kinetics is studied through the design, synthesis, and study of six series of molecules, comprising a total of 18 different molecules. Through this systematic study, we show that the structural fine-tuning of the linkers allows access to variations in kinetics of degradation of more than 6 orders of magnitude. Hammett correlations show that the ρ value for the hydrolysis of benzylidene acetals is about 614.06, which is comparable to an SN1-like process. This shows that there is a strong, developing positive charge at the benzylic position in the transition state during the degradation of acetals. This positively charged transition state is consistent with the relative degradation rates of acetals vs ketals (correlated to stabilities of 1°, 2°, and 3° carboxonium ion type intermediates) and the observed effect of proximal electron-withdrawing groups upon the degradation rates. Following this, we studied whether the...
[本文引用:1]
|
| [15] |
A chitosan-hydrazone-mPEG (CH-Hz-mPEG) copolymer which is stable at extracellular pH and cleaves at slightly acidic intracellular pH was synthesized and characterized. Blank polymeric nanoparticles (B-PNPs) and prednisone-loaded polymeric nanoparticles (P-PNPs) were then formulated by dialysis/precipitation method. The cell-specific ligand, atrial natriuretic peptide (ANP) was then conjugated to P-PNPs (ANP-P-PNPs) by a coupling reaction. Particle size and morphological analyses revealed uniform spherical shape of PNPs. In vitro pH dependent degradation of PNPs was investigated. Drug release profile of ANP-P-PNPs indicated a slow release of prednisone at pH 7.4, but a rapid release at pH 5.0 due to the cleavage of hydrazone linkage. Cytotoxicity studies demonstrated greater compatibility of B-PNPs compared to ANP-P-PNPs. Cellular internalization of ANP-P-PNPs was higher than P-PNPs owing to receptor-mediated endocytosis. The results from this investigation support the hypothesis that chitosan based ANP-P-PNPs could act as an intracellular pH-responsive and targeted drug delivery system.
[本文引用:1]
|
| [16] |
DOI:10.1002/adhm.v3.3
URL
[本文引用:1]
|
| [17] |
|
| [18] |
Efficient intracellular processes including cytosolic release and unpackaging of siRNA from the carrier in the cytoplasm are efficiency-determining steps in achieving successful gene silencing. In this study, acid-degradable ketalized linear polyethylenimine (KL-PEI) was synthesized for efficient, intracellular target-specific, and biocompatible siRNA delivery. The siRNA/KL-PEI polyplexes resulted in much higher RNA interference efficiency than unmodified L-PEI via selective cytoplasmic localization of the polyplexes and efficient disassembly of siRNA from the polyplexes, which were promoted upon acid-hydrolysis of amino ketal linkages. Confocal laser scanning microscopy demonstrated that siRNA was efficiently disassembled from the siRNA/KL-PEI polyplexes that were selectively localized in the cytoplasm. On the contrary, siRNA and unmodified linear PEI were colocalized in both the cytoplasm and the nucleus, and limited unpackaging of siRNA from the polyplexes was observed. In addition, ketalization further reduced the cytotoxicity of linear PEI but did not alter its serum-independent gene delivery efficiency. Therefore, KL-PEI is a promising nonviral vector for efficient and biocompatible siRNA delivery.
[本文引用:1]
|
| [19] |
Abstract A novel siRNA delivery vector has been developed, based on the self-assembly of monosubstituted cationic 0205-CD derivatives with a poly(vinyl alcohol)MW27kD (PVA) main-chain polymer bearing poly(ethylene glycol)MW2000 (PEG) and acid-labile cholesterol-modified (Chol) grafts through an acid-sensitive benzylidene acetal linkage. These components were investigated for their ability to form nanoparticles with siRNA using two different assembly schemes, involving either precomplexation of the pendant Chol-PVA-PEG polymer with the cationic 0205-CD derivatives before siRNA condensation or siRNA condensation with the cationic 0205-CD derivatives prior to addition of Chol-PVA-PEG to engage host:guest complexation. The pendant polymer:amino-0205-CD:siRNA complexes were shown to form nanoparticles in the size range of 120-170 nm, with a slightly negative zeta potential. Cell viability studies in CHO-GFP cells shows that these materials have 10(3)-fold lower cytotoxicities than 25 kD bPEI, while maintaining gene-silencing efficiencies that are comparable to those of benchmark transfection reagents such as bPEI and Lipofectamine 2000. These results suggest that the degradable Chol-PVA-PEG polymer is able to self-assemble in the presence of siRNA and cationic-0205-CD to form nanoparticles that are an effective and low-toxicity vehicle for delivering siRNA cargo to target cells.
[本文引用:1]
|
| [20] |
Multi-layered nanocomplexes (MLNs) were designed here to provide smart co-delivery of doxorubicin (DOX) and vascular endothelial growth factor (VEGF) siRNA. The electrostatically self-assembled MLNs were constructed by TAT peptide modified mesoporous silica nanoparticles (TAT-MSN) as the cationic core for DOX loading, poly(allylamine hydrochloride)-citraconic anhydride (PAH-Cit) as the anionic inner layer, and galactose-modified trimethyl chitosan-cysteine (GTC) conjugate as the cationic outer layer to encapsulate siRNA. Their strong stability at pH 7.4 and 6.5 protected siRNA from degradation in the blood and tumor microenvironment. Galactose ligands on the GTC outer layers effectively facilitated the internalization of MLNs through receptor-mediated endocytosis. Afterwards, the endosomal/lysosomal acidity (pH 5.0) triggered the charge reversal of PAH-Cit, thereby inducing the disassembly of MLNs and their escape to the cytosol. Cytoplasmic glutathione further accelerated siRNA release through cleaving disulfide bonds in GTC layers, leading to high silencing efficiencies. Meanwhile, the exposed DOX-loaded cores were transported into the nuclei by virtue of TAT peptide and exhibited sustained release thereafter. As a result, potent antitumor efficacies of MLNs were noted following intravenous injection at a low dose with no apparent toxicity detected. Therefore, MLNs served as an effective and safe vector to maximize synergistic effect of chemodrugs and therapeutic genes.
[本文引用:1]
|
| [21] |
A unique pH/redox dual-sensitive cationic unimolecular nanoparticle (NP) enabling excellent endosomal/lysosomal escape and efficient siRNA decomplexation inside the target cells was developed for tumor-targeted delivery of siRNA. siRNA was complexed into the cationic core of the unimolecular NP through electrostatic interactions. The cationic core used for complexing siRNA contained reducible disulfide bonds that underwent intracellular reduction owing to the presence of high concentrations of reduced glutathione (GSH) inside the cells, thereby facilitating the decomplexation of siRNA from the unimolecular NPs. The cationic polymers were conjugated onto the hyperbranched core (H40) via a pH-sensitive bond, which further facilitated the decomplexation of siRNA from the NPs. In vitro studies on the siRNA release behaviors showed that dual stimuli (pH=5.3, 10/mM GSH) induced the quickest release of siRNA from the NPs. In addition, the imidazole groups attached to the cationic polymer segments enhanced the endosomal/lysosomal escape of NPs via the proton sponge effect. Intracellular tracking studies revealed that siRNA delivered by unimolecular NPs was efficiently released to the cytosol. Moreover, the GE11 peptide, an anti-EGFR peptide, enhanced the cellular uptake of NPs in MDA-MB-468, an EFGR-overexpressing triple negative breast cancer (TNBC) cell line. The GE11-conjugated, GFP-siRNA-complexed NPs exhibited excellent GFP gene silencing efficiency in GFP-MDA-MB-468 TNBC cells without any significant cytotoxicity. Therefore, these studies suggest that this smart unimolecular NP could be a promising nanoplatform for targeted siRNA delivery to EFGR-overexpressing cancer cells.
[本文引用:1]
|
| [22] |
|
| [23] |
Die Bindung zwischen Phenylboronat und der 3090005-Ribose einer siRNA, die in einer Phenylboronat-funktionalisierten Polyionenkomplexmicelle eingeschlossen ist (siehe Schema), stabilisiert diesen Komplex unter Bedingungen, die der extrazellulren Umgebung entsprechen. Die Zugabe von ATP zerst0109rt den Komplex bei einer Konzentration, die der in Zellen hnelt.
[本文引用:1]
|
| [24] |
A liposome-based co-delivery system composed of a fusogenic liposome encapsulating ATP-responsive elements with chemotherapeutics and a liposome containing ATP was developed for ATP-mediated drug release triggered by liposomal fusion. The fusogenic liposome had a protein-DNA complex core containing an ATP-responsive DNA scaffold with doxorubicin (DOX) and could release DOX through a conformational change from the duplex to the aptamer/ATP complex in the presence of ATP. A cell-penetrating peptide-modified fusogenic liposomal membrane was coated on the core, which had an acid-triggered fusogenic potential with the ATP-loaded liposomes or endosomes/lysosomes. Directly delivering extrinsic liposomal ATP promoted the drug release from the fusogenic liposome in the acidic intracellular compartments upon a pH-sensitive membrane fusion and anticancer efficacy was enhanced both in vitro and in vivo.
[本文引用:1]
|
| [25] |
DOI:10.1021/ja505986a
URL
[本文引用:1]
|
| [26] |
Abstract Targeting nanoparticles (NPs) loaded with drugs and probes to precise locations in the body may improve the treatment and detection of many diseases. Generally, to achieve targeting, affinity ligands are introduced on the surface of NPs that can bind to molecules present on the cell of interest. Optimization of ligand density is a critical parameter in controlling NP binding to target cells, and a higher ligand density is not always the most effective. In this study, we investigated how NP avidity affects targeting to the pulmonary vasculature, using NPs targeted to ICAM-1. This cell adhesion molecule is expressed by quiescent endothelium at modest levels and is upregulated in a variety of pathological settings. NP avidity was controlled by ligand density, with the expected result that higher avidity NPs demonstrated greater pulmonary uptake than lower avidity NPs in both naive and pathological mice. However, in comparison with high-avidity NPs, low-avidity NPs exhibited several-fold higher selectivity of targeting to pathological endothelium. This finding was translated into a PET imaging platform that was more effective in detecting pulmonary vascular inflammation using low-avidity NPs. Furthermore, computational modeling revealed that elevated expression of ICAM-1 on the endothelium is critical for multivalent anchoring of NPs with low avidity, while high-avidity NPs anchor effectively to both quiescent and activated endothelium. These results provide a paradigm that can be used to optimize NP targeting by manipulating ligand density and may find biomedical utility for increasing detection of pathological vasculature.
[本文引用:1]
|
| [27] |
Abstract Targeted delivery of nanoparticles (NPs) carrying vaccine components to dendritic cells (DCs) is a promising strategy to initiate antigen-specific immune responses. Improving the interactions between nanoparticle-carried ligands and receptors on DCs is a major challenge. These NPs are generally coated with poly(ethylene glycol) (PEG), to shield non-specific interactions, and antibodies, to facilitate specific delivery to DC surface receptors. We have devised a strategy to covalently link PEG molecules of various chain length (Mw 2000-20000 g/moL) to poly(lactic-co-)glycolic acid (PLGA) NP vaccines. We coated these NPs with various antibodies recognizing the DC-specific receptor DC-SIGN to study the effects of shielding and antibody type on antibody--receptor interactions. Chemical attachment of PEG to the particle surface was followed by detailed zeta potential, DLS and NMR studies, and analyzed by analytical chemistry. Increasing the PEG chain length increased particle size and polydispersity index and reduced the intracellular degradation rate of encapsulated antigens. Binding and uptake of NPs by human DCs was affected by both PEG chain length and antibody type. NPs coated with PEG-3000 had the optimal chain length for antibody--receptor interactions and induction of antigen-specific T-cell responses. Interestingly, clear differences were observed upon targeting distinct epitopes of the same receptor. Binding and uptake of NPs carrying antibodies recognizing the carbohydrate recognition domain of DC-SIGN was enhanced when compared to those carrying antibodies recognizing the receptor's neck region. In conclusion, our data show that PEG chains cannot be extended beyond a certain length for shielding purposes without compromising the efficacy of targeted delivery. Thereby, the implications of our findings are not limited to the future design of nanovaccines specifically targeted to DC-SIGN, but apply to the general design of targeted nanocarriers. Copyright 2011 Elsevier Ltd. All rights reserved.
[本文引用:1]
|
| [28] |
Abstract PEGylated liposomes are attractive pharmaceutical nanocarriers; however, literature reports of ligand-targeted nanoparticles have not consistently shown successful results. Here, we employed a multifaceted synthetic strategy to prepare peptide-targeted liposomal nanoparticles with high purity, reproducibility, and precisely controlled stoichiometry of functionalities to evaluate the role of liposomal PEG coating, peptide EG-linker length, and peptide valency on cellular uptake in a systematic manner. We analyzed these parameters in two distinct disease models where the liposomes were functionalized with either HER2- or VLA-4-antagonistic peptides to target HER2-overexpressing breast cancer cells or VLA-4-overexpressing myeloma cells, respectively. When targeting peptides were tethered to nanoparticles with an EG45 (090804PEG2000) linker in a manner similar to a more traditional formulation, their cellular uptake was not enhanced compared to non-targeted versions regardless of the liposomal PEG coating used. Conversely, reduction of the liposomal PEG to PEG350 and the peptide linker to EG12 dramatically enhanced cellular uptake by 0908049 fold and 090804100 fold in the breast cancer and multiple myeloma cells, respectively. Uptake efficiency reached a maximum and a plateau with 0908042% peptide density in both disease models. Taken together, these results demonstrate the significance of using the right design elements such as the appropriate peptide EG-linker length in coordination with the appropriate liposomal PEG coating and optimal ligand density in efficient cellular uptake of liposomal nanoparticles.
[本文引用:1]
|
| [29] |
The development and application of nanoparticles as in vivo delivery vehicles for therapeutic and/or diagnostic agents has seen a drastic growth over the last decades. Novel imaging techniques allow real-time in vivo study of nanoparticle accumulation kinetics at the level of the cell and targeted tissue. Successful intravenous application of such nanocarriers requires a hydrophilic particle surface coating, of which polyethylene glycol (PEG) has become the most widely studied and applied. In the current study, the effect of nanoparticle PEG surface density on the targeting efficiency of ligand-functionalized nanoemulsions was investigated. We synthesized 100 nm nanoemulsions with a PEG surface density varying from 5 to 50 mol %. Fluorescent and paramagnetic lipids were included to allow their multimodal detection, while RGD peptides were conjugated to the PEG coating to obtain specificity for the (v) (3)-integrin. The development of a unique experimental imaging setup allowed us to study, in real time, nanoparticle accumulation kinetics at (sub)-cellular resolution in tumors that were grown in a window chamber model with confocal microscopy imaging, and at the macroscopic tumor level in subcutaneously grown xenografts with magnetic resonance imaging. Accumulation in the tumor occurred more rapidly for the targeted nanoemulsions than for the nontargeted versions, and the PEG surface density had a strong effect on nanoparticle targeting efficiency. Counterintuitively, yet consistent with the PEG density conformation models, the highest specificity and targeting efficiency was observed at a low PEG surface density.
[本文引用:1]
|
| [30] |
|
| [31] |
Abstract Polymeric materials have been extensively developed as a delivery vehicle for nucleic acids over the past two decades. Many previous studies have demonstrated that synthetic delivery vehicles can be highly functionalized by chemical approaches to overcome biological barriers in nucleic acid delivery, similar to viruses. Based on our current knowledge, this tutorial review describes rational strategies in the design of polymeric materials to achieve construction of the versatile vehicles, that is "artificial viruses", for successful gene therapy, especially focusing on the chemical structures with the minimal adverse effects.
[本文引用:1]
|
| [32] |
Abstract Polyethylenimine (PEI) shows high transfection efficiency and cytoxicity due to its high amine density. The new disulfide cationic polymer, linear poly(ethylenimine sulfide) (l-PEIS), was synthesized for efficient and safe gene delivery. As the amine density of l-PEIS increased, the transfection efficiency also increased. l-PEIS-6 and l-PEIS-8 show transfection efficiencies that are similar to that of PEI. However, cytotoxicity of l-PEIS was not observed due to the biodegradable disulfide bond. The disulfide bonds are stable in the oxidative extracellular condition and can be degraded rapidly in the reductive intracellular condition. The degradation of l-PEIS in HeLa cells was visualized by fluorescence microscopy using the probe-probe dequenching effect of BODIPY-FL fluorescence dye. l-PEIS was degraded completely within 3 h.
[本文引用:1]
|
| [33] |
The gene knockdown activity of small interfering RNA (siRNA) has led to their use as target validation tools and as potential therapeutics for a variety of diseases. The delivery of these double-stranded RNA macromolecules has proven to be challenging, however, and in many cases, is a barrier to their deployment. Here we report the development of a new diblock copolymer family that was designed to enhance the systemic and intracellular delivery of siRNA. These diblock copolymers were synthesized using the controlled reversible addition fragmentation chain transfer polymerization (RAFT) method and are composed of a positively-charged block of dimethylaminoethyl methacrylate (DMAEMA) to mediate siRNA condensation, and a second endosomal-releasing block composed of DMAEMA and propylacrylic acid (PAA) in roughly equimolar ratios, together with butyl methacylate (BMA). A related series of diblock compositions were characterized, with the cationic block kept constant, and with the ratio of DMAEMA and PAA to BMA varied. These carriers became sharply hemolytic at endosomal pH regimes, with increasing hemolytic activity seen as the percentage of BMA in the second block was systematically increased. The diblock copolymers condensed siRNA into 80-250 nm particles with slightly positive Zeta potentials. SiRNA-mediated knockdown of a model protein, namely glyceraldehyde 3-phosphate dehydrogenase (GAPDH), in HeLa cells generally followed the hemolytic activity trends, with the most hydrophobic second block (highest BMA content) exhibiting the best knockdown. This pH-responsive carrier designed to mediate endosomal release shows significant promise for the intracellular delivery of siRNA.
[本文引用:1]
|
| [34] |
Abstract Small interfering RNAs (siRNAs) of 19-25 bp mediate the cleavage of complementary mRNA, leading to post-transcriptional gene silencing. We examined cationic lipid (CL)-mediated delivery of siRNA into mammalian cells and made comparisons to CL-based DNA delivery. The effect of lipid composition and headgroup charge on the biophysical and biological properties of CL-siRNA vectors was determined. X-ray diffraction revealed that CL-siRNA complexes exhibited lamellar and inverted hexagonal phases, qualitatively similar to CL-DNA complexes, but also formed other nonlamellar structures. Surprisingly, optimally formulated inverted hexagonal 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) CL-siRNA complexes exhibited high toxicity and much lower target-specific gene silencing than lamellar CL-siRNA complexes even though optimally formulated, inverted hexagonal CL-DNA complexes show high transfection efficiency in cell culture. We further found that efficient silencing required cationic lipid/nucleic acid molar charge ratios (rhochg) nearly an order of magnitude larger than those yielding efficiently transfecting CL-DNA complexes. This second unexpected finding has implications for cell toxicity. Multivalent lipids (MVLs) require a smaller number of cationic lipids at a given rhochg of the complex. Consistent with this observation, the pentavalent lipid MVL5 exhibited lower toxicity and superior silencing efficiency over a large range in both the lipid composition and rhochg when compared to monovalent DOTAP. Most importantly, MVL5 achieved much higher total knockdown of the target gene in CL-siRNA complex regimes where toxicity was low. This property of CL-siRNA complexes contrasts to CL-DNA complexes, where the optimized transfection efficiencies of multivalent and monovalent lipids are comparable.
[本文引用:1]
|
| [35] |
We demonstrate a systematic and rational approach to create a library of natural and modified, dialkylated amino acids based upon arginine for development of an efficient small interfering RNA (siRNA) delivery system. These amino acids, designated DiLA 2 compounds, in conjunction with other components, demonstrate unique properties for assembly into monodisperse, 100-nm small liposomal particles containing siRNA. We show that DiLA 2 -based liposomes undergo a pH-dependent phase transition to an inverted hexagonal phase facilitating efficient siRNA release from endosomes to the cytosol. Using an arginine-based DiLA 2 , cationic liposomes were prepared that provide high in viv o siRNA delivery efficiency and are well-tolerated in both cell and animal models. DiLA 2 -based liposomes demonstrate a linear dose esponse with an ED 50 of 0.1 mg/kg against liver-specific target genes in BALB/c mice.
[本文引用:1]
|
| [36] |
Abstract In this study, hyaluronan (HA)-functionalized calcium phosphate nanoparticles (CaP-AHA/siRNA NPs) were developed for an injectable and targetable delivery of siRNA, which were prepared by coating the alendronate-hyaluronan graft polymer (AHA) around the surface of calcium phosphate-siRNA co-precipitates. The prepared CaP-AHA/siRNA NPs had a uniform spherical core-shell morphology with an approximate size of 170 nm and zeta potential of -12 mV. The coating of hydrophilic HA improved the physical stability of nanoparticles over one month due to the strong interactions between phosphonate and calcium. In vitro experiments demonstrated that the negatively charged CaP-AHA/siRNA NPs could effectively deliver EGFR-targeted siRNA into A549 cells through CD44-mediated endocytosis and significantly down-regulate the level of EGFR expression. Also, the internalized CaP-AHA/siRNA NPs exhibited a pH-responsive release of siRNA, indicating that the acidification of lysosomes probably facilitated the disassembling of nanoparticles and the resultant ions sharply increased the inner osmotic pressure and thus expedited the release of siRNA from late lysosomes into the cytoplasm. Furthermore, in vivo tumor therapy demonstrated that high accumulation of CaP-AHA/siEGFR NPs in tumor led to a significant tumor growth inhibition with a specific EGFR gene silencing effect after intravenous administration in nude mice xenografted with A549 tumor, along with a negligible body weight loss. These results suggested that the CaP-AHA/siRNA NPs could be an effective and safe systemic siRNA delivery system for a RNAi-based tumor targeted therapy strategy.
[本文引用:1]
|
| [37] |
At the forefront of medicine, Gene Therapy brings you the latest research into genetic and cell-based technologies to treat disease. It also publishes Progress & Prospects reviews and News and Commentary articles, which highlight the cutting edge of the field.
[本文引用:1]
|
| [38] |
Ca2+-siRNA nanocomplexes represent a simple yet an effective platform for siRNA delivery into the cell cytoplasm, with subsequent successful siRNA-induced target gene silencing. Herein, we aimed to elucidate the roles played by calcium ions in siRNA nanocomplex formation, cell uptake, and endosomal escape. We investigated whether the replacement of Ca2+in the nanocomplex by other bivalent cations would affect their cell entry and subsequent gene silencing. Our results indicate that Mg2+and Ba2+lead to the formation of nanocomplexes of similar physical features (size=100nm, surface charge ζ=618mV) as the Ca2+-siRNA nanocomplexes. Yet, these nanocomplexes were not uptaken by the cells to the same extent as those prepared with Ca2+, and siRNA-induced target gene silencing was not obtained. Cell internalization of Ca2+61-siRNA nanocomplexes, examined by employing chemical inhibitors to clathrin-, caveolin- and dynamin-mediated endocytosis pathways, indicated the involvement of all mechanisms in the process. Inhibition of endosome acidification by bafilomycin completely abolished the siRNA-mediated silencing by Ca2+-siRNA nanocomplexes. Collectively, our results indicate that Ca2+promotes cell internalization and rapid endosomal escape, thus leading to the efficient siRNA-induced target gene silencing elicited by the Ca2+-siRNA nanocomplexes.
[本文引用:1]
|
| [39] |
Recent progress in RNA biology has broadened the scope of therapeutic targets of RNA drugs for cancer therapy. However, RNA drugs, typically small interfering RNAs (siRNAs), are rapidly degraded by RNases and filtrated in the kidney, thereby requiring a delivery vehicle for efficient transport to the target cells. To date, various delivery formulations have been developed from cationic lipids, polymers, and/or inorganic nanoparticles for systemic delivery of siRNA to solid tumors. This review describes the current status of clinical trials related to siRNA-based cancer therapy, as well as the remaining issues that need to be overcome to establish a successful therapy. It, then introduces various promising design strategies of delivery vehicles for stable and targeted siRNA delivery, including the prospects for future design.
[本文引用:1]
|
| [40] |
Nanoparticle-based experimental therapeutics are currently being investigated in numerous human clinical trials. CALAA-01 is a targeted, polymer-based nanoparticle containing small interfering RNA (siRNA) and, to our knowledge, was the first RNA interference (RNAi)-based, experimental therapeutic to be administered to cancer patients. Here, we report the results from the initial phase I clinical trial where 24 patients with different cancers were treated with CALAA-01 and compare those results to data obtained from multispecies animal studies to provide a detailed example of translating this class of nanoparticles from animals to humans. The pharmacokinetics of CALAA-01 in mice, rats, monkeys, and humans show fast elimination and reveal that the maximum concentration obtained in the blood after i.v. administration correlates with body weight across all species. The safety profile of CALAA-01 in animals is similarly obtained in humans except that animal kidney toxicities are not observed in humans; this could be due to the use of a predosing hydration protocol used in the clinic. Taken in total, the animal models do appear to predict the behavior of CALAA-01 in humans.
[本文引用:1]
|
| [41] |
|
