Ma Kun, Fu Duo, Yu Dongli, Cui Changhao, Wang Li, Guo Zhaoming, Mao Chuanbin
School of Life Science and Medicine, Dalian University of Technology, Panjin, Liaoning 124221, China; Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, OK, 73019, USA.
School of Life Science and Medicine, Dalian University of Technology, Panjin, Liaoning 124221, China.
Biomaterials. 2017 Mar;121:55-63. doi: 10.1016/j.biomaterials.2016.12.033. Epub 2017 Jan 2.
A Sleeping Beauty (SB) transposon system is made of a transposon plasmid (containing gene encoding a desired functional or therapeutic protein) and a transposase plasmid (encoding an enzyme capable of cutting and pasting the gene into the host cell genome). It is a kind of natural, nonviral gene delivery vehicle, which can achieve efficient genomic insertion, providing long-term transgenic expression. However, before the SB transposon system could play a role in promoting gene expression, it has to be delivered efficiently first across cell membrane and then into cell nuclei. Towards this end, we used a nanoparticle-like lipid-based protocell, a closed bilayer of the neutral lipids with the DNA encapsulated inside, to deliver the SB transposon system to cancer cells. The SB transposon system was amplified in situ inside the protocells by a polymerase chain reaction (PCR) process, realizing more efficient loading and delivery of the target gene. To reach a high transfection efficiency, we introduced two targeting moieties, folic acid (FA) as a cancer cell-targeting motif and Dexamethasone (DEX) as a nuclear localization signaling molecule, into the protocells. As a result, the FA enabled the modified targeting protocells to deliver the DNA into the cancer cells with an increased efficiency and the DEX promoted the DNA to translocate to cell nuclei, eventually leading to the increased chromosome insertion efficiency of the SB transposon. In vivo study strongly suggested that the transfection efficiency of FA-modified protocells in the tumor tissue was much higher than that in other tissues, which was consistent with the in vitro results. Our studies implied that with the targeting ligand modification, the protocells could be utilized as an efficient targeting gene carrier. Since the protocells were made of neutral lipids without cationic charges, the cytotoxicity of protocells was significantly lower than that of traditional cationic gene carriers such as cationic liposomes and polyethylenimine, enabling the protocells to be employed in a wider dosage range in gene therapy. Our work shows that the protocells are a promising gene carrier for future clinical applications.
睡美人(SB)转座子系统由一个转座子质粒(包含编码所需功能或治疗性蛋白质的基因)和一个转座酶质粒(编码一种能够将基因切割并粘贴到宿主细胞基因组中的酶)组成。它是一种天然的非病毒基因递送载体,能够实现高效的基因组插入,提供长期的转基因表达。然而,在SB转座子系统能够在促进基因表达中发挥作用之前,它必须首先有效地穿过细胞膜,然后进入细胞核。为此,我们使用了一种类似纳米颗粒的脂质原细胞,即由中性脂质构成的封闭双层结构,内部包裹着DNA,将SB转座子系统递送至癌细胞。通过聚合酶链反应(PCR)过程,SB转座子系统在原细胞内原位扩增,实现了靶基因更高效的装载和递送。为了达到高转染效率,我们将两种靶向部分,即作为癌细胞靶向基序的叶酸(FA)和作为核定位信号分子的地塞米松(DEX)引入原细胞。结果,FA使修饰后的靶向原细胞能够更高效地将DNA递送至癌细胞,而DEX促进DNA转运至细胞核,最终导致SB转座子的染色体插入效率提高。体内研究有力地表明,FA修饰的原细胞在肿瘤组织中的转染效率远高于其他组织,这与体外结果一致。我们的研究表明,通过靶向配体修饰,原细胞可作为一种高效的靶向基因载体。由于原细胞由不带阳离子电荷的中性脂质制成,其细胞毒性明显低于传统的阳离子基因载体,如阳离子脂质体和聚乙烯亚胺,使得原细胞能够在基因治疗中以更宽的剂量范围使用。我们的工作表明,原细胞是未来临床应用中一种很有前景的基因载体。