新型阳离子基因传递载体PEI-PBLG的细胞转染研究

Transfection with a Novel Cationic Gene Carrier: PEI-PBLG

摘要:

对新型阳离子聚合物PEI(10kD)-PBLG进行研究，重点考察其基因转染效率与细胞毒性，探讨其作为基因载体的可能性。通过粒径分析及扫描电镜（SEM）观察PEI(10kD)-PBLG与质粒pEGFP自组装形成的颗粒形态及粒径，预测其进入细胞的可能性。使用MTT比色法分析PEI(10kD)-PBLG、PEI(25kD)-PBLG、PEI(10kD)和PEI(25kD)的细胞毒性差异。选用表达增强型绿色荧光蛋白的质粒pEGFP作为报告基因模型，将其与PEI(10kD)-PBLG自组装后，分别转染真核细胞株Hela、COS-7、Vero-E6和ECV304，应用流式细胞术检测细胞转染效率，并比较了血清、缓冲液、细胞谱等多种因素对基因转染效率的影响。PEI(10kD)-PBLG可包裹质粒形成粒径100～120nm的纳米复合物，适合介导质粒进入细胞。该纳米粒复合物对转染缓冲液的敏感度较低，并能够在10%血清存在的条件下，转染全部实验用细胞株，尤其对Hela的转染效率最高，其次是COS-7、Vero-E6和ECV304；其中PEI-PBLG(10kD)/pEGFP复合物转染Hela细胞的比率为45.02%，高于PEI(10kD)/pEGFP的29.16%；PEI(10kD)-PBLG的细胞毒性作用显著低于PEI(25kD)、PEI(10kD)和PEI(25kD)-PBLG。新型阳离子多聚物PEI(10kD)-PBLG在提高PEI介导的基因转染效率的同时降低了其细胞毒性，提高了生物相容性，有望成为基因转移的有效载体。

Abstract:

This study mainly deals with cell transfection and cytotoxicity for PEI(10kD)-PBLG, a novel cationic copolymer, to observe its potential as a gene carrier. Size measurement and SEM were used to show the modality of the PEI-PBLG/pDNA complexes. Cytotoxicity of PEI (10kD)-PBLG was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay and compared with PEI(25kD)-PBLG, PEI(10kD), and PEI(25kD). Furthermore, pEGFP that can express the enhanced green fluorescent protein was chosen as a reporter to observe the transfection efficiency directly. Then, PEI(10kD)-PBLG/pEGFP complexes were transfected into several cell lines, such as Hela, COS-7, Vero-E6, and ECV-304, and effects of the transfection conditions were evaluated. The efficiencies were measured by FACS. Size measurement of complex particles indicated that PEI-PBLG/pDNA tended to form smaller nanoparticles compared with PEI/pDNA. The representative size of the PEI(10kD)-PBLG/pDNA complex was approximately 100～200 nm. SEM images showed that the particles were condense and compact. This can be suitable for their entry into cells. Cytotoxicity studies suggested that PEI(10kD)-PBLG had considerably lower toxicity than the other three materials. In the transfection tests, PEI (10kD)-PBLG/pDNA complexes could be transfected into all the cell lines that were tested. These provided the highest level of EGFP expression (45.02%) in Hela cells, which was considerably higher than that of PEI(10kD)/pEGFP (29.16%). Being less affected by the serum during transfection, PEI-PBLG/pDNA complexes offered greater biocompatibility than PEI. PEI-PBLG copolymer reduces the cytotoxicity of PEI, improves the transfection efficiency, and offers greater biocompatibility than PEI. It shows considerable potential as an efficient nonviral carrier for gene delivery.