Thapa Bindu, Plianwong Samarwadee, Remant Bahadur K C, Rutherford Bradley, Uludağ Hasan
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada.
Faculty of Pharmacy, Silpakorn University, Thailand.
Acta Biomater. 2016 Mar;33:213-24. doi: 10.1016/j.actbio.2016.01.025. Epub 2016 Jan 21.
Cationic polymers have been turned into effective gene delivery agents by functionalizing with long-chain aliphatic lipids, but little information exists if small hydrophobic moieties can serve as effective substituents for this purpose. To explore this issue, we modified small molecular weight (1.2kDa) polyethylenimine (1.2PEI) by a small hydrophobe, propionic acid (PrA), through N-acylation and investigated the efficacy of resultant polymers to deliver plasmid DNA (pDNA) to breast cancer cells MDA-231 and MCF-7. A significant impact of PrA grafting was observed on physicochemical features of polymers and resultant pDNA complexes. pDNA binding capacity, as measured by BC50 (weight ratio for 50% binding), was decreased from 0.25 to 0.64 with PrA substitution. Hydrodynamic size of polymer/pDNA complexes was not altered, but the surface charge (ξ-potential) was increased with low PrA substitution and decreased at higher PrA substitutions. Similarly, in vitro pDNA transfection efficacy in MDA-231 and MCF-7 cells was significantly increased with PrA grafting and optimum efficacy was observed in polymers with modest substitution, 0.25-1.0 PrAs/PEI (mol/mol), but higher substitutions was detrimental to transfection. The transfection efficiency of PEI-PrAs was higher than aliphatic lipid (linoleic acid) substituted PEI and more stable than 25kDa branched PEI. However, unlike studies reported elsewhere, siRNA had no effect on transfection efficacy of pDNA/PEI-PrA complexes when used as an additive. We conclude that small hydrophobe substitution on low MW PEI converts it into effective pDNA delivery agent in breast cancer cells up to an optimal ratio, indicating that balancing hydrophobicity of polymer is critical for pDNA transfection.
This manuscript investigated the influence of small hydrophobe (propionic acid, PrA, 3 carbon) grafted onto small molecular weight polyethylenimine (1.2PEI) in pDNA delivery. We have explored this approach as an alternative of common strategies to graft long chain and/or bulky lipids [linoleic acid (18 carbon), cholesterol]. At optimal substitution, transfection efficiency of these polymers was significantly higher than long chain lipid substituted 1.2PEI, emphasizing a proper hydrophobic/hydrophilic balance for optimum gene delivery. The overall results establish the feasibility of using small hydrophobes to create functional carriers, as long as the polymers are engineered with optimal ratio of substituent. The reported studies should facilitate the efforts of biomaterials scientists and engineers to design new carriers for gene therapy.
通过用长链脂肪族脂质进行功能化，阳离子聚合物已转变为有效的基因传递载体，但对于小的疏水部分是否能作为有效的取代基用于此目的，相关信息较少。为探究此问题，我们通过N - 酰化反应，用小的疏水剂丙酸（PrA）修饰了小分子量（1.2kDa）的聚乙烯亚胺（1.2PEI），并研究了所得聚合物将质粒DNA（pDNA）递送至乳腺癌细胞MDA - 231和MCF - 7的效果。观察到PrA接枝对聚合物及所得pDNA复合物的物理化学特性有显著影响。通过BC50（50%结合时的重量比）测量的pDNA结合能力，随着PrA取代从0.25降至0.64。聚合物/pDNA复合物的流体力学尺寸未改变，但表面电荷（ζ电位）在低PrA取代时增加，在高PrA取代时降低。同样，在MDA - 231和MCF - 7细胞中，PrA接枝显著提高了体外pDNA转染效率，在适度取代（0.25 - 1.0 PrAs/PEI，摩尔/摩尔）的聚合物中观察到最佳效率，但更高的取代对转染有害。PEI - PrAs的转染效率高于脂肪族脂质（亚油酸）取代的PEI，且比25kDa支链PEI更稳定。然而，与其他地方报道的研究不同，当用作添加剂时，siRNA对pDNA/PEI - PrA复合物的转染效率没有影响。我们得出结论，低分子量PEI上的小疏水取代基可将其转变为乳腺癌细胞中有效的pDNA传递载体，直至达到最佳比例，这表明平衡聚合物的疏水性对pDNA转染至关重要。
本手稿研究了接枝到小分子量聚乙烯亚胺（1.2PEI）上的小疏水剂（丙酸，PrA，3个碳）在pDNA传递中的影响。我们探索了这种方法作为接枝长链和/或大分子脂质[亚油酸（18个碳）、胆固醇]的常见策略的替代方法。在最佳取代时，这些聚合物的转染效率显著高于长链脂质取代的1.2PEI，强调了适当的疏水/亲水平衡以实现最佳基因传递。总体结果确立了使用小疏水剂创建功能载体的可行性，只要聚合物以最佳取代比例进行设计。所报道的研究应有助于生物材料科学家和工程师设计用于基因治疗的新载体。
