Interleukin 12 (IL-12) is considered as an important molecule for cancer immunotherapy with significant roles in hindering tumor activity, mostly mediated by tumor-associated macrophages and anti-angiogenic factors. Mesenchymal stem cells (MSCs) have been come out as promising carriers to increase the accumulation of drug/gene in tumor sites. As a vehicle, MSCs have various advantages, including tumor-specific propensity and migratory ability; however, they have limited transfection efficiency, compared to other cells. In this study, we introduced a novel delivery system based on poly-(amidoamine) (PAMAM) (G5) to deliver a plasmid encoding IL-12 to MSCs. Initially, 30% of the amine surface of PAMAM was substituted by 10-bromodecanoic acid. Then, the low molecular weight of protamine peptide was conjugated to PAMAM and PAMAM-alkyl with N-succinimidyl 3-(2-pyridyldithio) propionate as a linker. Physicochemical properties of this modified PAMAM were evaluated, including size and surface charge, toxicity, transfection efficiency to deliver reporter and IL-12 genes into MSCs and finally the migration potential of the engineered stem cells into cancer and normal cell lines (HepG2 and NIH/3 T3). The results showed that alkyl-peptide modified PAMAM with low toxicity had a higher potential to deliver green fluorescent protein and IL-12 genes to stem cells, than PMAMAM, PAMAM-alkyl and PAMAM-peptide. These engineered stem cells had a greater ability to migrate to cancer cells than normal cells. It can be concluded that engineered stem cells containing the IL-12 gene can be considered as an efficient cell carrier for cancer immunotherapy. Further clinical studies are needed to confirm these results.

中文翻译：

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评估具有低分子量鱼精蛋白肽的修饰 PAMAM 树枝状大分子将 IL-12 质粒作为癌症治疗载体递送到干细胞中的效率

白细胞介素 12 (IL-12) 被认为是癌症免疫治疗的重要分子，在阻碍肿瘤活性方面具有重要作用，主要由肿瘤相关巨噬细胞和抗血管生成因子介导。间充质干细胞 (MSCs) 已成为有希望的载体，可增加药物/基因在肿瘤部位的积累。作为一种载体，间充质干细胞具有多种优势，包括肿瘤特异性倾向和迁移能力；然而，与其他细胞相比，它们的转染效率有限。在这项研究中，我们引入了一种基于聚（酰胺胺）（PAMAM）（G5）的新型递送系统，以将编码 IL-12 的质粒递送至 MSC。最初，PAMAM 的 30% 胺表面被 10-溴代癸酸取代。然后，将低分子量的鱼精蛋白肽与 PAMAM 和 PAMAM-烷基结合ñ-琥珀酰亚胺基 3-(2-吡啶基二硫代)丙酸酯作为接头。评估了这种修饰的 PAMAM 的物理化学性质，包括大小和表面电荷、毒性、将报告基因和 IL-12 基因传递到 MSCs 的转染效率，以及最终工程干细胞迁移到癌症和正常细胞系（HepG2 和 NIH/ 3 T3)。结果表明，与PMAMAM、PAMAM-烷基和PAMAM-肽相比，低毒性的烷基肽修饰的PAMAM具有更高的向干细胞递送绿色荧光蛋白和IL-12基因的潜力。这些工程干细胞比正常细胞具有更强的迁移到癌细胞的能力。可以得出结论，含有IL-12基因的工程干细胞可以被认为是癌症免疫治疗的有效细胞载体。