Šimčíková Michaela, Prather Kristala L J, Prazeres Duarte M F, Monteiro Gabriel A
a MIT-Portugal Program.
b iBB-Institute for Bioengineering and Biosciences , Lisbon , Portugal.
Biotechnol Genet Eng Rev. 2015 Apr-Oct;31(1-2):82-107. doi: 10.1080/02648725.2016.1178011.
Despite very good safety records, clinical trials using plasmid DNA failed due to low transfection efficiency and brief transgene expression. Although this failure is both due to poor plasmid design and to inefficient delivery methods, here we will focus on the former. The DNA elements like CpG motifs, selection markers, origins of replication, cryptic eukaryotic signals or nuclease-susceptible regions and inverted repeats showed detrimental effects on plasmids' performance as biopharmaceuticals. On the other hand, careful selection of promoter, polyadenylation signal, codon optimization and/or insertion of introns or nuclear-targeting sequences for therapeutic protein expression can enhance the clinical efficacy. Minimal vectors, which are devoid of the bacterial backbone and consist exclusively of the eukaryotic expression cassette, demonstrate better performance in terms of expression levels, bioavailability, transfection rates and increased therapeutic effects. Although the results are promising, minimal vectors have not taken over the conventional plasmids in clinical trials due to challenging manufacturing issues.
尽管有非常良好的安全记录，但使用质粒DNA的临床试验因转染效率低和转基因表达短暂而失败。虽然这种失败既归因于质粒设计不佳，也归因于递送方法效率低下，但在这里我们将重点关注前者。诸如CpG基序、选择标记、复制起点、隐蔽的真核信号或核酸酶敏感区域以及反向重复序列等DNA元件对质粒作为生物制药的性能产生了不利影响。另一方面，仔细选择启动子、聚腺苷酸化信号、密码子优化和/或插入内含子或核靶向序列以进行治疗性蛋白质表达，可以提高临床疗效。最小载体不含细菌骨架，仅由真核表达盒组成，在表达水平、生物利用度、转染率和增强治疗效果方面表现出更好的性能。尽管结果很有前景，但由于制造方面的挑战性问题，最小载体在临床试验中尚未取代传统质粒。
