Stable protein expression in therapeutic cells such as T cells and NK cells is important for long-lasting clinical effects in cell therapy such as CAR-T therapy. Stable protein expression can be achieved by the viral vector expression method, transposon based expression method and CRISPR/Cas9 mediated knock-in method. Transposon based expression method has the advantage of being relatively safe and cost-effective compared with other methods. However, in the actual application of the transposon systems such as the piggyBac (PB) system and the Sleeping Beauty (SB) system, it is quite challenging to achieve a high delivery efficiency and a high cell viability. We found that in addition to the choice of electroporation methodology, vector design and cell culture are two most important aspects that need to be optimized. Vector design dictates protein expression level as commonly anticipated, it also dictates the expression timing. We found that two distinct designs give two very different expression timing, one with initial high efficiency of expression which tapers down to about half, and another one with very low initial expression level and it goes up to a very high level after two weeks. We propose that the differential expression profiles of the vector systems can be applied to different circumstances to achieve better therapeutic effects.

Citation Format: Jian Chen, Youbang Chen. Optimization of the transposon expression system for electroporation based gene delivery [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4064.