January 2019  Vol. 29  No. 1 J. Microbiol. Biotechnol. (2019), 29(1), 55–58 https://doi.org/10.4014/jmb.1809.09018 Research Article jmb Review Efficient Development of Stable Recombinant Chinese Hamster Ovary (rCHO) Cell Lines to Produce Antibodies by Using Dimethyl Sulfoxide (DMSO) in Electroporation Juyoung Byun 2 , Sena Yoon 2 , Yunji Jeong 1 , Uitaek Oh 1 , Sujin Cho 1 , Jeongsoo Park 2 , Yongsu Jeong 1 , Kwanghee Baek 1 , and Jaeseung Yoon 1 * Graduate School of Biotechnology, Kyung Hee University, Yongin 17104, Republic of Korea PanGen Biotech Inc., Suwon 16675, Republic of Korea Commercial production of recombinant proteins and antibodies on a large scale for therapeutic purposes requires the harmonized combination of various technologies. Among these, the technologies involved in the establishment of stable producer cell lines are critical for successful development of a manufacturing process for commercial production. Chinese hamster ovary (CHO) cells are currently the most widely used host cells for the production of recombinant proteins and antibodies for therapeutic purposes [1]. Thus, various technologies and equipment allowing rapid and inexpensive establishment of stable recombinant CHO (rCHO) cell lines have been developed in the past few decades [2-4]. However, the establishment of stable rCHO cell lines is still a time-consuming and labor-intensive process. It usually takes longer than six months, however, often over one year is needed when numerous steps are required in the gene amplification process with antibiotics to obtain desirable expression levels. Efficient transfection methods of CHO host cells with the gene of interest is essential to establish stable rCHO cell lines. Transfection methods using cationic polymers and lipids have been developed for the transfection of adherent CHO host cells [5, 6] whereas the electroporation is widely used for transfection of suspension-adapted CHO host cells [7]. A number of compounds, so called transfection enhancers, can enhance transgene expression in various cell types when they are used as additives in transfection procedures [8]. Among these compounds, dimethyl sulfoxide (DMSO) can increase efficiency of transgene expression when it is used as an additive in electroporation of various host cells (HL60, TR146, Cos-7, and L132) [9]. DMSO can also enhance transient expression of transgenes in CHO cells [10]. However, advantages of using DMSO in transfection (electroporation) have not been reported for the establishment Received: September 12, 2018 Revised: October 19, 2018 Accepted: October 24, 2018 First published online October 26, 2018 *Corresponding author Phone: +82-31-201-2450; Fax: +82-31-203-4969; E-mail: jsyoon@khu.ac.kr pISSN 1017-7825, eISSN 1738-8872 Copyright © 2019 by The Korean Society for Microbiology and Biotechnology Development of stable rCHO cell lines is still time consuming and labor intensive, although it is a critical step in the commercial development of recombinant antibodies. The current work demonstrates, for the first time, that electroporation of CHO cells with DMSO can enhance stable expression of recombinant antibodies in rCHO cells. Electroporation with DMSO resulted in an average 3.7-fold and 2.8-fold increases in expression levels of aflibercept and pembrolizumab, respectively, in pools of stable rCHO cells. It also resulted in an average of 2.2-fold and 2.6-fold increases in the expression of aflibercept and pembrolizumab, respectively, in single-cell derived rCHO clones. Simple batch cultures of rCHO cell clones with the highest expression produced 1.0 g/l for aflibercept and 1.4 g/l for pembrolizumab without a time-consuming gene amplification process. Electroporation with DMSO also shortened the development of rCHO cell lines to 2-3 months, allowing rapid establishment of stable rCHO cell lines with a desirable expression level antibodies. Keywords: Dimethyl sulfoxide, stable cell line, Chinese hamster ovary cell, recombinant antibody, electroporation