The development of humanized culture system of human embryonic stem cells (hESCs) hold promise for therapeutic applications. However, conventional culture system contain animal-derived components such as fetal bovine serum and mouse embryonic fibroblasts that bear a risk of transmitting non-human pathogens and incorporation of non-human immunogenic molecules to hESCs. In this study, we developed an efficient xeno-free hESCs culture system using humanized materials, the CELLstartTM, human foreskin feeder and xeno-free medium containing knockOutTM SR XenoFree (XF-medium) without animal-derived material. The hESCs were gradually adapted to the XF-medium; 25:75, 50:50, 75:25 and 100:0. Two karyotypically normal hESC lines, SNUhES4 and H1, were used for the experiments of xeno-free culture condition. The attachment rates at xeno-free culture system were 52.6±12.4%, 67.0±16.6%, 59.0±13.9%, 28.3±2.9% in SNUhES4, 79.3±5.4%, 53.8±20.9%, 69.4 ±6.4%, 59.8±12.6% in H1 and the spontaneous differentiation rates were 42.2±12.7%, 31.4±2.9%, 40.8±14.5%, 55.2±35.5% in SNUhES4, 35.6±8.5%, 36.4±13.5%, 48.4±7.8%, 80.1±6.0% in H1 in the first four passage. Although the attachment rates were low and the spontaneous differentiation rates were high compared to that of conventional system in the early passages using this humanized culture condition, hESCs in this culture condition were found to maintain hESC characterizations; morphology, expression of cell surface markers and stable karyotype. Our results indicate that simplified compositions of humanized culture system can be applicable to the further optimization for a xeno-free culture of hESCs without the loss of pluripotency and contamination from xenogenic sources.

• Baek J.A.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University)
• Seol H.W.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University)
• Jung J.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University)
• Yoon B.A.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University)
• Kim H.S.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Department of Obstetrics and Gynecology, Seoul National University College of Medicine)
• Oh S.K.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Department of Obstetrics and Gynecology, Seoul National University College of Medicine)
• Koo S.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Department of Obstetrics and Gynecology, Seoul National University College of Medicine)
• Kim S.H.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Department of Obstetrics and Gynecology, Seoul National University College of Medicine)
• Moon S.Y.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Department of Obstetrics and Gynecology, Seoul National University College of Medicine)
• Choi Y.M.(Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Department of Obstetrics and Gynecology, Seoul National University College of Medicine)