Although three different research groups have reported the successful derivation of human somatic cell nuclear transfer-derived embryonic stem cells (SCNT-ESCs) using fetal, neonatal and adult fibroblasts, their extremely low efficiency of human blastocyst formation would be a main limitation for the potential application. Recently, our group has found that H3K9me3 in the human somatic cell genome is an SCNT reprogramming barrier and overexpression of KDM4A, a related H3K9me3 demethylase, significantly improves the blastocyst formation of SCNT embryos by facilitating transcriptional reprogramming. Since several approaches for the optimization of SCNT conditions such as the use of protein phosphatase inhibitors, oocyte activation method and epigenetic regulation have been applied in order to improve the efficiency, it may be a powerful method for establishment of the stem cell bank with pluripotent stem cells for public supply as well as personalized stem cells.