OBJECTIVES: The establishment of adult stem cell line by using CP-Nanog and CP-Oct4 proteins fused to Macromolecule Transduction Domain (MTD) METHODS: We used Macromolecule Transduction Domain (MTD) that allows macromolecules to transduce lipid bilayer structure of plasma membrane to deliver Nanog and Oct4 into cells in vitro and in vivo. To establish stem cell line, CP-Nanog and CP-Oct4 proteins fused to κFGF4-derived MTD were prepared in soluble form and confirmed their cell permeability by flow cytomerty and fluoresence confocal laser scanning microscopy RESULTS: Stem cells can proliferate indefinitely (self-renewal) and differentiate into cells of all types (pluripotency). These characteristics make a possibility that stem cells have become important resources for cell replacement therapy. Nanog and Oct4 are key regulators essential to maintain the pluripotency and self-renewal of stem cells. CP-Nanog and CP-Oct4 fused to Macromolcule Transduction Domain (MTD) have been developed. Self-renewal of adult stem cells was significantly increased in combinational treatment of CP-Nanog and CP-Oct4 in adult stem cells. In addition, Morphological stem cell identity was maintained even after termination of protein treatment. Treatment of CP-Nanog & CP-Oct4 induced immortality of stem cells by increasing telomerase activity and inhibiting CDK inhibitor p21, resulting in robust cell cycle progression. These results suggest that treatment of CP-Nanog and CP-Oct4 can result of establishment of cell lines to realize person tailored stem cell therapy. CONCLUSIONS: Establishment of the adult stem cell-derived cell line using CP-Nanog and CP-Oct4 proteins fused to κFGF4-derived MTD suggests that stem cell lines can be established for patient- and individual-specific stem cell therapy.