1 Materials and methods
1.1 Donor cells
Fetal-derived fibroblast cells were isolated from E32
fetus. The body wall was digested in 0.25% trypsin and
cells were cultured in DMEM (Gibco) with 20% FBS at
38.5℃ in 5% CO2, 95% air, and saturation humidity.
Confluent cells were stored in liquid nitrogen for future
transfection. DMEM with 10% FBS was used for culture
beyond the first passage.