Improved methods of cell therapy are provided using cells and tissues that are histocompatible with a human or non-human transplant recipient. The cells and tissues for transplant produced by the present invention exhibit a youthful state and can be committed to specific cell lineages to better infiltrate and proliferate at a desired target, e.g., a tissue, or organ in need of cell replacement therapy. For providing cells and tissues for transplant to a non-human mammal, the cells and tissues can be isolated from a gastrulating embryo produced by same-species nuclear transfer.
