The present application discloses a method for generating human tissues in a non-human animal comprising: (i) generating human naïve state stem cells and injecting them into a blastocyst or embryo of a non-human animal such that a chimeric animal is generated； (ii) harvesting human tissues, organs, cells or factors secreted by or made in the human tissues or cells from the chimeric animal； and (iii) transplanting or administering the harvested material into a human resulting in generation of human tissues in a non-human animal.
