•Liver engraftment of hepatoblast, hepatocytes and stem cell‐derived cells (ES or iPSC protocols), lung, gut, endocrine pancreas, kidney or other tissue•Validation of chimerism in the murine blood (ELISA human albumin other secreted proteins)•Functional validation: exogenous test drugs with known and different human metabolism, viral titers or antigens of human hepatotropic viruses (HBV, HCV, etc.)•Validation of chimerism postmortem by immunostaining (human nuclei or other human‐specific antibodies)•Onset of autoimmunity or diabetes. This evidence concerns the gene ALB and diabetes mellitus.