 Amniotic epithelial cells have not been known to produce cancerous tumors in the host despite the fact that these cells do express genes found in embryonic stem cells that are known to promote tumor formation.Organs engineered from amniotic epithelial cells obtained from the placenta associated with a particular person's birth would not be rejected by that person; such organs would have the same genotype as that person and thus be fully compatible with that person's immune system.Because there is not a sufficient amount of amniotic epithelial cells extracted from a single term placenta to be use in cellular therapies, the cells must be expanded in a lab.