Identifying Cells Through Embryonic Stem Cells Differentiation

They say that stem cells have the ability to self-renew so that new stem cells can be formed.  The  new stem cells can then be transplanted to a person who's suffering from a disease to help him get better.  The stem cells will replace damaged cells and help other cells get stronger.  But first stem cells have to be identified and this is done through embryonic stem cells differentiation; researcher will be able to tell which cells are strong enough to self-renew and which are not.  Once stem cells have been identified, that's the time they will be cultured and studied before they will be given to a patient.