This book is a continuum of the first two books published in the STEM CELLS series entitled "e;Stem Cells: From Drug to Drug Discovery"e; and "e;Stem Cells: From Hype to Real Hope"e; which were published in 2017 and 2019, respectively. The scope of the book encompasses a wide range of topics with a latitude from adult stem cells to pluripotent stem cells in regenerative medicine either alone or as part of the combinatorial therapeutic intervention approach as "e;drug"e; besides their application as tools (disease model) during drug development process. Written by a leading group of researchers, the book encompasses experimental to clinical aspects of stem/progenitors cells, their biology, and characteristics.