Introduction: Stem cells are cells with the ability to grow and differentiate into more than 200 cell types.
Sources of data: We review here the characteristics and potential of human embryonic stem cells (hESCs), induced pluripotent stem cells (iPSCs) and adult stem cells (ASCs).
Areas of agreement: The differentiation ability of all stem cell types could be stimulated to obtain specialized cells that represent renewable sources of functional cells useful for cell-based therapy.
Areas of controversy: The proof of functional differentiated cells needs to be investigated in more detail using both in vitro and in vivo assays including animal disease models and clinical studies.
Growing points: Much progress has been made in the ASCs-based therapies. Meanwhile hESCs and iPSCs have dramatically emerged as novel approaches to understand pathogenesis of different diseases.
Areas timely for developing research: A number of new strategies become very important in regenerative medicine. However, we discuss the limitations of stem cells and latest development in the reprogramming research.