Human stem cell research and regenerative medicine--present and future.

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.