Why regenerative stem cell medicine progresses slower than expected

Stem cell research has been acclaimed to revolutionize the future of medicine, and to offer new treatments for previously incurable diseases. Despite years of research, however, the therapeutic potential of stem cell research has not yet been fully realized. By June 2014, the US Food and Drug Administration had approved only five stem cell-based medicinal products, all of which cord blood derived hematopoietic stem cell products for the cure of blood and immunological diseases. Anticipated treatments for cancer, neurodegenerative disorders, gastroenterological, myocardial, and other diseases are still far from routine applications. What are the reasons for the slow progress in the stem cell field, and the mismatch between public expectations and actual achievements?