This book provides an overview of cell-based therapy for human diseases including the definition, history, and clinical applications of human stem cells and their use in regenerative medicine. It covers human pluripotent stem cells (human embryonic stem cells and human induced pluripotent stem cells), mesenchymal stem/stromal cells, and hematopoietic stem cells, bone marrow mononuclear cells. In terms of clinical applications, this book also provides an update on recent human trials using these cells to treat various diseases, including neurological disorders, pulmonary dysfunctions, metabolic/endocrine-related diseases, frailty, and cancer treatment. In addition, it discusses the authors' clinical trial experiences related to these conditions in a clinical setting to provide additional insight into regenerative medicine, especially cell-based therapy. The field of regenerative medicine has witnessed tremendous advancement in stem cell research and therapy in recent years, with thousands of preclinical studies supporting thousands of human clinical trials conducted worldwide. Emerging evidence in regenerative medicine and stem cell research suggests the treatments are safe, whereas their therapeutic potential, effectiveness, and mode of action require deeper investigation. It is important to introduce the science behind stem cell-based therapy to patients, clinicians, and researchers to further enhance understanding of responsible clinical conduct and so to educate and thus prevent the further emergence of unregulated, deceitful stem cell clinics solely operating for the sake of profit.