Stem cell applications in disease research: Recent advances in stem cell and cancer stem cell biology and their therapeutic implications

Recent advances in embryonic, fetal, umbilical cord, placental, amniotic and tissueresident adult stem/progenitor cell research is of great clinical interest due to their potential therapeutic applications in regenerative medicine and gene therapies. The tissue-resident adult stem/progenitor cells, which possess several characteristics common with embryonic stem cells (ESCs) but generally display more limited self-renewal ability and restricted differentiating potential, are emerging as promising sources of immature cells. The presence of a rare population of adult stem/progenitor cells in most tissues and organs offers the possibility to stimulate their in vivo differentiation or to use their ex vivo expanded progenies for cell replacement-based therapies with multiple applications in humans. Among the human diseases that could be treated by the stem cell-based therapies, the hematopoietic and immune disorders, cardiovascular disorders, multiple degenerative disorders such as Parkinson's and Alzeimeher's diseases, type 1 or 2 diabetes mellitus as well as eye, liver, lung, gastrointestinal and skin disorders and aggressive and metastatic cancers are of immediate attention. In addition, the geneticallymodified adult stem/progenitor cells could also be used as a delivery system for expressing the therapeutic molecules in specific damaged areas of different tissues in humans. Recent progress in cancer stem/progenitor cell research also offers the possibility to target these undifferentiated and malignant cells that provide critical functions in cancer initiation and progression and disease relapse for treating patients diagnosed with advanced and metastatic cancers which remain incurable in the clinics with the current therapies.