Issue link: https://tmcpulse.uberflip.com/i/457465
t m c ยป p u l s e | j a n / f e b 2 0 1 5 21 Introduction to Stem Cells This is because a patient's own cells could be expanded in culture, coaxed into assuming a specific cell type (differentiation), and then reintroduced into the patient. The use of adult stem cells and tissues derived from the patient's own adult stem cells would mean that the cells are unlikely to be rejected by the immune system. This rep- resents a significant advantage, as immune rejection can be circum- vented only by continuous administration of immunosuppressive drugs, and the drugs themselves may cause deleterious side effects. What are induced pluripotent stem cells? Induced pluripotent stem cells (iPSCs) are adult cells that have been genetically reprogrammed to an embryonic stem cell-like state by being forced to express genes and factors important for maintaining the defining properties of embryonic stem cells. Although these cells meet the defining criteria for pluripotent stem cells, it is not known if iPSCs and embryonic stem cells differ in clinically significant ways. Mouse iPSCs were first reported in 2006, and human iPSCs were first reported in late 2007. iPSCs are already useful tools for drug development and model- ing of diseases, and scientists hope to use them in transplantation medicine. This breakthrough discovery has created a powerful new way to "de-differentiate" cells whose developmental fates had been previously assumed to be determined. In addition, tissues derived from iPSCs will be a nearly identical match to the cell donor and thus probably avoid rejection by the immune system. The iPSC strategy creates pluripotent stem cells that, together with studies of other types of pluripotent stem cells, will help researchers learn how to reprogram cells to repair damaged tissues in the human body. What are the potential uses of human stem cells? There are many ways in which human stem cells can be used in research and the clinic. Studies of human embryonic stem cells will yield information about the complex events that occur during human development. A primary goal of this work is to identify how undif- ferentiated stem cells become the differentiated cells that form the tissues and organs. Human stem cells are currently being used to test new drugs. New medications are tested for safety on differentiated cells gen- erated from human pluripotent cell lines. Other kinds of cell lines have a long history of being used in this way. Cancer cell lines, for example, are used to screen potential anti-tumor drugs. Perhaps the most important potential application of human stem cells is the generation of cells and tissues that could be used for cell- based therapies. Today, donated organs and tissues are often used to replace ailing or destroyed tissue, but the need for transplantable tissues and organs far outweighs the available supply. Stem cells, directed to differentiate into specific cell types, offer the possibility of a renewable source of replacement cells and tissues to treat a wide range of diseases. M I T O S I S N E R V E C E L L S K I N C E L L B LO O D C E L L M U S C L E C E L L M O R U L A B L A S T O C Y S T Source: National Institutes of Health