Why Are Stem Cells Important?
Stem cells are important because they are the body’s raw materials for growth, repair, and renewal. Unlike most specialized cells, stem cells can both self-renew (produce more stem cells) and differentiate into many different cell types, including muscle, nerve, blood, and skin cells. This remarkable ability makes them essential for life and a major focus of medical research.
Role in development and maturity
Every human begins as a single fertilized egg. As that cell divides, embryonic stem cells give rise to the trillions of specialized cells that form the body’s organs and tissues. Stem cells continue to function long after birth. Adult stem cells replace cells that wear out or become damaged through normal use or injury. For example, stem cells in the bone marrow continually produce new blood cells, while stem cells in the skin and intestines replenish tissues that are constantly being renewed. This ongoing repair helps maintain healthy organs and supports healing after injury.
Use in medicine and research
Stem cells have been used in medicine for decades. The best-known example is bone marrow transplantation, in which blood-forming stem cells replace damaged bone marrow to treat leukemia, lymphoma, and other blood disorders. Researchers are also investigating whether stem cells can regenerate damaged heart muscle after heart attacks, replace dopamine-producing neurons lost to Parkinson disease, restore insulin-producing cells in people with diabetes, and repair spinal cord injuries. Although many of these therapies remain in clinical trials, several have shown encouraging results in select patients.
" height="20" alt="HEW Logo">
Stem cells have transformed biomedical research by allowing researchers to observe how tissues develop, investigate the causes of disease, and test the safety and effectiveness of new drugs. In particular, scientists can use stem cells to grow miniature, three-dimensional models of human organs—called organoids—in the laboratory. Brain, intestine, liver, and kidney organoids, for example, are used to study human development, to investigate genetic diseases, and to observe how viruses and cancers affect tissues.
The development of induced pluripotent stem (iPS) cells, first reported in 2006, has further expanded stem-cell research. These cells are created by reprogramming adult cells, such as skin cells, into a stem-cell-like state. Because iPS cells can be generated from individual patients, researchers can study diseases using cells that carry a patient’s own genetic mutations and investigate personalized treatments.
Ethical considerations
Stem-cell research has raised ethical, legal, and social questions, particularly when it involves embryonic stem cells. Because these cells are typically obtained from early-stage embryos donated through in vitro fertilization, their use has prompted debate over the moral status of human embryos. Advances in iPS cells have reduced many of these concerns by providing an alternative source of pluripotent cells. However, iPS cells raise other questions in reproductive medicine. For instance, because iPS cells may eventually be used to generate human eggs and sperm, they could enable new fertility treatments while also prompting debate over germ-line gene editing, genetic privacy, and the ethical limits of reproductive technologies. Ethical issues also include informed consent from tissue donors, the regulation of experimental therapies, the marketing of unproven stem-cell treatments, and equitable access to emerging regenerative medicines.