Stem cell research is the topic of some very intense debate in the US and around the world. Before forming an opinion on the bioethics of different forms of stem cell research, it's important to understand the potential benefits to using stem cells for biomedical research.
A stem cell line, once established from a cell in the body, is essentially immortal, meaning the cell line can be sub-cultured indefinitely, frozen for storage and shared with other researchers. Stem cells are pluripotent when harvested and can be studied to help us to understand how they transform into specialized cells that differentiate our various organs.
Many serious medical conditions, such as cancer and birth defects, arise from problems that occur during cell differentiation. Once those processes are understood, scientists may use genetic engineering methods to engineer stem cell lines for treatment of diseases, (therapeutic cloning), and possibly even for the generation of organs for transplantation (also known as regenerative medicine).