Stem Cell Debate

Few recent scientific issues have stimulated so much media attention, public debate and government involvement as that of stem cell research. Stem cells offer people hope by promising to greatly extend the number and range of patients who could benefit from transplants, and to provide novel therapies to treat debilitating diseases such as diabetes, Parkinson's, Huntington's, heart disease and stroke, as well as accidental damage such as spinal cord injury. So why would anyone object to research in this area? The problem is simply that a particular type of stem cell, which potentially could provide many cell types for a wide range of therapeutic uses, is obtained from the very early embryo. To make matters even more contentious, the same cloning technology that gave Dolly the sheep could in theory be used to tailor stem cells to the patient. Some people worry that we are taking research too far down paths that make them feel uncomfortable, others think it is downright immoral and against their deep-held, often religious, beliefs. But what are the scientific issues and why do many of us feel equally passionate that the research should be allowed?

What are meant by stem cells and how might they be used? There are many types of stem cell, but they share several interesting properties that set them aside from other cell types. The adult body contains hundreds of specialised or "differentiated" cell types, each playing a particular role. Some of these are long lived and do not divide, such as nerve cells; others are short lived and need to be replaced through cell division. Usually, when cells divide, their daughter cells are identical and of the same type as the parent cell. In other words they divide symmetrically. Additionally, their fate and their properties are fixed – once a liver cell, always a liver cell.

In contrast, stem cells undergo "asymmetric" divisions, producing both another stem cell, in a process called self-renewal, and a cell that will become