The Heated Debate Concerning Stem Cell Research

Stem Cell Research

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 differentiated. The differentiated cell may still be able to divide, but it cannot normally go back to form the original type of cell. In some circumstances stem cells can increase their numbers, giving rise only to more stem cells. However, stem cells in the adult are usually in tune with the tissue to which they belong. They divide at the appropriate rate to self renew and to...

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...ggests that they probably will be, but it is important to show this for human Embryonic Stem cells.

That Embryonic Stem cells are able to give rise to any cell type within the body is a normal process, not one that involves a rare cell changing its potential. They would therefore seem to be an ideal source of cells for cell-based therapies. However, if they were to be made on a patient-specific basis using current techniques, this would require the use of many unfertilised eggs, as discussed above. However the reprogramming mechanism elicited by egg cytoplasm after nuclear transfer is still the only way known to reprogram an adult cell in a controlled manner. Once the mechanisms are understood, perhaps adult cells could be treated in an appropriate way to turn them into the equivalent of Embryonic Stem cells, eventually without having to use any human eggs.

Clearly work on adult stem cells is also a priority. Adult stem cells will probably turn out to be entirely suitable to treat some diseases, whereas Embryonic Stem cells will be necessary for others. There is no logic in stopping research on one to concentrate on the other, especially when we know so little about either.