Stem cell research began in the 1950's but we are still in the early days of understanding them. Stem cells offer great opportunities to for scientists to learn more about human development and how our cells work. Currently, human stem cells are being used to test new drugs, for example to trial potential anti-tumour drugs for cancer treatment. They can also be used to create cell-based therapies to treat diseases such as diabetes. In the future, we may be able to use stem cells to create replacement cells and tissues to treat heart disease, arthritis and even spinal cord injury.

Recently there have been breakthroughs with the use of adult stem cells. These largely surround the development of a technique which allows adult stem cells to be returned to a state similar to embryonic stem cells in which they can more easily differentiate into a larger variety of other cells. These modified stem cells are called induced pluripotent stem cells. There is however, far more research needed to fully understand if there are other unexpected disadvantages to the induced pluripotent stem cells. They are however already being used to model the development of disease and for drug screening.

Embryonic stem cells are the cells which specialize into all the different parts of a body in early development. In the lab these cells are grown after in vitro fertilization (IVF), the process where an egg is fertilized outside of a human body with the full informed consent of the donor. These cells can proliferate for a year in the lab becoming millions of cells and can differentiate into any cell in the body - they are extremely versatile. Adult stem cells on the other hand are believed to be more specialized, differentiating into cells which are more specific to where they were taken from the body. However, there have been reported incidents of adult stem cells specializing into other cell types very different from their location, such as a stem cell which would usually differentiate into a blood cell instead differentiating into a muscle tissue cell. This process is called trans-differentiation. While this has been observed in other animals it is very rare and it is still debated as to whether it happens in humans at all. The advantage of using adult stem cells in medicine is that they can be taken directly from the patient’s body, specialized and then returned. The patient's immune system is less likely to reject these cells because they are from the patient’s body originally.

Stem cell research has invoked a large amount of controversy in the last few decades, largely surrounding the use of human embryonic stem cells. Some belief systems argue that the moment an egg is fertilized it is a human life, whilst others believe that the potential medical benefits outweigh the moral issues. The ethical debate surrounding the use of human embryonic stem cells is ongoing and far from resolved, however it has already shaped the path that stem cell research is taking.