From http://www.athenaweb.org : Scientists of today are breathing life into one of the myths of the past, human regeneration.

At the root of this potential for regeneration are cells, known as stem cells.

Stem Cells

To understand what a stem cell is, and as to why we apply a certain definition to say that a given cell is a stem cell, we need to understand what the function of a stem cell is.

A stem cell is above all a cell. And one of the major functions of every cell is to divide and give rise to two twin daughter cells, which will each in turn give rise to two daughter cells.

As soon as the egg is formed by the fusion of an ovule and a sperm, it rushes to divide again and again… until the embryo resembles a little blackberry composed of eight stem cells which are highly potent : each of them could in theory give rise to a full embryo, a foetus and finally a baby. Then around the fourth day, the dividing stem cells begin to specialise. They give rise to two types of cell : in the centre, a small internal mass will eventually become the future foetus, and at the periphery, the cells that will go on to form the placenta…

The cells of the internal mass are called embryonic stem cells. If we take cells from the internal mass, we find that every one of them has the potential, on dividing, either to form cells identical to themselves which can be grown to large quantities in culture, or alternatively, to form muscle, cartilage, neurons, blood and other tissues.

As the embryo advances in its development to become first a foetus and then a baby, most stem cells gradually specialize and lose their ability to form a wide diversity of different types of cells.

Medical Treatment by Stem Cells

There is already an example of medical treatment by stem cells, which has been used for ten years : patients suffering from leukaemia, a cancer of the white blood cells, can today be treated by the transplantation of blood stem cells obtained from the placenta. This is now simple and routine.

Transplantation of Dopamine Producing Cells

The idea is to cure patients suffering from Parkinsons disease. Parkinsons disease is a rather selective destruction of a certain type of nerve cells in the brain, those that produce dopamine. These patients cannot control their movements properly because dopamine is essential for the transmission of information between nerves.

In the last fourteen to fifteen years cells have been transplanted into eighteen patients suffering from Parkinsons disease, taking tissue from aborted foetuses, six to nine weeks old. The problem we are now facing is that we dont have enough cells to transplant into patients. So we’ve got to find alternatives to foetal cells and to do so we are focusing on the alternative of neural stem cells. These cells have been cultivated from cells taken from an aborted foetus that was ten weeks old. This is how the neural stem cells grow in cell culture. The next step is to analyze what they can do after being transplanted into the brain and we do that with rats. The researchers have not yet worked out how to make these cells produce the right kind of dopamine. Nor do they know how to get them to survive, grow and function correctly, in the same way as the normal dopamine cells. To solve these problems extensive research is needed.

Therapeutic Cloning

A major problem in stem cell therapy is the incompatibility between grafts and the patient which leads to rejection. Some scientists hope to overcome this problem using a technique called therapeutic cloning – a technique which has the potential to produce tissues and organs that are 100% compatible with the patient due to collecting embryonic stem cells from the fusion of a patients cell with a donors ovum.

A cell from the skin or muscle or indeed any sort of cell from the future recipient patient, and an ovum from a consenting donor are needed for this technique. The nucleus is taken out of the ovum, and replaced with the nucleus from the recipients cell.

The embryonic stem cells are collected and grown in a test tube. They carry all the genetic information contained in the nucleus of the recipient and are therefore a 100% compatible with all organs of his or her body. If we could learn to control the mechanisms by which stem cells differentiate into the various tissues, it would be possible to produce banks of muscle cells, bone cells, nerve cells and indeed all cell types, made to measure cells ready to repair all the organs of every individual person, with no risk of rejection.

Conclusion

Some of these techniques raise ethical questions : to what extent do we have the right to use embryos, and even create embryos, with the aim of healing the sick?

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