No matter how big a human becomes, it all began with an ovum and a sperm cell. This means that cells exist which have the potential to form a complete human. The first cells to arise from a fertilised ovum are described as totipotent (”potent for everything”). After a few days in the womb, the blastocyst forms. The cells contained in it are called embryonic stem cells. They are still very unspecialised and have the ability to divide endlessly and to develop into all of the 220 human cell types. However, a whole human cannot arise from these few cells. They have lost their toti-virility and are described as pluripotent (”potent for a lot”). As soon as the human’s development is completed, these former all-rounders will have changed into mature, differentiated cells taking over a specific function in our body, for example neurocytes which conduct electric impulses, muscle cells which contract and the ß-cells of the pancreas which produce insulin.

However, skin renews itself throughout adulthood, injuries heal and hair grows. Right to the end of our lives, we have cells which are very unspecialised, can divide often and help the organism to regenerate and repair itself. These cells are called adult stem cells. To date, adult stem cells have been found in nearly every body tissue, for example in the skin, the brain, the blood, the liver and the bone marrow.

Biological function of adult stem cells

If body tissue is damaged, stem cells head for the damaged area and advance the process of healing. However, day-to-day processes in the human body also rely on stem cells: our erythrocytes only live for about 120 to 130 days, by which time they have become too old, cannot transport enough oxygen and have to be replaced. This task is taken over by the haematopoietic stem cells that can be found in the bone marrow. According to theoretical calculations, about 350 million new erythrocytes are formed every minute. Most of the other somatic cells are also replaced regularly: liver cells after 10 to 15 days, white blood cells after 1 to 3 days.

In theory, the body has its own repair system. So why do people still become terminally ill? And why does the organism age if it has the ability to regenerate itself?

Limits of regeneration

One established theory is that special messengers lure adult stem cells to the damaged area; However, they often do not arrive in sufficient numbers, or may even fail to arrive at all because the artery is blocked. The damaged area then only heals very slowly, or may not heal at all if the cause of the disease is not eradicated. It might also be possible that some diseases develop covertly and are not recognised as being in need of repair. Another problem: adult stem cells also age. They have much higher regeneration potential than differentiated somatic cells, but it seems that this potential is exhausted after 130 years at the latest. Up to now, the oldest woman in the world lived in France and reached 122 years of age. The process of aging cannot be stopped. However, with the help of modern medicine, it is possible to abstract stem cells from the body, to clean them, concentrate them and then apply them to the diseased area. In many cases, the physiological healing process can be enhanced.

Stem cells from cord blood

Nowadays, a lot of parents have their newborns’ cord blood frozen in order to give their children the chance to resort to their own adult stem cells in the event of a serious disease. In principle, this does make sense, because these cells seem to be less differentiated than the cells in the blood of adult organism, and they have higher potential for changing into different types of cells. These stem cells are also less immunological and therefore might be suited to use in foreigners. But nevertheless, certain restrictions have to be taken into consideration. Problems are inevitable if providers do not obtain and store the stem cells in compliance with the globally valid “Good Manufacturing Practice” quality standards, or if the stem cells are not isolated from the cord blood and the blood bottle is frozen throughout. While no hospital is allowed to use the cells in the first case, the cells suffer damage through the use of anti-freezers and the comparatively long time needed for unfreezing. In both cases, the stem cells are rendered practically worthless.

There are some further aspects that have to be considered when extracting stem cells from cord blood. Predispositions to diseases such as Alzheimer’s or Parkinson’s, leukaemia or other types of cancer can be saved in one’s own stem cells, thus making it possible to transmit the disease further. Moreover, only a limited number of stem cells remain in the cord blood. However, as a certain minimum of cells is needed for therapy, researchers are today working on the increase of adult stem cells outside the body; the XCell-Center is also taking part in this research. If the breakthrough comes, it might be assumed that the disposal of stem cell depots will soon become common practice. An article from the professional journal “The Lancet” shows that the unique possibility of obtaining stem cells from cord blood is already realistic. It says that since 1989, more than 7,000 transplantations have been carried out worldwide using stem cells from cord blood.

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