In this chapter you will learn more about the umbilical cord blood findings that are currently available. Science moves forward very quickly in this and related areas. New, unforeseen relations often appear, recognised theories could be swept from the table in a moment and, the other way around, the older and forgotten theories could be dusted off. In the most cases, however, there are more different views on the same problem, sometimes affected by emotions, or even greed. Therefore it is necessary to read the following lines with healthy scepticism and not to take the presented knowledge as fixed and absolute.

          Umbilical cord blood is the new-born blood that remains after umbilical cord interruption in placenta. It is actually biological waste.

          Placental blood uniqueness is based on the fact that it contains cells that never occur in such a form again throughout the life of the organism. They are so-called stem cells. Stem cells have one common attribute – they are able to multiply and give rise to different types of cells, needed for the organism. Research shows that stem cells from placental blood are not only able to transform to haematopoietic cells, but also to bone marrow cells, insulin- producing cells, specific brain cells, heart muscle- cells and more. In practice, mostly the haematopoietic stem cells are currently used.

          Haematopoietic cells from umbilical cord blood are used in transplantation as replacements for damaged and/or destroyed bone marrow cells. Today, haematopoietic cells transplantation is used in the treatment of about 50 diseases (see the Registry of diseases treated by haematopoietic cells transplantation).

          Throughout life, new blood and immune system cells are constantly built up in the bone marrow. The haematopoietic cells multiply in the bone marrow and give rise to red blood cells, platelets and white blood cells. Bone marrow failure leads to anaemia - causing decreased tissue oxygenation; immune system disorders - which cause severe infections; and a lack of platelet cells - manifesting in internal or external bleeding. Each one of these defects alone can cause a patient’s death.

          Haematopoietic disorder can be caused either by diseases like leukaemia, or by therapy, mainly the therapy of malignant tumours. Cancer therapy considerably impairs the bone marrow. Therapy, which tries to destroy tumour cells, destroys the haematopoietic stem cells at the same time. In an effort to save the bone marrow cells, limited doses of chemo-therapeutics or radiation are given. They may not be adequate to destruct malign tumour and its metastasis. This compromise often leads to tumour cells remaining in the patient’s body, which cause the renewal of the tumour. In many cases it is possible to remove the tumour cells at the cost of destroying the bone marrow cells. This is the strategy of bone marrow cells transplantation. However, such therapy can be used only in cases where the patient’s alternative source of haematopoietic cells is available. Only then is it possible to carry out the bone marrow transplant, which repopulates haematopoiesis in destroyed bone marrow.

          The most serious obstacle for the majority of patients is the lack of an alternative source of haematopoietic stem cells, needed for transplant. A source can be either a bone marrow donor, or umbilical cord blood transplant. In both cases the compatibility between the patient and the donor is very important, hence the donor for a specific patient can not be just anybody. First, the search begins among siblings, a sibling has a 25% probability of being a suitable donor. Other family relatives, including the parents, are only very rarely suitable donors. After that, the search process continues among volunteer donors (and transplants of cord blood donor) all over the world. More than 8 million voluntary bone marrow donors are registered, but there is only a 50 % chance of finding a compatible donor. Generally, more than one third of the patients have no matching source of haematopoietic cells. Even patients receiving a compatible haematopoietic cell transplant are exposed to complications caused by foreign cells, even in the case of transplantation of a sibling’s haematopoietic stem cells. Incompatibility causing graft versus host disease results the death of 40 % transplanted patients. The risk of missing a source of haematopoietic cells, and of adverse post-transplant reaction can be avoided by using the patient’s own, healthy, haematopoietic cells. In some diseases it is possible to harvest healthy haematopoietic stem cells from patient during a disease. It has its drawbacks, for instance in case of bone marrow failure it is not possible at all, and in some malignant diseases there is a risk here that in the harvesting of haematopoietic cells some tumorous cells will be taken with. These cells can cause the cancer disease relapse after transplantation. Mostly the harvesting is made after prior chemotherapy and the cells’ vitality and ability to multiply can be reduced. Hence the best source of haematopoietic cells is the own umbilical cord blood – there is no risk of post-transplant reaction, cells are absolute vital and if the child is not already ill at birth, the cells are certainly healthy. Unfortunately, we cannot estimate in advance, which child will need the transplant and which will not. The only solution is to preserve the child’s own umbilical cord blood with the knowledge that maybe it never will be needed. The probability of a child becoming ill with a disease that possibly could need haematopoietic stem cell transplantation, during childhood or adulthood, is about 15 %.