The probability that you will be able to donate blood stem cells and thus save lives, is relatively small and doesn't apply to all registered individuals. Often years or decades may pass between registration and the request for a blood withdrawal for an in-depth tissue typing.

In Switzerland, approximately 150 registered donors per year receive such an initial request. 

If the search of the databank shows that the tissue markers of the patient could match those of a donor, a blood test of the donor has to be done in order to do an in-depth tissue typing, as well as a determination of the most important infection markers.

Even if they are asked for further blood tests, chances of peripheral blood cell or blood stem cell donation are small.

Until today there a more than 35’000 registered donors in Switzerland. In 2011 there have been 177 persons requested for compatibility test.

If you are requested to do a more in-depth tissue typing, it will show whether you are compatible with this patient. If you are found incompatible with the patient, it only means that in this case, you are not eligible to donate blood stem cells.

It can also happen that after some time you are again asked for a donation for another patient. It is therefore very important that after registration, you always keep your address up to date.

After a donor has been asked for an in-depth blood test, it can take a few weeks until it is determined who is a suitable donor for a bone marrow or peripheral blood stem cell donation.

If a donor is suitable due to matching tissue markers and willing to donate blood stem cells, an appointment for the collection and collection type is made. The  donation procedure is decided by the transplant team and the donor always has a right to voice his or her wishes. 

Then about 3-4 weeks before collection at the collection center, a physical exam will be done: only healthy individuals can donate.

When everything is checked thoroughly and the donor is healthy, a transplantation can be performed. It is understood that the donor always retains the right to withdraw consent.

Transplantation of blood stem cells is only performed in specialized hospitals. Medical preparation of the patient is guided toward the type and stage of the disease. The goal is to eliminate the diseased hematopoietic stem cells and create the space for new ones. This happens either through chemotherapy and/or through whole-body radio-therapy. The new blood stem cells are administered intravenously similar to a blood transfusion.

The so-called "homing receptors" are responsible for the stem cells finding their way from the blood to the bone marrow. There they are supposed to multiply, and after two to four weeks build new red and white blood cells as well as blood platelets.

Afterward, the sustained healing success mainly depends on whether all former diseased blood stem cells of the patient have been destroyed.

The time factor plays an important role during transplantation: Because blood stem cells have a very short lifespan, harvesting and transplantion must be done so that the harvested cells are transplanted within 48-72 hours - even if the cells have to be transported over thousands of kilometers.

As with blood donation, the donor and recipient of blood stem cells cannot be acquainted. They are not allowed to know each other's name or other personal information. This regulation was introduced for the personal protection of donor and recipient.

Until a few years ago the donor and the recipient could meet - if both sides agreed- or at least exchange letters with each other. In spite of all safety measures being followed, there were cases where this loosening of anonymity had negative consequences.