During many serious diseases the production of blood fails and the only way to save the patient's life is to give him healthy hematopoietic stem cells. These are obtainable from either bone marrow or cord blood. If it's necessary to obtain cells from a different person, this donor must be compatible with the recipient in certain tissue characteristics called HLA antigens. That's why it is important to create databases of volunteer donors of bone marrow or cord blood, in which possible donors can be found.

Cord blood from volunteer donors is collected, processed and stored by public cord blood banks/registries. Registries from all over the world are interlinked through the international database BMDW. Transplant centers across the globe search this database for compatible donors for their patients.

Despite the fact that it is possible to find donors from across the world, it is extremely important that each country has its own cord blood registry. The genetic relationship is much closer in one area and so the probability of finding a suitable donor in a national registry is much higher than finding a donor in an international one.