[Umbilical cord blood from an unrelated donor as source for stem cell transplantations in inborn errors of...

In certain inborn errors of metabolism, an allogeneic stem cell transplantation is able to prevent disease progression. This is only possible when the stem cell transplantation (SCT) is performed early in life, before cerebral involvement has occurred. In addition to bone marrow and peripheral blood, unrelated umbilical cord blood appears to be an effective stem cell source as well. Important advantages of umbilical blood as stem cell source are: the time between diagnosis and SCT can be considerably reduced; there is a greater chance of finding a suitable donor and the risk of graft-versus-host disease and viral transmission is decreased. By far the most common disease in the group of inborn metabolic errors for which SCTs are performed is Hurler's disease. In these patients, the percentage of successful transplantations is considerably higher after the use ofunrelated cord blood than when bone marrow or peripheral blood is used as a stem cell source. In addition, donor chimerism occurred significantly more often in those patients who had received unrelated umbilical cord blood. There are also potential disadvantages attached to the use of umbilical blood as stem cell source: the possibility of only one donation per donor and less adaptive immunity following umbilical blood SCT with an increased risk of reactivation of a previous viral infection. However, these disadvantages are less applicable to young children with inborn errors of metabolism. The improvement of transplantation techniques and the availability of this new stem cell source could improve the success rate of this procedure and consequently the prognosis of these severely affected patients.