Cord blood transplantation 15 years later: What promises have been kept since its first successful application?

Cord blood transplantation (CBT) has become a widely employed treatment for patients with both non-malignant and malignant diseases. The undisputed advantages of using this type of transplant are linked to the low risk of viral contamination (i.e. Cytomegalovirus, Epstein-Barr virus, etc.) of cord blood, to the prompt availability of hematopoietic stem cells for transplantation between unrelated individuals, and to the reduced incidence and severity of graft-versus-host disease (GVHD). However, analysis of the patients given CBT has shown that in comparison with patients receiving bone marrow transplantation there is a higher risk of failed engraftment of the hematopoiesis of the donor, a modest delay in the kinetics of granulocytic recovery, and a more conspicuous delay in platelet count reconstitution. The probability of donor cell engraftment and the kinetics of hematological reconstitution are directly correlated to the number of infused placental cells per kg of recipient body weight. Since it has been also demonstrated that an inverse correlation exists between the number of cells infused and the risk of death for transplant-related complications, CBT has been mainly employed for patients with a body weight lower than 40 kg. Thus, in patients in need of an allograft who lack an HLA-compatible relative, the choice of using preferentially cord blood or bone marrow cells should be made after considering the original disease and the urgency of transplant, the patient's body weight, the number of cells available and HLA-compatibility between donor and recipient.