The World Marrow Donor Association: 20 years of international collaboration for the support of unrelated donor and cord blood hematopoietic cell transplantation.

The transplantation of hematopoietic stem cells from unrelated volunteer donors and cord blood units is made possible through an international collaboration of registries and cord blood banks. The World Marrow Donor Association (WMDA) is a non-profit association based in Leiden, the Netherlands, whose mission is to assure that high-quality stem cell products are available for all patients in need, while maintaining the health and safety of the volunteer donors. This goal is accomplished through the work of six working groups and six board committees, in which issues of global significance to the clinical hematopoietic cell transplantation community are identified and guidelines are established. In this special issue of Bone Marrow Transplantation, the activities of the WMDA and a vision for future directions in the field are presented.