 Because the odds that two random individuals are HLA matched exceeds one in 20,000, a registry's success depends on a large number of volunteer donors.The NMDP coordinates hematopoietic cell transplants by managing a worldwide network of affiliated organizations.These organizations (mostly hospitals and blood banks) have established relationships with the NMDP and work together to arrange the collection and transfer of donated bone marrow or PBSCs, or the transfer of previously collected cord blood.