Stem-cell transplants that treat blood diseases typically rely on bone marrow as the donor source. But some use umbilical-cord blood a rarer commodity. Dutch researchers believe that by modifying how donors and recipients are matched, they might make what little cord blood is available more useful. Currently, matches are determined by how many human leukocyte antigens the donor and recipient share. Another set of markers, called noninherited maternal antigens, may also be good indicators. Using these as criteria could expand the number of matches 18-fold.