The feasibility of using blood bank-stored (4 degrees C) cord blood, unmatched for HLA for marrow transplantation

The main purpose for storing large numbers of umbilical cord blood (CB) uni ts by cryopreservation is to obtain a close HLA match for use in bone marro w transplantation. The use of partially matched or unmatched CB has been su ggested, and publications about the success of 3 antigen mismatches have gi ven some credence to this suggestion. Graft vs host disease still is consid ered a major barrier for successful CB transplantation. The cost per frozen CB unit of approximately $15,000 considerably Limits its availability in d eveloping countries. Eleven human umbilical cord specimens were stored in g as-permeable bags at 4 degrees C for up to 3 weeks. Clonal growth, replatin g efficiency in methylcellulose cultures, differential count, and flow cyto metric immunophenotyping results were examined at intervals up to 21 days. Mixed lymphocyte cultures were evaluated on 13 similarly stored specimens a t intervals tip to 14 days. When plated at 1, 10 and 21 days, the combined percentage of the more primitive colonies increased on days 10 and 21. Repl ating efficiency of blast cell colonies when stem cell factor was added was 81.2% and 67.8% on days 10 and 21, respectively. When mononuclear cells we re immunophenotyped, the mean percentage of CD34(+) and CD117(+) cells, con sidered primitive stem cell markers, increased significantly from day 1 to day 21. The ability of stored CB cells to respond to phytohemagglutinin or alloantigens decreased progressively from day 1 to day 14 By day 14 the rea ctivity of CB responder cells, in mixed lymphocyte cultures, to fresh allog eneic CB stimulator cells declined significantly. These findings suggest th at CB can be stored in existing blood bank facilities and retain ifs hemato poietic potential for transplantation. Furthermore, it may be feasible to c ombine individual CB samples to provide a sufficient number of viable stem cells for transplantation, substantially expanding the number of potential recipients.