The main purpose for storing large numbers of umbilical cord blood (CB) units by cryopreservation is to obtain a close HLA match for use in bone marrow transplantation. The use of partially matched or unmatched CB has been suggested, and publications about the success of 3 antigen mismatches have given some credence to this suggestion. Graft vs host disease still is considered a major barrier for successful CB transplantation. The cost per frozen CB unit of approximately $15,000 considerably limits its availability in developing countries. Eleven human umbilical cord specimens were stored in gas-permeable bags at 4°C for up to 3 weeks. Clonal growth, replating efficiency in methylcellulose cultures, differential count, and flow cytometric immunophenotyping results were examined at intervals up to 21 days. Mixed lymphocyte cultures were evaluated on 13 similarly stored specimens at intervals up 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. Replating 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 were immunophenotyped, the mean percentage of CD34+ and CD117+ cells, considered 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 reactivity of CB responder cells, in mixed lymphocyte cultures, to fresh allogeneic CB stimulator cells declined significantly. These findings suggest that CB can be stored in existing blood bank facilities and retain its hematopoietic potential for transplantation. Furthermore, it may be feasible to combine individual CB samples to provide a sufficient number of viable stem cells for transplantation, substantially expanding the number of potential recipients.
All Science Journal Classification (ASJC) codes
- Pathology and Forensic Medicine
- Blood bank-stored
- Human cord blood
- Marrow transplantation