Methods of CD34⁺ Cells Enumeration at Cord Blood Banks in Japan

Abstract

The success of the cord blood bank program in Japan was associated with the establishment of the Japanese Cord Blood Bank Network in 1999. Using the network system patients and their physicians were able to search for the most suitable cord blood units as their transplants. On the first screen of donor information, HLA mismatched loci, sex, blood type, and the number of nucleated cells in the unit was indicated. However, the number of CD34⁺ cells was not indicated until 2008. The main reason was that the comparison of these numbers between banks was difficult because the methods were different among the banks. The method of CD34⁺ cell enumeration was finally reached to the ISHAGE single platform method after improvement by changing dual platform to single. This was accomplished by using the control beads and by using 7-AAD reagents. The ISHAGE method has made it possible to accurately measure freeze-thawed samples that included dead cells. However, it took 5 years before all banks adopted this method. Keihan cord blood bank has used the CD34⁺ cell standard in addition to the nucleated cell standard for selection of cord blood to be processed since 2008. This contributed to the rise in quality of cord blood units and resulted in increase of their supply. This has made Keihan the largest contributor of cord blood in Japan. Due to fine constraints other banks have yet to adapt the CD34⁺ cell standard. Therefore, the development of the method to shorten the time for measurement is expected to make the CD34+ cell standard more feasible for other cord blood banks. This cell standard will also improve the quality of cord blood units.