DEFINITION OF OPTIMAL CONDITIONS FOR COLLECTION AND CRYOPRESERVATION OF UMBILICAL-CORD HEMATOPOIETIC-CELLS

Prior studies have shown that human umbilical cord blood cells can res tore hematopoiesis and be used as a source of stem cells for hematopoi etic transplantation. We have performed a study of the best conditions of collection and cryopreservation of blood from eight umbilical cord s. We compared the influence of cell separation and of delay between c ollection and cryopreservation on the numbers of nucleated cells and o f hematopoietic progenitors recovered before and after cryopreservatio n. Ficoll separation resulted in the loss of more than 50% of nucleate d cells, but also of a significant number of progenitors before freezi ng. Unseparated cells could be kept at 25 degrees C as long as 24 h be fore freezing with minimal loss of progenitors before and after freezi ng and thawing. In contrast, there was a significant decrease in the n umber of viable cells and progenitors when cells were maintained at 4 degrees C before freezing. Our data show that cord blood banking is fe asible with simple collection and cryopreservation procedures. (C) 199 5 Academic Press, Inc.