According to a study from Japan, "A novel filter system was developed for umbilical cord blood (UCB) volume reduction. The aim of this study was to compare the functions of cryopreserved UCB cells processed by the filter and by the hydroxyethyl starch (HES) sedimentation method from the aspect of the graft quality."

M. Yasutake and colleagues at the University of Tokyo explained, "UCB specimens were divided into two portions, processed in parallel by the filter or HES, and then cryopreserved in the clinical setting. The thawed UCB specimens containing 1 x 105 CD34 cells were injected into nonobese diabetic/Shi-SCID mice, and the engraftment capacity in primary and secondary transplants was assessed. The functions of natural killer (NK) cells and monocyte-derived dendritic cells (DCs) were also assayed in vitro."

The data indicated, "The percentage of recovery of CD34 cells by both methods was equivalent. In the marrow of the primary transplant recipients, the percentage of hCD45 cells in the filter group and HES group was 58.2±31.6 and 46.5±28.4 percent, respectively (p=0.016). The engraftment capacity and multilineage differentiation in the secondary transplantations were equal in both groups. The cytotoxic activity of the NK cells and phagocytosis activity of the DCs from both the groups were similar."

"The filter yielded a desirable percentage of recovery of hematopoietic cells with engraftment ability in the clinical setting. Thus, it is considered that the filter system may be useful for UCB banking for cord blood transplantation," the authors concluded.

Yasutake and colleagues published their study in Transfusion (SCID-repopulating activity of human umbilical cord blood-derived hematopoietic stem and/or progenitor cells in a nonobese diabetic/Shi-SCID mice serial xenotransplantation model and immune cell activities in vitro: a comparative study of the filter method and the hydroxyethyl starch method. Transfusion, 2005;45(12):1899-1908).

For more information, contact T.A. Takahashi, University of Tokyo, Institute of Medical Science, Division of Cell Processing, Minato Ku, 4-6-1 Shirokanedai, Tokyo 1088639, Japan.

Publisher contact information for the journal Transfusion is: Blackwell Publishing, 9600 Garsington Rd., Oxford OX4 2DQ, England.