Yuko Mogi

Efficacy of Measurement of CD 34+ Cells in Peripheral Blood Before Leukapheresis for Collection of Peripheral Blood Progenitor Cells.

We evaluated the efficacy of measurement of CD 34+ cells in peripheral blood (PB) before leukapheresis (LA). Forty-five patients with malignant diseases underwent 65 LAs for collection of peripheral blood progenitor cells (PBPC). Median values for white blood cells (WBC), mononuclear cells (MNC) and CD 34+ cells in PB before LA were 18, 900/μl, 3, 110/vl and 39.6/μl, respectively. Median values for CD 34+ cells, colony forming unit-granulocyte/macrophage (CFU-GM) and total colony forming cells (CFC) in LA products were 3.19×106/kg, 5.7×105/kg and 12.90×105/kg, respectively. The strong correlation between CD 34+ cells and CFU-GM or CFC (r=0.88 and 0.87) indicates that the number of CD 34+ cells represents clonogenic activity. Regression analysis revealed a very strong correlation between CD 34+ cells in LA products (Y) and those in PB before LA (X) (r=0.97, Y=5.43×105X-37.2×105), while only a weak correlation was seen between CD 34+ cells in LA products and the number of WBC and MNC in PB before LA (r=0.60 and 0.56). These results indicated that the number of CD 34+ cells in PB before LA can accurately predict that in LA products. We therefore conclude that the measurement of CD 34+ cells in PB before LA is useful in the collection of PBPC with LA.

Analysis of hematopoietic stem cells and progenitor cells in human umbilical cord blood.

Human umbilical cord blood (HUC) has been considered as a possible source of hematopoietic stem and progenitor cells for transplantation. In this study, we characterized mononuclear cells and hematopoietic stem/progenitor cells in cord blood and compared them to those in human peripheral blood (HPB). The concentration of mononuclear cells in HUC was twice as high as that in HPB. The percentage of CD34-positive cells in HUC was 4.0 times that in HPB and the result of subset analysis suggested that HUC involves many immature cells. The plating efficiency of colony forming unit in mononuclear cells in HUC was 0.446±0.295%, 14.4 times higher than in HPB. Thus, HUC contains a large number of hematopoietic stem cells. In addition the rate of CFU-GM and CFU-mix in HUC was more than in HPB. It is suggested that HUC is better source of stem/progenitor cells. The limitation of HUC as a potential source of transplantable hematopoietic stem cells is its small quantity. It is necessary to develop a method to expand the number of hematopoietic stem/progenitor cells in HUC to obtain enough cells for allogeneic transplantation in adults.

Evaluation of a new leukocyte removal filter, the R-S350, in a closed system.

The new high-performance R-S350 leukocyte removal filter was developed to deplete leukocytes from red cell concentrate and whole blood with high efficiency, that is, a higher than 4-log reduction. When 1 unit of red cell concentrate stored for 1 to 2 days was applied, the leukocytes were removed by 4.77 logs with 86.4% red cell recovery and the average filtration time was 15.5min. The average number of residual leukocytes was 4.56±6.74×104/unit (n=25). The R-5350 is also able to remove leukocytes from freshly drawn or 1-day-stored whole blood in a closed system. The leukocyte removal rate was 4.60 logs for fresh whole blood and 4.88 logs for blood stored for 1 day. Platelet removal rates were 2.4 to 2.8 logs and red cell recovery was about 90%. The filtration time was less than 15min for fresh whole blood. During storage of red cell concentrates prepared from filtered or nonfiltered whole blood for 3 weeks at 4°C, neither the ATP and 2, 3-DPG levels nor the morphological score of red cells significantly differed between the two types but the level of supernatant hemoglobin was less in the filtered red cell concentrates.A closed system with a leukocyte-removal filter has advantages for the extension of the storage period for more than 24 hours and keeps the cells in better physiological condition. The new R-5350 filter can be used in a closed system for leukocyte removal from whole blood before storage and is expected to be useful for the prevention of alloimmunization and other side effects of blood transfusion.