Cryopreservation is a method used to store blood cells for a long period without loss of viability and functions. However, the method is rather limited because the procedures of freezing and thawing, and removal of cryoprotectants are complicated. In addition, it requires an expensive programming freezer and special freezing bags which do not break at low temperature. In this study, we developed a new freezing bag (KFB : Kawasumi Freezing Bag) which is made of laminated plastic composed of fluoride and polyolefin. The tensile strength and elongation percentage at break and gas permeability of laminated plastic sheet were examined in accord with Japan Industrial Standard. The tensile strength at -80℃ and the gas permeability of laminated plastic sheet were almost equal to those of a polyvinyl chloride (PVC) sheet. However, the elongation percentage of laminated plastic sheet was twice as much as the PVC sheet at -80℃. Platelets, red cells and peripheral blood stem cells were frozen in the newly developed freezing bags with their standard procedures. Platelets and peripheral blood stem cells were stored in liquid nitrogen, and red cells were stored at -80℃. There were no significant differences in the numerical recovery and the overall functions between cells frozen in the new freezing bag and the conventional bags (PVC or ethylene vinyl acetate). The freezing bags did not break in liquid nitrogen. These results suggest that the freezing bag developed in this study is useful for cryopreservation of blood cells in liquid nitrogen.
A Pall leukocyte-removal filter (PL-F1) for platelet concentrates (PCs), which has been developed for platelet transfusion for pediatric patients to handle an optimum filtration amount of 1-2 units of PCs, was evaluated to find out leukocyte-removal efficiency and recovery rate platelets. The influence of filtration on platelet functions and amount of anaphylatoxin were examined. With regard to leukocyte-removal efficiency of PL-F1,the number of residual leukocytes in PCs stored for 1,2 and 3 days was found <1.85×10^3,and their log mean removal ratet was 3.89 or higher. The platelet recovery rate after filtration of PCs stored for 1,2 and 3 days with PL-F1 was found 92.8% on average in a form of concentration recovery rate, and 85.8% when taking the amount to fill the filter into consideration. There were no significant differences in pH, morphologic score, coagulability, shape change of platelets, % HSR (% hypotonic shock response) between before and after the filtration. The amount of anaphylatoxin showed a significant decrease in C_<3a> and C_<4a>, but it showed no significant difference in C_<5a>. As for β-TG and PF-4,it showed a drop after the filtration process. Based on these results, PL-F1 was found appropriate as a filter for platelet transfusion in the pediatric field.