[Effects of preparation and quality control of cryopreserved platelets]

The purpose of this study was to establish a set of techniques for cryopreservation of platelets with dimethylsulphoxide (DMSO) to insure high quality of cryopreserved platelet. The methods were as following: (1) DMSO was filtered in stead of being sterilized before infusion into the bag with platelets. (2) The whole blood was centrifuged immediately after blood collection and the attached tube was tied on the top of the bucket. (3) The related centrifugal force was 480 x g, the accelerating and braking grades of the centrifuge for acceleration and deceleration were 9 and 4 respectively. (4) The flow rate of platelet rich plasma (PRP) could not be too high, 80 - 100 ml PRP should be harvested at 1 minute or so. The infusion rate of DMSO into the PRP was 1 ml/min. After the infusion of DMSO, the PRP bag must be put into the -80 degrees C ultra low freezer at once to make the product to be freezed as soon as possible. The cryopreserved platelet should be thawed in the cycling warm water at the temperature of 38 - 40 degrees C. (5) After thawing of platelet, the platelet, red blood cell and white blood cell were counted, and the bacteria culturing, tests for HBsAg, anti-HCV, anti-HIV, TP and ALT were carried out. The results showed that altogether 14 800 units of cryopreserved platelets were prepared including 80 units collected with blood cell separator, of which quality control was accomplished in 300 units. The manually collected platelet mean count >/= 2.4 x 10(10)/unit, while the apheresis platelet count >/= 2.5 x 10(11)/unit. The yield was over 70%. The contaminated red and white blood cells were