Effect of temperature on functional response of platelet concentrates stored in PVC bags.

Haemostatic efficacy of platelet concentrates prepared and stored in locally available PVC triple bags was compared against a Japanese bag. In vitro functional parameters studied included shape change, aggregation and secretion in response to ADP. We have observed remarkable difference in the aggregatory response of platelets stored at slightly varying temperatures. The stimulatory responses of platelets stored with constant agitation at 70 strokes per min and 23 +/- 2 degrees C, deteriorated drastically by the time platelets were stored for 48 h. Both the rate and the extent of aggregation were affected showing no response to ADP at 72 h. However, when platelets were stored in a BOD incubator, thermostated at 22 +/- 0.5 degrees C, with continuous horizontal agitation at 70 strokes per min, 50 per cent functional response was retained till 72 h. We also demonstrated fragmentation of platelet membrane during storage. The membrane fragments collected by high speed centrifugation, expressed PF3 activity. Shedding of microvesicles indicates alterations at the membrane level that possibly cause functional lesion during storage. Our data suggest the significance of controlling the storage temperature steadily, to get maximum post transfusion efficacy.

Morphological & ultrastructural changes of platelet concentrates stored in PVC bags.

To assess the effect of storage bags on platelets, we studied the morphological and ultrastructural changes of samples drawn from platelet concentrates (PC) prepared and stored in triple, poly vinyl chloride (PVC) bags, manufactured in India. Using the scanning electron microscopy, we demonstrate formation of long pseudopods, and interaction through these to form aggregates. When platelets were stored at 23 +/- 2 degrees C, morphological changes were severe compared to the deleterious effects when kept at 22 +/- 0.5 degrees C. Ultrastructural analysis also showed that maintenance of discoid shape and prevention of granule secretion could be improved by storing the platelets at 22 +/- 0.5 degrees C. Significant degree of platelet fragmentation took place when the storage temperature was high. The morphology score done for platelets stored at both 22 +/- 0.5 degrees C and 23 +/- 2 degrees C showed that preservation of discoid shape was better with the former.

Biochemical lesions of platelets stored as concentrates in PVC bags.

Acid-base status of platelet suspension during storage is a measure of the gas permeability of the bag material. To assess the efficacy of the bags available in our market to store platelets, we compared biochemical lesions of platelets stored in an Indian polyvinyl chloride (PVC) triple bag against a Japanese PVC bag standardized for 5 days platelet storage. Platelet concentrates prepared in both control and test PVC bags were stored for 72 h. Two ml samples were drawn 1 h after preparation, and then at 24 h intervals, for analysis. Our data show that the mean pH value in the test bags was maintained above 6.5. However, the CO2 tension was high and O2 tension was low. We also analyzed malondialdehyde (MDA) formation which is a measure of arachidonic acid metabolism, and seemed to be unaffected in stored platelets. Lactate dehydrogenase (LDH) was not released into the plasma excessively and hence significant platelet lysis was absent during storage. Hypotonic shock response (HSR) of platelets stored in both test and control bags was comparable, indicating the possibility of satisfactory post-transfusion recovery.

Adenosine and ATP: mutually exclusive modifiers of the kinetics of ADP-induced aggregation of calf-platelets.

Modulations of initial rate kinetics of ADP-induced aggregation of citrated calf platelet-rich plasma by adenosine and ATP were investigated employing a spectrophotometric platelet aggregation assay. The data were analysed according to the tenets of sequential shape-change and interaction model of aggregation. Adenosine and ATP increased the slopes and intercepts of double-reciprocal plots of ADP-aggregation kinetics. Examination of their slope and intercept effects together with their effects individually and in combination, on aggregation rates, suggested that adenosine and ATP acted at multiple, nonoverlapping, sites.