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Apoptotic markers are increased in platelets stored at 37 degrees C
1Department of Medicine, Division of Hematology and Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Insights
Platelets (PLTs) stored at 37°C undergo apoptosis, a programmed cell death process, leading to rapid viability loss. Caspase activation accelerates this decline, suggesting potential therapeutic targets for improving platelet storage.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Platelets (PLTs) lose viability during blood banking storage.
- Storage at 37°C accelerates PLT viability loss and bacterial contamination risk.
- Routine PLT storage occurs at 22°C due to these concerns.
Purpose of the Study:
- To determine if PLTs undergo apoptosis during storage.
- To investigate if 37°C storage accelerates PLT apoptosis.
Main Methods:
- PLT-rich plasma stored at 37°C or 22°C.
- Analysis of PLT number, pH, LDH, and metabolic activity over time.
- Western blotting and enzyme assays to detect apoptotic protein activation.
Main Results:
- PLT viability significantly reduced within 1-2 days at 37°C.
- Apoptosis signs, including caspase-3 activation and cleavage, observed within 3 hours.
- Caspase inhibitors prevented activation but did not improve viability at 37°C.
Conclusions:
- PLTs possess apoptotic proteins activated during 37°C storage.
- Activated apoptosis contributes to rapid PLT viability loss.
- Inhibiting PLT apoptosis may enhance cellular viability during storage.
Background:
PLTs for transfusion lose viability during storage in blood banking. This loss of viability is accelerated at 37 degrees C, as is the risk of bacterial contamination, and has led to the selection of 22 degrees C as the routine storage temperature. Because PLTs contain an intact apoptotic mechanism, we sought to determine whether PLTs undergo apoptosis during storage and whether storage at 37 degrees C accelerated this process.
Study Design And Methods:
PLT-rich plasma from PLT concentrates was stored at 37 or 22 degrees C in small aliquots or whole bags, with and without cell-permeable caspase inhibitors. Number of PLTs, pH, LDH level, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium activity were analyzed over time. PLT lysates were prepared and tested for the presence and activation of apoptotic proteins by enzyme assay and Western blotting.
Results:
PLT viability was greatly reduced after 1 to 2 days of storage at 37 degrees C; however, signs of apoptosis were evident by 3 hours after temperature shift. In temperature-stressed PLTs only, a gradual rise in caspase-3 activity was detected that correlated with the appearance of the 17- to 20-kDa cleavage products of caspase-3. Gelsolin, a caspase-3 substrate, underwent cleavage within the same time frame. Bcl-xL and caspase-2 also declined significantly; caspase-9 activity rose. Specific caspase inhibitors could prevent caspase activation but did not improve PLT cellular viability at 37 degrees C.
Conclusions:
PLTs contain apoptotic proteins that are activated during PLT storage at 37 degrees C and may account for the rapid decline in PLT cellular viability. Although ineffective here, inhibition of PLT apoptosis may improve PLT cellular viability.