Evaluation of platelet storage lesions in platelet concentrates stored for seven days

Platelet storage lesions (PSL) are detrimental to the post transfusion functional capacity of platelets. As EDTA enhances the storage-induced changes, changes in platelet indices with and without EDTA incubation are promising new tests to monitor the PSL. The present study was undertaken to monitor the PSL in 40 units of pooled platelet concentrates harvested by platelet rich plasma (PRP) method and stored for seven days in second generation platelet storage containers using conventional in vitro tests and platelet indices.

Morphological changes in platelets were monitored by automated haematological cell counter for platelet count and mean platelet volume (MPV). Samples were incubated with K2EDTA for 1 h and platelet indices were repeated on the EDTA incubated samples. Difference between pre-and post-EDTA incubation of platelet count (dPLT) and MPV (dMPV) were calculated. Metabolic parameters such as pH, pO2, pCO2 and ATP were measured.

There was no significant change in the indices without EDTA during storage, however, after EDTA incubation, significant changes were noted in dPLT and dMPV. The mean dPLT on day 0 was 75.15 x 10(3)/microl decreasing to 44.4 x 10(3)/microl on day 7, while dMPV from 0.76 fl on day 0 increased to 1.34 fl on day 7 (P < 0.05). Metabolic parameters showed a significant decrease in pH and pCO2 concurrent with increasing pO2 during storage (P < 0.05). Average ATP level on day 0 was 21.09 micromol/dl falling to 10.59 micromol/dl on day 7.

The results indicate that storage induced lesions take place even in second generation platelet storage containers under recommended conditions of storage. Platelet indices especially after EDTA incubation are useful in monitoring PSL. However, how much these changes contribute to poor post transfusion survival and haemostatic function of platelets need to be investigated.