Platelet storage lesion and apoptosis: are they related?

The relationship between the platelet storage lesion (PSL) and programmed c ell death (apoptosis) is poorly understood. Nevertheless, there is some exp erimental evidence that platelets contain most of the components of the apo ptosis machinery and both the apoptotic process and the PSL lead to platele t activation and microvesiculation with expression of phosphatidyl serine ( PS) on the outer layer of cell membrane, a hallmark of all nucleated cells. The PS exposure is believed to contribute to the development of inflammato ry or immunomodulation process, to the regulation of haemostatic balance an d the ultimate clearance of dead or fragmented cells from the circulation. While there is no doubt that apoptosis, as a form of genetically encoded pr ogrammed cell death in nucleated cells, is triggered by several signalling stimuli at the nuclear level, there is some doubt as to whether platelets, as enucleated cells have retained the memory of the "parental" megakaryocyt es for apoptosis or whether platelet mitochondrial DNA has a major role in both the apoptotic process and the PSL. The storage lesion occurs during pr ocessing and storage subsequent to mechanical trauma, hypoxic conditions or exposure to cold. In this brief report some observational evidence is prov ided in support of the notion that the PSL and apoptosis may be related to each other. despite the Fact that, in contrast to the 'parental' megakarocy te, the platelets appear to survive upon stimulation with a high concentrat ion of protein kinase inhibitors such as staurosporine (STS), in the presen ce of cycloheximide (CHX) which inhibit protein synthesis. This is a model which is often used to regulate the level of survival signals. The possible relevance of platelet microvesiculation to transfusion practice is briefly discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.