Platelet microparticles and cancer: An intimate cross-talk.

Blood cell-derived microparticles (MP), in general, and platelet MPs (PMPs), in particular, have emerged as important contributors, as well as markers, of the delicate balance between health and disease. They may, on one hand, have beneficial effects by supporting tissue repair and regeneration, as well as hemostasis, but may, on the other hand, be a pro-coagulant promoter leading to the thrombotic events seen in the context of cancer. PMPs can act as a direct tumor growth enhancer through the release of potent growth factors in the tumor micro-environment. Tumor engraftment can also be stimulated by the pro-angiogenic potentials of platelet growth factors released by PMPs. PMPs, by their pro-inflammatory and immunomodulatory functions, can also exert an indirect role in the metastatic multistep process by helping malignant cells to escape from immunological surveillance. The possible detrimental effect of transfusions in cancer patients has been debated for several years and the role played by PMPs present in blood products is receiving specific attention, considering their propensity to trigger thrombosis and support tumors. The intimate PMP-tumors crosstalk may therefore result in pro-thrombotic states and a physiological state favorable to tumor growth, tethering and dissemination. Laboratory and experimental studies are needed to better unveil the contribution of PMPs as coagulation promoters, as well as potential markers and targets to treat cancer.