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Semin Thromb Hemost 2010; 36(8): 803-804
DOI: 10.1055/s-0030-1267032
FOREWORD

© Thieme Medical Publishers

FOREWORD

Emmanuel J. Favaloro1
  • 1Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, SWAHS, Westmead, NSW, Australia
Further Information

Publication History

Publication Date:
03 November 2010 (online)

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Welcome to another issue of Seminars in Thrombosis and Hemostasis. Nigel S Key and Hau C Kwaan have gathered together a collection of articles that review several various aspects of microparticles, beginning with methodology related to their measurement,[1] [2] [3] then leading to their formation and composition,[4] [5] [6] [7] [8] [9] and ending with their involvement or measurement in different disease states.[10] [11] [12] [13] This is the first issue of Seminars in Thrombosis and Hemostasis to feature microparticles; accordingly, the current issue is certainly timely. Although Nigel Key has contributed to this journal in the past, this issue represents his first contribution as a guest editor. Hau Kwaan has contributed extensively to Seminars in Thrombosis and Hemostasis, last guest editing an issue in 2010 on endothelial cells,[14] and prior to that an issue in 2007 on hemostatic dysfunction in malignant hematologic diseases.[15]

That cells, in particular platelets, but also white blood cells and red blood cells, contribute to hemostasis has been known for some time.[16] Microparticles are small fragments of membrane-bound cytoplasm shed from the surface of activated or apoptotic cells.[17] Although most microparticles in normal plasma are platelet derived, microparticles can also originate from other cellular sources including white and red blood cells. Several clinical conditions are associated with elevated microparticles, with most also associated with an increased risk of thrombosis. Apart from cardiovascular disease and venous thromboembolism, microparticles are also elevated in solid tumors with metastatic disease and can also be detected in bleeding disorders such as hemophilia.[10] [11] [12] [13] [17] [18] [19]

Importantly, the differential presentation of microparticles can also be used as a marker of specific disease. A nice example that highlights the breadth of potential usefulness in this arena is presented in the current issue by Kwaan and Rego.[12] In acute promyelocytic leukemia (APL), serious bleeding and thrombotic complications are frequent and major causes of morbidity and mortality. Because the cellular origin of microparticles can be identified by specific cell surface markers, comparison of the various populations of microparticles in APL in samples collected at diagnosis versus at molecular remission can help assess status, with elevations of microparticles derived from leukemic cells observed during the course of disease and disappearing over time after remission. Importantly, these leukemic cell–derived microparticles carry tissue factor, and their presence during disease progression is a likely risk factor for thrombosis.

Various methodologies may be employed in the measurement of microparticles, although most are based on their measurement as particles counted by flow cytometry. Like other emerging tests of hemostasis, current limitations include sample handling issues, methodological complexity, assay standardization, and instrument limitations (e.g., many flow cytometers cannot measure most microparticles due to sizing limitations). Also, many assays do not measure functional effects of these microparticles. Accordingly, functional methodologies may hold further utility.[8] [20] My own personal interest in this arena is expressed by assessment of the factor Xa clotting time assay as a measure of microparticle procoagulant activity, most recently to help explain short activated partial thromboplastin times and their association with thrombosis.[20]

In summary, the further development of various methods for the detection, characterization, and measurement of microparticles, their better standardization, reduced complexity, and use in prospective clinical trials to establish their clinical utility for a wide spectrum of diseases will be critical before their routine measurement in the diagnostic laboratory. In the interim, the current issue of Seminars in Thrombosis and Hemostasis represents a state-of-the-art review of the current literature and will provide valuable resource material for many of our readers.

I would like to thank both Nigel Key and Hau Kwaan for putting together this excellent issue, and I hope that our readers enjoy its many treasures.

REFERENCES

Emmanuel J FavaloroPh.D. M.A.I.M.S. 

Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital

WSAHS, Westmead, NSW 2145, Australia

Email: emmanuel.favaloro@swahs.health.nsw.gov.au