Microvesicles heterogeneity...a possible marker for cardiovascular diseases?

S. Oggero¹, H. Rhys¹, M. Perretti^1,2. ¹William Harvey research Institute, Queen Mary University, London, United Kingdom, ²Biochemical Pharmacology, William Harvey Research Institute, London, United Kingdom.

Introduction: Microvesicles (MV) are membrane bound vesicles with a diameter range from 100 to 1000nm, shed from the surface of all cell types (1). They are present in blood and are known to bear markers that identify their cell of origin (2). However, it has recently been shown that different cells can release several subsets of vesicles with distinct components, in relation to the mode of activation. This new concept has been named microvesicle heterogeneity and raises the question as to whether these small entities might represent a new strategy for diagnosing different inflammatory diseases (3-4). Although in the past two decades several MV (e.g. in platelets and endothelial) have been deeply studied, monocyte-derived MV have been poorly investigated. The objective of this project is to study human monocyte-derived MV in vitro, mimicking events that occur in inflamed vasculature.

Method: Monocyte-derived MV from whole blood stimulated with TNFa and PAF have been characterized with ImagestreamX technology and nanoparticle tracking analysis. Furthermore, monocyte-derived MV from isolated, negatively-selected monocytes obtained using the rosette-sep technology were further characterized upon stimulation with PAF, TNFα and LTB4.

Results: Aggregation of platelets and monocytes in whole blood seems to affect the numbers of monocyte and platelets MV released, increasing in all cases. During both the whole blood assay and the isolation of monocytes with the rosette-sep technology, monocytes and platelets aggregated together and the presence of MV from platelets and monocytes (double positive for CD41 and CD14) was detected.

Conclusion: The presence of double positive MV suggests the occurrence of heterogeneity of the vesicles formed in response to different stimulants. In line with these findings, future work will include investigation of this heterogeneity in response to stimulants in both the methods used in this study to better comprehend the composition of these vesicles. In order to do so proteomic and lipidomic analysis will be relevant methodologies that will be used to asses these questions.

References:

(1) Raposo G and Stoorvogel W (2013). Journal of Cell Biology 200: 373-383.

(2) Hargett L and Bauer NN (2013). Pulm. Circ 3: 329-340.

(3) Burger D et al (2013). Clin. Sci. (Lond) 124: 423-41.

(4) Giebel B (2017). Ann. Transl. Med. 5: 150