Thromb Haemost 2007; 98(05): 1096-1107
DOI: 10.1160/TH05-04-0231
Endothelium and Vascular Development
Schattauer GmbH

Inhibition of microparticle release triggers endothelial cell apoptosis and detachment

Mohammed N. Abid Hussein*
1   Department of Clinical Chemistry, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
,
Anita N. Böing*
1   Department of Clinical Chemistry, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
,
Augueste Sturk
1   Department of Clinical Chemistry, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
,
Chi M. Hau
1   Department of Clinical Chemistry, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
,
Rienk Nieuwland
1   Department of Clinical Chemistry, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
› Author Affiliations
Further Information

Publication History

Received 05 April 2005

Accepted after resubmission 12 August 2007

Publication Date:
30 November 2017 (online)

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Summary

Endothelial cell cultures contain caspase 3-containing microparticles (EMP), which are reported to form during or after cell detachment. We hypothesize that also adherent endothelial cells release EMP, thus protecting these cells from caspase 3 accumulation, detachment and apoptosis. Human umbilical vein endothelial cells (HUVEC) were incubated with and without inhibitors of microparticle release (Y-27632,calpeptin), both in the absence or presence of additional “external stress”, i.e. the apoptotic agent staurosporin (200 nM) or the activating cytokine interleukin (IL)-1α (5 ng/ml). Control cultures contained mainly viable adherent cells and minor fractions of apoptotic detached cells and microparticles in the absence of inhibitors. In the presence of inhibitors, caspase 3 accumulated in adherent cells and detachment tended to increase. During incubation with either staurosporin or IL-1α in the absence of inhibitors of microparticle release, adherent cells remained viable, and detachment and EMP release increased slightly. In the presence of inhibitors, dramatic changes occurred in staurosporin-treated cultures. Caspase 3 accumulated in adherent cells and >90% of the cells detached within 48 hours. In IL-1α-treated cultures no accumulation of caspase 3 was observed in adherent cells, although detachment increased. Scanning electron microscopy studies confirmed the presence of EMP on both adherent and detached cells. Prolonged culture of detached cells indicated a rapid EMP formation as well as some EMP formation at longer culture periods. Inhibition of EMP release causes accumulation of caspase 3 and promotes cell detachment, although the extent depends on the kind of “external stress”. Thus, the release of caspase 3-containing microparticles may contribute to endothelial cell survival.

* Both authors contributed equally to this manuscript.