A simple clot based assay for detection of procoagulant cell-derived microparticles

Background: Cell-derived microparticles (MPs) are important biomarkers in many facets of medicine. However, the MP detection methods used till date are costly and time consuming. The main aim of this study was to standardize an in-house clot based screening method for MP detection which would not only be specific and sensitive, but also inexpensive. Methods: Four different methods of MP assessment were performed and the results correlated. Using the flow cytometry technique as the gold standard, 25 samples with normal phosphatidylserine (PS) expressing MP levels and 25 samples with elevated levels were selected, which was cross checked by the commercial STA Procoag PPL clotting time (CT) assay. A simple recalcification time and an in-house clot assay were the remaining two tests. The in-house test measures the CT after the addition of calcium chloride to MP rich plasma, following incubation with Russell viper venom and phospholipid free plasma. Results: The CT obtained by the in-house assay significantly correlated with the results obtained by flow cytometry (R-2 = 0.87, p < 0.01). Conclusions: Though preliminary, the in-house assay seems to be efficient, inexpensive and promising. It could definitely be utilized routinely for procoagulant MP assessment in various clinical settings.