Detection of tissue factor-positive extracellular vesicles using the ExoView R100 system.

BACKGROUND

Tissue factor (TF) is essential for hemostasis. TF-expressing extracellular vesicles (TF EVs) are released in pathological conditions, such as trauma and cancer, and are linked to thrombosis. Detection of TF EV antigenically in plasma is challenging due to their low concentration but may be of clinical utility.

OBJECTIVES

We hypthesised that ExoView can allow for direct measurement of TF EV in plasma, antigenically.

METHODS

We utilized the anti-TF monoclonal antibody 5G9 to capture TF EV onto specialized ExoView chips. This was combined with fluorescent TF EV detection using anti-TF monoclonal antibody IIID8-AF647. We measured tumor cell-derived (BxPC-3) TF EV and TF EVs from plasma derived from whole blood with or without lipopolysaccharide (LPS) stimulation. We used this system to analyze TF EVs in 2 relevant clinical cohorts: trauma and ovarian cancer. We compared ExoView results with an EV TF activity assay.

RESULTS

BxPC-3-derived TF EVs were identified with ExoView using 5G9 capture with IIID8-AF647 detection. 5G9 capture with IIID8-AF647 detection was significantly higher in LPS+ samples than in LPS samples and correlated with EV TF activity ( = 0.28). Trauma patient samples had higher levels of EV TF activity than healthy controls, but activity did not correlate with TF measurements made by ExoView ( = 0.15). Samples from patients with ovarian cancer have higher levels of EV TF activity than those from healthy controls, but activity did not correlate with TF measurement by ExoView ( = 0.0063).

CONCLUSION

TF EV measurement is possible in plasma, but the threshold and potential clinical applicability of ExoView R100, in this context, remain to be established.