Coherent Optical Scattering and Interferometry (COSI) for label-free multiparameter quantitative imaging of intra-thrombus stabilityin vitro

Abstract

Although existing microfluidics in vitro assays recapitulate blood vessel microenvironment using surface-immobilized agonists under biofluidic flows, these assays do not quantify intra-thrombus mass and activities of adhesive platelets at agonist margin and uses fluorescence labeling, therefore limiting clinical translation potential. Here, we describe a real time label-free in vitro quantitative imaging flow assay called Coherent Optical Scattering and phase Interferometry (COSI) that evaluates both intra-thrombus and adhesive-only platelet dynamics using only changes in refractive index. By combining coherent optical scattering and optical interferometry, we evaluated and quantified both intra-thrombus mass with picogram accuracy and adhesive platelet-only events/dynamics with high spatial-temporal resolution (400 nm/s) under fluid shear stress using only changes in refractive index. Using oblique illumination, COSI provide a ~ 4 μm thin axial slice that quantifies the magnitude of physical of surface adhesive platelets (spreading, adhesion and consolidation) in a developing thrombus without labelling under fluid shear stress. We achieve real time visualization of recruitment of single platelet into thrombus and further correlate it to the developing mass of a thrombus. The adhesive platelet activity exhibit stabilized surface activity of around 2 μm/s and intra-thrombus mass exchange were balanced at around 1 picogram after treatment of a broad range metalloproteinase inhibitor (250 μM GM6001).