Microfluidic assessment of functional culture-derived platelets in human thrombi under flow

Despite their clinical significance, human platelets are not amenable to genetic manipulation, thus forcing a reliance on mouse models. Culture-derived platelets (CDPs) from human peripheral blood CD34+ cells can be genetically altered and may eventually be used for transfusions. By use of microfluidics, the time-dependent incorporation of CD41+CD42+ CDPs into clots was measured using only 54,000 CDPs doped into 27 μL of human whole blood perfused over collagen at a wall shear rate of 100 sec−1. With the use of fluorescence-labeled human platelets (instead of CDPs) doped between 0.25% and 2% of total platelets, incorporation was highly quantitative and allowed monitoring of the anti-αIIbβ3 antagonism that occurred after collagen adhesion. CDPs were only 15% as efficient as human platelets in their incorporation into human thrombi under flow, although both cell types were equally antagonized by αIIbβ3 inhibition. Transient transfection allowed the monitoring of GFP+ human CDP incorporation into clots. This assay quantifies genetically altered CDP function under flow.