Cellular uptake of platelet MPs. Intact platelets stained positive for PAR-4 and integrin αIIb (CD41) among the PBMNCs counterstained with DAPI (day 1). Over time, the platelets disintegrated, but platelet proteins remained detectable in EPC cultures (day 3) and were taken up by the adherent cell population (day 5, inset). By day 7, most cells stained positive for platelet markers (insets: scale bar represents 25 μm).