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. 2017 Jan 12;2(1):e89761. doi: 10.1172/jci.insight.89761

Figure 2. Microembolic or in situ nucleated neutrophil-platelet aggregates occlude the arteriolar bottlenecks.

Figure 2

Sickle cell disease (SCD) mice were injected intravenously (IV) with 0.1 μg/kg of LPS, and arterioles were imaged using quantitative fluorescence intravital lung microscopy (qFILM) to evaluate the formation of pulmonary vaso-occlusion within arteriolar bottlenecks. (A) qFILM images of the same field of view (FOV) at 3 different time points in a SCD mouse administered 0.1 μg/kg IV LPS showing pulmonary vaso-occlusion enabled by a microembolic large neutrophil-platelet aggregate. t = 0 s shows the arteriole before the microembolus appears in the FOV. At t = 1.5 seconds, a microembolus comprising several neutrophils attached to a few platelets appears (white dotted circle) and begins to travel down the arteriole. The microembolus gets trapped in the “arteriolar bottleneck,” resulting in a pulmonary vaso-occlusion by t = 16.2 seconds. (B) qFILM images of the same FOV at 3 different time points in a SCD mouse administered 0.1 μg/kg IV LPS showing the formation of a pulmonary vaso-occlusion via an in situ nucleation of a large neutrophil-platelet aggregate. At t = 0 seconds, an aggregate comprising 3 neutrophils attached to a few platelets (dotted white circle) is partially occluding an arteriolar bottleneck. A neutrophil (thick white arrow) begins to travel down the arteriole at t = 0 seconds and nucleates on top of the existing neutrophil-platelet aggregate by t = 2.2 seconds. Another neutrophil (thick white arrow) appears in the FOV at t = 2.2 seconds and flows down the arteriole to nucleate on top of the existing neutrophil-platelet aggregate (t = 4.4 seconds), resulting in the formation of a large aggregate composed of 5 neutrophils and a few platelets (dotted white circle) that completely occludes the arteriolar bottleneck. The times displayed are relative to the selected frames. Neutrophils are shown in red, platelets in green, pulmonary microcirculation in purple. Asterisks denote alveoli. Thin white arrows mark the direction of blood flow within the feeding arterioles. The diameters of the arterioles shown in A and B are 26 μm and 30 μm, respectively. Scale bars: 20 μm. See Supplemental Videos 11 and 14 for the complete qFILM time series corresponding to A and B.