Figure 1.

Freshly isolated platelets extend projections with distinct cell bodies. (A) Localization of actin (green, phalloidin) in human platelets that were fixed immediately after isolation (Baseline) or after 6 hours in suspension (Cultured). The bottom row displays corresponding transmission images. This figure is representative of more than 20 independent experiments. Scale bars represent 5 μm. (B) Lower magnification of freshly isolated platelets that were stained for actin at baseline or after they were cultured for 6 hours (scale bars, 10 μm). Panel is representative of more than 20 experiments. (C) The bar graph indicates the number of extended platelets with at least 2 cell bodies per microliter of culture media (mean ± SEM; n = 13). *P < .05, baseline versus cultured. (D) Two separate cultures of platelets were labeled (blue or green) and then incubated with one another for 6 hours. Left and right panels: 2 independent experiments, which are representative of 3. (E) Platelets were loaded into “parked” microdrops and examined at baseline or after 6 hours (Cultured). The thin arrows point to single platelets (Baseline) or the same platelet that formed 2 distinct cell bodies after 6 hours (Cultured). The thick arrows point to unique landmarks for each position in the microfluidic device. (F) Sequential images of platelets using low-resolution wide-field microscopy. The arrows highlight the location of the platelets within each drop during the course of the experiment and the formation of 2 distinct cell bodies after 6 hours (far right panels). Distance between the white brackets (E-F, far left panels) is 50 μm.