Fig. 3: Arp2/3-dependent lamellipodia formation regulates platelet haptotaxis.
From: Vascular surveillance by haptotactic blood platelets in inflammation and infection
a–c Early shape changes of human platelets on fibrinogen surfaces. a Micrograph of spreading cell. Arrows: filopodia; asterisk: lamellipodium. b Evolution of lamellipodia/filopodia over time, and c direction of filopodia and lamellipodia in relation to the subsequent direction of migration. b, c n = 32 cells from three experiments. Lines: mean; error bands: s.d. d, e Platelet decision-making upon encountering substrate gradients. d (left) Exemplary line profile of fibrinogen gradients encountered by cells and (right) representative micrographs of the substrate (green: fibrinogen-AF488) and platelet tracks (white), 30 min after cell seeding. Scale bar = 5 µm. e Tracks of cells (n = 256 cells) in contact with interface, and (right) platelet positioning before (0 min) and after migration of cells getting in contact with the interface (45 min), n = 4 experiments, paired t test. Scale bar = 10 µm. f Arp2/3 and F-actin distribution in migrating and retracting cells, and FMI profiles along short axes in n = 50 (migrating) and n = 53 (retracting) cells pooled from three experiments. Scale bar = 5 µm. g Effect of Arp2/3 inhibition with CK666 compared to control CK689 on the number of filopodia per cell (Mann–Whitney), solidity (t test), lamellipodia formation, and F-actin distribution (compare Fig. 1d). n = 41 cells from three experiments. Scale bar = 5 µm. h, i Decision-making upon encountering substrate gradients, control (CK689) and Arp2/3 inhibited (CK666) platelets (h) representative micrograph. Scale bar = 5 µm and i direction of lamellipodia and filopodia in relation to the fibrinogen gradient, n = 168 filopodia and n = 51 lamellipodia, χ2 test. Error bars = s.e.m. Scale bars = 5 µm. All statistical tests are two-sided. Source data are provided as a Source Data file.
