Fig. 3: Apoptotic cells promote platelet aggregation on tumor cells, and the effect of apoptotic cells on metastasis depends on coagulation.

Lungs were harvested at 15 min or indicated timepoints after I.V. injection and processed for fluorescent imaging (A–H). Met-1 tumor cells expressed ZsGreen (green), apoptotic acCasp9 Met-1 expressed mCherry (red), platelets are stained with αGPIbβ (white, A), cleaved caspase-3 (white, F) scale bar = 200 µm (A–H). Dotted line is the mean of naive lung controls (B, C). Average size of clots that contained either an Apoptotic cell (AC), Tumor cell (TC), or an AC and TC was quantified (D), and lines connect values from individual lung sections (D, G, H). Striped portion of the bar is the % of tumor cells in a clot that also contains an apoptotic cell (E). Low-molecular-weight heparin (LMWH) was administered s.c. at −4, 0, and 24 h in relation to I.V. tumor cell injection and metastasis quantified after 14 days (I–K). Error bars represent SEM, dots are multiple slices of lung from n = 3–4 biological replicates (B–H), or dots are biological replicates (I–K). Analysis with unpaired T-tests (B, C, E), paired T-test (G, H), or by ordinary one-way ANOVA with Tukey’s multiple comparisons test (D, I–K).