Fig. 7. Inflammation-induced binding and turnover of exogenous TSP1. (A) HASMC were cultured for 15 h in either control (left panels) or 5 µg ml^–1 poly I:C containing medium (right panels). TSP1 (10 µg ml^–1) was added at the indicated time points before completion of the 15 hour incubation period. Immunofluorescent staining of nonpermeabilized cells shows that TSP1 binding to the extracellular matrix is induced by poly I:C in a time dependent manner. However, prolonged incubation with soluble TSP1 in the presence of poly I:C shows reorganization of matrix-associated TSP1 into punctate structures. (B) Confocal microscopy of HASMC, followed by stimulation with 5 µg ml^–1 poly I:C in the presence of TSP1 (10 µg ml^–1) at 4 hours. Permeabilized or non-permeabilized cells were fixed and stained for TSP1 (green), nuclei (blue) and F-actin (red). Representative confocal images showing that TSP1 containing punctate structures have both an intracellular (bottom, left) and an extracellular distribution (upper right panel). Bars, 50 µm (A); 10 µm (B).