Talc remains the most effective
sclerosing agent for
pleurodesis. However, its mechanism of action in resolving pleural malignant disease remains unclear. The present study evaluated the angiogenic balance in the pleural space in patients with
malignant pleural effusions (MPE) following
talc insufflation. Patient pleural fluid samples were collected both before and after
talc insufflation. The ability of pleural mesothelial cells (PMC) and
malignant mesothelioma cells (MMC) to produce
endostatin in vitro was compared. The
biological effects of pleural fluids and
conditioned media from
talc-activated PMC on endothelial cells were evaluated by performing proliferation, invasion, tube formation and apoptosis assays. Pleural fluids from patients with MPE who received thoracoscopic
talc insufflation contained significantly higher levels of
endostatin (median 16.75 ng.mL(-1)) compared with pre-
talc instillation (1.06 ng.mL(-1)).
Talc-activated PMC released significantly greater amounts of
endostatin (mean+/-SEM 1052.39+/-38.66 pg.mL(-1)) when compared with a MMC line (134.73+/-8.72 pg.mL(-1)). In conclusion,
talc alters the angiogenic balance in the pleural space from a biologically active and angiogenic environment to an angiostatic milieu. Functional improvement following
talc poudrage in patients with
malignant pleural effusions may, in part, reflect these alterations in the pleural space.