Fig. 1.

Cytotoxic effect of PTX on cultured U87MG cells. U87MG cells treated with PTX undergo aberrant mitoses with monopolar or multipolar spindles, as assessed by immunostaining of mitotic spindles and centrosomes by anti-α-tubulin and anti-γ-tubulin antibodies, respectively (a). The percentage of abnormal spindles is dose dependent. Changes in the percentage of monopolar and multipolar spindle mitoses are significant at 50 and 100 nM PTX (*p <0.05 and **p <0.0005) (b) (left panel). n >1000 cells were counted from each of three independent experiments. Exposure of U87MG cells to the CM of PTX-loaded MSCs induces a strong cytotoxic effect, quantitatively similar to 100 nM PTX, with significant increase of multipolar spindle mitoses (***p <0.0001) (b) (right panel). As a consequence of multispindle mitoses, the percentage of multinucleated U87MG cells (c) (lower panel) versus mononucleated U87MG cells (c) (upper panel) significantly increases (***p <0.0001) both after direct PTX treatment (d) (left panel) and after exposure to CM from PTX-loaded MSCs (d) (right panel). n >2000 cells were counted from each of three independent experiments. Scale bars = 10 μm. CM conditioned medium, CTRL control, DAPI 4′,6-diamidino-2-phenylindole, MSC mesenchymal stem/stromal cell, PTX paclitaxel